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{{short description|The natural process by which life arises from non-living matter}}

{{short description|The natural process by which life arises from non-living matter}}

{{Use American English|date=December 2019}}

{{Use American English|date=December 2019}}

[[File:Champagne vent white smokers.jpg|thumb|upright=1.5|The [[earliest known life forms|earliest known life-forms]] on [[Earth]] are putative fossilized [[microorganism]]s, found in [[Hydrothermal vent|hydrothermal vent precipitates]], that may have lived as early as 4.28 Gya (billion years ago), relatively soon after the [[ocean]]s [[Origin of water on Earth#Water in the development of Earth|formed 4.41 Gya]], and not long after the [[Age of the Earth|formation of the Earth]] 4.54 Gya.

[[File:Champagne vent white smokers.jpg|thumb|upright=1.5|The [[earliest known life forms|earliest known life-forms]] on [[Earth]] are putative fossilized [[microorganism]]s, found in [[Hydrothermal vent|hydrothermal vent precipitates]], that may have lived as early as 4.28 Gya (billion years ago), relatively soon after the [[ocean]]s [[Origin of water on Earth#Water in the development of Earth|formed 4.41 Gya]], and not long after the [[Age of the Earth|formation of the Earth]] 4.54 Gya.<ref name="NAT-20170301" /><ref name="NYT-20170301" />]]

The earliest known life-forms on Earth are putative fossilized microorganisms, found in hydrothermal vent precipitates, that may have lived as early as 4.28 Gya (billion years ago), relatively soon after the oceans formed 4.41 Gya, and not long after the formation of the Earth 4.54 Gya.

The earliest known life-forms on Earth are putative fossilized microorganisms, found in hydrothermal vent precipitates, that may have lived as early as 4.28 Gya (billion years ago), relatively soon after the oceans formed 4.41 Gya, and not long after the formation of the Earth 4.54 Gya.

地球上已知最早的生命形式是在热液喷口沉淀物中发现并推断存在的化石微生物，它们可能早在42.8亿年前就已活着，相对而言，是在44.1亿年前海洋形成的不久之后，以及是45.4亿年前地球形成的不长时间后<ref name="NAT-20170301" /><ref name="NYT-20170301" />]]。

地球上已知最早的生命形式是在热液喷口沉淀物中发现的假定化石微生物，它们可能早在42.8亿年前就已活着，相对而言，是在44.1亿年前海洋形成的不久之后，以及是45.4亿年前地球形成的不长时间后。

In [[evolutionary biology]], '''abiogenesis''', or informally the '''origin of life''' (OoL), is the [[natural]] process by which [[life]] has arisen from non-living matter, such as simple [[organic compound]]s. While the details of this process are still unknown, the prevailing scientific hypothesis is that the transition from non-living to living entities was not a single event, but an evolutionary process of increasing complexity that involved molecular [[self-replication]], [[self-assembly]], [[autocatalysis]], and the emergence of [[cell membrane]]s. Although the occurrence of abiogenesis is uncontroversial among scientists, its possible mechanisms are poorly understood. There are several principles and hypotheses for {{em|how}} abiogenesis could have occurred.

In [[evolutionary biology]], '''abiogenesis''', or informally the '''origin of life''' (OoL),<ref>{{cite book| last1 = Oparin| first1 = Aleksandr Ivanovich| author-link1 = Alexander Oparin| translator1-last = Morgulis| translator1-first = Sergius| year = 1938| title = The Origin of Life| url = https://books.google.com/books?id=Jv8psJCtI0gC| series = Phoenix Edition Series| edition = 2| location = Mineola, New York| publisher = Courier Corporation| publication-date = 2003| isbn = 978-0486495224| access-date = 2018-06-16}}</ref><ref name=Pereto /><ref name="AST-20151218">Compare: {{cite journal |author= Scharf, Caleb |title= A Strategy for Origins of Life Research |date= 18 December 2015 |journal= [[Astrobiology (journal)|Astrobiology]] |volume= 15 |issue= 12 |pages= 1031–1042 |doi= 10.1089/ast.2015.1113 |display-authors= etal |pmid= 26684503 |pmc= 4683543|bibcode= 2015AsBio..15.1031S | quote = What do we mean by the origins of life (OoL)? [...] Since the early 20th century the phrase OoL has been used to refer to the events that occurred during the transition from non-living to living systems on Earth, i.e., the origin of terrestrial biology (Oparin, 1924; Haldane, 1929). The term has largely replaced earlier concepts such as abiogenesis (Kamminga, 1980; Fry, 2000).}}</ref>{{efn|Also occasionally called biopoiesis (Bernal, 1960, p. 30)}} is the [[natural]] process by which [[life]] has arisen from non-living matter, such as simple [[organic compound]]s.<ref name=Oparin>{{harvnb|Oparin|1953|p=vi}}</ref><ref name=Pereto>{{cite journal|last= Peretó |first= Juli |year= 2005 |title= Controversies on the origin of life |url= http://www.im.microbios.org/0801/0801023.pdf |journal= [[International Microbiology]] |volume= 8 |issue= 1 |pages= 23–31 |pmid= 15906258 |accessdate= 2015-06-01 |url-status= dead |archiveurl= https://web.archive.org/web/20150824074726/http://www.im.microbios.org/0801/0801023.pdf |archivedate= 24 August 2015 |quote = Ever since the historical contributions by Aleksandr I. Oparin, in the 1920s, the intellectual challenge of the origin of life enigma has unfolded based on the assumption that life originated on Earth through physicochemical processes that can be supposed, comprehended, and simulated; that is, there were neither miracles nor spontaneous generations.}}</ref><ref>{{cite journal |last1= Warmflash |first1= David |last2= Warmflash |first2= Benjamin |date= November 2005 |title= Did Life Come from Another World? |journal= [[Scientific American]] |volume= 293 |issue= 5 |pages= 64–71 |doi= 10.1038/scientificamerican1105-64|pmid= 16318028 |bibcode= 2005SciAm.293e..64W | quote = According to the conventional hypothesis, the earliest living cells emerged as a result of chemical evolution on our planet billions of years ago in a process called abiogenesis.}}</ref><ref>{{harvnb|Yarus|2010|p=47}}</ref> While the details of this process are still unknown, the prevailing scientific hypothesis is that the transition from non-living to living entities was not a single event, but an evolutionary process of increasing complexity that involved molecular [[self-replication]], [[self-assembly]], [[autocatalysis]], and the emergence of [[cell membrane]]s.<ref>{{cite journal|url=http://www.biocommunication.at/pdf/publications/biosystems_2016.pdf |title=Crucial steps to life: From chemical reactions to code using agents|journal=Biosystems|volume=140|pages=49–57|doi=10.1016/j.biosystems.2015.12.007|pmid=26723230|year=2016|last1=Witzany|first1=Guenther}}</ref><ref name="AB-20141208">{{cite web |last= Howell |first= Elizabeth |title= How Did Life Become Complex, And Could It Happen Beyond Earth? |url= https://www.astrobio.net/origin-and-evolution-of-life/life-become-complex-happen-beyond-earth/ |date= 8 December 2014 |work= [[Astrobiology Magazine]] |accessdate= 14 February 2018 }}</ref><ref name="EA-20150420">{{Cite book |last= Tirard |first= Stephane |title= Abiogenesis – Definition|date= 20 April 2015 |doi= 10.1007/978-3-642-27833-4_2-4 |journal= Encyclopedia of Astrobiology|pages= 1 | quote = Thomas Huxley (1825–1895) used the term abiogenesis in an important text published in 1870. He strictly made the difference between spontaneous generation, which he did not accept, and the possibility of the evolution of matter from inert to living, without any influence of life. [...] Since the end of the nineteenth century, evolutive abiogenesis means increasing complexity and evolution of matter from inert to living state in the abiotic context of evolution of primitive Earth. |isbn= 978-3-642-27833-4 }}</ref> Although the occurrence of abiogenesis is uncontroversial among scientists, its possible mechanisms are poorly understood. There are several principles and hypotheses for {{em|how}} abiogenesis could have occurred.<ref>{{Cite book |title=Rethinking evolution: the revolution that's hiding in plain sight  |last=Levinson |first=Gene |publisher=World Scientific |year=2020 |isbn=978-1786347268 |url=https://rethinkingevolution.com/}}</ref>

In evolutionary biology, abiogenesis, or informally the origin of life (OoL), is the natural process by which life has arisen from non-living matter, such as simple organic compounds. While the details of this process are still unknown, the prevailing scientific hypothesis is that the transition from non-living to living entities was not a single event, but an evolutionary process of increasing complexity that involved molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes. Although the occurrence of abiogenesis is uncontroversial among scientists, its possible mechanisms are poorly understood. There are several principles and hypotheses for abiogenesis could have occurred.

In evolutionary biology, abiogenesis, or informally the origin of life (OoL), is the natural process by which life has arisen from non-living matter, such as simple organic compounds. While the details of this process are still unknown, the prevailing scientific hypothesis is that the transition from non-living to living entities was not a single event, but an evolutionary process of increasing complexity that involved molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes. Although the occurrence of abiogenesis is uncontroversial among scientists, its possible mechanisms are poorly understood. There are several principles and hypotheses for abiogenesis could have occurred.

<!--Please do not change the lead sentence without first discussing on the talk page.-->

<!--Please do not change the lead sentence without first discussing on the talk page.-->

The study of abiogenesis aims to determine how pre-life [[chemical reaction]]s gave rise to life under conditions strikingly different from those on Earth today.<ref>{{harvnb|Voet|Voet|2004|p=29}}</ref> It primarily uses tools from [[biology]], [[chemistry]], and [[geophysics]], more specifically, [[astrobiology]], [[biochemistry]], [[biophysics]], [[geochemistry]], [[molecular biology]], [[oceanography]] and [[paleontology]]. Life functions through the specialized chemistry of [[carbon]] and [[water]] and builds largely upon four key families of chemicals: [[lipids]] (cell membranes), [[carbohydrates]] (sugars, cellulose), [[amino acid]]s (protein metabolism), and [[nucleic acids]] (DNA and RNA). Any successful theory of abiogenesis must explain the origins and interactions of these classes of molecules.  Many approaches to abiogenesis investigate how [[Self-replication|self-replicating]] [[molecule]]s, or their components, came into existence. Researchers generally think that current life descends from an [[RNA world]],<ref name="RNA" /> although other self-replicating molecules may have preceded RNA.

The study of abiogenesis aims to determine how pre-life [[chemical reaction]]s gave rise to life under conditions strikingly different from those on Earth today.<ref>{{harvnb|Voet|Voet|2004|p=29}}</ref> It primarily uses tools from [[biology]], [[chemistry]], and [[geophysics]],<ref name="Dyson 1999">{{harvnb|Dyson|1999}}</ref> with more recent approaches attempting a synthesis of all three:<ref>{{cite book |author= Davies, Paul |date= 1998 |title= The Fifth Miracle, Search for the origin and meaning of life |publisher= Penguin}}{{page needed|date=February 2017}}</ref> more specifically, [[astrobiology]], [[biochemistry]], [[biophysics]], [[geochemistry]], [[molecular biology]], [[oceanography]] and [[paleontology]]. Life functions through the specialized chemistry of [[carbon]] and [[water]] and builds largely upon four key families of chemicals: [[lipids]] (cell membranes), [[carbohydrates]] (sugars, cellulose), [[amino acid]]s (protein metabolism), and [[nucleic acids]] (DNA and RNA). Any successful theory of abiogenesis must explain the origins and interactions of these classes of molecules.<ref>{{cite book |author1= Ward, Peter|author2= Kirschvink, Joe |date= 2015 |title= A New History of Life: the radical discoveries about the origins and evolution of life on earth |publisher= Bloomsbury Press |pages= 39–40 |isbn= 978-1608199105}}</ref> Many approaches to abiogenesis investigate how [[Self-replication|self-replicating]] [[molecule]]s, or their components, came into existence. Researchers generally think that current life descends from an [[RNA world]],<ref name="RNA" /> although other self-replicating molecules may have preceded RNA.<ref name="Robertson2012" /><ref name="Cech2012" />

The study of abiogenesis aims to determine how pre-life chemical reactions gave rise to life under conditions strikingly different from those on Earth today. It primarily uses tools from biology, chemistry, and geophysics, with more recent approaches attempting a synthesis of all three: more specifically, astrobiology, biochemistry, biophysics, geochemistry, molecular biology, oceanography and paleontology. Life functions through the specialized chemistry of carbon and water and builds largely upon four key families of chemicals: lipids (cell membranes), carbohydrates (sugars, cellulose), amino acids (protein metabolism), and nucleic acids (DNA and RNA). Any successful theory of abiogenesis must explain the origins and interactions of these classes of molecules.  Many approaches to abiogenesis investigate how self-replicating molecules, or their components, came into existence. Researchers generally think that current life descends from an RNA world, although other self-replicating molecules may have preceded RNA.

The study of abiogenesis aims to determine how pre-life chemical reactions gave rise to life under conditions strikingly different from those on Earth today. It primarily uses tools from biology, chemistry, and geophysics, with more recent approaches attempting a synthesis of all three: more specifically, astrobiology, biochemistry, biophysics, geochemistry, molecular biology, oceanography and paleontology. Life functions through the specialized chemistry of carbon and water and builds largely upon four key families of chemicals: lipids (cell membranes), carbohydrates (sugars, cellulose), amino acids (protein metabolism), and nucleic acids (DNA and RNA). Any successful theory of abiogenesis must explain the origins and interactions of these classes of molecules.  Many approaches to abiogenesis investigate how self-replicating molecules, or their components, came into existence. Researchers generally think that current life descends from an RNA world, although other self-replicating molecules may have preceded RNA.

[[File:Miller-Urey experiment JP.png|thumb|'''Miller–Urey experiment'''  Synthesis of small organic molecules in a mixture of simple gases that is placed in a thermal gradient by heating (left) and cooling (right) the mixture at the same time, a mixture that is also subject to electrical discharges]]

[[File:Miller-Urey experiment JP.png|thumb|'''Miller–Urey experiment'''  Synthesis of small organic molecules in a mixture of simple gases that is placed in a thermal gradient by heating (left) and cooling (right) the mixture at the same time, a mixture that is also subject to electrical discharges]]

Miller–Urey experiment Synthesis of small organic molecules in a mixture of simple gases that is placed in a thermal gradient by heating (left) and cooling (right) the mixture at the same time, a mixture that is also subject to electrical discharges

Miller–Urey experiment Synthesis of small organic molecules in a mixture of simple gases that is placed in a thermal gradient by heating (left) and cooling (right) the mixture at the same time, a mixture that is also subject to electrical discharges

米勒-尤里Miller–Urey实验 将简单气体混合物置于有热梯度的环境中，同时加热（左）和冷却（右），并施加电的作用，这种条件下能够合成小有机分子。

米勒-乌雷Miller–Urey实验 在简单气体混合物中合成有机小分子，通过同时加热（左）和冷却（右）将混合物置于热梯度中，这种混合物也会受到放电的作用

The classic 1952 [[Miller–Urey experiment]] and similar research demonstrated that most amino acids, the chemical constituents of the [[protein]]s used in all living organisms, can be synthesized from [[inorganic compound]]s under conditions intended to replicate those of the [[History of Earth|early Earth]]. Scientists have proposed various external sources of energy that may have triggered these reactions, including [[lightning]] and [[radiation]]. Other approaches ("metabolism-first" hypotheses) focus on understanding how [[catalysis]] in chemical systems on the early Earth might have provided the [[Precursor (chemistry)|precursor molecules]] necessary for self-replication.

The classic 1952 [[Miller–Urey experiment]] and similar research demonstrated that most amino acids, the chemical constituents of the [[protein]]s used in all living organisms, can be synthesized from [[inorganic compound]]s under conditions intended to replicate those of the [[History of Earth|early Earth]]. Scientists have proposed various external sources of energy that may have triggered these reactions, including [[lightning]] and [[radiation]]. Other approaches ("metabolism-first" hypotheses) focus on understanding how [[catalysis]] in chemical systems on the early Earth might have provided the [[Precursor (chemistry)|precursor molecules]] necessary for self-replication.<ref name="Ralser 2014">{{cite journal |last1= Keller |first1= Markus A. |last2= Turchyn |first2= Alexandra V. |last3= Ralser |first3= Markus |date= 25 March 2014 |title= Non‐enzymatic glycolysis and pentose phosphate pathway‐like reactions in a plausible Archean ocean |journal= [[Molecular Systems Biology]] |volume= 10 |issue= 725 |page= 725 |doi= 10.1002/msb.20145228 |pmc= 4023395 |pmid= 24771084}}</ref>

The classic 1952 Miller–Urey experiment and similar research demonstrated that most amino acids, the chemical constituents of the proteins used in all living organisms, can be synthesized from inorganic compounds under conditions intended to replicate those of the early Earth. Scientists have proposed various external sources of energy that may have triggered these reactions, including lightning and radiation. Other approaches ("metabolism-first" hypotheses) focus on understanding how catalysis in chemical systems on the early Earth might have provided the precursor molecules necessary for self-replication.

The classic 1952 Miller–Urey experiment and similar research demonstrated that most amino acids, the chemical constituents of the proteins used in all living organisms, can be synthesized from inorganic compounds under conditions intended to replicate those of the early Earth. Scientists have proposed various external sources of energy that may have triggered these reactions, including lightning and radiation. Other approaches ("metabolism-first" hypotheses) focus on understanding how catalysis in chemical systems on the early Earth might have provided the precursor molecules necessary for self-replication.

1952年经典的Miller-Urey实验和类似的研究表明，大多数氨基酸（即所有生物体中使用的蛋白质的化学成分）可以在复制早期地球环境的条件下从无机化合物中合成。科学家们提出了各种可能引发这些反应的外部能量来源，包括闪电和辐射。其他方法("新陈代谢优先 "假说)则侧重于了解早期地球化学系统中的催化作用如何提供自我复制所需的前体分子。<ref name="Ralser 2014">{{cite journal |last1= Keller |first1= Markus A. |last2= Turchyn |first2= Alexandra V. |last3= Ralser |first3= Markus |date= 25 March 2014 |title= Non‐enzymatic glycolysis and pentose phosphate pathway‐like reactions in a plausible Archean ocean |journal= [[Molecular Systems Biology]] |volume= 10 |issue= 725 |page= 725 |doi= 10.1002/msb.20145228 |pmc= 4023395 |pmid= 24771084}}</ref>

1952年经典的Miller-Urey实验和类似的研究表明，大多数氨基酸，即所有生物体中使用的蛋白质的化学成分，可以在旨在复制早期地球的条件下从无机化合物中合成。科学家们提出了各种可能引发这些反应的外部能量来源，包括闪电和辐射。其他方法（“新陈代谢优先”假说）则侧重于了解早期地球化学系统中的催化作用如何提供自复制所需的前体分子。

The alternative [[panspermia hypothesis]] speculates that [[Microorganism|microscopic life]] arose outside Earth by unknown mechanisms, and spread to the early Earth on [[space dust]] and [[meteoroid]]s. It is known that complex [[List of interstellar and circumstellar molecules|organic molecules]] occur in the [[Solar System]] and in [[interstellar space]], and these molecules may have provided [[Precursor (chemistry)|starting material]] for the development of life on Earth.

The alternative [[panspermia hypothesis]]<ref name="USRA-2010">{{cite conference|last=Rampelotto|first=Pabulo Henrique|date=26 April 2010|title=Panspermia: A Promising Field of Research|url=http://www.lpi.usra.edu/meetings/abscicon2010/pdf/5224.pdf|url-status=live|conference=Astrobiology Science Conference 2010|location=Houston, TX|publisher=[[Lunar and Planetary Institute]]|page=5224|bibcode=2010LPICo1538.5224R|archiveurl=https://web.archive.org/web/20160327005016/http://www.lpi.usra.edu//meetings/abscicon2010/pdf/5224.pdf|archivedate=27 March 2016|accessdate=2014-12-03|conference-url=http://www.lpi.usra.edu/meetings/abscicon2010/}} Conference held at League City, TX</ref> speculates that [[Microorganism|microscopic life]] arose outside Earth by unknown mechanisms, and spread to the early Earth on [[space dust]]<ref name="ARX-20171106">{{cite journal |last= Berera |first= Arjun |title= Space dust collisions as a planetary escape mechanism |journal= Astrobiology |date= 6 November 2017 |arxiv= 1711.01895 |bibcode= 2017AsBio..17.1274B |doi= 10.1089/ast.2017.1662 |pmid= 29148823 |volume= 17 |issue= 12 |pages= 1274–1282|s2cid= 126012488 }}</ref> and [[meteoroid]]s.<ref name="SA-20180110">{{cite journal|last1=Chan|first1=Queenie H.S.|date=10 January 2018|title=Organic matter in extraterrestrial water-bearing salt crystals|journal=[[Science Advances]]|volume=4|page=eaao3521|bibcode=2018SciA....4O3521C|doi=10.1126/sciadv.aao3521|pmc=5770164|pmid=29349297|number=1, eaao3521}}</ref> It is known that complex [[List of interstellar and circumstellar molecules|organic molecules]] occur in the [[Solar System]] and in [[interstellar space]], and these molecules may have provided [[Precursor (chemistry)|starting material]] for the development of life on Earth.<ref name="Ehrenfreund2010" /><ref name="Science 2015">{{cite news|url=http://news.sciencemag.org/chemistry/2015/04/organic-molecules-found-circling-nearby-star?rss=1|title=Organic molecules found circling nearby star|last=Perkins|first=Sid|date=8 April 2015|work=[[Science (journal)|Science]]|accessdate=2015-06-02|publisher=[[American Association for the Advancement of Science]]|location=Washington, DC|type=News}}</ref><ref>{{cite news|url=http://www.rsc.org/chemistryworld/2015/04/meteorites-may-have-delivered-chemicals-started-life-earth|title=Chemicals formed on meteorites may have started life on Earth|last=King|first=Anthony|date=14 April 2015|work=[[Chemistry World]]|accessdate=2015-04-17|archiveurl=https://web.archive.org/web/20150417142723/http://www.rsc.org/chemistryworld/2015/04/meteorites-may-have-delivered-chemicals-started-life-earth|archivedate=17 April 2015|url-status=live|publisher=[[Royal Society of Chemistry]]|location=London|type=News}}</ref><ref>{{cite journal|last1=Saladino|first1=Raffaele|last2=Carota|first2=Eleonora|last3=Botta|first3=Giorgia|last4=Kapralov|first4=Mikhail|last5=Timoshenko|first5=Gennady N.|last6=Rozanov|first6=Alexei Y.|last7=Krasavin|first7=Eugene|last8=Di Mauro|first8=Ernesto|display-authors=3|date=13 April 2015|title=Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation|journal=[[Proceedings of the National Academy of Sciences of the United States of America|Proc. Natl. Acad. Sci. U.S.A.]]|volume=112|issue=21|pages=E2746–E2755|bibcode=2015PNAS..112E2746S|doi=10.1073/pnas.1422225112|pmc=4450408|pmid=25870268}}</ref>

The alternative panspermia hypothesis speculates that microscopic life arose outside Earth by unknown mechanisms, and spread to the early Earth on space dust and meteoroids. It is known that complex organic molecules occur in the Solar System and in interstellar space, and these molecules may have provided starting material for the development of life on Earth.

The alternative panspermia hypothesis speculates that microscopic life arose outside Earth by unknown mechanisms, and spread to the early Earth on space dust and meteoroids. It is known that complex organic molecules occur in the Solar System and in interstellar space, and these molecules may have provided starting material for the development of life on Earth.

Earth remains the only place in the [[universe]] known to harbour life, and [[Earliest known life forms|fossil evidence from the Earth]] informs most studies of abiogenesis. The [[age of the Earth]] is 4.54 Gy (Giga or billion year); the earliest undisputed evidence of life on Earth dates from at least 3.5 Gya (Gy ago), and possibly as early as the [[Eoarchean]] Era (3.6-4.0 Gya). In 2017 scientists found possible evidence of early life [[Evolutionary history of life#Colonization of land|on land]] in 3.48 Gyo (Gy old) [[geyserite]] and other related mineral deposits (often found around [[hot spring]]s and [[geyser]]s) uncovered in the [[Pilbara Craton]] of [[Western Australia]]. However, a number of discoveries suggest that life may have appeared on Earth even earlier. {{As of | 2017}}, [[Micropaleontology#Microfossils|microfossils]] (fossilised [[microorganism]]s) within [[Hydrothermal vent|hydrothermal-vent precipitates]] dated 3.77 to 4.28 Gya in rocks in [[Quebec]] may harbour the oldest record of life on Earth, suggesting life started soon after [[Origin of water on Earth#Water in the development of Earth|ocean formation 4.4 Gya]] during the [[Hadean]] [[Geologic time scale|Eon]].

Earth remains the only place in the [[universe]] known to harbour life,<ref name="NASA-1990">{{cite web |url= https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900013148.pdf |title= Extraterrestrial Life in the Universe |last= Graham |first= Robert W. |date= February 1990 |place= [[Glenn Research Center|Lewis Research Center]], Cleveland, Ohio |publisher= [[NASA]] |type= NASA Technical Memorandum 102363 |accessdate= 2015-06-02 |url-status= live |archiveurl= https://web.archive.org/web/20140903100534/http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900013148.pdf |archivedate= 3 September 2014}}</ref><ref>{{harvnb|Altermann|2009|p=xvii}}</ref> and [[Earliest known life forms|fossil evidence from the Earth]] informs most studies of abiogenesis. The [[age of the Earth]] is 4.54 Gy (Giga or billion year);<ref name="USGS1997">{{cite web |url= http://pubs.usgs.gov/gip/geotime/age.html |title= Age of the Earth |date= 9 July 2007 |publisher= [[United States Geological Survey]] |accessdate= 2006-01-10 |url-status= live |archiveurl= https://web.archive.org/web/20051223072700/http://pubs.usgs.gov/gip/geotime/age.html |archivedate= 23 December 2005}}</ref><ref>{{harvnb|Dalrymple|2001|pp= 205–221}}</ref><ref>{{cite journal |last1= Manhesa |first1= Gérard |last2= Allègre |first2= Claude J. |authorlink2= Claude Allègre |last3= Dupréa |first3= Bernard |last4= Hamelin |first4= Bruno |date= May 1980 |title= Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics |journal= [[Earth and Planetary Science Letters]] |volume= 47 |issue= 3 |pages= 370–382 |bibcode= 1980E&PSL..47..370M |doi= 10.1016/0012-821X(80)90024-2 }}</ref> the earliest undisputed evidence of life on Earth dates from at least 3.5 Gya (Gy ago),<ref name="Origin1">{{cite journal |last1= Schopf |first1= J. William |authorlink1= J. William Schopf |last2= Kudryavtsev |first2= Anatoliy B. |last3= Czaja |first3= Andrew D. |last4= Tripathi |first4= Abhishek B. |date= 5 October 2007 |title= Evidence of Archean life: Stromatolites and microfossils |journal= [[Precambrian Research]] |volume= 158 |pages= 141–155 |issue= 3–4 |doi= 10.1016/j.precamres.2007.04.009 |bibcode= 2007PreR..158..141S }}</ref><ref name="Origin2">{{cite journal |last= Schopf |first= J. William |date= 29 June 2006 |title= Fossil evidence of Archaean life |journal= [[Philosophical Transactions of the Royal Society B]] |volume= 361 |issue= 1470 |pages= 869–885 |doi= 10.1098/rstb.2006.1834 |pmid= 16754604 |pmc=1578735}}</ref><ref name="RavenJohnson2002">{{harvnb|Raven|Johnson|2002|p=68}}</ref> and possibly as early as the [[Eoarchean]] Era (3.6-4.0 Gya). In 2017 scientists found possible evidence of early life [[Evolutionary history of life#Colonization of land|on land]] in 3.48 Gyo (Gy old) [[geyserite]] and other related mineral deposits (often found around [[hot spring]]s and [[geyser]]s) uncovered in the [[Pilbara Craton]] of [[Western Australia]].<ref name="PO-20170509">{{cite news |author= Staff |title= Oldest evidence of life on land found in 3.48-billion-year-old Australian rocks |url= https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html |date= 9 May 2017 |work= [[Phys.org]] |accessdate= 13 May 2017 |url-status= live |archiveurl= https://web.archive.org/web/20170510013721/https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html |archivedate= 10 May 2017}}</ref><ref name="NC-20170509">{{cite journal |last1= Djokic |first1= Tara |last2= Van Kranendonk |first2= Martin J. |last3= Campbell |first3= Kathleen A. |last4= Walter |first4= Malcolm R. |last5= Ward |first5= Colin R. |title= Earliest signs of life on land preserved in ca. 3.5 Gao hot spring deposits |date= 9 May 2017 |journal= [[Nature Communications]] |doi= 10.1038/ncomms15263 |pmid= 28486437 |pmc= 5436104 |volume= 8 |page= 15263 |bibcode= 2017NatCo...815263D}}</ref><ref name="PNAS-2017">{{cite journal |last1= Schopf |first1= J. William |last2= Kitajima |first2= Kouki |last3= Spicuzza |first3= Michael J. |last4= Kudryavtsev |first4= Anatolly B. |last5= Valley |first5= John W. |title= SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions |date= 2017 |journal= [[Proceedings of the National Academy of Sciences of the United States of America|PNAS]] |doi= 10.1073/pnas.1718063115 |pmid= 29255053 |pmc= 5776830 |volume= 115 |issue= 1 |pages= 53–58|bibcode= 2018PNAS..115...53S }}</ref><ref name="WU-20171218">{{cite web |last= Tyrell |first= Kelly April |title= Oldest fossils ever found show life on Earth began before 3.5 billion years ago |url= https://news.wisc.edu/oldest-fossils-ever-found-show-life-on-earth-began-before-3-5-billion-years-ago/ |date= 18 December 2017 |work= [[University of Wisconsin-Madison]] |accessdate= 18 December 2017 }}</ref> However, a number of discoveries suggest that life may have appeared on Earth even earlier. {{As of | 2017}}, [[Micropaleontology#Microfossils|microfossils]] (fossilised [[microorganism]]s) within [[Hydrothermal vent|hydrothermal-vent precipitates]] dated 3.77 to 4.28 Gya in rocks in [[Quebec]] may harbour the oldest record of life on Earth, suggesting life started soon after [[Origin of water on Earth#Water in the development of Earth|ocean formation 4.4 Gya]] during the [[Hadean]] [[Geologic time scale|Eon]].<ref name="NAT-20170301">{{cite journal |last1= Dodd |first1= Matthew S. |last2= Papineau |first2= Dominic |last3= Grenne |first3= Tor |last4= Slack |first4= John F. |last5= Rittner |first5= Martin |last6= Pirajno |first6= Franco |last7= O'Neil |first7= Jonathan |last8= Little |first8= Crispin T.S. |title= Evidence for early life in Earth's oldest hydrothermal vent precipitates |url= http://eprints.whiterose.ac.uk/112179/ |journal= [[Nature (journal)|Nature]] |date= 1 March 2017 |volume= 543 |issue= 7643 |pages= 60–64 |doi= 10.1038/nature21377 |pmid= 28252057 |accessdate= 2 March 2017 |bibcode= 2017Natur.543...60D |url-status= live |archiveurl= https://web.archive.org/web/20170908201821/http://eprints.whiterose.ac.uk/112179/ |archivedate= 8 September 2017|doi-access= free }}</ref><ref name="NYT-20170301">{{cite news |last= Zimmer |first= Carl |authorlink= Carl Zimmer |title= Scientists Say Canadian Bacteria Fossils May Be Earth's Oldest |url= https://www.nytimes.com/2017/03/01/science/earths-oldest-bacteria-fossils.html |date= 1 March 2017 |work= [[The New York Times]] |accessdate= 2 March 2017 |url-status= live |archiveurl= https://web.archive.org/web/20170302042424/https://www.nytimes.com/2017/03/01/science/earths-oldest-bacteria-fossils.html |archivedate= 2 March 2017}}</ref><ref name="BBC-20170301">{{Cite news |last= Ghosh |first= Pallab |title= Earliest evidence of life on Earth found |url= https://www.bbc.co.uk/news/science-environment-39117523 |publisher= [[BBC News]] |date= 1 March 2017 |accessdate= 2 March 2017 |url-status= live |archiveurl= https://web.archive.org/web/20170302002134/http://www.bbc.co.uk/news/science-environment-39117523 |archivedate= 2 March 2017|work= BBC News }}</ref><ref name="4.3b oldest">{{cite news |last1= Dunham |first1= Will |title= Canadian bacteria-like fossils called oldest evidence of life |url= http://ca.reuters.com/article/topNews/idCAKBN16858B?sp=true |date= 1 March 2017 |agency= [[Reuters]] |accessdate= 1 March 2017 |url-status= live |archiveurl= https://web.archive.org/web/20170302114728/http://ca.reuters.com/article/topNews/idCAKBN16858B?sp=true |archivedate= 2 March 2017}}</ref><ref>{{cite news|title=Researchers uncover 'direct evidence' of life on Earth 4 billion years ago|url= http://dw.com/p/2YUnT|accessdate= 5 March 2017|publisher= Deutsche Welle}}</ref>

Earth remains the only place in the universe known to harbour life, and fossil evidence from the Earth informs most studies of abiogenesis. The age of the Earth is 4.54 Gy (Giga or billion year); the earliest undisputed evidence of life on Earth dates from at least 3.5 Gya (Gy ago), and possibly as early as the Eoarchean Era (3.6-4.0 Gya). In 2017 scientists found possible evidence of early life on land in 3.48 Gyo (Gy old) geyserite and other related mineral deposits (often found around hot springs and geysers) uncovered in the Pilbara Craton of Western Australia. However, a number of discoveries suggest that life may have appeared on Earth even earlier. , microfossils (fossilised microorganisms) within hydrothermal-vent precipitates dated 3.77 to 4.28 Gya in rocks in Quebec may harbour the oldest record of life on Earth, suggesting life started soon after ocean formation 4.4 Gya during the Hadean Eon.

Earth remains the only place in the universe known to harbour life, and fossil evidence from the Earth informs most studies of abiogenesis. The age of the Earth is 4.54 Gy (Giga or billion year); the earliest undisputed evidence of life on Earth dates from at least 3.5 Gya (Gy ago), and possibly as early as the Eoarchean Era (3.6-4.0 Gya). In 2017 scientists found possible evidence of early life on land in 3.48 Gyo (Gy old) geyserite and other related mineral deposits (often found around hot springs and geysers) uncovered in the Pilbara Craton of Western Australia. However, a number of discoveries suggest that life may have appeared on Earth even earlier. As of 2017, microfossils (fossilised microorganisms) within hydrothermal-vent precipitates dated 3.77 to 4.28 Gya in rocks in Quebec may harbour the oldest record of life on Earth, suggesting life started soon after ocean formation 4.4 Gya during the Hadean Eon.

地球仍然是宇宙中已知的唯一一个孕育生命的地方<ref name="NASA-1990">{{cite web |url= https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900013148.pdf |title= Extraterrestrial Life in the Universe |last= Graham |first= Robert W. |date= February 1990 |place= [[Glenn Research Center|Lewis Research Center]], Cleveland, Ohio |publisher= [[NASA]] |type= NASA Technical Memorandum 102363 |accessdate= 2015-06-02 |url-status= live |archiveurl= https://web.archive.org/web/20140903100534/http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900013148.pdf |archivedate= 3 September 2014}}</ref><ref>{{harvnb|Altermann|2009|p=xvii}}</ref>，来自地球的化石证据为大多数关于无生源说的研究提供了依据。地球的年龄是45.5亿年 (千兆或十亿年) ; <ref name="USGS1997">{{cite web |url= http://pubs.usgs.gov/gip/geotime/age.html |title= Age of the Earth |date= 9 July 2007 |publisher= [[United States Geological Survey]] |accessdate= 2006-01-10 |url-status= live |archiveurl= https://web.archive.org/web/20051223072700/http://pubs.usgs.gov/gip/geotime/age.html |archivedate= 23 December 2005}}</ref><ref>{{harvnb|Dalrymple|2001|pp= 205–221}}</ref><ref>{{cite journal |last1= Manhesa |first1= Gérard |last2= Allègre |first2= Claude J. |authorlink2= Claude Allègre |last3= Dupréa |first3= Bernard |last4= Hamelin |first4= Bruno |date= May 1980 |title= Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics |journal= [[Earth and Planetary Science Letters]] |volume= 47 |issue= 3 |pages= 370–382 |bibcode= 1980E&PSL..47..370M |doi= 10.1016/0012-821X(80)90024-2 }}</ref>地球上最早的无可争议的生命证据至少可以追溯到35亿年前，<ref name="Origin1">{{cite journal |last1= Schopf |first1= J. William |authorlink1= J. William Schopf |last2= Kudryavtsev |first2= Anatoliy B. |last3= Czaja |first3= Andrew D. |last4= Tripathi |first4= Abhishek B. |date= 5 October 2007 |title= Evidence of Archean life: Stromatolites and microfossils |journal= [[Precambrian Research]] |volume= 158 |pages= 141–155 |issue= 3–4 |doi= 10.1016/j.precamres.2007.04.009 |bibcode= 2007PreR..158..141S }}</ref><ref name="Origin2">{{cite journal |last= Schopf |first= J. William |date= 29 June 2006 |title= Fossil evidence of Archaean life |journal= [[Philosophical Transactions of the Royal Society B]] |volume= 361 |issue= 1470 |pages= 869–885 |doi= 10.1098/rstb.2006.1834 |pmid= 16754604 |pmc=1578735}}</ref><ref name="RavenJohnson2002">{{harvnb|Raven|Johnson|2002|p=68}}</ref>也可能还要追溯到始太古代(36-40亿年前之间)。2017年，科学家在西澳大利亚的皮尔巴拉环形山裸露的34.8亿岁的硅华和其他相关矿藏(通常在温泉和喷泉附近发现) 中发现了陆地上早期生命存在的可能证据。<ref name="PO-20170509">{{cite news |author= Staff |title= Oldest evidence of life on land found in 3.48-billion-year-old Australian rocks |url= https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html |date= 9 May 2017 |work= [[Phys.org]] |accessdate= 13 May 2017 |url-status= live |archiveurl= https://web.archive.org/web/20170510013721/https://phys.org/news/2017-05-oldest-evidence-life-billion-year-old-australian.html |archivedate= 10 May 2017}}</ref><ref name="NC-20170509">{{cite journal |last1= Djokic |first1= Tara |last2= Van Kranendonk |first2= Martin J. |last3= Campbell |first3= Kathleen A. |last4= Walter |first4= Malcolm R. |last5= Ward |first5= Colin R. |title= Earliest signs of life on land preserved in ca. 3.5 Gao hot spring deposits |date= 9 May 2017 |journal= [[Nature Communications]] |doi= 10.1038/ncomms15263 |pmid= 28486437 |pmc= 5436104 |volume= 8 |page= 15263 |bibcode= 2017NatCo...815263D}}</ref><ref name="PNAS-2017">{{cite journal |last1= Schopf |first1= J. William |last2= Kitajima |first2= Kouki |last3= Spicuzza |first3= Michael J. |last4= Kudryavtsev |first4= Anatolly B. |last5= Valley |first5= John W. |title= SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions |date= 2017 |journal= [[Proceedings of the National Academy of Sciences of the United States of America|PNAS]] |doi= 10.1073/pnas.1718063115 |pmid= 29255053 |pmc= 5776830 |volume= 115 |issue= 1 |pages= 53–58|bibcode= 2018PNAS..115...53S }}</ref><ref name="WU-20171218">{{cite web |last= Tyrell |first= Kelly April |title= Oldest fossils ever found show life on Earth began before 3.5 billion years ago |url= https://news.wisc.edu/oldest-fossils-ever-found-show-life-on-earth-began-before-3-5-billion-years-ago/ |date= 18 December 2017 |work= [[University of Wisconsin-Madison]] |accessdate= 18 December 2017 }}</ref>然而，许多发现表明，地球上的生命可能出现得更早。截止2017年，在加拿大魁北克省的岩石中的深海热液喷口沉淀物内的微化石(微生物化石)的年代为37.7亿年前至42.8亿年前，它可能蕴藏着地球上最古老的生命记录，这表明生命在海洋形成后不久的冥古宙就开始了。<ref name="NAT-20170301">{{cite journal |last1= Dodd |first1= Matthew S. |last2= Papineau |first2= Dominic |last3= Grenne |first3= Tor |last4= Slack |first4= John F. |last5= Rittner |first5= Martin |last6= Pirajno |first6= Franco |last7= O'Neil |first7= Jonathan |last8= Little |first8= Crispin T.S. |title= Evidence for early life in Earth's oldest hydrothermal vent precipitates |url= http://eprints.whiterose.ac.uk/112179/ |journal= [[Nature (journal)|Nature]] |date= 1 March 2017 |volume= 543 |issue= 7643 |pages= 60–64 |doi= 10.1038/nature21377 |pmid= 28252057 |accessdate= 2 March 2017 |bibcode= 2017Natur.543...60D |url-status= live |archiveurl= https://web.archive.org/web/20170908201821/http://eprints.whiterose.ac.uk/112179/ |archivedate= 8 September 2017|doi-access= free }}</ref><ref name="NYT-20170301">{{cite news |last= Zimmer |first= Carl |authorlink= Carl Zimmer |title= Scientists Say Canadian Bacteria Fossils May Be Earth's Oldest |url= https://www.nytimes.com/2017/03/01/science/earths-oldest-bacteria-fossils.html |date= 1 March 2017 |work= [[The New York Times]] |accessdate= 2 March 2017 |url-status= live |archiveurl= https://web.archive.org/web/20170302042424/https://www.nytimes.com/2017/03/01/science/earths-oldest-bacteria-fossils.html |archivedate= 2 March 2017}}</ref><ref name="BBC-20170301">{{Cite news |last= Ghosh |first= Pallab |title= Earliest evidence of life on Earth found |url= https://www.bbc.co.uk/news/science-environment-39117523 |publisher= [[BBC News]] |date= 1 March 2017 |accessdate= 2 March 2017 |url-status= live |archiveurl= https://web.archive.org/web/20170302002134/http://www.bbc.co.uk/news/science-environment-39117523 |archivedate= 2 March 2017|work= BBC News }}</ref><ref name="4.3b oldest">{{cite news |last1= Dunham |first1= Will |title= Canadian bacteria-like fossils called oldest evidence of life |url= http://ca.reuters.com/article/topNews/idCAKBN16858B?sp=true |date= 1 March 2017 |agency= [[Reuters]] |accessdate= 1 March 2017 |url-status= live |archiveurl= https://web.archive.org/web/20170302114728/http://ca.reuters.com/article/topNews/idCAKBN16858B?sp=true |archivedate= 2 March 2017}}</ref><ref>{{cite news|title=Researchers uncover 'direct evidence' of life on Earth 4 billion years ago|url= http://dw.com/p/2YUnT|accessdate= 5 March 2017|publisher= Deutsche Welle}}</ref>

地球仍然是宇宙中已知的唯一一个孕育生命的地方，来自地球的化石证据为大多数关于自然发生论的研究提供了信息。地球的年龄是45.5亿年；地球上最早的无可争议的生命证据至少可以追溯到35亿年前，也可能还要追溯到早至始太古代（36-40亿年前之间）。2017年，科学家在西澳大利亚的皮尔巴拉古地台发现的34.8亿岁的硅华和其他相关矿藏(通常在温泉和间歇泉附近发现) 中发现了陆地上早期生命的可能证据。然而，许多发现表明，地球上的生命可能出现得更早。截至2017年，加拿大魁北克省的岩石中37.7亿至42.8亿年前的深海热液喷口沉淀物内的微化石（化石微生物）可能蕴藏着地球上最古老的生命记录，这表明生命在冥古宙44亿年前海洋形成后不久就开始了。

The NASA strategy on abiogenesis states that it is necessary to identify interactions, intermediary structures and functions, energy sources, and environmental factors that contributed to the diversity, selection, and replication of evolvable macromolecular systems. Emphasis must continue to map the chemical landscape of potential primordial informational [[polymers]]. The advent of polymers that could replicate, store genetic information, and exhibit properties subject to selection likely was a critical step in the [[emergence]] of prebiotic chemical evolution.

The NASA strategy on abiogenesis states that it is necessary to identify interactions, intermediary structures and functions, energy sources, and environmental factors that contributed to the diversity, selection, and replication of evolvable macromolecular systems.<ref name="NASA strategy 2015">{{cite web|url=https://nai.nasa.gov/media/medialibrary/2015/10/NASA_Astrobiology_Strategy_2015_151008.pdf|title=NASA Astrobiology Strategy|year=2015|work=NASA|url-status=dead|archiveurl=https://web.archive.org/web/20161222190306/https://nai.nasa.gov/media/medialibrary/2015/10/NASA_Astrobiology_Strategy_2015_151008.pdf|archivedate=22 December 2016|access-date=24 September 2017}}</ref> Emphasis must continue to map the chemical landscape of potential primordial informational [[polymers]]. The advent of polymers that could replicate, store genetic information, and exhibit properties subject to selection likely was a critical step in the [[emergence]] of prebiotic chemical evolution.<ref name="NASA strategy 2015"/>

The NASA strategy on abiogenesis states that it is necessary to identify interactions, intermediary structures and functions, energy sources, and environmental factors that contributed to the diversity, selection, and replication of evolvable macromolecular systems. Emphasis must continue to map the chemical landscape of potential primordial informational polymers. The advent of polymers that could replicate, store genetic information, and exhibit properties subject to selection likely was a critical step in the emergence of prebiotic chemical evolution.

The NASA strategy on abiogenesis states that it is necessary to identify interactions, intermediary structures and functions, energy sources, and environmental factors that contributed to the diversity, selection, and replication of evolvable macromolecular systems. Emphasis must continue to map the chemical landscape of potential primordial informational polymers. The advent of polymers that could replicate, store genetic information, and exhibit properties subject to selection likely was a critical step in the emergence of prebiotic chemical evolution.

热力学原理：能量与熵

热力学原理：能量与熵

In antiquity it was commonly thought, for instance by Empedocles and Aristotle, that the life of the individuals of some species, and more generally, life itself, could start with high temperature, i.e. implicitly by thermal cycling.

In antiquity it was commonly thought, for instance by Empedocles and Aristotle, that the life of the individuals of some species, and more generally, life itself, could start with high temperature, i.e. implicitly by thermal cycling.<ref>{{cite book|title=In the beginning: Some Greek views on the origins of life and the early state of man |year= 1957|last1= Guthrie|first1= W. K. C.|publisher=Methuen, London}}</ref>

In antiquity it was commonly thought, for instance by Empedocles and Aristotle, that the life of the individuals of some species, and more generally, life itself, could start with high temperature, i.e. implicitly by thermal cycling.

In antiquity it was commonly thought, for instance by Empedocles and Aristotle, that the life of the individuals of some species, and more generally, life itself, could start with high temperature, i.e. implicitly by thermal cycling.

Similarly, it was realized early on that life requires a loss of [[entropy]], or disorder, when molecules organize themselves into living matter. This [[Second law of thermodynamics|Second Law of thermodynamics]] needs to be considered when self-organization of matter to higher complexity happens. Because living organisms are machines, the Second Law applies to life as well.

Similarly, it was realized early on that life requires a loss of [[entropy]], or disorder, when molecules organize themselves into living matter. This [[Second law of thermodynamics|Second Law of thermodynamics]] needs to be considered when self-organization of matter to higher complexity happens. Because living organisms are machines,<ref>{{cite book| last1 = Simon| first1 = Michael A. | year = 1971| title = The Matter of Life | edition = 1| location = New Haven and London| publisher = Yale University Press}}</ref> the Second Law applies to life as well.

Similarly, it was realized early on that life requires a loss of entropy, or disorder, when molecules organize themselves into living matter. This Second Law of thermodynamics needs to be considered when self-organization of matter to higher complexity happens. Because living organisms are machines, the Second Law applies to life as well.

Similarly, it was realized early on that life requires a loss of entropy, or disorder, when molecules organize themselves into living matter. This Second Law of thermodynamics needs to be considered when self-organization of matter to higher complexity happens. Because living organisms are machines, the Second Law applies to life as well.

====Obtaining free energy ====

====Obtaining free energy ====

获得自由能

获得自由能

Bernal said on the Miller–Urey experiment that < blockquote >it is not enough to explain the formation of such molecules, what is necessary, is a physical-chemical explanation of the origins of these molecules that suggests the presence of suitable sources and sinks for free energy.

Bernal said on the Miller–Urey experiment that < blockquote >it is not enough to explain the formation of such molecules, what is necessary, is a physical-chemical explanation of the origins of these molecules that suggests the presence of suitable sources and sinks for free energy.<ref>{{harvnb|Bernal|1967|p=143}}</ref>

< /blockquote >

< /blockquote >

Bernal said on the Miller–Urey experiment that < blockquote >it is not enough to explain the formation of such molecules, what is necessary, is a physical-chemical explanation of the origins of these molecules that suggests the presence of suitable sources and sinks for free energy.< /blockquote >

Bernal said on the Miller–Urey experiment that < blockquote >it is not enough to explain the formation of such molecules, what is necessary, is a physical-chemical explanation of the origins of these molecules that suggests the presence of suitable sources and sinks for free energy.< /blockquote >

伯纳尔Bernal对 Miller-Urey 的实验说到，

伯纳尔Bernal在 Miller-Urey 的实验中说，

< blockquote >仅仅解释这些分子的形成是不够的，需要的是对这些分子的起源作出物理化学解释，表明存在合适的自由能源和自由能汇。<ref>{{harvnb|Bernal|1967|p=143}}</ref>

< blockquote >仅仅解释这些分子的形成是不够的，需要的是对这些分子的起源作出物理-化学解释，表明存在合适的自由能源和自由能汇。

</blockquote >

</blockquote >

Multiple sources of energy were available for chemical reactions on the early Earth. For example, heat (such as from [[geothermal energy|geothermal]] processes) is a standard energy source for chemistry. Other examples include sunlight and electrical discharges (lightning), among others.<ref name="Follmann2009" /> In fact, lightning is a plausible energy source for the origin of life, given that just in the tropics lightning strikes about 100 million times a year.

Multiple sources of energy were available for chemical reactions on the early Earth. For example, heat (such as from [[geothermal energy|geothermal]] processes) is a standard energy source for chemistry. Other examples include sunlight and electrical discharges (lightning), among others.<ref name="Follmann2009" /> In fact, lightning is a plausible energy source for the origin of life, given that just in the tropics lightning strikes about 100 million times a year.<ref>{{Cite journal|last1=Gora|first1=Evan M.|last2=Burchfield|first2=Jeffrey C.|last3=Muller‐Landau|first3=Helene C.|last4=Bitzer|first4=Phillip M.|last5=Yanoviak|first5=Stephen P.|title=Pantropical geography of lightning-caused disturbance and its implications for tropical forests|journal=Global Change Biology|year=2020|language=en|volume=n/a|issue=n/a|pages=5017–5026|doi=10.1111/gcb.15227|pmid=32564481|bibcode=2020GCBio..26.5017G|issn=1365-2486}}</ref>

Multiple sources of energy were available for chemical reactions on the early Earth. For example, heat (such as from geothermal processes) is a standard energy source for chemistry. Other examples include sunlight and electrical discharges (lightning), among others. In fact, lightning is a plausible energy source for the origin of life, given that just in the tropics lightning strikes about 100 million times a year.

Multiple sources of energy were available for chemical reactions on the early Earth. For example, heat (such as from geothermal processes) is a standard energy source for chemistry. Other examples include sunlight and electrical discharges (lightning), among others. In fact, lightning is a plausible energy source for the origin of life, given that just in the tropics lightning strikes about 100 million times a year.

Computer simulations also suggest that [[cavitation]] in primordial water reservoirs such as breaking sea waves, streams and oceans can potentially lead to the synthesis of biogenic compounds.

Computer simulations also suggest that [[cavitation]] in primordial water reservoirs such as breaking sea waves, streams and oceans can potentially lead to the synthesis of biogenic compounds.<ref>{{cite journal|doi=10.1021/acscentsci.7b00325|pmid= 28979946|pmc= 5620973|title= Cavitation-Induced Synthesis of Biogenic Molecules on Primordial Earth|journal= ACS Central Science|volume= 3|issue= 9|pages= 1041–1049|year= 2017|last1= Kalson|first1= Natan-Haim|last2= Furman|first2= David|last3= Zeiri|first3= Yehuda}}</ref>

Computer simulations also suggest that cavitation in primordial water reservoirs such as breaking sea waves, streams and oceans can potentially lead to the synthesis of biogenic compounds.

Computer simulations also suggest that cavitation in primordial water reservoirs such as breaking sea waves, streams and oceans can potentially lead to the synthesis of biogenic compounds.

Unfavourable reactions can also be driven by highly favourable ones, as in the case of iron-sulfur chemistry. For example, this was probably important for [[carbon fixation]] (the conversion of carbon from its inorganic form to an organic one). Carbon fixation via iron-sulfur chemistry is highly favourable, and occurs at neutral pH and 100C. Iron-sulfur surfaces, which are abundant near hydrothermal vents, are also capable of producing small amounts of amino acids and other biological metabolites.

Unfavourable reactions can also be driven by highly favourable ones, as in the case of iron-sulfur chemistry. For example, this was probably important for [[carbon fixation]] (the conversion of carbon from its inorganic form to an organic one). Carbon fixation via iron-sulfur chemistry is highly favourable, and occurs at neutral pH and 100C. Iron-sulfur surfaces, which are abundant near hydrothermal vents, are also capable of producing small amounts of amino acids and other biological metabolites.

Unfavourable reactions can also be driven by highly favourable ones, as in the case of iron-sulfur chemistry. For example, this was probably important for carbon fixation (the conversion of carbon from its inorganic form to an organic one). Carbon fixation via iron-sulfur chemistry is highly favourable, and occurs at neutral pH and 100C. Iron-sulfur surfaces, which are abundant near hydrothermal vents, are also capable of producing small amounts of amino acids and other biological metabolites.

Unfavourable reactions can also be driven by highly favourable ones, as in the case of iron-sulfur chemistry. For example, this was probably important for carbon fixation (the conversion of carbon from its inorganic form to an organic one). Carbon fixation via iron-sulfur chemistry is highly favourable, and occurs at neutral pH and 100C. Iron-sulfur surfaces, which are abundant near hydrothermal vents, are also capable of producing small amounts of amino acids and other biological metabolites.

===Self-organization===

===Self-organization===

[[File:Hermann Haken, Pour le Merite 2014.jpg|thumb|upright|Hermann Haken]]

[[File:Hermann Haken, Pour le Merite 2014.jpg|thumb|upright|Hermann Haken]]

赫尔曼•哈肯Hermann Haken

赫尔曼•哈肯Hermann Haken

The discipline of synergetics studies self-organization in physical systems. In his book ''[[Synergetics (Haken)|Synergetics]]'' [[Hermann Haken]] has pointed out that different physical systems can be treated in a similar way. He gives as examples of self-organization several types of lasers, instabilities in fluid dynamics, including convection, and chemical and biochemical oscillations. In his preface he mentions the origin of life, but only in general terms:

The discipline of synergetics studies self-organization in physical systems. In his book ''[[Synergetics (Haken)|Synergetics]]''<ref>{{cite book |last1 = Haken| first1= Hermann | title=Synergetics. An Introduction. |year=1978 | publisher=Springer | location= Berlin  }}</ref> [[Hermann Haken]] has pointed out that different physical systems can be treated in a similar way. He gives as examples of self-organization several types of lasers, instabilities in fluid dynamics, including convection, and chemical and biochemical oscillations. In his preface he mentions the origin of life, but only in general terms:

The discipline of synergetics studies self-organization in physical systems. In his book Synergetics Hermann Haken has pointed out that different physical systems can be treated in a similar way. He gives as examples of self-organization several types of lasers, instabilities in fluid dynamics, including convection, and chemical and biochemical oscillations. In his preface he mentions the origin of life, but only in general terms:

The discipline of synergetics studies self-organization in physical systems. In his book Synergetics Hermann Haken has pointed out that different physical systems can be treated in a similar way. He gives as examples of self-organization several types of lasers, instabilities in fluid dynamics, including convection, and chemical and biochemical oscillations. In his preface he mentions the origin of life, but only in general terms:

协同学这门学科研究的是物理系统的自组织。Hermann Haken在其《协同学》<ref>{{cite book |last1 = Haken| first1= Hermann | title=Synergetics. An Introduction. |year=1978 | publisher=Springer | location= Berlin  }}</ref>一书中指出，不同的物理系统可以用类似的方式处理。他举了几种类型的激光、流体动力学（包括对流）中的不稳定性以及化学和生化振荡作为自组织的例子。他在序言中提到了生命的起源，但只是泛泛而谈。

协同学这门学科研究的是物理系统的自组织。Hermann Haken在其《协同论》一书中指出，不同的物理系统可以用类似的方式处理。他举了几种类型的激光、流体动力学（包括对流）中的不稳定性以及化学和生化振荡作为自组织的例子。在他的序言中他提到了生命的起源，但只是泛泛而谈。

< blockquote >

< blockquote >

The spontaneous formation of well organized structures out of germs or even out of chaos is one of the most fascinating phenomena and most challenging problems scientists are confronted with. Such phenomena are an experience of our daily life when we observe the growth of plants and animals. Thinking of much larger time scales, scientists are led into the problems of evolution, and, ultimately, of the origin of living matter. When we try to explain or understand in some sense these extremely complex biological phenomena it is a natural question, whether processes of self-organization may be found in much simpler systems of the unanimated world.

The spontaneous formation of well organized structures out of germs or even out of chaos is one of the most fascinating phenomena and most challenging problems scientists are confronted with. Such phenomena are an experience of our daily life when we observe the growth of plants and animals. Thinking of much larger time scales, scientists are led into the problems of evolution, and, ultimately, of the origin of living matter. When we try to explain or understand in some sense these extremely complex biological phenomena it is a natural question, whether processes of self-organization may be found in much simpler systems of the unanimated world.

In recent years it has become more and more evident that there exists numerous examples in physical and chemical systems where well organized spatial, temporal, or spatio-temporal structures arise out of chaotic states. Furthermore, as in living organisms, the functioning of these systems can be maintained only by a flux of energy (and matter) through them. In contrast to man-made machines, which are devised to exhibit special structures and functionings, these structures develop spontaneously—they are selforganizing. ...

In recent years it has become more and more evident that there exists numerous examples in physical and chemical systems where well organized spatial, temporal, or spatio-temporal structures arise out of chaotic states. Furthermore, as in living organisms, the functioning of these systems can be maintained only by a flux of energy (and matter) through them. In contrast to man-made machines, which are devised to exhibit special structures and functionings, these structures develop spontaneously—they are selforganizing. ...

近年来，越来越明显的是，在物理和化学系统中存在着许多例子，在这些例子中，从混沌状态中产生了组织良好的空间、时间或时空结构。此外，就像在生物体中一样，这些系统的功能只能通过能量（和物质）的流动来维持。与人造机器不同的是，人造机器被设计来表现出特殊的结构和功能，而这些结构是自发发展的，它们是自组织的...

近年来，越来越明显的是，在物理和化学系统中存在着许多例子，在这些例子中，从混沌状态中产生了组织良好的空间、时间或时空结构。此外，就像在生物体中一样，这些系统的功能只能通过流通它们的能量（和物质）流来维持。与人造机器不同的是，人造机器被设计成表现出特殊的结构和功能，这些结构是自发发展的——它们是自组织的...

</blockquote >

</blockquote >

多重耗散结构

多重耗散结构

This theory postulates that the hallmark of the origin and evolution of life is the microscopic dissipative structuring of [[Biological pigment|organic pigments]] and their proliferation over the entire Earth surface. Present day life augments the entropy production of Earth in its solar environment by dissipating [[ultraviolet]] and [[Visible spectrum|visible]] [[photon]]s into heat through organic pigments in water. This heat then catalyzes a host of secondary dissipative processes such as the [[water cycle]], [[Ocean current|ocean]] and [[wind]] currents, [[Tropical cyclone|hurricanes]], etc.

This theory postulates that the hallmark of the origin and evolution of life is the microscopic dissipative structuring of [[Biological pigment|organic pigments]] and their proliferation over the entire Earth surface.<ref name="Michaelian, K. 2017" /> Present day life augments the entropy production of Earth in its solar environment by dissipating [[ultraviolet]] and [[Visible spectrum|visible]] [[photon]]s into heat through organic pigments in water. This heat then catalyzes a host of secondary dissipative processes such as the [[water cycle]], [[Ocean current|ocean]] and [[wind]] currents, [[Tropical cyclone|hurricanes]], etc.<ref name="Michaelian, K. 2011"/><ref name="HESS Opinions 'Biological catalysis">{{cite journal |doi=10.5194/hess-16-2629-2012 |title=HESS Opinions 'Biological catalysis of the hydrological cycle: Life's thermodynamic function' |journal=Hydrology and Earth System Sciences |volume=16 |issue=8 |pages=2629–2645 |year=2012 |last1=Michaelian |first1=K |bibcode=2012HESS...16.2629M |arxiv= 0907.0040 }}</ref>

This theory postulates that the hallmark of the origin and evolution of life is the microscopic dissipative structuring of organic pigments and their proliferation over the entire Earth surface. Present day life augments the entropy production of Earth in its solar environment by dissipating ultraviolet and visible photons into heat through organic pigments in water. This heat then catalyzes a host of secondary dissipative processes such as the water cycle, ocean and wind currents, hurricanes, etc.

This theory postulates that the hallmark of the origin and evolution of life is the microscopic dissipative structuring of organic pigments and their proliferation over the entire Earth surface. Present day life augments the entropy production of Earth in its solar environment by dissipating ultraviolet and visible photons into heat through organic pigments in water. This heat then catalyzes a host of secondary dissipative processes such as the water cycle, ocean and wind currents, hurricanes, etc.

==== Selforganization by dissipative structures====

==== Selforganization by dissipative structures====

[[File:Ilya Prigogine 1977c.jpg|thumb|upright|Ilya Prigogine 1977c]]

[[File:Ilya Prigogine 1977c.jpg|thumb|upright|Ilya Prigogine 1977c]]

The 19th-century physicist [[Ludwig Boltzmann]] first recognized that the struggle for existence of living organisms was neither over raw material nor [[energy]], but instead had to do with [[entropy production]] derived from the conversion of the solar [[spectrum]] into [[heat]] by these systems. Boltzmann thus realized that living systems, like all [[Reversible process (thermodynamics)|irreversible processes]], were dependent on the [[dissipation]] of a generalized chemical potential for their existence. In his book "What is Life", the 20th-century physicist [[Erwin Schrödinger]] emphasized the importance of Boltzmann's deep insight into the irreversible thermodynamic nature of living systems, suggesting that this was the physics and chemistry behind the origin and evolution of life.

The 19th-century physicist [[Ludwig Boltzmann]] first recognized that the struggle for existence of living organisms was neither over raw material nor [[energy]], but instead had to do with [[entropy production]] derived from the conversion of the solar [[spectrum]] into [[heat]] by these systems.<ref>Boltzmann, L. (1886) The Second Law of Thermodynamics, in: Ludwig Boltzmann: Theoretical physics and Selected writings, edited by: McGinness, B., D. Reidel, Dordrecht, The Netherlands, 1974.</ref> Boltzmann thus realized that living systems, like all [[Reversible process (thermodynamics)|irreversible processes]], were dependent on the [[dissipation]] of a generalized chemical potential for their existence. In his book "What is Life", the 20th-century physicist [[Erwin Schrödinger]]<ref>Schrödinger, Erwin (1944) What is Life? The Physical Aspect of the Living Cell. Cambridge University Press</ref> emphasized the importance of Boltzmann's deep insight into the irreversible thermodynamic nature of living systems, suggesting that this was the physics and chemistry behind the origin and evolution of life.

The 19th-century physicist Ludwig Boltzmann first recognized that the struggle for existence of living organisms was neither over raw material nor energy, but instead had to do with entropy production derived from the conversion of the solar spectrum into heat by these systems. Boltzmann thus realized that living systems, like all irreversible processes, were dependent on the dissipation of a generalized chemical potential for their existence. In his book "What is Life", the 20th-century physicist Erwin Schrödinger emphasized the importance of Boltzmann's deep insight into the irreversible thermodynamic nature of living systems, suggesting that this was the physics and chemistry behind the origin and evolution of life.

The 19th-century physicist Ludwig Boltzmann first recognized that the struggle for existence of living organisms was neither over raw material nor energy, but instead had to do with entropy production derived from the conversion of the solar spectrum into heat by these systems. Boltzmann thus realized that living systems, like all irreversible processes, were dependent on the dissipation of a generalized chemical potential for their existence. In his book "What is Life", the 20th-century physicist Erwin Schrödinger emphasized the importance of Boltzmann's deep insight into the irreversible thermodynamic nature of living systems, suggesting that this was the physics and chemistry behind the origin and evolution of life.

19世纪的物理学家路德维希-玻尔兹曼Ludwig Boltzmann首先认识到，生物体的生存斗争既不是为了原料，也不是为了能源，而是与这些系统将太阳光谱转化为热能所带来的熵增有关。<ref>Boltzmann, L. (1886) The Second Law of Thermodynamics, in: Ludwig Boltzmann: Theoretical physics and Selected writings, edited by: McGinness, B., D. Reidel, Dordrecht, The Netherlands, 1974.</ref>Boltzmann由此认识到，生物系统和所有不可逆的过程一样，其存在依赖于广义化学势的消散。20世纪物理学家Erwin Schrödinger在其《生命是什么》一书中<ref>Schrödinger, Erwin (1944) What is Life? The Physical Aspect of the Living Cell. Cambridge University Press</ref>强调了Boltzmann对生命系统不可逆的热力学本质的深刻洞察，认为这就是生命起源和演化背后的物理学和化学。

19世纪的物理学家路德维希-玻尔兹曼Ludwig Boltzmann首先认识到，生物体的生存斗争既不是为了原料，也不是为了能源，而是与这些系统将太阳光谱转化为热能所产生的熵有关。Boltzmann由此认识到，生命系统和所有不可逆的过程一样，其存在依赖于广义化学势的耗散。20世纪物理学家埃尔温·薛定谔 Erwin Schrödinger在其《生命是什么》一书中强调了Boltzmann对生命系统不可逆的热力学本质的深刻洞察，认为这就是生命起源和进化背后的物理学和化学。

However, irreversible processes, and much less living systems, could not be conveniently analyzed under this perspective until [[Lars Onsager]], and later Ilya [[Ilya Prigogine|Prigogine]], developed an elegant mathematical formalism for treating the "self-organization" of material under a generalized chemical potential. This formalism became known as Classical Irreversible Thermodynamics and Prigogine was awarded the [[Nobel Prize in Chemistry]] in 1977 "for his contributions to [[non-equilibrium thermodynamics]], particularly the theory of [[Dissipative system|dissipative structures]]". The analysis by Prigogine showed that if a [[system]] were left to evolve under an imposed external potential, material could spontaneously organize (lower its [[entropy]]) forming what he called "dissipative structures" which would increase the dissipation of the externally imposed potential (augment the global entropy production). Non-equilibrium thermodynamics has since been successfully applied to the analysis of living systems, from the biochemical production of [[Adenosine triphosphate|ATP]] to optimizing bacterial metabolic pathways to complete ecosystems.

However, irreversible processes, and much less living systems, could not be conveniently analyzed under this perspective until [[Lars Onsager]],<ref>Onsager, L. (1931) Reciprocal Relations in Irreversible Processes I and II, ''Phys. Rev.'' 37, 405; 38, 2265 (1931)</ref> and later Ilya [[Ilya Prigogine|Prigogine]],<ref>Prigogine, I. (1967) An Introduction to the Thermodynamics of Irreversible Processes, Wiley, New York</ref> developed an elegant mathematical formalism for treating the "self-organization" of material under a generalized chemical potential. This formalism became known as Classical Irreversible Thermodynamics and Prigogine was awarded the [[Nobel Prize in Chemistry]] in 1977 "for his contributions to [[non-equilibrium thermodynamics]], particularly the theory of [[Dissipative system|dissipative structures]]". The analysis by Prigogine showed that if a [[system]] were left to evolve under an imposed external potential, material could spontaneously organize (lower its [[entropy]]) forming what he called "dissipative structures" which would increase the dissipation of the externally imposed potential (augment the global entropy production). Non-equilibrium thermodynamics has since been successfully applied to the analysis of living systems, from the biochemical production of [[Adenosine triphosphate|ATP]]<ref>{{cite journal | last1 = Dewar | first1 = R | last2 = Juretić | first2 = D. | last3 = Županović | first3 = P. | year = 2006 | title = The functional design of the rotary enzyme ATP synthase is consistent with maximum entropy production | journal = Chem. Phys. Lett. | volume = 430 | issue = 1| pages = 177–182 | doi=10.1016/j.cplett.2006.08.095| bibcode = 2006CPL...430..177D }}</ref> to optimizing bacterial metabolic pathways<ref>Unrean, P., Srienc, F. (2011) Metabolic networks evolve towards states of maximum entropy production, Metabolic Engineering 13, 666–673.</ref> to complete ecosystems.<ref>Zotin, A.I. (1984) "Bioenergetic trends of evolutionary progress of organisms", in: ''Thermodynamics and regulation of biological processes'' Lamprecht, I. and Zotin, A.I. (eds.), De Gruyter, Berlin, pp. 451–458.</ref><ref>{{cite journal | last1 = Schneider | first1 = E.D. | last2 = Kay | first2 = J.J. | year = 1994 | title = Life as a Manifestation of the Second Law of Thermodynamics | journal = Mathematical and Computer Modelling | volume = 19 | issue = 6–8| pages = 25–48 | doi=10.1016/0895-7177(94)90188-0| citeseerx = 10.1.1.36.8381 }}</ref><ref>{{cite journal | last1 = Michaelian | first1 = K. | year = 2005 | title = Thermodynamic stability of ecosystems  | journal = Journal of Theoretical Biology | volume = 237 | issue = 3| pages = 323–335 | bibcode = 2004APS..MAR.P9015M | doi=10.1016/j.jtbi.2005.04.019| pmid = 15978624 }}</ref>

However, irreversible processes, and much less living systems, could not be conveniently analyzed under this perspective until Lars Onsager, and later Ilya Prigogine, developed an elegant mathematical formalism for treating the "self-organization" of material under a generalized chemical potential. This formalism became known as Classical Irreversible Thermodynamics and Prigogine was awarded the Nobel Prize in Chemistry in 1977 "for his contributions to non-equilibrium thermodynamics, particularly the theory of dissipative structures". The analysis by Prigogine showed that if a system were left to evolve under an imposed external potential, material could spontaneously organize (lower its entropy) forming what he called "dissipative structures" which would increase the dissipation of the externally imposed potential (augment the global entropy production). Non-equilibrium thermodynamics has since been successfully applied to the analysis of living systems, from the biochemical production of ATP to optimizing bacterial metabolic pathways to complete ecosystems.

However, irreversible processes, and much less living systems, could not be conveniently analyzed under this perspective until Lars Onsager, and later Ilya Prigogine, developed an elegant mathematical formalism for treating the "self-organization" of material under a generalized chemical potential. This formalism became known as Classical Irreversible Thermodynamics and Prigogine was awarded the Nobel Prize in Chemistry in 1977 "for his contributions to non-equilibrium thermodynamics, particularly the theory of dissipative structures". The analysis by Prigogine showed that if a system were left to evolve under an imposed external potential, material could spontaneously organize (lower its entropy) forming what he called "dissipative structures" which would increase the dissipation of the externally imposed potential (augment the global entropy production). Non-equilibrium thermodynamics has since been successfully applied to the analysis of living systems, from the biochemical production of ATP to optimizing bacterial metabolic pathways to complete ecosystems.

然而，不可逆的过程，更不用说生命系统，直到Lars Onsager<ref>Onsager, L. (1931) Reciprocal Relations in Irreversible Processes I and II, ''Phys. Rev.'' 37, 405; 38, 2265 (1931)</ref>和后来的Ilya Prigogine<ref>Prigogine, I. (1967) An Introduction to the Thermodynamics of Irreversible Processes, Wiley, New York</ref>发展了一种优雅的数学形式论，才能在这个角度下方便地进行分析。这个形式论用于处理广义化学势下物质的 "自组织"，这个形式论后来被称为经典不可逆热力学，1977年Prigogine被授予诺贝尔化学奖，"以表彰他对非平衡热力学，特别是耗散结构理论的贡献"。Prigogine的分析表明，如果让一个系统在一个强加的外部势下演化，物质可以自发地组织起来（降低其熵），形成他所说的 "耗散结构"，从而增加外部强加势的耗散（增强全局熵的产生）。此后，非平衡热力学被成功地应用于生命系统的分析，从ATP的生化生产<ref>{{cite journal | last1 = Dewar | first1 = R | last2 = Juretić | first2 = D. | last3 = Županović | first3 = P. | year = 2006 | title = The functional design of the rotary enzyme ATP synthase is consistent with maximum entropy production | journal = Chem. Phys. Lett. | volume = 430 | issue = 1| pages = 177–182 | doi=10.1016/j.cplett.2006.08.095| bibcode = 2006CPL...430..177D }}</ref>到优化细菌代谢途径<ref>Unrean, P., Srienc, F. (2011) Metabolic networks evolve towards states of maximum entropy production, Metabolic Engineering 13, 666–673.</ref>，再到完整的生态系统。<ref>Zotin, A.I. (1984) "Bioenergetic trends of evolutionary progress of organisms", in: ''Thermodynamics and regulation of biological processes'' Lamprecht, I. and Zotin, A.I. (eds.), De Gruyter, Berlin, pp. 451–458.</ref><ref>{{cite journal | last1 = Schneider | first1 = E.D. | last2 = Kay | first2 = J.J. | year = 1994 | title = Life as a Manifestation of the Second Law of Thermodynamics | journal = Mathematical and Computer Modelling | volume = 19 | issue = 6–8| pages = 25–48 | doi=10.1016/0895-7177(94)90188-0| citeseerx = 10.1.1.36.8381 }}</ref><ref>{{cite journal | last1 = Michaelian | first1 = K. | year = 2005 | title = Thermodynamic stability of ecosystems  | journal = Journal of Theoretical Biology | volume = 237 | issue = 3| pages = 323–335 | bibcode = 2004APS..MAR.P9015M | doi=10.1016/j.jtbi.2005.04.019| pmid = 15978624 }}</ref>

然而，不可逆的过程，更不用说生命系统了，在这个角度下无法方便地进行分析，直到拉斯·昂萨格 Lars Onsager和后来的Ilya Prigogine，发展了一种优雅的数学形式体系，用于处理广义化学势下物质的 "自组织"。这个形式体系后来被称为经典不可逆热动力学，1977年Prigogine被授予诺贝尔化学奖，"以表彰他对非平衡热动力学，特别是耗散结构理论的贡献"。Prigogine的分析表明，如果让一个系统在一个强加的外部势下演化，物质可以自发地组织起来（降低其熵），形成他所说的 "耗散结构"，从而增加外部强加势的耗散（增强全局熵的产生）。此后，非平衡热动力学被成功地应用于生命系统的分析，从ATP的生化生产到优化细菌代谢通路以形成完整的生态系统。

==当前的生命，生物发生的结果：生物学 Current life, the result of abiogenesis: biology==

==当前的生命，生物发生的结果：生物学 Current life, the result of abiogenesis: biology==

When discussing the origin of life, a definition of life itself is fundamental. The definition is somewhat disagreed upon (although follows the same basic principles) because different biology textbooks define life differently. James Gould:

When discussing the origin of life, a definition of life itself is fundamental. The definition is somewhat disagreed upon (although follows the same basic principles) because different biology textbooks define life differently. James Gould:

当讨论生命的起源时，最基本的问题时对生命本身的定义。由于不同的生物学教科书对生命的定义不同，所以这个定义存在一定的分歧（虽然遵循相同的基本原则）。詹姆斯·古尔德 James·Gould :

当讨论生命的起源时，最基本的问题是对生命本身的定义。由于不同的生物学教科书对生命的定义不同，所以这个定义存在一定的分歧（虽然遵循相同的基本原则）。詹姆斯·古尔德 James Gould :

<blockquote>

<blockquote>

Most dictionaries define life as the property that distinguishes the living from the dead, and define dead as being deprived of life. These singularly circular and unsatisfactory definitions give us no clue to what we have in common with protozoans and plants.

Most dictionaries define life as the property that distinguishes the living from the dead, and define dead as being deprived of life. These singularly circular and unsatisfactory definitions give us no clue to what we have in common with protozoans and plants.

大多数字典将生命定义为区别于活人和死人的属性，并将死亡定义为被剥夺了生命。这些奇怪的、循环的、难以令人满意的定义，没有给我们提供任何线索，使我们了解我们与原生动物和植物的共同之处。<ref name="Gould">{{cite book| last1 = Gould | first1 = James L. | last2 = Keeton | first2 = William T. | year = 1996| edition = 6 | title = Biological Science | location= New York | publisher = W.W. Norton }}</ref>

大多数字典将生命定义为区别于存活和死亡的属性，并将死亡定义为被剥夺了生命。这些奇怪循环的、难以令人满意的定义，没有给我们提供任何线索，使我们了解我们与原生动物和植物的共同之处。<ref name="Gould">{{cite book| last1 = Gould | first1 = James L. | last2 = Keeton | first2 = William T. | year = 1996| edition = 6 | title = Biological Science | location= New York | publisher = W.W. Norton }}</ref>

</blockquote>

</blockquote>

The phenomenon we call life defies a simple, one-sentence definition.

The phenomenon we call life defies a simple, one-sentence definition.

</blockquote>

</blockquote>

This difference can also be found in books on the origin of life. John Casti gives a single sentence:

This difference can also be found in books on the origin of life. John Casti gives a single sentence:

在关于生命起源的书籍中也可以找到这种差异。约翰-卡斯蒂John Casti给出了一句话：

在关于生命起源的书籍中也可以找到这种差异。约翰·卡斯蒂John Casti给出了一句话：

<blockquote>

<blockquote>

By more or general consensus nowadays, an entity is considered to be "alive" if it has the capacity to carry out three basic functional activities: metabolism, self-repair, and replication.

By more or general consensus nowadays, an entity is considered to be "alive" if it has the capacity to carry out three basic functional activities: metabolism, self-repair, and replication.

</blockquote>  

</blockquote>  

Dirk Schulze-Makuch and Louis Irwin spend in contrast the whole first chapter of their book on this subject.

Dirk Schulze-Makuch and Louis Irwin spend in contrast the whole first chapter of their book on this subject.

德克·舒尔茨-马库奇Dirk Schulze-Makuch 和 路易斯 · 欧文Louis Irwin 在他们的书中花了整整一章的篇幅来讨论这个问题。

相比之下，德克·舒尔茨-马库奇Dirk Schulze-Makuch 和 路易斯·欧文 Louis Irwin 在他们的书中花了整整第一章来讨论这个问题。

====发酵 Fermentation====

====发酵 Fermentation====

[[File:Citric acid cycle.svg|thumb|upright=1.5|left|Citric acid cycle]]

[[File:Citric acid cycle.svg|thumb|upright=1.5|left|Citric acid cycle]]

柠檬酸循环

柠檬酸循环

[[File:Metabolism diagram.svg|thumb|Overall diagram of the chemical reactions of metabolism, in which the citric acid cycle can be recognized as the circle just below the middle of the figure 代谢化学反应的整体图，其中柠檬酸循环可以看作是位于图中间下方的圆圈]] [[Albert L. Lehninger|Albert Lehninger]] has stated around 1970 that fermentation, including glycolysis, is a suitable primitive energy source for the origin of life.<ref name="Lehninger">{{cite book| last1 = Lehninger | first1 = Albert L. | year = 1970| title = Biochemistry. The Molecular Basis of Cell Structure and Function | location= New York | publisher = Worth | page = 313}}</ref>

[[File:Metabolism diagram.svg|thumb|Overall diagram of the chemical reactions of metabolism, in which the citric acid cycle can be recognized as the circle just below the middle of the figure 代谢化学反应的整体图，其中柠檬酸循环可以认为是位于图中间下方的圆圈]] [[Albert L. Lehninger|Albert Lehninger]] has stated around 1970 that fermentation, including glycolysis, is a suitable primitive energy source for the origin of life.<ref name="Lehninger">{{cite book| last1 = Lehninger | first1 = Albert L. | year = 1970| title = Biochemistry. The Molecular Basis of Cell Structure and Function | location= New York | publisher = Worth | page = 313}}</ref>

Since living organisms probably first arose in an atmosphere lacking oxygen, anaerobic fermentation is the simplest and most primitive type of biological mechanism for obtaining energy from nutrient molecules.  

Since living organisms probably first arose in an atmosphere lacking oxygen, anaerobic fermentation is the simplest and most primitive type of biological mechanism for obtaining energy from nutrient molecules.  

</blockquote>

</blockquote>

Fermentation involves glycolysis, which, rather inefficiently, transduces the chemical energy of sugar into the chemical energy of ATP.

Fermentation involves glycolysis, which, rather inefficiently, transduces the chemical energy of sugar into the chemical energy of ATP.

====化学渗透 Chemiosmosis====

====化学渗透 Chemiosmosis====

As Fermentation had around 1970 been elucidated, whereas the mechanism of oxidative phosphorylation had not and some controversies still existed, fermentation may have looked too complex for investigators of the origin of life at that time. Peter Mitchell's Chemiosmosis is now however generally accepted as correct.

As Fermentation had around 1970 been elucidated, whereas the mechanism of oxidative phosphorylation had not and some controversies still existed, fermentation may have looked too complex for investigators of the origin of life at that time. Peter Mitchell's Chemiosmosis is now however generally accepted as correct.

由于在1970年左右发酵原理已经被阐明，而氧化磷酸化的机制还没有，而且存在一些争议，所以发酵作用在当时对生命起源的研究者来说可能显得过于复杂。不过，彼得-米切尔Peter Mitchell 的化学渗透现在被普遍认为是正确的。

由于在1970年左右发酵已经被阐明，而氧化磷酸化的机制还没有，而且存在一些争议，所以发酵作用在当时对生命起源的研究者来说可能显得过于复杂。不过，彼得·米切尔Peter Mitchell 的化学渗透现在被普遍接受是正确的。

Even Peter Mitchell himself assumed that fermentation preceded chemiosmosis. Chemiosmosis is however ubiquitous in life. A model for the origin of life has been presented in terms of chemiosmosis.

Even Peter Mitchell himself assumed that fermentation preceded chemiosmosis. Chemiosmosis is however ubiquitous in life. A model for the origin of life has been presented in terms of chemiosmosis.

连Peter Mitchell自己也认为发酵是在化学渗透之前发生的。然而，化学渗透在生命中无处不在的。一个以化学渗透为基础的生命起源模型已经被提出来了。

连Peter Mitchell自己也认为发酵先于化学渗透。然而，化学渗透在生命中无处不在。一个依据化学渗透的生命起源模型已经被提出来了。

Both respiration by mitochondria and photosynthesis in chloroplasts make use of chemiosmosis to generate most of their ATP.

Both respiration by mitochondria and photosynthesis in chloroplasts make use of chemiosmosis to generate most of their ATP.

Today the energy source of all life can be linked to photosynthesis, and one speaks of primary production by sunlight. The oxygen used for oxidizing reducing compounds by organisms at hydrothermal vents at the bottom of the ocean is the result of photosynthesis at the Oceans' surface.

Today the energy source of all life can be linked to photosynthesis, and one speaks of primary production by sunlight. The oxygen used for oxidizing reducing compounds by organisms at hydrothermal vents at the bottom of the ocean is the result of photosynthesis at the Oceans' surface.

=====ATP合成酶 ATP synthase=====

=====ATP合成酶 ATP synthase=====

Depiction of ATP synthase using the chemiosmotic proton gradient to power ATP synthesis through [[oxidative phosphorylation.]]

Depiction of ATP synthase using the chemiosmotic proton gradient to power ATP synthesis through [[oxidative phosphorylation.]]

[[File:Paul D. Boyer.jpg|thumb|upright|Paul Boyer]]

[[File:Paul D. Boyer.jpg|thumb|upright|Paul Boyer]]

The mechanism of ATP synthesis is complex and involves a closed membrane in which the ATP synthase is embedded. The ATP is synthesized by the F1 subunit of ATP synthase by the binding change mechanism discovered by Paul Boyer. The energy required to release formed strongly-bound ATP has its origin in protons that move across the membrane. These protons have been set across the membrane during respiration or photosynthesis.

The mechanism of ATP synthesis is complex and involves a closed membrane in which the ATP synthase is embedded. The ATP is synthesized by the F1 subunit of ATP synthase by the binding change mechanism discovered by Paul Boyer. The energy required to release formed strongly-bound ATP has its origin in protons that move across the membrane. These protons have been set across the membrane during respiration or photosynthesis.

ATP的合成机制很复杂，涉及到ATP合成酶所嵌入的闭合膜。ATP是由ATP合成酶的''F1亚基''通过 Paul Boyer 发现的结合变化机制合成的。释放强结合ATP所需的能量源自穿过膜的质子。这些质子在呼吸作用或光合作用过程中被穿过在膜上。

ATP的合成机制很复杂，涉及到ATP合成酶所嵌入的闭合膜。ATP是由ATP合成酶的F1亚基通过 Paul Boyer 发现的结合变化机制合成的。释放形成的牢固结合的ATP所需的能量源自跨膜移动的质子。这些质子在呼吸作用或光合作用过程中穿过膜。

====RNA世界 RNA world====

====RNA世界 RNA world====

[[File:010 small subunit-1FKA.gif|thumb|upright=1.25|Molecular structure of the [[30S|ribosome 30S subunit]] from ''[[Thermus thermophilus]]''. 在分子结构核糖体30S亚基从嗜热。蛋白质显示为蓝色，单个RNA链显示为橙色。 <ref name="Venki">{{cite journal |last1=Wimberly |first1=Brian T. |last2=Brodersen |first2=Ditlev E. |last3=Clemons |first3=William M. Jr. |last4=Morgan-Warren |first4=Robert J. |last5=Carter |first5=Andrew P. |last6=Vonrhein |first6=Clemens |last7=Hartsch |first7=Thomas |last8=Ramakrishnan |first8=V. |authorlink8=Venkatraman Ramakrishnan |display-authors=3 |date=21 September 2000 |title=Structure of the 30S ribosomal subunit |journal=Nature |volume=407 |issue=6802 |pages=327–339 |doi=10.1038/35030006 |pmid=11014182|bibcode=2000Natur.407..327W |s2cid=4419944 }}</ref> [[Protein]]s are shown in blue and the single [[RNA]] chain in orange.]]

[[File:010 small subunit-1FKA.gif|thumb|upright=1.25|Molecular structure of the [[30S|ribosome 30S subunit]] from ''[[Thermus thermophilus]]''. 嗜热细菌核糖体30S亚基的分子结构。蛋白质显示为蓝色，单个RNA链显示为橙色。 <ref name="Venki">{{cite journal |last1=Wimberly |first1=Brian T. |last2=Brodersen |first2=Ditlev E. |last3=Clemons |first3=William M. Jr. |last4=Morgan-Warren |first4=Robert J. |last5=Carter |first5=Andrew P. |last6=Vonrhein |first6=Clemens |last7=Hartsch |first7=Thomas |last8=Ramakrishnan |first8=V. |authorlink8=Venkatraman Ramakrishnan |display-authors=3 |date=21 September 2000 |title=Structure of the 30S ribosomal subunit |journal=Nature |volume=407 |issue=6802 |pages=327–339 |doi=10.1038/35030006 |pmid=11014182|bibcode=2000Natur.407..327W |s2cid=4419944 }}</ref> [[Protein]]s are shown in blue and the single [[RNA]] chain in orange.]]

The RNA world hypothesis describes an early Earth with self-replicating and catalytic RNA but no DNA or proteins. It is widely accepted that current life on Earth descends from an RNA world, although RNA-based life may not have been the first life to exist. The structure of the ribosome has been called the "smoking gun," as it showed that the ribosome is a ribozyme, with a central core of RNA and no amino acid side chains within 18 angstroms of the active site where peptide bond formation is catalyzed.

The RNA world hypothesis describes an early Earth with self-replicating and catalytic RNA but no DNA or proteins. It is widely accepted that current life on Earth descends from an RNA world, although RNA-based life may not have been the first life to exist. The structure of the ribosome has been called the "smoking gun," as it showed that the ribosome is a ribozyme, with a central core of RNA and no amino acid side chains within 18 angstroms of the active site where peptide bond formation is catalyzed.

RNA世界假说描述了一个具有自我复制和催化的RNA，但没有DNA和蛋白质的早期地球。<ref name="NYT-20140925-CZ">{{cite news |last=Zimmer |first=Carl |date=25 September 2014 |title=A Tiny Emissary From the Ancient Past |url=https://www.nytimes.com/2014/09/25/science/a-tiny-emissary-from-the-ancient-past.html |newspaper=The New York Times |location=New York |accessdate=2014-09-26 |url-status=live |archiveurl=https://web.archive.org/web/20140927022738/http://www.nytimes.com/2014/09/25/science/a-tiny-emissary-from-the-ancient-past.html |archivedate=27 September 2014}}</ref> 现在普遍认为现在地球上的生命起源于这个RNA世界，尽管基于RNA的生命可能并不是最早存在的生命。<ref name="RNA">*{{cite journal |last1=Copley |first1=Shelley D. |last2=Smith |first2=Eric |last3=Morowitz |first3=Harold J. |authorlink3=Harold J. Morowitz |date=December 2007 |title=The origin of the RNA world: Co-evolution of genes and metabolism |url=http://tuvalu.santafe.edu/~desmith/PDF_pubs/Copley_BOG.pdf |journal=Bioorganic Chemistry |volume=35 |issue=6 |pages=430–443 |doi=10.1016/j.bioorg.2007.08.001 |pmid=17897696 |accessdate=2015-06-08 |quote=The proposal that life on Earth arose from an RNA world is widely accepted. |url-status=live |archiveurl=https://web.archive.org/web/20130905070129/http://tuvalu.santafe.edu/~desmith/PDF_pubs/Copley_BOG.pdf |archivedate=5 September 2013}}这个结论是由许多独立的证据得出的，例如观察到RNA是翻译过程的核心，并且小RNA可以催化生命所需的所有化学基团和信息转移。核糖体的结构被称为 "确凿的证据"，因为它表明核糖体是一个核糖体，其核心是RNA，并且在催化肽键形成的活性位点18角以内没有氨基酸侧链。

RNA世界假说描述了一个具有自我复制和催化能力的RNA，但没有DNA或蛋白质的早期地球。<ref name="NYT-20140925-CZ">{{cite news |last=Zimmer |first=Carl |date=25 September 2014 |title=A Tiny Emissary From the Ancient Past |url=https://www.nytimes.com/2014/09/25/science/a-tiny-emissary-from-the-ancient-past.html |newspaper=The New York Times |location=New York |accessdate=2014-09-26 |url-status=live |archiveurl=https://web.archive.org/web/20140927022738/http://www.nytimes.com/2014/09/25/science/a-tiny-emissary-from-the-ancient-past.html |archivedate=27 September 2014}}</ref> 现在普遍认为现在地球上的生命起源于一个RNA世界，尽管基于RNA的生命可能并不是最早存在的生命。<ref name="RNA">*{{cite journal |last1=Copley |first1=Shelley D. |last2=Smith |first2=Eric |last3=Morowitz |first3=Harold J. |authorlink3=Harold J. Morowitz |date=December 2007 |title=The origin of the RNA world: Co-evolution of genes and metabolism |url=http://tuvalu.santafe.edu/~desmith/PDF_pubs/Copley_BOG.pdf |journal=Bioorganic Chemistry |volume=35 |issue=6 |pages=430–443 |doi=10.1016/j.bioorg.2007.08.001 |pmid=17897696 |accessdate=2015-06-08 |quote=The proposal that life on Earth arose from an RNA world is widely accepted. |url-status=live |archiveurl=https://web.archive.org/web/20130905070129/http://tuvalu.santafe.edu/~desmith/PDF_pubs/Copley_BOG.pdf |archivedate=5 September 2013}}***缺乏对应英文***这个结论是由许多独立的证据得出的，例如观察到RNA是翻译过程的核心，并且小RNA可以催化生命所需的所有化学基团和信息转移。***缺乏对应英文***核糖体的结构被称为 "确凿的证据"，因为它表明核糖体是一个核酶，其核心是RNA，并且在催化肽键形成的活性位点18埃以内没有氨基酸侧链。

The concept of the RNA world was first proposed in 1962 by [[Alexander Rich]],<ref>{{cite journal |last1=Neveu |first1=Marc |last2=Kim |first2=Hyo-Joong |last3=Benner |first3=Steven A. |date=22 April 2013 |title=The 'Strong' RNA World Hypothesis: Fifty Years Old |journal=Astrobiology |volume=13 |issue=4 |pages=391–403 |bibcode=2013AsBio..13..391N |doi=10.1089/ast.2012.0868 |pmid=23551238 |ref=harv}}</ref> and the term was coined by [[Walter Gilbert]] in 1986.<ref name="Cech2012">{{cite journal |last=Cech |first=Thomas R. |authorlink=Thomas Cech |date=July 2012 |title=The RNA Worlds in Context |journal=Cold Spring Harbor Perspectives in Biology |volume=4 |issue=7 |page=a006742 |doi=10.1101/cshperspect.a006742 |pmc=3385955 |pmid=21441585}}</ref><ref>{{cite journal |last=Gilbert |first=Walter |authorlink=Walter Gilbert |date=20 February 1986 |title=Origin of life: The RNA world |journal=Nature |volume=319 |issue=6055 |page=618 |bibcode=1986Natur.319..618G |doi=10.1038/319618a0 |s2cid=8026658 }}</ref>  

The concept of the RNA world was first proposed in 1962 by [[Alexander Rich]],<ref>{{cite journal |last1=Neveu |first1=Marc |last2=Kim |first2=Hyo-Joong |last3=Benner |first3=Steven A. |date=22 April 2013 |title=The 'Strong' RNA World Hypothesis: Fifty Years Old |journal=Astrobiology |volume=13 |issue=4 |pages=391–403 |bibcode=2013AsBio..13..391N |doi=10.1089/ast.2012.0868 |pmid=23551238 |ref=harv}}</ref> and the term was coined by [[Walter Gilbert]] in 1986.<ref name="Cech2012">{{cite journal |last=Cech |first=Thomas R. |authorlink=Thomas Cech |date=July 2012 |title=The RNA Worlds in Context |journal=Cold Spring Harbor Perspectives in Biology |volume=4 |issue=7 |page=a006742 |doi=10.1101/cshperspect.a006742 |pmc=3385955 |pmid=21441585}}</ref><ref>{{cite journal |last=Gilbert |first=Walter |authorlink=Walter Gilbert |date=20 February 1986 |title=Origin of life: The RNA world |journal=Nature |volume=319 |issue=6055 |page=618 |bibcode=1986Natur.319..618G |doi=10.1038/319618a0 |s2cid=8026658 }}</ref>  

The concept of the RNA world was first proposed in 1962 by Alexander Rich, and the term was coined by Walter Gilbert in 1986.  

The concept of the RNA world was first proposed in 1962 by Alexander Rich, and the term was coined by Walter Gilbert in 1986.  

RNA世界的概念是由亚历山大-里奇Alexander Rich在1962年首次提出的<ref>{{cite journal |last1=Neveu |first1=Marc |last2=Kim |first2=Hyo-Joong |last3=Benner |first3=Steven A. |date=22 April 2013 |title=The 'Strong' RNA World Hypothesis: Fifty Years Old |journal=Astrobiology |volume=13 |issue=4 |pages=391–403 |bibcode=2013AsBio..13..391N |doi=10.1089/ast.2012.0868 |pmid=23551238 |ref=harv}}</ref> ，而这个术语则是由沃尔特-吉尔伯特Walter Gilbert在1986年创造的。<ref name="Cech2012">{{cite journal |last=Cech |first=Thomas R. |authorlink=Thomas Cech |date=July 2012 |title=The RNA Worlds in Context |journal=Cold Spring Harbor Perspectives in Biology |volume=4 |issue=7 |page=a006742 |doi=10.1101/cshperspect.a006742 |pmc=3385955 |pmid=21441585}}</ref><ref>{{cite journal |last=Gilbert |first=Walter |authorlink=Walter Gilbert |date=20 February 1986 |title=Origin of life: The RNA world |journal=Nature |volume=319 |issue=6055 |page=618 |bibcode=1986Natur.319..618G |doi=10.1038/319618a0 |s2cid=8026658 }}</ref>  

RNA世界的概念是由亚历山大·里奇Alexander Rich在1962年首次提出的<ref>{{cite journal |last1=Neveu |first1=Marc |last2=Kim |first2=Hyo-Joong |last3=Benner |first3=Steven A. |date=22 April 2013 |title=The 'Strong' RNA World Hypothesis: Fifty Years Old |journal=Astrobiology |volume=13 |issue=4 |pages=391–403 |bibcode=2013AsBio..13..391N |doi=10.1089/ast.2012.0868 |pmid=23551238 |ref=harv}}</ref> ，而这个术语则是由沃尔特·吉尔伯特Walter Gilbert在1986年创造的。<ref name="Cech2012">{{cite journal |last=Cech |first=Thomas R. |authorlink=Thomas Cech |date=July 2012 |title=The RNA Worlds in Context |journal=Cold Spring Harbor Perspectives in Biology |volume=4 |issue=7 |page=a006742 |doi=10.1101/cshperspect.a006742 |pmc=3385955 |pmid=21441585}}</ref><ref>{{cite journal |last=Gilbert |first=Walter |authorlink=Walter Gilbert |date=20 February 1986 |title=Origin of life: The RNA world |journal=Nature |volume=319 |issue=6055 |page=618 |bibcode=1986Natur.319..618G |doi=10.1038/319618a0 |s2cid=8026658 }}</ref>  

In March 2020, astronomer Tomonori Totani presented a statistical approach for explaining how an initial active RNA molecule might have been produced randomly in the [[universe]] sometime since the [[Big Bang]].<ref name="UT-20200310">{{cite news |last=Gough |first=Evan |title=Life Could be Common Across the Universe, Just Not in Our Region |url=https://www.universetoday.com/145304/life-could-be-common-across-the-universe-just-not-in-our-region/ |date=10 March 2020 |work=[[Universe Today]] |accessdate=15 March 2020 }}</ref><ref name="SR-20200203">{{cite journal |last=Totani |first=Tomonori |title=Emergence of life in an inflationary universe |date=3 February 2020 |journal=[[Scientific Reports]] |volume=10 |number=1671 |pages=1671 |doi=10.1038/s41598-020-58060-0 |pmid=32015390 |pmc=6997386 |arxiv=1911.08092 |bibcode=2020NatSR..10.1671T |doi-access=free }}</ref>

In March 2020, astronomer Tomonori Totani presented a statistical approach for explaining how an initial active RNA molecule might have been produced randomly in the [[universe]] sometime since the [[Big Bang]].<ref name="UT-20200310">{{cite news |last=Gough |first=Evan |title=Life Could be Common Across the Universe, Just Not in Our Region |url=https://www.universetoday.com/145304/life-could-be-common-across-the-universe-just-not-in-our-region/ |date=10 March 2020 |work=[[Universe Today]] |accessdate=15 March 2020 }}</ref><ref name="SR-20200203">{{cite journal |last=Totani |first=Tomonori |title=Emergence of life in an inflationary universe |date=3 February 2020 |journal=[[Scientific Reports]] |volume=10 |number=1671 |pages=1671 |doi=10.1038/s41598-020-58060-0 |pmid=32015390 |pmc=6997386 |arxiv=1911.08092 |bibcode=2020NatSR..10.1671T |doi-access=free }}</ref>

In March 2020, astronomer Tomonori Totani presented a statistical approach for explaining how an initial active RNA molecule might have been produced randomly in the universe sometime since the Big Bang.

In March 2020, astronomer Tomonori Totani presented a statistical approach for explaining how an initial active RNA molecule might have been produced randomly in the universe sometime since the Big Bang.

在2020年3月，天文学家Tomonori Totani提出了一种统计方法，用于解释初始的活性RNA分子是如何在宇宙大爆炸后某个时间随机产生的。<ref name="UT-20200310">{{cite news |last=Gough |first=Evan |title=Life Could be Common Across the Universe, Just Not in Our Region |url=https://www.universetoday.com/145304/life-could-be-common-across-the-universe-just-not-in-our-region/ |date=10 March 2020 |work=[[Universe Today]] |accessdate=15 March 2020 }}</ref><ref name="SR-20200203">{{cite journal |last=Totani |first=Tomonori |title=Emergence of life in an inflationary universe |date=3 February 2020 |journal=[[Scientific Reports]] |volume=10 |number=1671 |pages=1671 |doi=10.1038/s41598-020-58060-0 |pmid=32015390 |pmc=6997386 |arxiv=1911.08092 |bibcode=2020NatSR..10.1671T |doi-access=free }}</ref>

在2020年3月，天文学家户谷友则 Tomonori Totani提出了一种统计方法，用于解释初始的活性RNA分子是如何在宇宙大爆炸后某个时间随机产生的。<ref name="UT-20200310">{{cite news |last=Gough |first=Evan |title=Life Could be Common Across the Universe, Just Not in Our Region |url=https://www.universetoday.com/145304/life-could-be-common-across-the-universe-just-not-in-our-region/ |date=10 March 2020 |work=[[Universe Today]] |accessdate=15 March 2020 }}</ref><ref name="SR-20200203">{{cite journal |last=Totani |first=Tomonori |title=Emergence of life in an inflationary universe |date=3 February 2020 |journal=[[Scientific Reports]] |volume=10 |number=1671 |pages=1671 |doi=10.1038/s41598-020-58060-0 |pmid=32015390 |pmc=6997386 |arxiv=1911.08092 |bibcode=2020NatSR..10.1671T |doi-access=free }}</ref>

===系统发育和最后的普遍共同祖先 Phylogeny and LUCA===

===系统发育和最后的普遍共同祖先 Phylogeny and LUCA===

[[File:Phylogenic Tree-en.svg|upright=1.65|thumb|A [[cladistics|cladogram]] demonstrating extreme [[hyperthermophile]]s as occur in volcanic hot springs at the base of the [[Phylogenetic tree|phylogenetic tree of life 甲分支图表明极端超嗜热处的基部作为发生在火山温泉寿命的系统发生树。]]]]

[[File:Phylogenic Tree-en.svg|upright=1.65|thumb|A [[cladistics|cladogram]] demonstrating extreme [[hyperthermophile]]s as occur in volcanic hot springs at the base of the [[Phylogenetic tree|phylogenetic tree of life 一个描述出现在生命系统发育树基部的火山热泉中的极端超嗜热菌的进化分枝图。]]]]

The most commonly accepted location of the root of the tree of life is between a monophyletic domain Bacteria and a clade formed by Archaea and Eukaryota of what is referred to as the "traditional tree of life" based on several molecular studies starting with Carl Woese.

The most commonly accepted location of the root of the tree of life is between a monophyletic domain Bacteria and a clade formed by Archaea and Eukaryota of what is referred to as the "traditional tree of life" based on several molecular studies starting with Carl Woese.

根据从 卡尔·沃斯Carl Woese 开始的一些分子研究，,对于生命树的根部的位置，最普遍接受的观点是位于''一元细菌域和古细菌''和''真核生物''形成的分支之间，这被称为“传统生命树”。<ref>{{cite book |editor1-first=David R. |editor1-last=Boone |editor2-first=Richard W. |editor2-last=Castenholz |editor3-first=George M. |editor3-last=Garrity |title=The ''Archaea'' and the Deeply Branching and Phototrophic ''Bacteria'' |series=Bergey's Manual of Systematic Bacteriology |isbn=978-0-387-21609-6 |url=https://www.springer.com/life+sciences/microbiology/book/978-0-387-98771-2 |url-status=live |archiveurl=https://web.archive.org/web/20141225112809/http://www.springer.com/life+sciences/microbiology/book/978-0-387-98771-2 |archivedate=25 December 2014|publisher=Springer |year=2001 }}{{page needed|date=June 2014}}</ref><ref>{{cite journal |vauthors=Woese CR, Fox GE |title= Phylogenetic structure of the prokaryotic domain: the primary kingdoms. |journal= Proc Natl Acad Sci U S A |volume=74|pages= 5088–5090 |year=1977 |issue= 11 |pmid=270744 |pmc=432104|doi=10.1073/pnas.74.11.5088|bibcode= 1977PNAS...74.5088W }}</ref>

根据从卡尔·沃斯 Carl Woese 开始的一些分子研究，对于生命树的根部的位置，最普遍接受的观点是位于单系域细菌和一个由古细菌和真核生物组成的演化枝之间，这被称为“传统生命树”。<ref>{{cite book |editor1-first=David R. |editor1-last=Boone |editor2-first=Richard W. |editor2-last=Castenholz |editor3-first=George M. |editor3-last=Garrity |title=The ''Archaea'' and the Deeply Branching and Phototrophic ''Bacteria'' |series=Bergey's Manual of Systematic Bacteriology |isbn=978-0-387-21609-6 |url=https://www.springer.com/life+sciences/microbiology/book/978-0-387-98771-2 |url-status=live |archiveurl=https://web.archive.org/web/20141225112809/http://www.springer.com/life+sciences/microbiology/book/978-0-387-98771-2 |archivedate=25 December 2014|publisher=Springer |year=2001 }}{{page needed|date=June 2014}}</ref><ref>{{cite journal |vauthors=Woese CR, Fox GE |title= Phylogenetic structure of the prokaryotic domain: the primary kingdoms. |journal= Proc Natl Acad Sci U S A |volume=74|pages= 5088–5090 |year=1977 |issue= 11 |pmid=270744 |pmc=432104|doi=10.1073/pnas.74.11.5088|bibcode= 1977PNAS...74.5088W }}</ref>

A very small minority of studies have concluded differently, namely that the root is in the domain Bacteria, either in the phylum Firmicutes or’’’<font color=’’#32CD32’’> that the phylum Chloroflexi is basal to a clade with Archaea+Eukaryotes and the rest of Bacteria as proposed by Thomas Cavalier-Smith. </font>’’’More recently, Peter Ward has proposed an alternative view which is rooted in abiotic RNA synthesis which becomes enclosed within a capsule and then creates RNA ribozyme replicates. It is proposed that this then bifurcates between Dominion Ribosa (RNA life), and after the loss of ribozymes RNA viruses as Domain Viorea, and Dominion Terroa, which after creating a large cell within a lipid wall, creating DNA the 20 based amino acids and the triplet code, is established as the last universal common ancestor or LUCA, of earlier phylogenic trees.

A very small minority of studies have concluded differently, namely that the root is in the domain Bacteria, either in the phylum Firmicutes or’’’<font color=’’#32CD32’’> that the phylum Chloroflexi is basal to a clade with Archaea+Eukaryotes and the rest of Bacteria as proposed by Thomas Cavalier-Smith. </font>’’’More recently, Peter Ward has proposed an alternative view which is rooted in abiotic RNA synthesis which becomes enclosed within a capsule and then creates RNA ribozyme replicates. It is proposed that this then bifurcates between Dominion Ribosa (RNA life), and after the loss of ribozymes RNA viruses as Domain Viorea, and Dominion Terroa, which after creating a large cell within a lipid wall, creating DNA the 20 based amino acids and the triplet code, is established as the last universal common ancestor or LUCA, of earlier phylogenic trees.

有一小部分研究得出了不同的结论，亦即生命树的根部的位置根也许是在细菌域，要么在门厚壁菌，要么是在 托马斯·卡弗利尔-史密斯Thomas Cavalier-Smith 所提出的氯化物门与''古细菌+真核生物''的一个分支和其余的细菌为基础的一个门类。最近，彼得 · 沃德Peter Ward 提出了另一种以非生物的 RNA 合成为基础的观点。这种合成被包裹在一个胶囊中，然后产生 RNA 核糖体。有人提出，这然后在自治核糖体（RNA生命）之间分岔，在失去核酶RNA病毒作为Dominion Viorea，和Dominion Terroa之后，在脂质壁内创造一个大细胞，创造DNA的20个基于氨基酸和三联密码，被确立为早期系统发育树的最后一个普遍共同祖先或LUCA。

极少数的研究得出了不同的结论，即生命树的根部在细菌域中，要么在厚壁菌门中，要么是在绿弯菌门中，是古细菌+真核生物组成的一个演化枝和其余的细菌的基础，按照托马斯·卡弗利尔-史密斯Thomas Cavalier-Smith 所提出的那样。最近，彼得·沃德 Peter Ward 提出了另一种基于非生物的 RNA 合成的观点，该合成被包裹在一个胶囊中，然后产生RNA核酶复制品。有人提出，这然后在核糖核酸主导（RNA生命）之间分岔，在失去核酶RNA后病毒成为病毒主导，在脂质壁内形成一个大隔室，在20种氨基酸和三联子密码基础上形成DNA后成为细胞主导，它被确立为早期系统发育树的最后一个普遍共同祖先或LUCA。

In 2016, a set of 355 genes likely present in the Last Universal Common Ancestor (LUCA) of all organisms living on Earth was identified. A total of 6.1 million prokaryotic protein coding genes from various phylogenic trees were sequenced, identifying 355 protein clusters from amongst 286,514 protein clusters that were probably common to LUCA. The results  

In 2016, a set of 355 genes likely present in the Last Universal Common Ancestor (LUCA) of all organisms living on Earth was identified. A total of 6.1 million prokaryotic protein coding genes from various phylogenic trees were sequenced, identifying 355 protein clusters from amongst 286,514 protein clusters that were probably common to LUCA. The results  

2016年，确定了一组可能存在于生活在地球上的所有生物的最后一个宇宙共同祖先（LUCA）中的355个基因，对来自各种系统发育树的610万个原核生物蛋白编码基因进行了测序，从286,514个蛋白簇中确定了355个可能是LUCA共同的蛋白簇。结果

2016年，一组355个基因被识别为可能存在于生活在地球上的所有生物的最后一个普遍共同祖先（LUCA）中。对来自各种系统发育树的610万个原核生物蛋白编码基因进行了测序，从286,514个蛋白簇中识别了355个蛋白簇，它们很可能是LUCA共有的。结果

  | doi = 10.1016/0079-6107(95)00004-7

  | doi = 10.1016/0079-6107(95)00004-7

< blockquote >. . . depict LUCA as anaerobic, CO₂-fixing, H₂-dependent with a Wood–Ljungdahl pathway, N₂-fixing and thermophilic. LUCA's biochemistry was replete with FeS clusters and radical reaction mechanisms. Its cofactors reveal dependence upon transition metals, flavins, S-adenosyl methionine, coenzyme A, ferredoxin, molybdopterin, corrins and selenium. Its genetic code required nucleoside modifications and S-adenosylmethionine-dependent methylations."  

< blockquote >. . . depict LUCA as anaerobic, CO₂-fixing, H₂-dependent with a Wood–Ljungdahl pathway, N₂-fixing and thermophilic. LUCA's biochemistry was replete with FeS clusters and radical reaction mechanisms. Its cofactors reveal dependence upon transition metals, flavins, S-adenosyl methionine, coenzyme A, ferredoxin, molybdopterin, corrins and selenium. Its genetic code required nucleoside modifications and S-adenosylmethionine-dependent methylations."  

..说明LUCA是厌氧的、固定二氧化碳的、依赖H2的、具有Wood-Ljungdahl途径的、固定N2的和嗜热的。LUCA的生物化学中充斥着FeS簇和自由基反应机制。它的辅助因子揭示了对过渡金属、黄素、S-腺苷蛋氨酸、辅酶A、铁氧化还原蛋白、亚钼嘌呤、柯啉环和硒的依赖性。其遗传密码需要核苷修饰和S-腺苷蛋氨酸依赖的甲基化"。

..说明LUCA是厌氧的、固定二氧化碳的、氢气依赖的且具有Wood-Ljungdahl通路的、固定氮气的和嗜热的。LUCA的生物化学中充斥着FeS簇和自由基反应机制。它的辅因子揭示了对过渡金属、黄素、S-腺苷甲硫氨酸、辅酶A、铁氧化还原蛋白、钼蝶呤、柯啉环和硒的依赖性。其遗传密码需要核苷修饰和S-腺苷甲硫氨酸依赖的甲基化"。

  | pmid = 7542789

  | pmid = 7542789

< /blockquote >The results depict methanogenic clostridia as a basal clade in the 355 phylogenies examined, and suggest that LUCA inhabited an anaerobic hydrothermal vent setting in a geochemically active environment rich in H₂, CO₂ and iron.

< /blockquote >The results depict methanogenic clostridia as a basal clade in the 355 phylogenies examined, and suggest that LUCA inhabited an anaerobic hydrothermal vent setting in a geochemically active environment rich in H₂, CO₂ and iron.

  | issue = 2

  | issue = 2

A study at the University of Düsseldorf created phylogenic trees based upon 6 million genes from bacteria and archaea, and identified 355 protein families that were probably present in the LUCA. They were based upon an anaerobic metabolism fixing carbon dioxide and nitrogen. It suggests that the LUCA evolved in an environment rich in hydrogen, carbon dioxide and iron.

A study at the University of Düsseldorf created phylogenic trees based upon 6 million genes from bacteria and archaea, and identified 355 protein families that were probably present in the LUCA. They were based upon an anaerobic metabolism fixing carbon dioxide and nitrogen. It suggests that the LUCA evolved in an environment rich in hydrogen, carbon dioxide and iron.

杜塞尔多夫大学的一项研究基于细菌和古生菌的600万个基因创建了系统发育树，并确定了可能存在于 LUCA 中的355个蛋白质家族。它们是基于一种固定二氧化碳和氮的厌氧代谢。这表明LUCA是在一个富含氢、二氧化碳和铁的环境中进化的。

杜塞尔多夫大学的一项研究基于细菌和古细菌的600万个基因创建了系统发育树，并识别出了很可能存在于 LUCA 中的355个蛋白质家族。它们是基于一种固定二氧化碳和氮的厌氧代谢。这表明LUCA是在一个富含氢、二氧化碳和铁的环境中进化的。

===Key issues in abiogenesis===

===Key issues in abiogenesis===

====What came first: protein or nucleic acids?====

====What came first: protein or nucleic acids?====

Possible precursors for the evolution of protein synthesis include a mechanism to synthesize short peptide cofactors or form a mechanism for the duplication of RNA. It is likely that the ancestral ribosome was composed entirely of RNA, although some roles have since been taken over by proteins. Major remaining questions on this topic include identifying the selective force for the evolution of the ribosome and determining how the [[genetic code]] arose.<ref name="Noller2012">{{cite journal |last=Noller |first=Harry F. |authorlink=Harry F. Noller |date=April 2012 |title=Evolution of protein synthesis from an RNA world. |journal=Cold Spring Harbor Perspectives in Biology |volume=4 |issue=4 |page=a003681 |doi=10.1101/cshperspect.a003681 |pmc=3312679 |pmid=20610545}}</ref>

Possible precursors for the evolution of protein synthesis include a mechanism to synthesize short peptide cofactors or form a mechanism for the duplication of RNA. It is likely that the ancestral ribosome was composed entirely of RNA, although some roles have since been taken over by proteins. Major remaining questions on this topic include identifying the selective force for the evolution of the ribosome and determining how the [[genetic code]] arose.<ref name="Noller2012">{{cite journal |last=Noller |first=Harry F. |authorlink=Harry F. Noller |date=April 2012 |title=Evolution of protein synthesis from an RNA world. |journal=Cold Spring Harbor Perspectives in Biology |volume=4 |issue=4 |page=a003681 |doi=10.1101/cshperspect.a003681 |pmc=3312679 |pmid=20610545}}</ref>

Possible precursors for the evolution of protein synthesis include a mechanism to synthesize short peptide cofactors or form a mechanism for the duplication of RNA. It is likely that the ancestral ribosome was composed entirely of RNA, although some roles have since been taken over by proteins. Major remaining questions on this topic include identifying the selective force for the evolution of the ribosome and determining how the genetic code arose.

Possible precursors for the evolution of protein synthesis include a mechanism to synthesize short peptide cofactors or form a mechanism for the duplication of RNA. It is likely that the ancestral ribosome was composed entirely of RNA, although some roles have since been taken over by proteins. Major remaining questions on this topic include identifying the selective force for the evolution of the ribosome and determining how the genetic code arose.

  | volume = 36

  | volume = 36

Eugene Koonin said, < blockquote >Despite considerable experimental and theoretical effort, no compelling scenarios currently exist for the origin of replication and translation, the key processes that together comprise the core of biological systems and the apparent pre-requisite of biological evolution. The RNA World concept might offer the best chance for the resolution of this conundrum but so far cannot adequately account for the emergence of an efficient RNA replicase or the translation system. The MWO ["many worlds in one"] version of the cosmological model of eternal inflation could suggest a way out of this conundrum because, in an infinite multiverse with a finite number of distinct macroscopic histories (each repeated an infinite number of times), emergence of even highly complex systems by chance is not just possible but inevitable.< /blockquote >

Eugene Koonin said, < blockquote >Despite considerable experimental and theoretical effort, no compelling scenarios currently exist for the origin of replication and translation, the key processes that together comprise the core of biological systems and the apparent pre-requisite of biological evolution. The RNA World concept might offer the best chance for the resolution of this conundrum but so far cannot adequately account for the emergence of an efficient RNA replicase or the translation system. The MWO ["many worlds in one"] version of the cosmological model of eternal inflation could suggest a way out of this conundrum because, in an infinite multiverse with a finite number of distinct macroscopic histories (each repeated an infinite number of times), emergence of even highly complex systems by chance is not just possible but inevitable.< /blockquote >

尤金-库宁Eugene Koonin 说，

尤金·库宁Eugene Koonin 说，

< blockquote >

< blockquote >

尽管在实验和理论上做了大量的努力，但对于复制和翻译的起源，目前还没有令人信服的设想，而复制和翻译是构成生物系统核心的关键过程，也是生物进化的明显先决条件。RNA世界概念可能为这一难题的解决提供了最好的机会，但迄今为止还不能充分说明高效RNA复制酶或翻译系统的出现。MWO["多世界合一"]版本的永恒膨胀的宇宙学模型可以提出解决这一难题的方法，因为在一个无限的多元宇宙中，有有限数量的不同的宏观历史（每个历史重复无限次），即使是高度复杂的系统也是偶然出现的，这不仅是可能的，而且是不可避免的

尽管在实验和理论上做了大量的努力，但对于复制和翻译的起源，目前还没有令人信服的设想，而复制和翻译是共同构成了生物系统核心的关键过程，也是生物进化的明显先决条件。RNA世界概念可能为这一难题的解决提供了最好的机会，但迄今为止还不能充分说明高效RNA复制酶或翻译系统的出现。MWO["多世界合一"]版本的永恒膨胀的宇宙模型可能提出了解决这一难题的方法，因为在一个无限的多元宇宙中，有有限数量的不同的宏观历史（每个历史重复无限次），即使是高度复杂的系统的偶然出现，不仅是可能的，而且是不可避免的。

</blockquote >

</blockquote >

Homochirality refers to a geometric uniformity of some materials composed of chiral units. Chiral refers to nonsuperimposable 3D forms that are mirror images of one another, as are left and right hands. Living organisms use molecules that have the same chirality ("handedness"): with almost no exceptions, amino acids are left-handed while nucleotides and sugars are right-handed. Chiral molecules can be synthesized, but in the absence of a chiral source or a chiral catalyst, they are formed in a 50/50 mixture of both enantiomers (called a racemic mixture). Known mechanisms for the production of non-racemic mixtures from racemic starting materials include: asymmetric physical laws, such as the electroweak interaction; asymmetric environments, such as those caused by circularly polarized light, quartz crystals, or the Earth's rotation, statistical fluctuations during racemic synthesis, and spontaneous symmetry breaking.

Homochirality refers to a geometric uniformity of some materials composed of chiral units. Chiral refers to nonsuperimposable 3D forms that are mirror images of one another, as are left and right hands. Living organisms use molecules that have the same chirality ("handedness"): with almost no exceptions, amino acids are left-handed while nucleotides and sugars are right-handed. Chiral molecules can be synthesized, but in the absence of a chiral source or a chiral catalyst, they are formed in a 50/50 mixture of both enantiomers (called a racemic mixture). Known mechanisms for the production of non-racemic mixtures from racemic starting materials include: asymmetric physical laws, such as the electroweak interaction; asymmetric environments, such as those caused by circularly polarized light, quartz crystals, or the Earth's rotation, statistical fluctuations during racemic synthesis, and spontaneous symmetry breaking.

同手性是指某些材料由手性单元组成的几何均匀性。手性是指不可互换的三维形态，它们是彼此的镜像，就像左手和右手一样。生物体使用的分子具有相同的手性（"手性"）：几乎没有例外，氨基酸是左手，而核苷酸和糖类是右手。手性分子可以合成，但在没有手性源或手性催化剂的情况下，它们是以两种对映体50/50的混合物形成的（称为外消旋混合物）。已知从外消旋起始材料产生非外消旋混合物的机制包括：不对称物理规律，如电弱相互作用；不对称环境，如圆偏振光、石英晶体或地球自转引起的环境，外消旋合成过程中的统计波动，以及自发的对称性破坏。

同手性是指由手性单元组成的某些材料的几何均匀性。手性是指不可重叠的三维形态，它们是彼此的镜像，就像左手和右手一样。生物体使用的分子具有相同的手性（"利手性"）：几乎没有例外，氨基酸是左旋的，而核苷酸和糖类是右旋的。手性分子可以合成，但在没有手性源或手性催化剂的情况下，它们是以两种对映体以50/50的混合物（称为外消旋混合物）形成的。已知从外消旋起始原料产生非外消旋混合物的机制包括：非对称物理定律，如弱电相互作用；非对称环境，如圆偏振光、石英晶体或地球自转引起的环境，外消旋合成过程中的统计波动，以及自发的对称性破缺。

Once established, chirality would be selected for.<ref>{{cite journal |last=Clark |first=Stuart |authorlink=Stuart Clark (author) |date=July–August 1999 |title=Polarized Starlight and the Handedness of Life |journal=[[American Scientist]] |volume=87 |issue=4 |page=336 |bibcode=1999AmSci..87..336C |doi=10.1511/1999.4.336}}</ref> A small bias ([[enantiomeric excess]]) in the population can be amplified into a large one by [[Autocatalysis#Asymmetric autocatalysis|asymmetric autocatalysis]], such as in the [[Soai reaction]].<ref>{{cite journal |last1=Shibata |first1=Takanori |last2=Morioka |first2=Hiroshi |last3=Hayase |first3=Tadakatsu |last4=Choji |first4=Kaori |last5=Soai |first5=Kenso |display-authors=3 |date=17 January 1996 |title=Highly Enantioselective Catalytic Asymmetric Automultiplication of Chiral Pyrimidyl Alcohol |journal=Journal of the American Chemical Society |volume=118 |issue=2 |pages=471–472 |doi=10.1021/ja953066g }}</ref> In asymmetric autocatalysis, the catalyst is a chiral molecule, which means that a chiral molecule is catalyzing its own production. An initial enantiomeric excess, such as can be produced by polarized light, then allows the more abundant enantiomer to outcompete the other.<ref name="Soai2001">{{cite journal |last1=Soai |first1=Kenso |last2=Sato |first2=Itaru |last3=Shibata |first3=Takanori |year=2001 |title=Asymmetric autocatalysis and the origin of chiral homogeneity in organic compounds |journal=The Chemical Record |volume=1 |issue=4 |pages=321–332 |doi=10.1002/tcr.1017 |pmid=11893072}}</ref>

Once established, chirality would be selected for.<ref>{{cite journal |last=Clark |first=Stuart |authorlink=Stuart Clark (author) |date=July–August 1999 |title=Polarized Starlight and the Handedness of Life |journal=[[American Scientist]] |volume=87 |issue=4 |page=336 |bibcode=1999AmSci..87..336C |doi=10.1511/1999.4.336}}</ref> A small bias ([[enantiomeric excess]]) in the population can be amplified into a large one by [[Autocatalysis#Asymmetric autocatalysis|asymmetric autocatalysis]], such as in the [[Soai reaction]].<ref>{{cite journal |last1=Shibata |first1=Takanori |last2=Morioka |first2=Hiroshi |last3=Hayase |first3=Tadakatsu |last4=Choji |first4=Kaori |last5=Soai |first5=Kenso |display-authors=3 |date=17 January 1996 |title=Highly Enantioselective Catalytic Asymmetric Automultiplication of Chiral Pyrimidyl Alcohol |journal=Journal of the American Chemical Society |volume=118 |issue=2 |pages=471–472 |doi=10.1021/ja953066g }}</ref> In asymmetric autocatalysis, the catalyst is a chiral molecule, which means that a chiral molecule is catalyzing its own production. An initial enantiomeric excess, such as can be produced by polarized light, then allows the more abundant enantiomer to outcompete the other.<ref name="Soai2001">{{cite journal |last1=Soai |first1=Kenso |last2=Sato |first2=Itaru |last3=Shibata |first3=Takanori |year=2001 |title=Asymmetric autocatalysis and the origin of chiral homogeneity in organic compounds |journal=The Chemical Record |volume=1 |issue=4 |pages=321–332 |doi=10.1002/tcr.1017 |pmid=11893072}}</ref>

Once established, chirality would be selected for. A small bias (enantiomeric excess) in the population can be amplified into a large one by asymmetric autocatalysis, such as in the Soai reaction. In asymmetric autocatalysis, the catalyst is a chiral molecule, which means that a chiral molecule is catalyzing its own production. An initial enantiomeric excess, such as can be produced by polarized light, then allows the more abundant enantiomer to outcompete the other.

Once established, chirality would be selected for. A small bias (enantiomeric excess) in the population can be amplified into a large one by asymmetric autocatalysis, such as in the Soai reaction. In asymmetric autocatalysis, the catalyst is a chiral molecule, which means that a chiral molecule is catalyzing its own production. An initial enantiomeric excess, such as can be produced by polarized light, then allows the more abundant enantiomer to outcompete the other.

Clark has suggested that homochirality may have started in outer space, as the studies of the amino acids on the [[Murchison meteorite]] showed that [[Alanine|L-alanine]] is more than twice as frequent as its D form, and [[Glutamic acid|L-glutamic acid]] was more than three times prevalent than its D counterpart. Various chiral crystal surfaces can also act as sites for possible concentration and assembly of chiral monomer units into macromolecules.<ref>{{harvnb|Hazen|2005|p=184}}</ref><ref name=Meierhenrich>{{cite book|last1=Meierhenrich|first1=Uwe|title=Amino acids and the asymmetry of life caught in the act of formation|date=2008|publisher=Springer|location=Berlin|isbn=978-3540768869|pages=76–79}}</ref> Compounds found on meteorites suggest that the chirality of life derives from abiogenic synthesis, since amino acids from meteorites show a left-handed bias, whereas sugars show a predominantly right-handed bias, the same as found in living organisms.<ref name=StarStuff>{{cite journal |last=Mullen |first=Leslie |date=5 September 2005 |title=Building Life from Star-Stuff |url=http://www.astrobio.net/news-exclusive/building-life-from-star-stuff/ |journal=[[Astrobiology Magazine]] |accessdate=2015-06-15 |url-status=live |archiveurl=https://web.archive.org/web/20150714084344/http://www.astrobio.net/news-exclusive/building-life-from-star-stuff/ |archivedate=14 July 2015}}</ref>

Clark has suggested that homochirality may have started in outer space, as the studies of the amino acids on the [[Murchison meteorite]] showed that [[Alanine|L-alanine]] is more than twice as frequent as its D form, and [[Glutamic acid|L-glutamic acid]] was more than three times prevalent than its D counterpart. Various chiral crystal surfaces can also act as sites for possible concentration and assembly of chiral monomer units into macromolecules.<ref>{{harvnb|Hazen|2005|p=184}}</ref><ref name=Meierhenrich>{{cite book|last1=Meierhenrich|first1=Uwe|title=Amino acids and the asymmetry of life caught in the act of formation|date=2008|publisher=Springer|location=Berlin|isbn=978-3540768869|pages=76–79}}</ref> Compounds found on meteorites suggest that the chirality of life derives from abiogenic synthesis, since amino acids from meteorites show a left-handed bias, whereas sugars show a predominantly right-handed bias, the same as found in living organisms.<ref name=StarStuff>{{cite journal |last=Mullen |first=Leslie |date=5 September 2005 |title=Building Life from Star-Stuff |url=http://www.astrobio.net/news-exclusive/building-life-from-star-stuff/ |journal=[[Astrobiology Magazine]] |accessdate=2015-06-15 |url-status=live |archiveurl=https://web.archive.org/web/20150714084344/http://www.astrobio.net/news-exclusive/building-life-from-star-stuff/ |archivedate=14 July 2015}}</ref>

Clark has suggested that homochirality may have started in outer space, as the studies of the amino acids on the Murchison meteorite showed that L-alanine is more than twice as frequent as its D form, and L-glutamic acid was more than three times prevalent than its D counterpart. Various chiral crystal surfaces can also act as sites for possible concentration and assembly of chiral monomer units into macromolecules. Compounds found on meteorites suggest that the chirality of life derives from abiogenic synthesis, since amino acids from meteorites show a left-handed bias, whereas sugars show a predominantly right-handed bias, the same as found in living organisms.

Clark has suggested that homochirality may have started in outer space, as the studies of the amino acids on the Murchison meteorite showed that L-alanine is more than twice as frequent as its D form, and L-glutamic acid was more than three times prevalent than its D counterpart. Various chiral crystal surfaces can also act as sites for possible concentration and assembly of chiral monomer units into macromolecules. Compounds found on meteorites suggest that the chirality of life derives from abiogenic synthesis, since amino acids from meteorites show a left-handed bias, whereas sugars show a predominantly right-handed bias, the same as found in living organisms.

Clark认为，同手性可能始于外太空，因为对默奇森 Murchison陨石上氨基酸的研究表明，L-丙氨酸是其D形式的两倍多，L-谷氨酸是其D形式的三倍多。各种手性晶体表面也可以作为手性单体单元可能集中和组装成大分子的场所.在陨石上发现的化合物表明，生命的手性来源于非生物合成，因为陨石上的氨基酸表现出左手偏向，而糖类则主要表现出右手偏向，这与生物体中发现的情况相同。

克拉克 Clark认为，同手性可能始于外太空，因为对默奇森 Murchison陨石上氨基酸的研究表明，L-丙氨酸的出现频率是其D形式的两倍多，L-谷氨酸是其D形式的三倍多。各种手性晶体表面也可以作为手性单体单元可能集中和组装成大分子的场所。在陨石上发现的化合物表明，生命的手性来源于非生物合成，因为陨石上的氨基酸表现出左手旋偏向，而糖类则主要表现出右手旋偏向，这与在生物体中发现的相同。

===Early universe with first stars===

===Early universe with first stars===

Soon after the Big Bang, which occurred roughly 14 Gya, the only chemical elements present in the universe were hydrogen, helium, and lithium, the three lightest atoms in the periodic table. These elements gradually came together to form stars. These early stars were massive and short-lived, producing heavier elements through stellar nucleosynthesis. Carbon, currently the fourth most abundant chemical element in the universe (after hydrogen, helium and oxygen), was formed mainly in white dwarf stars, particularly those bigger than two solar masses.

Soon after the Big Bang, which occurred roughly 14 Gya, the only chemical elements present in the universe were hydrogen, helium, and lithium, the three lightest atoms in the periodic table. These elements gradually came together to form stars. These early stars were massive and short-lived, producing heavier elements through stellar nucleosynthesis. Carbon, currently the fourth most abundant chemical element in the universe (after hydrogen, helium and oxygen), was formed mainly in white dwarf stars, particularly those bigger than two solar masses.

As these stars reached the end of their [[Stellar life cycle|lifecycles]], they ejected these heavier elements, among them carbon and oxygen, throughout the universe. These heavier elements allowed for the formation of new objects, including rocky planets and other bodies.<ref>{{Cite web | url=https://wmap.gsfc.nasa.gov/universe/uni_life.html |title = WMAP- Life in the Universe}}</ref>

As these stars reached the end of their [[Stellar life cycle|lifecycles]], they ejected these heavier elements, among them carbon and oxygen, throughout the universe. These heavier elements allowed for the formation of new objects, including rocky planets and other bodies.<ref>{{Cite web | url=https://wmap.gsfc.nasa.gov/universe/uni_life.html |title = WMAP- Life in the Universe}}</ref>

As these stars reached the end of their lifecycles, they ejected these heavier elements, among them carbon and oxygen, throughout the universe. These heavier elements allowed for the formation of new objects, including rocky planets and other bodies.

As these stars reached the end of their lifecycles, they ejected these heavier elements, among them carbon and oxygen, throughout the universe. These heavier elements allowed for the formation of new objects, including rocky planets and other bodies.

===Emergence of the Solar System===

===Emergence of the Solar System===

According to the nebular hypothesis, the formation and evolution of the Solar System began 4.6 Gya with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed.

According to the nebular hypothesis, the formation and evolution of the Solar System began 4.6 Gya with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed.

===Emergence of Earth===

===Emergence of Earth===

The Earth, formed 4.5 Gya, was at first inhospitable to any living organisms. Based on numerous observations and studies of the geological time-scale, the Hadean Earth is thought to have had a secondary atmosphere, formed through degassing of the rocks that accumulated from planetesimal impactors. At first, it was thought that the Earth's atmosphere consisted of hydrogen compounds—methane, ammonia and Water vapor—and that life began under such reducing conditions, which are conducive to the formation of organic molecules. According to later models, suggested by studying ancient minerals, the atmosphere in the late Hadean period consisted largely of water vapor, nitrogen and carbon dioxide, with smaller amounts of carbon monoxide, hydrogen, and sulfur compounds. During its formation, the Earth lost a significant part of its initial mass, with a nucleus of the heavier rocky elements of the protoplanetary disk remaining. As a consequence, Earth lacked the gravity to hold any molecular hydrogen in its atmosphere, and rapidly lost it during the Hadean period, along with the bulk of the original inert gases. The solution of carbon dioxide in water is thought to have made the seas slightly acidic, giving them a pH of about 5.5. The atmosphere at the time has been characterized as a "gigantic, productive outdoor chemical laboratory."

The Earth, formed 4.5 Gya, was at first inhospitable to any living organisms. Based on numerous observations and studies of the geological time-scale, the Hadean Earth is thought to have had a secondary atmosphere, formed through degassing of the rocks that accumulated from planetesimal impactors. At first, it was thought that the Earth's atmosphere consisted of hydrogen compounds—methane, ammonia and Water vapor—and that life began under such reducing conditions, which are conducive to the formation of organic molecules. According to later models, suggested by studying ancient minerals, the atmosphere in the late Hadean period consisted largely of water vapor, nitrogen and carbon dioxide, with smaller amounts of carbon monoxide, hydrogen, and sulfur compounds. During its formation, the Earth lost a significant part of its initial mass, with a nucleus of the heavier rocky elements of the protoplanetary disk remaining. As a consequence, Earth lacked the gravity to hold any molecular hydrogen in its atmosphere, and rapidly lost it during the Hadean period, along with the bulk of the original inert gases. The solution of carbon dioxide in water is thought to have made the seas slightly acidic, giving them a pH of about 5.5. The atmosphere at the time has been characterized as a "gigantic, productive outdoor chemical laboratory."

形成于45亿年前的地球，起初是不适合任何生物体生存的。根据对地质学时间尺度的大量观察和研究，人们认为冥古代地球曾有过一个次级大气层，是通过行星撞击物所积累的岩石脱气而形成的。起初，人们认为地球的大气层由氢化合物--甲烷、氨和水蒸气组成，生命就是在这种有利于有机分子形成的还原条件下开始的。根据后来的模型，通过对古代矿物的研究提出，冥古代晚期的大气层主要由水蒸气、氮气和二氧化碳组成，还有少量的一氧化碳、氢气和硫化合物。在地球形成过程中，地球失去了其初始质量的很大一部分，原行星盘中较重的岩石元素核仍然存在。因此，地球缺乏重力，无法在大气层中容纳任何氢分子，并且在冥古代迅速失去了氢气，同时失去了大部分的原始惰性气体.。二氧化碳在水中形成的溶液被认为使海洋呈微酸性，使海洋的pH值约为5.5。当时的大气层被描述为 "巨大的、富有成效的室外化学实验室。"它可能与今天火山释放的混合气体相似，它仍然支持一些非生物化学。

地球，形成于45亿年前，起初是不适合任何生物体生存的。根据对地质学时间尺度的大量观察和研究，人们认为冥古代地球曾有过一个次级大气层，是通过小行星撞击物所积累的岩石脱气而形成的。起初，人们认为地球的大气层由氢化合物——甲烷、氨和水蒸气组成，生命就是在这种有利于有机分子形成的还原性条件下开始的。根据后来的模型，通过对古代矿物的研究提出，冥古代晚期的大气层主要由水蒸气、氮气和二氧化碳组成，还有少量的一氧化碳、氢气和硫化合物。在地球形成过程中，地球失去了其初始质量的很大一部分，原行星盘中较重的岩石元素组成的核仍然存在。因此，地球缺乏在大气层中容纳任何氢分子的引力，并且在冥古代迅速失去了它，以及大部分的原始惰性气体.。二氧化碳在水中形成的溶液被认为使海洋呈微酸性，使海洋的pH值约为5.5。当时的大气层被描述为 "巨大的、高产的露天化学实验室。"***缺乏对应英文：它可能与今天火山释放的混合气体相似，它仍然支持一些非生物化学。***

===Emergence of the ocean===

===Emergence of the ocean===

Oceans may have appeared first in the Hadean Eon, as soon as 200 My after the Earth formed, in a hot, 100 C, reducing environment, and the pH of about 5.8 rose rapidly towards neutral.This scenario has found support from the dating of 4.404  Gyo zircon crystals from metamorphosed quartzite of Mount Narryer in the Western Australia Jack Hills of the Pilbara, which provide evidence that oceans and continental crust existed within 150 Ma of Earth's formation.Despite the likely increased volcanism and existence of many smaller tectonic "platelets," it has been suggested that between 4.4-4.3 Gyo, the Earth was a water world, with little if any continental crust, an extremely turbulent atmosphere and a hydrosphere subject to intense ultraviolet (UV) light, from a T Tauri stage Sun, cosmic radiation and continued bolide impacts.

Oceans may have appeared first in the Hadean Eon, as soon as 200 My after the Earth formed, in a hot, 100 C, reducing environment, and the pH of about 5.8 rose rapidly towards neutral.This scenario has found support from the dating of 4.404  Gyo zircon crystals from metamorphosed quartzite of Mount Narryer in the Western Australia Jack Hills of the Pilbara, which provide evidence that oceans and continental crust existed within 150 Ma of Earth's formation.Despite the likely increased volcanism and existence of many smaller tectonic "platelets," it has been suggested that between 4.4-4.3 Gyo, the Earth was a water world, with little if any continental crust, an extremely turbulent atmosphere and a hydrosphere subject to intense ultraviolet (UV) light, from a T Tauri stage Sun, cosmic radiation and continued bolide impacts.

海洋可能最早出现在冥古宙，即地球形成后的200多年，在100摄氏度的高温的还原性环境中，pH值约为5.8，迅速上升到中性。这一假设的在来自西澳大利亚皮尔巴拉杰克山纳瑞耶山的44.04亿年前的锆石晶体的年代测定中得到了支持，它提供了地球形成后15000万年前内存在海洋和大陆地壳的证据。 尽管可能增加了火山活动，并存在许多较小的构造 "板块"，但有人认为，在44-43亿年前之间，地球是一个水世界，几乎没有大陆地壳，大气层极度动荡，水圈受到强烈的紫外线(UV)，来自T 金牛座阶段的太阳、宇宙辐射和持续的巨浪撞击。

海洋可能最早出现在冥古宙，即地球形成后的2亿年，在一个100 C的高温的还原性环境中，pH值约为5.8，迅速上升到中性。这一假设已经得到了来自澳大利亚西部纳里尔山变质石英岩的4.404 Gyo锆石晶体的年代测定的支持。这一设想已经得到了来自澳大利亚西部的皮尔巴拉的杰克高地的纳瑞耶山的变质石英岩的44.04亿年前的锆石晶体的年代测定的支持，它提供了地球形成后1.5亿年前内存在海洋和大陆地壳的证据。尽管可能增加了火山活动，并存在许多较小的构造 "板块"，但有人认为，在44-43亿年之间，地球是一个水世界，几乎没有大陆地壳，大气层极度动荡，水圈受到来自T金牛座阶段的太阳的强烈的紫外线(UV)照射、宇宙辐射和持续的天体撞击。

===Late heavy bombardment===

===Late heavy bombardment===

The Hadean environment would have been highly hazardous to modern life. Frequent collisions with large objects, up to 500&nbsp;km in diameter, would have been sufficient to sterilize the planet and vaporize the oceans within a few months of impact, with hot steam mixed with rock vapor becoming high altitude clouds that would completely cover the planet. After a few months, the height of these clouds would have begun to decrease but the cloud base would still have been elevated for about the next thousand years. After that, it would have begun to rain at low altitude. For another two thousand years, rains would slowly have drawn down the height of the clouds, returning the oceans to their original depth only 3,000&nbsp;y after the impact event.<ref>{{cite journal |last1=Sleep |first1=Norman H. |last2=Zahnle |first2=Kevin J. |authorlink2=Kevin J. Zahnle |last3=Kasting |first3=James F. |last4=Morowitz |first4=Harold J. |authorlink4=Harold J. Morowitz |display-authors=3 |date=9 November 1989 |title=Annihilation of ecosystems by large asteroid impacts on early Earth |journal=Nature |volume=342 |issue=6246|pages=139–142 |url=https://www.researchgate.net/publication/11809063|bibcode=1989Natur.342..139S |doi=10.1038/342139a0 |pmid=11536616|s2cid=1137852 }}</ref>

The Hadean environment would have been highly hazardous to modern life. Frequent collisions with large objects, up to 500&nbsp;km in diameter, would have been sufficient to sterilize the planet and vaporize the oceans within a few months of impact, with hot steam mixed with rock vapor becoming high altitude clouds that would completely cover the planet. After a few months, the height of these clouds would have begun to decrease but the cloud base would still have been elevated for about the next thousand years. After that, it would have begun to rain at low altitude. For another two thousand years, rains would slowly have drawn down the height of the clouds, returning the oceans to their original depth only 3,000&nbsp;y after the impact event.<ref>{{cite journal |last1=Sleep |first1=Norman H. |last2=Zahnle |first2=Kevin J. |authorlink2=Kevin J. Zahnle |last3=Kasting |first3=James F. |last4=Morowitz |first4=Harold J. |authorlink4=Harold J. Morowitz |display-authors=3 |date=9 November 1989 |title=Annihilation of ecosystems by large asteroid impacts on early Earth |journal=Nature |volume=342 |issue=6246|pages=139–142 |url=https://www.researchgate.net/publication/11809063|bibcode=1989Natur.342..139S |doi=10.1038/342139a0 |pmid=11536616|s2cid=1137852 }}</ref>

Traditionally it was thought that during the period between 4.28<ref name="NAT-20170301" /><ref name="NYT-20170301" /> and 3.8&nbsp;Gya, changes in the orbits of the [[giant planet]]s may have caused a [[Late Heavy Bombardment|heavy bombardment]] by asteroids and [[comet]]s<ref>{{cite journal |last1=Gomes |first1=Rodney |last2=Levison |first2=Hal F. |authorlink2=Harold F. Levison |last3=Tsiganis |first3=Kleomenis |last4=Morbidelli |first4=Alessandro |authorlink4=Alessandro Morbidelli (astronomer) |date=26 May 2005 |title=Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets |journal=Nature |volume=435 |issue=7041 |pages=466–469 |bibcode=2005Natur.435..466G |doi=10.1038/nature03676 |pmid=15917802|doi-access=free }}</ref> that pockmarked the [[Moon]] and the other inner planets ([[Mercury (planet)|Mercury]], [[Mars]], and presumably Earth and [[Venus]]). This would likely have repeatedly sterilized the planet, had life appeared before that time.<ref name="Follmann2009" /> Geologically, the Hadean Earth would have been far more active than at any other time in its history. Studies of [[meteorite]]s suggests that [[Radionuclide|radioactive isotopes]] such as [[aluminium-26]] with a [[half-life]] of 7.17&nbsp;ky, and [[potassium-40]] with a half-life of 1.25&nbsp;Gy, isotopes mainly produced in [[supernova]]e, were much more common.<ref>{{harvnb|Davies|2007|pp=61–73}}</ref> Internal heating as a result of [[Convection#Gravitational or buoyant convection|gravitational sorting]] between the [[Earth core|core]] and the [[Mantle (geology)|mantle]] would have caused a great deal of [[mantle convection]], with the probable result of many more smaller and more active tectonic plates than now exist.

Traditionally it was thought that during the period between 4.28<ref name="NAT-20170301" /><ref name="NYT-20170301" /> and 3.8&nbsp;Gya, changes in the orbits of the [[giant planet]]s may have caused a [[Late Heavy Bombardment|heavy bombardment]] by asteroids and [[comet]]s<ref>{{cite journal |last1=Gomes |first1=Rodney |last2=Levison |first2=Hal F. |authorlink2=Harold F. Levison |last3=Tsiganis |first3=Kleomenis |last4=Morbidelli |first4=Alessandro |authorlink4=Alessandro Morbidelli (astronomer) |date=26 May 2005 |title=Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets |journal=Nature |volume=435 |issue=7041 |pages=466–469 |bibcode=2005Natur.435..466G |doi=10.1038/nature03676 |pmid=15917802|doi-access=free }}</ref> that pockmarked the [[Moon]] and the other inner planets ([[Mercury (planet)|Mercury]], [[Mars]], and presumably Earth and [[Venus]]). This would likely have repeatedly sterilized the planet, had life appeared before that time.<ref name="Follmann2009" /> Geologically, the Hadean Earth would have been far more active than at any other time in its history. Studies of [[meteorite]]s suggests that [[Radionuclide|radioactive isotopes]] such as [[aluminium-26]] with a [[half-life]] of 7.17&nbsp;ky, and [[potassium-40]] with a half-life of 1.25&nbsp;Gy, isotopes mainly produced in [[supernova]]e, were much more common.<ref>{{harvnb|Davies|2007|pp=61–73}}</ref> Internal heating as a result of [[Convection#Gravitational or buoyant convection|gravitational sorting]] between the [[Earth core|core]] and the [[Mantle (geology)|mantle]] would have caused a great deal of [[mantle convection]], with the probable result of many more smaller and more active tectonic plates than now exist.

传统上认为，在42.8亿年前和38亿年前之间的时期，巨行星轨道的变化可能造成了小行星和彗星对月球和其他内行星（水星、火星，大概还有地球和金星）的猛烈轰击。如果生命在那之前出现的话，这很可能会反复地对这个星球进行消毒.从地质学上来说，哈德安地球会比历史上任何其他时间都要活跃得多。对陨石的研究表明，放射性同位素，如半衰期为7.17 ky的铝-26和半衰期为1.25 Gy的钾-40，这些主要产生于超新星的同位素更为常见.由于地核和地幔之间的引力分选而产生的内部加热会引起大量的地幔对流，其结果可能是产生了比现在更小、更活跃的构造板块。

传统上认为，在42.8亿年前到38亿年前之间的时期，巨行星轨道的变化可能造成了小行星和彗星对月球和其他内行星（水星、火星，大概还有地球和金星）的猛烈轰击。如果生命在那之前出现的话，这很可能会使这个星球反复成为不毛之地。从地质学上来说，冥古代地球会比历史上任何其他时间都要活跃得多。对陨石的研究表明，放射性同位素，如半衰期为7.17 千年的铝-26和半衰期为12.5亿年的钾-40，这些主要产生于超新星的同位素更为常见。由于地核和地幔之间的重力分选而产生的内部加热会引起大量的地幔对流，其结果可能是产生了比现在更小、更活跃的构造板块。

The time periods between such devastating environmental events give time windows for the possible origin of life in the early environments. If the deep marine hydrothermal setting was the site for the origin of life, then abiogenesis could have happened as early as 4.0-4.2&nbsp;Gya. If the site was at the surface of the Earth, abiogenesis could only have occurred between 3.7-4.0 Gya.<ref>{{cite journal |last1=Maher |first1=Kevin A. |last2=Stevenson |first2=David J. |date=18 February 1988 |title=Impact frustration of the origin of life |journal=Nature |volume=331 |issue=6157 |pages=612–614 |bibcode=1988Natur.331..612M |doi=10.1038/331612a0 |pmid=11536595|s2cid=4284492 }}</ref>

The time periods between such devastating environmental events give time windows for the possible origin of life in the early environments. If the deep marine hydrothermal setting was the site for the origin of life, then abiogenesis could have happened as early as 4.0-4.2&nbsp;Gya. If the site was at the surface of the Earth, abiogenesis could only have occurred between 3.7-4.0 Gya.<ref>{{cite journal |last1=Maher |first1=Kevin A. |last2=Stevenson |first2=David J. |date=18 February 1988 |title=Impact frustration of the origin of life |journal=Nature |volume=331 |issue=6157 |pages=612–614 |bibcode=1988Natur.331..612M |doi=10.1038/331612a0 |pmid=11536595|s2cid=4284492 }}</ref>

这种破坏性环境事件之间的时间段，为早期环境中生命可能的起源提供了时间窗口。如果深海热液环境是生命起源的场所，那么非生物发生可能早在40-42亿年前就发生了。如果地点在地球表面，那么非生物发生只能发生在37-40亿年前之间。

这种毁灭性的环境事件之间的时间段，为早期环境中可能的生命起源提供了时间窗口。如果深海热液环境是生命起源的场所，那么自然发生可能早在40-42亿年前就发生了。如果地点在地球表面，那么自然发生只能发生在37-40亿年前之间。

Estimates of the production of organics from these sources suggest that the [[Late Heavy Bombardment]] before 3.5&nbsp;Ga within the early atmosphere made available quantities of organics comparable to those produced by terrestrial sources.<ref>{{cite journal |last1=Chyba |first1=Christopher |authorlink=Christopher Chyba |last2=Sagan |first2=Carl |authorlink2=Carl Sagan |date=9 January 1992 |title=Endogenous production, exogenous delivery and impact-shock synthesis of organic molecules: an inventory for the origins of life |journal=Nature |volume=355 |issue=6356 |pages=125–132 |bibcode=1992Natur.355..125C |doi=10.1038/355125a0 |pmid=11538392|s2cid=4346044 }}</ref><ref>{{cite journal |last1=Furukawa |first1=Yoshihiro |last2=Sekine |first2=Toshimori |last3=Oba |first3=Masahiro |last4=Kakegawa |first4=Takeshi |last5=Nakazawa |first5=Hiromoto |display-authors=3 |date=January 2009 |title=Biomolecule formation by oceanic impacts on early Earth |journal=Nature Geoscience |volume=2 |issue=1 |pages=62–66 |bibcode=2009NatGe...2...62F |doi=10.1038/NGEO383}}</ref>

Estimates of the production of organics from these sources suggest that the [[Late Heavy Bombardment]] before 3.5&nbsp;Ga within the early atmosphere made available quantities of organics comparable to those produced by terrestrial sources.<ref>{{cite journal |last1=Chyba |first1=Christopher |authorlink=Christopher Chyba |last2=Sagan |first2=Carl |authorlink2=Carl Sagan |date=9 January 1992 |title=Endogenous production, exogenous delivery and impact-shock synthesis of organic molecules: an inventory for the origins of life |journal=Nature |volume=355 |issue=6356 |pages=125–132 |bibcode=1992Natur.355..125C |doi=10.1038/355125a0 |pmid=11538392|s2cid=4346044 }}</ref><ref>{{cite journal |last1=Furukawa |first1=Yoshihiro |last2=Sekine |first2=Toshimori |last3=Oba |first3=Masahiro |last4=Kakegawa |first4=Takeshi |last5=Nakazawa |first5=Hiromoto |display-authors=3 |date=January 2009 |title=Biomolecule formation by oceanic impacts on early Earth |journal=Nature Geoscience |volume=2 |issue=1 |pages=62–66 |bibcode=2009NatGe...2...62F |doi=10.1038/NGEO383}}</ref>

It has been estimated that the Late Heavy Bombardment may also have effectively sterilized the Earth's surface to a depth of tens of meters. If life evolved deeper than this, it would have also been shielded from the early high levels of ultraviolet radiation from the T Tauri stage of the Sun's evolution. Simulations of geothermically heated oceanic crust yield far more organics than those found in the Miller–Urey experiments. In the deep [[hydrothermal vent]]s, Everett Shock has found "there is an enormous thermodynamic drive to form organic compounds, as [[seawater]] and hydrothermal fluids, which are far from equilibrium, mix and move towards a more stable state."<ref>{{harvnb|Davies|1999|p=155}}</ref> Shock has found that the available energy is maximized at around 100–150 C, precisely the temperatures at which the [[Hyperthermophile|hyperthermophilic]] bacteria and [[Thermoacidophile|thermoacidophilic]] [[archaea]] have been found, at the base of the [[Phylogenetic tree|phylogenetic tree of life]] closest to the [[Last universal ancestor|Last Universal Common Ancestor]] (LUCA).<ref>{{harvnb|Bock|Goode|1996}}</ref>

It has been estimated that the Late Heavy Bombardment may also have effectively sterilized the Earth's surface to a depth of tens of meters. If life evolved deeper than this, it would have also been shielded from the early high levels of ultraviolet radiation from the T Tauri stage of the Sun's evolution. Simulations of geothermically heated oceanic crust yield far more organics than those found in the Miller–Urey experiments. In the deep [[hydrothermal vent]]s, Everett Shock has found "there is an enormous thermodynamic drive to form organic compounds, as [[seawater]] and hydrothermal fluids, which are far from equilibrium, mix and move towards a more stable state."<ref>{{harvnb|Davies|1999|p=155}}</ref> Shock has found that the available energy is maximized at around 100–150 C, precisely the temperatures at which the [[Hyperthermophile|hyperthermophilic]] bacteria and [[Thermoacidophile|thermoacidophilic]] [[archaea]] have been found, at the base of the [[Phylogenetic tree|phylogenetic tree of life]] closest to the [[Last universal ancestor|Last Universal Common Ancestor]] (LUCA).<ref>{{harvnb|Bock|Goode|1996}}</ref>

据估计，晚期重型轰炸还可能对数十米深的地球表面进行了有效的消毒。如果生命进化到比这更深的地方，它也会被屏蔽在太阳进化的T金牛座阶段的早期高水平紫外线辐射之外。对地热加热的海洋地壳进行模拟，得到的有机物远比Miller–Urey实验中发现的多。在深层热液喷口中，埃弗雷特-休克发现 "存在着形成有机化合物的巨大热力学驱动力，因为海水和热液远未达到平衡，混合并向更稳定的状态发展。"休克发现，可用能量在100-150℃左右达到最大，而这正是发现嗜热细菌和嗜热古菌的温度，处于最接近最后一个宇宙共同祖先（LUCA）的生命系统发育树的底部。

据估计，晚期重型轰炸还可能对数十米深的地球表面进行了有效的灭菌。如果生命进化到比这更深的地方，它也会被屏蔽在太阳进化的T金牛座阶段的早期高水平紫外线辐射之外。对地热加热的海洋地壳进行模拟，得到的有机物远比Miller–Urey实验中发现的多。在深层热液喷口中，埃弗雷特·休克 Everett Shock发现 "存在着形成有机化合物的巨大热力学驱动力，因为海水和热液远未达到平衡，混合并向更稳定的状态发展。"Shock发现，可用的能量在100-150 C左右达到最大，而这正是发现嗜热细菌和嗜热古细菌的温度，处于最接近最后普遍共同祖先（LUCA）的生命系统发育树的底部。

== 生命的最早证据：古生物学==

== 生命的最早证据：古生物学==

{{Main|Earliest known life forms}}

{{Main|Earliest known life forms}}

[[File:Stromatolites.jpg|left|thumb|[[Precambrian]] [[stromatolite]]s in the Siyeh Formation, [[Glacier National Park (U.S.)|Glacier National Park]].  

[[File:Stromatolites.jpg|left|thumb|[[Precambrian]] [[stromatolite]]s in the Siyeh Formation, [[Glacier National Park (U.S.)|Glacier National Park]].  

A 2002 study suggested that these 3.5 Gyo (billion year old) [[Geologic formation|formations]] contain fossilized [[cyanobacteria]] [[microorganism|microbes]]. This suggests they are evidence of one of the [[Earliest known life forms|earliest life forms]] on [[Earth]]. 冰川国家公园锡耶组的前寒武纪叠层。2002年的一项研究表明，这些35亿年前的岩层中含有蓝藻微生物化石。这表明它们是地球上最早的生命形式之一的证据。]]  

A 2002 study suggested that these 3.5 Gyo (billion year old) [[Geologic formation|formations]] contain fossilized [[cyanobacteria]] [[microorganism|microbes]]. This suggests they are evidence of one of the [[Earliest known life forms|earliest life forms]] on [[Earth]]. 冰川国家公园锡耶组 Siyeh Formation的前寒武纪叠层石。2002年的一项研究表明，这些35亿岁的岩层中含有蓝藻微生物化石。这表明它们是地球上最早的生命形式之一的证据。]]  

The earliest life on Earth existed more than 3.5 Gya (billion years ago),<ref name="Origin1" /><ref name="Origin2" /><ref name="RavenJohnson2002" /> during the [[Eoarchean]] Era when sufficient crust had solidified following the molten Hadean Eon. The earliest physical evidence so far found consists of [[Micropaleontology#Microfossils|microfossils]] in the [[Nuvvuagittuq Greenstone Belt]] of Northern Quebec, in [[banded iron formation]] rocks at least 3.77 and possibly 4.28&nbsp;Gyo.<ref name="NAT-20170301" /><ref>{{cite web |url=http://www.cbc.ca/news/technology/oldest-record-life-earth-found-quebec-1.4004545 |title=Oldest traces of life on Earth found in Quebec, dating back roughly 3.8&nbsp;Gya |author=Mortillaro, Nicole |publisher=CBC News |date=1 March 2017 |accessdate=2 March 2017 |url-status=live |archiveurl=https://web.archive.org/web/20170301221842/http://www.cbc.ca/news/technology/oldest-record-life-earth-found-quebec-1.4004545 |archivedate=1 March 2017}}</ref> This finding suggested life developed very soon after oceans formed. The structure of the microbes was noted to be similar to bacteria found near [[hydrothermal vents]] in the modern era, and provided support for the hypothesis that abiogenesis began near hydrothermal vents.<ref name="4.3b oldest" /><ref name="NAT-20170301" />

The earliest life on Earth existed more than 3.5 Gya (billion years ago),<ref name="Origin1" /><ref name="Origin2" /><ref name="RavenJohnson2002" /> during the [[Eoarchean]] Era when sufficient crust had solidified following the molten Hadean Eon. The earliest physical evidence so far found consists of [[Micropaleontology#Microfossils|microfossils]] in the [[Nuvvuagittuq Greenstone Belt]] of Northern Quebec, in [[banded iron formation]] rocks at least 3.77 and possibly 4.28&nbsp;Gyo.<ref name="NAT-20170301" /><ref>{{cite web |url=http://www.cbc.ca/news/technology/oldest-record-life-earth-found-quebec-1.4004545 |title=Oldest traces of life on Earth found in Quebec, dating back roughly 3.8&nbsp;Gya |author=Mortillaro, Nicole |publisher=CBC News |date=1 March 2017 |accessdate=2 March 2017 |url-status=live |archiveurl=https://web.archive.org/web/20170301221842/http://www.cbc.ca/news/technology/oldest-record-life-earth-found-quebec-1.4004545 |archivedate=1 March 2017}}</ref> This finding suggested life developed very soon after oceans formed. The structure of the microbes was noted to be similar to bacteria found near [[hydrothermal vents]] in the modern era, and provided support for the hypothesis that abiogenesis began near hydrothermal vents.<ref name="4.3b oldest" /><ref name="NAT-20170301" />

地球上最早的生命存在于35亿年前，<ref name="Origin1" /><ref name="Origin2" /><ref name="RavenJohnson2002" />在早太宙时期，随着冥古宙的溶化，地壳已经凝固。迄今为止发现的最早的物理证据包括魁北克北部努夫雅集图克绿岩带中的微生物化石，位于带状铁形成的岩石中，形成时间至少在37.7亿年前，也可能在42.8亿年前。<ref name="NAT-20170301" /><ref>{{cite web |url=http://www.cbc.ca/news/technology/oldest-record-life-earth-found-quebec-1.4004545 |title=Oldest traces of life on Earth found in Quebec, dating back roughly 3.8&nbsp;Gya |author=Mortillaro, Nicole |publisher=CBC News |date=1 March 2017 |accessdate=2 March 2017 |url-status=live |archiveurl=https://web.archive.org/web/20170301221842/http://www.cbc.ca/news/technology/oldest-record-life-earth-found-quebec-1.4004545 |archivedate=1 March 2017}}</ref>这个发现表明生命在海洋形成后不久便出现了。据悉，微生物的结构与现代热液喷口附近发现的细菌相似，为生物发生始于热液喷口附近的假说提供了支持。

地球上最早的生命存在于35亿年前，<ref name="Origin1" /><ref name="Origin2" /><ref name="RavenJohnson2002" />在始太古代时期，在熔化的冥古宙之后，充足的地壳已经凝固。迄今为止发现的最早的物理证据包括魁北克北部努夫雅集图克绿岩带中的微生物化石，位于至少37.7亿岁，也可能42.8亿岁的带状铁层岩石中。<ref name="NAT-20170301" /><ref>{{cite web |url=http://www.cbc.ca/news/technology/oldest-record-life-earth-found-quebec-1.4004545 |title=Oldest traces of life on Earth found in Quebec, dating back roughly 3.8&nbsp;Gya |author=Mortillaro, Nicole |publisher=CBC News |date=1 March 2017 |accessdate=2 March 2017 |url-status=live |archiveurl=https://web.archive.org/web/20170301221842/http://www.cbc.ca/news/technology/oldest-record-life-earth-found-quebec-1.4004545 |archivedate=1 March 2017}}</ref>这个发现表明生命在海洋形成后不久便出现了。据悉，这种微生物的结构与现代热液喷口附近发现的细菌相似，为无生源论始于热液喷口附近的假说提供了支持。

Biogenic [[graphite]] has been found in 3.7&nbsp;Gyo metasedimentary rocks from southwestern [[Greenland]]<ref name="NG-20131208">{{cite journal |last1=Ohtomo |first1=Yoko |last2=Kakegawa |first2=Takeshi |last3=Ishida |first3=Akizumi |last4=Nagase |first4=Toshiro |last5=Rosing |first5=Minik T. |display-authors=3 |date=January 2014 |title=Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks |journal=[[Nature Geoscience]] |volume=7 |issue=1 |pages=25–28 |bibcode=2014NatGe...7...25O |doi=10.1038/ngeo2025 }}</ref> and [[microbial mat]] fossils found in 3.48&nbsp;Gyo sandstone from [[Western Australia]].<ref name="AP-20131113">{{cite news |last=Borenstein |first=Seth |date=13 November 2013 |title=Oldest fossil found: Meet your microbial mom |url=http://apnews.excite.com/article/20131113/DAA1VSC01.html |work=[[Excite]] |location=Yonkers, NY |publisher=[[Mindspark Interactive Network]] |agency=[[Associated Press]] |accessdate=2015-06-02 |url-status=live |archiveurl=https://web.archive.org/web/20150629230719/http://apnews.excite.com/article/20131113/DAA1VSC01.html |archivedate=29 June 2015}}</ref><ref name="AST-20131108">{{cite journal |last1=Noffke |first1=Nora |last2=Christian |first2=Daniel |last3=Wacey |first3=David |last4=Hazen |first4=Robert M. |authorlink4=Robert Hazen |date=16 November 2013 |title=Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ''ca.'' 3.48 Gyo Dresser Formation, Pilbara, Western Australia |journal=[[Astrobiology (journal)|Astrobiology]] |volume=13 |issue=12 |pages=1103–1124 |bibcode=2013AsBio..13.1103N |doi=10.1089/ast.2013.1030 |pmc=3870916 |pmid=24205812}}</ref> Evidence of early life in rocks from [[Akilia]] Island, near the [[Isua Greenstone Belt|Isua supracrustal belt]] in southwestern Greenland, dating to 3.7&nbsp;Gya have shown biogenic [[carbon isotope]]s.<ref name="NYT-20160831">{{cite news |last=Wade |first=Nicholas |title=World's Oldest Fossils Found in Greenland |url=https://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |date=31 August 2016 |work=[[The New York Times]] |accessdate=31 August 2016 |url-status=live |archiveurl=https://web.archive.org/web/20160831185959/http://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |archivedate=31 August 2016}}</ref><ref>{{harvnb|Davies|1999}}</ref> In other parts of the Isua supracrustal belt, graphite inclusions trapped within [[garnet]] crystals are connected to the other elements of life: oxygen, nitrogen, and possibly phosphorus in the form of [[phosphate]], providing further evidence for life 3.7&nbsp;Gya.<ref>{{Cite journal |last1=Hassenkam|first1=T. |last2=Andersson |first2=M.P. |last3=Dalby|first3=K.N. |last4=Mackenzie |first4=D.M.A.|last5=Rosing |first5=M.T. |title=Elements of Eoarchean life trapped in mineral inclusions |journal=Nature |doi=10.1038/nature23261 |pmid=28738409 |volume=548|issue=7665|pages=78–81 |year=2017 |bibcode=2017Natur.548...78H|s2cid=205257931 }}</ref> At Strelley Pool, in the [[Pilbara]] region of Western Australia, compelling evidence of early life was found in [[pyrite]]-bearing sandstone in a fossilized beach, that showed rounded tubular cells that [[Redox|oxidized]] sulfur by [[photosynthesis]] in the absence of oxygen.<ref name="TG-20131113-JP">{{cite news |last=Pearlman |first=Jonathan |date=13 November 2013 |title=Oldest signs of life on Earth found |url=https://www.telegraph.co.uk/news/science/science-news/10445788/Oldest-signs-of-life-on-Earth-found.html |newspaper=[[The Daily Telegraph]] |location=London |accessdate=2014-12-15 |url-status=live |archiveurl=https://web.archive.org/web/20141216062531/http://www.telegraph.co.uk/news/science/science-news/10445788/Oldest-signs-of-life-on-Earth-found.html |archivedate=16 December 2014}}</ref><ref>{{cite journal |last=O'Donoghue |first=James |date=21 August 2011 |url=https://www.newscientist.com/article/dn20813-oldest-reliable-fossils-show-early-life-was-a-beach.html |title=Oldest reliable fossils show early life was a beach |journal=[[New Scientist]] |url-status=live |archiveurl=https://web.archive.org/web/20150630201918/http://www.newscientist.com/article/dn20813-oldest-reliable-fossils-show-early-life-was-a-beach.html |archivedate=30 June 2015|doi=10.1016/S0262-4079(11)62064-2 |volume=211 |page=13 }}</ref><ref>{{cite journal |last1=Wacey |first1=David |last2=Kilburn |first2=Matt R. |last3=Saunders |first3=Martin |last4=Cliff |first4=John |last5=Brasier |first5=Martin D. |authorlink5=Martin Brasier |display-authors=3 |date=October 2011 |title=Microfossils of sulphur-metabolizing cells in 3.4-billion-year-old rocks of Western Australia |journal=Nature Geoscience |volume=4 |issue=10 |pages=698–702 |bibcode=2011NatGe...4..698W |doi=10.1038/ngeo1238}}</ref> Further research on [[zircon]]s from Western Australia in 2015 suggested that life likely existed on Earth at least 4.1 Gya.<ref name="AP-20151019">{{cite news |last=Borenstein |first=Seth |title=Hints of life on what was thought to be desolate early Earth |url=https://apnews.com/e6be2537b4cd46ffb9c0585bae2b2e51 |date=19 October 2015 |work=AP News |publisher=[[Associated Press]] |accessdate=9 October 2018}}</ref><ref name="PNAS-20151014-pdf">{{cite journal |last1=Bell |first1=Elizabeth A. |last2=Boehnike |first2=Patrick |last3=Harrison |first3=T. Mark |last4=Mao |first4=Wendy L. |display-authors=3 |date=19 October 2015 |title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon|journal=Proc. Natl. Acad. Sci. U.S.A. |doi=10.1073/pnas.1517557112|pages=14518–14521 |pmid=26483481 |pmc=4664351 |volume=112 |issue=47 |bibcode=2015PNAS..11214518B}} Early edition, published online before print.</ref><ref name="UCLA-20151019">{{cite web |last1=Wolpert |first1=Stuart |title=Life on Earth likely started at least 4.1 billion years ago – much earlier than scientists had thought |url=http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought |date=19 October 2015 |publisher=[[ULCA]] |accessdate=20 October 2015 |url-status=live |archiveurl=https://web.archive.org/web/20151020164038/http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought |archivedate=20 October 2015}}</ref>

Biogenic [[graphite]] has been found in 3.7&nbsp;Gyo metasedimentary rocks from southwestern [[Greenland]]<ref name="NG-20131208">{{cite journal |last1=Ohtomo |first1=Yoko |last2=Kakegawa |first2=Takeshi |last3=Ishida |first3=Akizumi |last4=Nagase |first4=Toshiro |last5=Rosing |first5=Minik T. |display-authors=3 |date=January 2014 |title=Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks |journal=[[Nature Geoscience]] |volume=7 |issue=1 |pages=25–28 |bibcode=2014NatGe...7...25O |doi=10.1038/ngeo2025 }}</ref> and [[microbial mat]] fossils found in 3.48&nbsp;Gyo sandstone from [[Western Australia]].<ref name="AP-20131113">{{cite news |last=Borenstein |first=Seth |date=13 November 2013 |title=Oldest fossil found: Meet your microbial mom |url=http://apnews.excite.com/article/20131113/DAA1VSC01.html |work=[[Excite]] |location=Yonkers, NY |publisher=[[Mindspark Interactive Network]] |agency=[[Associated Press]] |accessdate=2015-06-02 |url-status=live |archiveurl=https://web.archive.org/web/20150629230719/http://apnews.excite.com/article/20131113/DAA1VSC01.html |archivedate=29 June 2015}}</ref><ref name="AST-20131108">{{cite journal |last1=Noffke |first1=Nora |last2=Christian |first2=Daniel |last3=Wacey |first3=David |last4=Hazen |first4=Robert M. |authorlink4=Robert Hazen |date=16 November 2013 |title=Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ''ca.'' 3.48 Gyo Dresser Formation, Pilbara, Western Australia |journal=[[Astrobiology (journal)|Astrobiology]] |volume=13 |issue=12 |pages=1103–1124 |bibcode=2013AsBio..13.1103N |doi=10.1089/ast.2013.1030 |pmc=3870916 |pmid=24205812}}</ref> Evidence of early life in rocks from [[Akilia]] Island, near the [[Isua Greenstone Belt|Isua supracrustal belt]] in southwestern Greenland, dating to 3.7&nbsp;Gya have shown biogenic [[carbon isotope]]s.<ref name="NYT-20160831">{{cite news |last=Wade |first=Nicholas |title=World's Oldest Fossils Found in Greenland |url=https://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |date=31 August 2016 |work=[[The New York Times]] |accessdate=31 August 2016 |url-status=live |archiveurl=https://web.archive.org/web/20160831185959/http://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |archivedate=31 August 2016}}</ref><ref>{{harvnb|Davies|1999}}</ref> In other parts of the Isua supracrustal belt, graphite inclusions trapped within [[garnet]] crystals are connected to the other elements of life: oxygen, nitrogen, and possibly phosphorus in the form of [[phosphate]], providing further evidence for life 3.7&nbsp;Gya.<ref>{{Cite journal |last1=Hassenkam|first1=T. |last2=Andersson |first2=M.P. |last3=Dalby|first3=K.N. |last4=Mackenzie |first4=D.M.A.|last5=Rosing |first5=M.T. |title=Elements of Eoarchean life trapped in mineral inclusions |journal=Nature |doi=10.1038/nature23261 |pmid=28738409 |volume=548|issue=7665|pages=78–81 |year=2017 |bibcode=2017Natur.548...78H|s2cid=205257931 }}</ref> At Strelley Pool, in the [[Pilbara]] region of Western Australia, compelling evidence of early life was found in [[pyrite]]-bearing sandstone in a fossilized beach, that showed rounded tubular cells that [[Redox|oxidized]] sulfur by [[photosynthesis]] in the absence of oxygen.<ref name="TG-20131113-JP">{{cite news |last=Pearlman |first=Jonathan |date=13 November 2013 |title=Oldest signs of life on Earth found |url=https://www.telegraph.co.uk/news/science/science-news/10445788/Oldest-signs-of-life-on-Earth-found.html |newspaper=[[The Daily Telegraph]] |location=London |accessdate=2014-12-15 |url-status=live |archiveurl=https://web.archive.org/web/20141216062531/http://www.telegraph.co.uk/news/science/science-news/10445788/Oldest-signs-of-life-on-Earth-found.html |archivedate=16 December 2014}}</ref><ref>{{cite journal |last=O'Donoghue |first=James |date=21 August 2011 |url=https://www.newscientist.com/article/dn20813-oldest-reliable-fossils-show-early-life-was-a-beach.html |title=Oldest reliable fossils show early life was a beach |journal=[[New Scientist]] |url-status=live |archiveurl=https://web.archive.org/web/20150630201918/http://www.newscientist.com/article/dn20813-oldest-reliable-fossils-show-early-life-was-a-beach.html |archivedate=30 June 2015|doi=10.1016/S0262-4079(11)62064-2 |volume=211 |page=13 }}</ref><ref>{{cite journal |last1=Wacey |first1=David |last2=Kilburn |first2=Matt R. |last3=Saunders |first3=Martin |last4=Cliff |first4=John |last5=Brasier |first5=Martin D. |authorlink5=Martin Brasier |display-authors=3 |date=October 2011 |title=Microfossils of sulphur-metabolizing cells in 3.4-billion-year-old rocks of Western Australia |journal=Nature Geoscience |volume=4 |issue=10 |pages=698–702 |bibcode=2011NatGe...4..698W |doi=10.1038/ngeo1238}}</ref> Further research on [[zircon]]s from Western Australia in 2015 suggested that life likely existed on Earth at least 4.1 Gya.<ref name="AP-20151019">{{cite news |last=Borenstein |first=Seth |title=Hints of life on what was thought to be desolate early Earth |url=https://apnews.com/e6be2537b4cd46ffb9c0585bae2b2e51 |date=19 October 2015 |work=AP News |publisher=[[Associated Press]] |accessdate=9 October 2018}}</ref><ref name="PNAS-20151014-pdf">{{cite journal |last1=Bell |first1=Elizabeth A. |last2=Boehnike |first2=Patrick |last3=Harrison |first3=T. Mark |last4=Mao |first4=Wendy L. |display-authors=3 |date=19 October 2015 |title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon|journal=Proc. Natl. Acad. Sci. U.S.A. |doi=10.1073/pnas.1517557112|pages=14518–14521 |pmid=26483481 |pmc=4664351 |volume=112 |issue=47 |bibcode=2015PNAS..11214518B}} Early edition, published online before print.</ref><ref name="UCLA-20151019">{{cite web |last1=Wolpert |first1=Stuart |title=Life on Earth likely started at least 4.1 billion years ago – much earlier than scientists had thought |url=http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought |date=19 October 2015 |publisher=[[ULCA]] |accessdate=20 October 2015 |url-status=live |archiveurl=https://web.archive.org/web/20151020164038/http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought |archivedate=20 October 2015}}</ref>

人们在格陵兰岛西南部距今37亿年前的变质岩中发现了生物石墨<ref name="NG-20131208">{{cite journal |last1=Ohtomo |first1=Yoko |last2=Kakegawa |first2=Takeshi |last3=Ishida |first3=Akizumi |last4=Nagase |first4=Toshiro |last5=Rosing |first5=Minik T. |display-authors=3 |date=January 2014 |title=Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks |journal=[[Nature Geoscience]] |volume=7 |issue=1 |pages=25–28 |bibcode=2014NatGe...7...25O |doi=10.1038/ngeo2025 }}</ref> ，在西澳大利亚距今34.8亿年前的砂岩中发现了微生物垫层化石<ref name="AP-20131113">{{cite news |last=Borenstein |first=Seth |date=13 November 2013 |title=Oldest fossil found: Meet your microbial mom |url=http://apnews.excite.com/article/20131113/DAA1VSC01.html |work=[[Excite]] |location=Yonkers, NY |publisher=[[Mindspark Interactive Network]] |agency=[[Associated Press]] |accessdate=2015-06-02 |url-status=live |archiveurl=https://web.archive.org/web/20150629230719/http://apnews.excite.com/article/20131113/DAA1VSC01.html |archivedate=29 June 2015}}</ref><ref name="AST-20131108">{{cite journal |last1=Noffke |first1=Nora |last2=Christian |first2=Daniel |last3=Wacey |first3=David |last4=Hazen |first4=Robert M. |authorlink4=Robert Hazen |date=16 November 2013 |title=Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ''ca.'' 3.48 Gyo Dresser Formation, Pilbara, Western Australia |journal=[[Astrobiology (journal)|Astrobiology]] |volume=13 |issue=12 |pages=1103–1124 |bibcode=2013AsBio..13.1103N |doi=10.1089/ast.2013.1030 |pmc=3870916 |pmid=24205812}}</ref>。在格陵兰岛西南部伊苏亚超地壳带附近的阿基利亚岛的岩石中发现了早期生命的证据，这些可追溯到37亿年前的证据中发现了生物碳同位素<ref name="NYT-20160831">{{cite news |last=Wade |first=Nicholas |title=World's Oldest Fossils Found in Greenland |url=https://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |date=31 August 2016 |work=[[The New York Times]] |accessdate=31 August 2016 |url-status=live |archiveurl=https://web.archive.org/web/20160831185959/http://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |archivedate=31 August 2016}}</ref><ref>{{harvnb|Davies|1999}}</ref> 。在伊苏亚超地壳带的其他地方，被困在石榴石晶体内的石墨包裹体与生命的其他元素：氧气、氮气和可能以磷酸盐形式存在的磷相连，为生命存在于37亿年前提供了进一步的证据<ref>{{Cite journal |last1=Hassenkam|first1=T. |last2=Andersson |first2=M.P. |last3=Dalby|first3=K.N. |last4=Mackenzie |first4=D.M.A.|last5=Rosing |first5=M.T. |title=Elements of Eoarchean life trapped in mineral inclusions |journal=Nature |doi=10.1038/nature23261 |pmid=28738409 |volume=548|issue=7665|pages=78–81 |year=2017 |bibcode=2017Natur.548...78H|s2cid=205257931 }}</ref> 。在西澳大利亚皮尔巴拉地区的斯特•雷利池，在一个化石滩的含黄铁矿砂岩中发现了早期生命的令人信服的证据，它显示了圆形的管状细胞，在没有氧气的情况下通过光合作用氧化硫。2015年对西澳大利亚的锆石的进一步研究表明，地球上至少在41亿年前可能存在生命。<ref name="AP-20151019">{{cite news |last=Borenstein |first=Seth |title=Hints of life on what was thought to be desolate early Earth |url=https://apnews.com/e6be2537b4cd46ffb9c0585bae2b2e51 |date=19 October 2015 |work=AP News |publisher=[[Associated Press]] |accessdate=9 October 2018}}</ref><ref name="PNAS-20151014-pdf">{{cite journal |last1=Bell |first1=Elizabeth A. |last2=Boehnike |first2=Patrick |last3=Harrison |first3=T. Mark |last4=Mao |first4=Wendy L. |display-authors=3 |date=19 October 2015 |title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon|journal=Proc. Natl. Acad. Sci. U.S.A. |doi=10.1073/pnas.1517557112|pages=14518–14521 |pmid=26483481 |pmc=4664351 |volume=112 |issue=47 |bibcode=2015PNAS..11214518B}} Early edition, published online before print.</ref><ref name="UCLA-20151019">{{cite web |last1=Wolpert |first1=Stuart |title=Life on Earth likely started at least 4.1 billion years ago – much earlier than scientists had thought |url=http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought |date=19 October 2015 |publisher=[[ULCA]] |accessdate=20 October 2015 |url-status=live |archiveurl=https://web.archive.org/web/20151020164038/http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought |archivedate=20 October 2015}}</ref>

人们在格陵兰岛西南部37亿岁的变质沉积岩中发现了生物来源的石墨<ref name="NG-20131208">{{cite journal |last1=Ohtomo |first1=Yoko |last2=Kakegawa |first2=Takeshi |last3=Ishida |first3=Akizumi |last4=Nagase |first4=Toshiro |last5=Rosing |first5=Minik T. |display-authors=3 |date=January 2014 |title=Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks |journal=[[Nature Geoscience]] |volume=7 |issue=1 |pages=25–28 |bibcode=2014NatGe...7...25O |doi=10.1038/ngeo2025 }}</ref> ，在西澳大利亚距今34.8亿年前的砂岩中发现了微生物垫层化石<ref name="AP-20131113">{{cite news |last=Borenstein |first=Seth |date=13 November 2013 |title=Oldest fossil found: Meet your microbial mom |url=http://apnews.excite.com/article/20131113/DAA1VSC01.html |work=[[Excite]] |location=Yonkers, NY |publisher=[[Mindspark Interactive Network]] |agency=[[Associated Press]] |accessdate=2015-06-02 |url-status=live |archiveurl=https://web.archive.org/web/20150629230719/http://apnews.excite.com/article/20131113/DAA1VSC01.html |archivedate=29 June 2015}}</ref><ref name="AST-20131108">{{cite journal |last1=Noffke |first1=Nora |last2=Christian |first2=Daniel |last3=Wacey |first3=David |last4=Hazen |first4=Robert M. |authorlink4=Robert Hazen |date=16 November 2013 |title=Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ''ca.'' 3.48 Gyo Dresser Formation, Pilbara, Western Australia |journal=[[Astrobiology (journal)|Astrobiology]] |volume=13 |issue=12 |pages=1103–1124 |bibcode=2013AsBio..13.1103N |doi=10.1089/ast.2013.1030 |pmc=3870916 |pmid=24205812}}</ref>。在格陵兰岛西南部伊苏亚上地壳带附近的阿基利亚岛的岩石中发现了早期生命的证据，这些可追溯到37亿年前的证据中发现了生源碳同位素<ref name="NYT-20160831">{{cite news |last=Wade |first=Nicholas |title=World's Oldest Fossils Found in Greenland |url=https://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |date=31 August 2016 |work=[[The New York Times]] |accessdate=31 August 2016 |url-status=live |archiveurl=https://web.archive.org/web/20160831185959/http://www.nytimes.com/2016/09/01/science/oldest-fossils-on-earth.html |archivedate=31 August 2016}}</ref><ref>{{harvnb|Davies|1999}}</ref> 。在伊苏亚上地壳带的其他地方，被困在石榴石晶体内的石墨包裹体与生命的其他元素相连：氧、氮和可能以磷酸盐形式存在的磷，为37亿年前的生命提供了进一步的证据<ref>{{Cite journal |last1=Hassenkam|first1=T. |last2=Andersson |first2=M.P. |last3=Dalby|first3=K.N. |last4=Mackenzie |first4=D.M.A.|last5=Rosing |first5=M.T. |title=Elements of Eoarchean life trapped in mineral inclusions |journal=Nature |doi=10.1038/nature23261 |pmid=28738409 |volume=548|issue=7665|pages=78–81 |year=2017 |bibcode=2017Natur.548...78H|s2cid=205257931 }}</ref> 。在西澳大利亚皮尔巴拉地区的斯特雷利池，在一个化石滩的含黄铁矿砂岩中发现了早期生命的令人信服的证据，它显示了圆形的管状细胞，在没有氧气的情况下通过光合作用氧化硫。2015年对西澳大利亚的锆石的进一步研究表明，生命很可能在至少41亿年前就存在于地球上。<ref name="AP-20151019">{{cite news |last=Borenstein |first=Seth |title=Hints of life on what was thought to be desolate early Earth |url=https://apnews.com/e6be2537b4cd46ffb9c0585bae2b2e51 |date=19 October 2015 |work=AP News |publisher=[[Associated Press]] |accessdate=9 October 2018}}</ref><ref name="PNAS-20151014-pdf">{{cite journal |last1=Bell |first1=Elizabeth A. |last2=Boehnike |first2=Patrick |last3=Harrison |first3=T. Mark |last4=Mao |first4=Wendy L. |display-authors=3 |date=19 October 2015 |title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon|journal=Proc. Natl. Acad. Sci. U.S.A. |doi=10.1073/pnas.1517557112|pages=14518–14521 |pmid=26483481 |pmc=4664351 |volume=112 |issue=47 |bibcode=2015PNAS..11214518B}} Early edition, published online before print.</ref><ref name="UCLA-20151019">{{cite web |last1=Wolpert |first1=Stuart |title=Life on Earth likely started at least 4.1 billion years ago – much earlier than scientists had thought |url=http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought |date=19 October 2015 |publisher=[[ULCA]] |accessdate=20 October 2015 |url-status=live |archiveurl=https://web.archive.org/web/20151020164038/http://newsroom.ucla.edu/releases/life-on-earth-likely-started-at-least-4-1-billion-years-ago-much-earlier-than-scientists-had-thought |archivedate=20 October 2015}}</ref>

<!--This section is linked from The Selfish Gene-->

<!--This section is linked from The Selfish Gene-->

Panspermia is the [[hypothesis]] that [[life]] exists throughout the [[universe]], distributed by [[meteoroids]], [[asteroids]], [[comets]]<ref name="cometary panspermia">

Panspermia is the [[hypothesis]] that [[life]] exists throughout the [[universe]], distributed by [[meteoroids]], [[asteroids]], [[comets]]<ref name="cometary panspermia">

泛种论是一种假说，即生命存在于整个宇宙，由流星体、小行星、彗星和行星分布。<ref name="cometary panspermia">

泛种论是一种假说，即生命存在于整个宇宙，由流星体、小行星、彗星分布。<ref name="cometary panspermia">

The panspermia hypothesis does not attempt to explain how life first originated but merely shifts the origin to another planet or a comet. The advantage of an extraterrestrial origin of primitive life is that life is not required to have formed on each planet it occurs on, but rather in a single location, and then spread about the [[galaxy]] to other star systems via cometary and/or meteorite impact.<ref name="NYT-20160912">{{cite news |last=Chang |first=Kenneth |title=Visions of Life on Mars in Earth's Depths |url=https://www.nytimes.com/2016/09/13/science/south-african-mine-life-on-mars.html |date=12 September 2016 |work=[[The New York Times]] |accessdate=12 September 2016 |url-status=live |archiveurl=https://web.archive.org/web/20160912225220/http://www.nytimes.com/2016/09/13/science/south-african-mine-life-on-mars.html |archivedate=12 September 2016}}</ref>  

The panspermia hypothesis does not attempt to explain how life first originated but merely shifts the origin to another planet or a comet. The advantage of an extraterrestrial origin of primitive life is that life is not required to have formed on each planet it occurs on, but rather in a single location, and then spread about the [[galaxy]] to other star systems via cometary and/or meteorite impact.<ref name="NYT-20160912">{{cite news |last=Chang |first=Kenneth |title=Visions of Life on Mars in Earth's Depths |url=https://www.nytimes.com/2016/09/13/science/south-african-mine-life-on-mars.html |date=12 September 2016 |work=[[The New York Times]] |accessdate=12 September 2016 |url-status=live |archiveurl=https://web.archive.org/web/20160912225220/http://www.nytimes.com/2016/09/13/science/south-african-mine-life-on-mars.html |archivedate=12 September 2016}}</ref>  

Evidence for the panspermia hypothesis is scant, but it finds some support in studies of [[Martian meteorite]]s found in [[Antarctica]] and in studies of [[extremophile]] microbes' survival in outer space tests.<ref>{{cite journal |last=Clark |first=Stuart |date=25 September 2002 |title=Tough Earth bug may be from Mars |url=https://www.newscientist.com/article/dn2844 |journal=New Scientist |accessdate=2015-06-21 |url-status=live |archiveurl=https://web.archive.org/web/20141202003401/http://www.newscientist.com/article/dn2844 |archivedate=2 December 2014}}</ref><ref name="Gerda Horneck">{{cite journal |last1=Horneck |first1=Gerda |last2=Klaus |first2=David M. |last3=Mancinelli |first3=Rocco L. |date=March 2010 |title=Space Microbiology |journal=[[Microbiology and Molecular Biology Reviews]] |volume=74 |issue=1 |pages=121–156 |doi=10.1128/MMBR.00016-09  |pmc=2832349 |pmid=20197502|bibcode=2010MMBR...74..121H }}</ref><ref name="Rabbow">{{cite journal |last1=Rabbow |first1=Elke |last2=Horneck |first2=Gerda |last3=Rettberg |first3=Petra |last4=Schott |first4=Jobst-Ulrich |last5=Panitz |first5=Corinna |last6=L'Afflitto |first6=Andrea |last7=von Heise-Rotenburg |first7=Ralf |last8=Willnecker |first8=Reiner |last9=Baglioni |first9=Pietro |last10=Hatton |first10=Jason |last11=Dettmann |first11=Jan |last12=Demets |first12=René |last13=Reitz |first13=Günther |display-authors=3 |date=December 2009 |title=EXPOSE, an Astrobiological Exposure Facility on the International Space Station – from Proposal to Flight |journal=Origins of Life and Evolution of Biospheres |volume=39 |issue=6 |pages=581–598 |bibcode=2009OLEB...39..581R |doi=10.1007/s11084-009-9173-6|pmid=19629743|s2cid=19749414 }}</ref><ref>{{cite journal |last1=Onofri |first1=Silvano |last2=de la Torre |first2=Rosa |last3=de Vera |first3=Jean-Pierre |last4=Ott |first4=Sieglinde |last5=Zucconi |first5=Laura |last6=Selbmann |first6=Laura |last7=Scalzi |first7=Giuliano |last8=Venkateswaran |first8=Kasthuri J. |last9=Rabbow |first9=Elke |last10=Sánchez Iñigo |first10=Francisco J. |last11=Horneck |first11=Gerda |display-authors=3 |date=May 2012 |title=Survival of Rock-Colonizing Organisms After 1.5 Years in Outer Space |journal=Astrobiology |volume=12 |issue=5 |pages=508–516 |bibcode=2012AsBio..12..508O |doi=10.1089/ast.2011.0736 |pmid=22680696}}</ref>

Evidence for the panspermia hypothesis is scant, but it finds some support in studies of [[Martian meteorite]]s found in [[Antarctica]] and in studies of [[extremophile]] microbes' survival in outer space tests.<ref>{{cite journal |last=Clark |first=Stuart |date=25 September 2002 |title=Tough Earth bug may be from Mars |url=https://www.newscientist.com/article/dn2844 |journal=New Scientist |accessdate=2015-06-21 |url-status=live |archiveurl=https://web.archive.org/web/20141202003401/http://www.newscientist.com/article/dn2844 |archivedate=2 December 2014}}</ref><ref name="Gerda Horneck">{{cite journal |last1=Horneck |first1=Gerda |last2=Klaus |first2=David M. |last3=Mancinelli |first3=Rocco L. |date=March 2010 |title=Space Microbiology |journal=[[Microbiology and Molecular Biology Reviews]] |volume=74 |issue=1 |pages=121–156 |doi=10.1128/MMBR.00016-09  |pmc=2832349 |pmid=20197502|bibcode=2010MMBR...74..121H }}</ref><ref name="Rabbow">{{cite journal |last1=Rabbow |first1=Elke |last2=Horneck |first2=Gerda |last3=Rettberg |first3=Petra |last4=Schott |first4=Jobst-Ulrich |last5=Panitz |first5=Corinna |last6=L'Afflitto |first6=Andrea |last7=von Heise-Rotenburg |first7=Ralf |last8=Willnecker |first8=Reiner |last9=Baglioni |first9=Pietro |last10=Hatton |first10=Jason |last11=Dettmann |first11=Jan |last12=Demets |first12=René |last13=Reitz |first13=Günther |display-authors=3 |date=December 2009 |title=EXPOSE, an Astrobiological Exposure Facility on the International Space Station – from Proposal to Flight |journal=Origins of Life and Evolution of Biospheres |volume=39 |issue=6 |pages=581–598 |bibcode=2009OLEB...39..581R |doi=10.1007/s11084-009-9173-6|pmid=19629743|s2cid=19749414 }}</ref><ref>{{cite journal |last1=Onofri |first1=Silvano |last2=de la Torre |first2=Rosa |last3=de Vera |first3=Jean-Pierre |last4=Ott |first4=Sieglinde |last5=Zucconi |first5=Laura |last6=Selbmann |first6=Laura |last7=Scalzi |first7=Giuliano |last8=Venkateswaran |first8=Kasthuri J. |last9=Rabbow |first9=Elke |last10=Sánchez Iñigo |first10=Francisco J. |last11=Horneck |first11=Gerda |display-authors=3 |date=May 2012 |title=Survival of Rock-Colonizing Organisms After 1.5 Years in Outer Space |journal=Astrobiology |volume=12 |issue=5 |pages=508–516 |bibcode=2012AsBio..12..508O |doi=10.1089/ast.2011.0736 |pmid=22680696}}</ref>

泛种论假说并不试图解释生命最初是如何起源的，而只是将起源转移到另一颗行星或彗星上。原始生命的地外起源的优点是，生命不需要在它出现的每个星球上形成，而是在一个单一的位置，然后通过彗星和/或陨石撞击在银河系周围传播到其他恒星系统.泛孢子虫假说的证据很少，但它在对南极洲发现的火星陨石的研究和对极端微生物在外太空测试中生存的研究中找到了一些支持。

泛种论假说并不试图解释生命最初是如何起源的，而只是将起源转移到另一颗行星或彗星上。原始生命的地外起源的优点是，生命不需要在它出现的每个星球上形成，而是在一个单一的位置，然后通过彗星和/或陨石撞击在银河系周围传播到其他恒星系统。泛种论假说的证据很少，但它在对南极洲发现的火星陨石的研究和对极端微生物在外太空测试中生存的研究中找到了一些支持。

In August 2020, scientists reported that [[bacteria]] from Earth, particularly ''[[Deinococcus radiodurans]]'', which is highly resistant to [[environmental hazard]]s, were found to survive for three years in [[outer space]], based on studies conducted on the [[International Space Station]].<ref name="CNN-20200826">{{cite news |last=Strickland |first=Ashley |title=Bacteria from Earth can survive in space and could endure the trip to Mars, according to new study |url=https://www.cnn.com/2020/08/26/world/earth-mars-bacteria-space-scn/index.html |date=26 August 2020 |work=[[CNN News]] |accessdate=26 August 2020 }}</ref><ref name="FM-20200826">{{cite journal |author=Kawaguchi, Yuko |display-authors=et al. |title=DNA Damage and Survival Time Course of Deinococcal Cell Pellets During 3 Years of Exposure to Outer Space |date=26 August 2020 |journal=[[Frontiers in Microbiology]] |volume=11 |page=2050 |doi=10.3389/fmicb.2020.02050 |pmid=32983036 |pmc=7479814 |s2cid=221300151 |doi-access=free }}</ref>

In August 2020, scientists reported that [[bacteria]] from Earth, particularly ''[[Deinococcus radiodurans]]'', which is highly resistant to [[environmental hazard]]s, were found to survive for three years in [[outer space]], based on studies conducted on the [[International Space Station]].<ref name="CNN-20200826">{{cite news |last=Strickland |first=Ashley |title=Bacteria from Earth can survive in space and could endure the trip to Mars, according to new study |url=https://www.cnn.com/2020/08/26/world/earth-mars-bacteria-space-scn/index.html |date=26 August 2020 |work=[[CNN News]] |accessdate=26 August 2020 }}</ref><ref name="FM-20200826">{{cite journal |author=Kawaguchi, Yuko |display-authors=et al. |title=DNA Damage and Survival Time Course of Deinococcal Cell Pellets During 3 Years of Exposure to Outer Space |date=26 August 2020 |journal=[[Frontiers in Microbiology]] |volume=11 |page=2050 |doi=10.3389/fmicb.2020.02050 |pmid=32983036 |pmc=7479814 |s2cid=221300151 |doi-access=free }}</ref>

====Origin of life posited directly after the Big Bang and have spread over the entire Universe====

====Origin of life posited directly after the Big Bang and have spread over the entire Universe====

An extreme speculation is that the [[biochemistry]] of life could have begun as early as 17 My (million years) after the [[Big Bang]], during a [[Chronology of the universe#Speculative "habitable epoch"|habitable epoch]], and that life may exist throughout the [[universe]].<ref name="IJA-2014October_ARXIV-20131202">{{cite journal|last=Loeb|first=Abraham|authorlink=Abraham (Avi) Loeb|date=2014|title=The habitable epoch of the early universe|journal=[[International Journal of Astrobiology]]|volume=13|issue=4|pages=337–339|arxiv=1312.0613|bibcode=2014IJAsB..13..337L|citeseerx=10.1.1.748.4820|doi=10.1017/S1473550414000196|s2cid=2777386}}</ref><ref name="NYT-20141202">{{cite news|url=https://www.nytimes.com/2014/12/02/science/avi-loeb-ponders-the-early-universe-nature-and-life.html|title=Much-Discussed Views That Go Way Back|last=Dreifus|first=Claudia|date=2 December 2014|newspaper=[[The New York Times]]|accessdate=2014-12-03|archiveurl=https://web.archive.org/web/20141203010758/http://www.nytimes.com/2014/12/02/science/avi-loeb-ponders-the-early-universe-nature-and-life.html|archivedate=3 December 2014|url-status=live|location=New York|page=D2|authorlink=Claudia Dreifus}}</ref>

An extreme speculation is that the [[biochemistry]] of life could have begun as early as 17 My (million years) after the [[Big Bang]], during a [[Chronology of the universe#Speculative "habitable epoch"|habitable epoch]], and that life may exist throughout the [[universe]].<ref name="IJA-2014October_ARXIV-20131202">{{cite journal|last=Loeb|first=Abraham|authorlink=Abraham (Avi) Loeb|date=2014|title=The habitable epoch of the early universe|journal=[[International Journal of Astrobiology]]|volume=13|issue=4|pages=337–339|arxiv=1312.0613|bibcode=2014IJAsB..13..337L|citeseerx=10.1.1.748.4820|doi=10.1017/S1473550414000196|s2cid=2777386}}</ref><ref name="NYT-20141202">{{cite news|url=https://www.nytimes.com/2014/12/02/science/avi-loeb-ponders-the-early-universe-nature-and-life.html|title=Much-Discussed Views That Go Way Back|last=Dreifus|first=Claudia|date=2 December 2014|newspaper=[[The New York Times]]|accessdate=2014-12-03|archiveurl=https://web.archive.org/web/20141203010758/http://www.nytimes.com/2014/12/02/science/avi-loeb-ponders-the-early-universe-nature-and-life.html|archivedate=3 December 2014|url-status=live|location=New York|page=D2|authorlink=Claudia Dreifus}}</ref>

====General acceptance of spontaneous generation until the 19th century====

====General acceptance of spontaneous generation until the 19th century====

{{Main|Spontaneous generation}}

{{Main|Spontaneous generation}}

Traditional religion attributed the origin of life to supernatural deities who created the natural world. ''Spontaneous generation,'' the first naturalistic theory of life arising from non-life, goes back to [[Aristotle]] and [[ancient Greek philosophy]], and continued to have support in Western scholarship until the 19th century.<ref>{{harvnb|Sheldon|2005}}</ref> Classical notions of spontaneous generation held that certain "lower" or "vermin" animals are generated by decaying organic substances. According to Aristotle, it was readily observable that [[aphid]]s arise from dew on plants, [[fly|flies]] from putrid matter, mice from dirty hay, crocodiles from rotting sunken logs, and so on.<ref>{{harvnb|Lennox|2001|pp=229–258}}</ref> A related theory was ''heterogenesis'': that some forms of life could arise from different forms (e.g. bees from flowers).<ref>{{harvnb|Vartanian|1973|pp=307–312}}</ref> The modern scientist [[John Desmond Bernal|John Bernal]] said that the basic idea of such theories was that life was continuously created as a result of chance events.<ref name="Bernal 1967">{{harvnb|Bernal|1967}}</ref>

Traditional religion attributed the origin of life to supernatural deities who created the natural world. ''Spontaneous generation,'' the first naturalistic theory of life arising from non-life, goes back to [[Aristotle]] and [[ancient Greek philosophy]], and continued to have support in Western scholarship until the 19th century.<ref>{{harvnb|Sheldon|2005}}</ref> Classical notions of spontaneous generation held that certain "lower" or "vermin" animals are generated by decaying organic substances. According to Aristotle, it was readily observable that [[aphid]]s arise from dew on plants, [[fly|flies]] from putrid matter, mice from dirty hay, crocodiles from rotting sunken logs, and so on.<ref>{{harvnb|Lennox|2001|pp=229–258}}</ref> A related theory was ''heterogenesis'': that some forms of life could arise from different forms (e.g. bees from flowers).<ref>{{harvnb|Vartanian|1973|pp=307–312}}</ref> The modern scientist [[John Desmond Bernal|John Bernal]] said that the basic idea of such theories was that life was continuously created as a result of chance events.<ref name="Bernal 1967">{{harvnb|Bernal|1967}}</ref>

传统宗教把生命的起源归结为超自然的神灵，他们创造了自然界。自发生成是第一个从非生命中产生生命的自然主义理论，它可以追溯到Aristotle和古希腊哲学，并在西方学术界一直得到支持，直到19世纪。"自然发生”的古典观念认为，某些 "低等 "或 "害虫 "动物是由腐烂的有机物质产生的。根据Aristotle的观点，很容易观察到蚜虫从植物上的露水中产生，苍蝇从腐烂的物质中产生，老鼠从肮脏的干草中产生，鳄鱼从腐烂的沉木中产生，等等。一个相关的理论是异生论：某些生命形式可以从不同的形式中产生（如蜜蜂从花中产生）。现代科学家约翰-贝纳尔John Desmond Bernal说，这种理论的基本思想是生命是作为偶然事件的结果而不断产生的。

传统宗教把生命的起源归结为超自然的神灵，他们创造了自然界。“自然发生”，是第一个从非生命中产生生命的自然主义理论，它可以追溯到Aristotle和古希腊哲学，并在西方学术界一直得到支持，直到19世纪。"自然发生”的古典观念认为，某些 "低等 "或 "害虫 "动物是由腐烂的有机物质产生的。根据Aristotle的观点，很容易观察到蚜虫从植物上的露水中产生，苍蝇从腐烂的物质中产生，老鼠从肮脏的干草中产生，鳄鱼从腐烂的沉木中产生，等等。一个相关的理论是异生论：某些生命形式可以从不同的形式中产生（如蜜蜂从花中产生）。现代科学家约翰·德斯蒙德·贝纳尔John Desmond Bernal说，这种理论的基本思想是生命是作为偶然事件的结果而不断产生的。

In the 17th century, people began to question such assumptions. In 1646, [[Sir Thomas Browne|Thomas Browne]] published his ''[[Pseudodoxia Epidemica]]'' (subtitled ''Enquiries into Very many Received Tenets, and commonly Presumed Truths''), which was an attack on false beliefs and "vulgar errors." His contemporary, [[Alexander Ross (writer)|Alexander Ross]], erroneously refuted him, stating:

In the 17th century, people began to question such assumptions. In 1646, [[Sir Thomas Browne|Thomas Browne]] published his ''[[Pseudodoxia Epidemica]]'' (subtitled ''Enquiries into Very many Received Tenets, and commonly Presumed Truths''), which was an attack on false beliefs and "vulgar errors." His contemporary, [[Alexander Ross (writer)|Alexander Ross]], erroneously refuted him, stating:

< blockquote > To question this [spontaneous generation], is to question Reason, Sense, and Experience: If he doubts of this, let him go to ''[[Egypt|Ægypt]]'', and there he will find the fields swarming with mice begot of the mud of ''[[Nile|Nylus]]'', to the great calamity of the Inhabitants.<ref>{{cite journal |last=Balme |first=D.M. |authorlink=David Mowbray Balme |year=1962 |title=Development of Biology in Aristotle and Theophrastus: Theory of Spontaneous Generation |journal=[[Phronesis (journal)|Phronesis]] |volume=7 |issue=1–2 |pages=91–104 |doi=10.1163/156852862X00052}}</ref><ref>{{harvnb|Ross|1652}}</ref>< /blockquote >

< blockquote > To question this [spontaneous generation], is to question Reason, Sense, and Experience: If he doubts of this, let him go to ''[[Egypt|Ægypt]]'', and there he will find the fields swarming with mice begot of the mud of ''[[Nile|Nylus]]'', to the great calamity of the Inhabitants.<ref>{{cite journal |last=Balme |first=D.M. |authorlink=David Mowbray Balme |year=1962 |title=Development of Biology in Aristotle and Theophrastus: Theory of Spontaneous Generation |journal=[[Phronesis (journal)|Phronesis]] |volume=7 |issue=1–2 |pages=91–104 |doi=10.1163/156852862X00052}}</ref><ref>{{harvnb|Ross|1652}}</ref>< /blockquote >

在17世纪，人们开始质疑这些假设。1646年，托马斯·布朗出版了他的《伪传染病》(副标题为《对许多公认的原则和公认的真理的询问》)，该书攻击了错误的信仰和“庸俗的错误”。与他同时代的亚历山大·罗斯错误地驳斥了他，称:

在17世纪，人们开始质疑这些假设。1646年，托马斯·布朗爵士 Sir Thomas Browne出版了他的《伪传染病》(副标题为“对许多公认的原则和通常假定的真理的询问”)，该书攻击了错误的信念和“庸俗的错误”。与他同时代的亚历山大·罗斯 Alexander Ross错误地驳斥了他，称:

< blockquote >  

< blockquote >  

质疑这个自然发生，就是质疑理性、感觉和经验。如果他怀疑这一点，让他去埃及， 在那里，他将会发现田野里到处都是由尼罗斯的泥土生出的老鼠， 给当地居民带来了巨大的灾难。

质疑这个自然发生，就是质疑理性、感觉和经验。如果他怀疑这一点，让他去埃及， 在那里，他将会发现田野里到处都是由尼罗斯的泥土生出的老鼠，给当地居民带来了巨大的灾难。

< /blockquote >  

< /blockquote >  

[[File:Anton van Leeuwenhoek.png|thumb|upright|Antonie van Leeuwenhoek]]

[[File:Anton van Leeuwenhoek.png|thumb|upright|Antonie van Leeuwenhoek]]

In 1665, [[Robert Hooke]] published the first drawings of a [[microorganism]]. Hooke was followed in 1676 by [[Antonie van Leeuwenhoek]], who drew and described microorganisms that are now thought to have been [[protozoa]] and [[bacteria]].<ref>{{harvnb|Dobell|1960}}</ref> Many felt the existence of microorganisms was evidence in support of spontaneous generation, since microorganisms seemed too simplistic for [[sexual reproduction]], and [[asexual reproduction]] through [[mitosis|cell division]] had not yet been observed. Van Leeuwenhoek took issue with the ideas common at the time that fleas and lice could spontaneously result from [[putrefaction]], and that frogs could likewise arise from slime. Using a broad range of experiments ranging from sealed and open meat incubation and the close study of insect reproduction he became, by the 1680s, convinced that spontaneous generation was incorrect.<ref>{{harvnb|Bondeson|1999}}</ref>

In 1665, [[Robert Hooke]] published the first drawings of a [[microorganism]]. Hooke was followed in 1676 by [[Antonie van Leeuwenhoek]], who drew and described microorganisms that are now thought to have been [[protozoa]] and [[bacteria]].<ref>{{harvnb|Dobell|1960}}</ref> Many felt the existence of microorganisms was evidence in support of spontaneous generation, since microorganisms seemed too simplistic for [[sexual reproduction]], and [[asexual reproduction]] through [[mitosis|cell division]] had not yet been observed. Van Leeuwenhoek took issue with the ideas common at the time that fleas and lice could spontaneously result from [[putrefaction]], and that frogs could likewise arise from slime. Using a broad range of experiments ranging from sealed and open meat incubation and the close study of insect reproduction he became, by the 1680s, convinced that spontaneous generation was incorrect.<ref>{{harvnb|Bondeson|1999}}</ref>

1665年，罗伯特-胡克Robert Hooke发表了第一本微生物的图画。1676年，安东尼·范·列文虎克(Antonie van Leeuwenhoek)紧随其后，绘制并描述了现在被认为是原生动物和细菌的微生物。许多人认为微生物的存在是支持自然发生的证据，因为微生物对于有性生殖来说似乎过于简单，而通过细胞分裂的无性生殖尚未被观察到。范·列文虎克对当时常见的跳蚤和虱子可能由腐烂作用自发产生，以及青蛙同样可能由粘液产生的观点提出了异议。他利用广泛的实验，从密封和开放的肉体孵化以及对昆虫繁殖的仔细研究，到1680年代，他确信自然发生是不正确的。

1665年，罗伯特·胡克Robert Hooke发表了第一本微生物的图画。1676年，安东尼·范·列文虎克(Antonie van Leeuwenhoek)紧随其后，他绘制并描述了现在被认为是原生动物和细菌的微生物。许多人认为微生物的存在是支持自然发生的证据，因为微生物对于有性生殖来说似乎过于简单，而通过细胞分裂的无性生殖尚未被观察到。Van Leeuwenhoek对当时常见的跳蚤和虱子可能由腐烂作用自发产生，以及青蛙同样可能由粘液产生的观点提出了异议。他利用广泛的实验，从密封和开放的肉孵化以及对昆虫繁殖的仔细研究，到1680年代，他确信自然发生是不正确的。

The first experimental evidence against spontaneous generation came in 1668 when [[Francesco Redi]] showed that no [[maggot]]s appeared in meat when flies were prevented from laying eggs. It was gradually shown that, at least in the case of all the higher and readily visible organisms, the previous sentiment regarding spontaneous generation was false. The alternative hypothesis was ''[[biogenesis]]'': that every living thing came from a pre-existing living thing (''omne vivum ex ovo'', Latin for "every living thing from an egg").<ref name=lev>{{cite web |vauthors=Levine R, Evers C |title=The Slow Death of Spontaneous Generation (1668-1859) |url=http://www.accessexcellence.org/RC/AB/BC/Spontaneous_Generation.php |accessdate=18 April 2013 |url-status=dead |archiveurl=https://web.archive.org/web/20080426191204/http://www.accessexcellence.org/RC/AB/BC/Spontaneous_Generation.php |archivedate=26 April 2008 }}</ref> In 1768, [[Lazzaro Spallanzani]] demonstrated that [[microorganism|microbes]] were present in the air, and could be killed by boiling. In 1861, [[Louis Pasteur]] performed a series of experiments that demonstrated that organisms such as bacteria and fungi do not spontaneously appear in sterile, nutrient-rich media, but could only appear by invasion from without.

The first experimental evidence against spontaneous generation came in 1668 when [[Francesco Redi]] showed that no [[maggot]]s appeared in meat when flies were prevented from laying eggs. It was gradually shown that, at least in the case of all the higher and readily visible organisms, the previous sentiment regarding spontaneous generation was false. The alternative hypothesis was ''[[biogenesis]]'': that every living thing came from a pre-existing living thing (''omne vivum ex ovo'', Latin for "every living thing from an egg").<ref name=lev>{{cite web |vauthors=Levine R, Evers C |title=The Slow Death of Spontaneous Generation (1668-1859) |url=http://www.accessexcellence.org/RC/AB/BC/Spontaneous_Generation.php |accessdate=18 April 2013 |url-status=dead |archiveurl=https://web.archive.org/web/20080426191204/http://www.accessexcellence.org/RC/AB/BC/Spontaneous_Generation.php |archivedate=26 April 2008 }}</ref> In 1768, [[Lazzaro Spallanzani]] demonstrated that [[microorganism|microbes]] were present in the air, and could be killed by boiling. In 1861, [[Louis Pasteur]] performed a series of experiments that demonstrated that organisms such as bacteria and fungi do not spontaneously appear in sterile, nutrient-rich media, but could only appear by invasion from without.

第一个反对自然发生的实验证据是在1668年，当时弗朗西斯科·雷迪 Francesco Redi表明，当阻止苍蝇产卵时，肉中不会出现蛆虫。人们逐渐发现，至少在所有高等和易见生物的情况下，以前关于自发生成的观点是错误的。1768年，拉扎罗-斯帕兰扎尼（Lazzaro Spallanzani）证明了空气中存在微生物，并且可以通过煮沸杀死。1861年，路易-巴斯德Louis Pasteur进行了一系列实验，证明细菌和真菌等生物在无菌、营养丰富的培养基中不会自发出现，只能通过从外部入侵出现。

第一个反对自然发生的实验证据是在1668年，当时弗朗西斯科·雷迪 Francesco Redi表明，当阻止苍蝇产卵时，肉中不会出现蛆虫。人们逐渐发现，至少在所有高等和易见生物的情况下，以前关于自发生成的观点是错误的。另一种假设是“生源论”：每个生物都来自一个已经存在的生物（“ omne vivum ex ovo”，拉丁语的意思是“每个生物来自于一个蛋”）。1768年，拉扎罗·斯帕兰扎尼（Lazzaro Spallanzani）证明了空气中存在微生物，并且可以通过煮沸杀死。1861年，路易·巴斯德 Louis Pasteur进行了一系列实验，证明细菌和真菌等生物在无菌、营养丰富的培养基中不会自发出现，只能通过从外部入侵出现。

====Spontaneous generation considered disproven in the 19th century====

====Spontaneous generation considered disproven in the 19th century====

[[File:Louis Pasteur, foto av Paul Nadar, Crisco edit.jpg|thumb|upright|left|Louis Pasteur]]

[[File:Louis Pasteur, foto av Paul Nadar, Crisco edit.jpg|thumb|upright|left|Louis Pasteur]]

[[File:Darwin restored2.jpg|thumb|upright|alt=Head and shoulders portrait, increasingly bald with rather uneven bushy white eyebrows and beard, his wrinkled forehead suggesting a puzzled frown|[[Charles Darwin]] in 1879]]

[[File:Darwin restored2.jpg|thumb|upright|alt=Head and shoulders portrait, increasingly bald with rather uneven bushy white eyebrows and beard, his wrinkled forehead suggesting a puzzled frown|[[Charles Darwin]] in 1879]]

By the middle of the 19th century, biogenesis had accumulated so much evidence in support that the alternative theory of spontaneous generation had been effectively disproven. [[Louis Pasteur|Pasteur]] remarked, about a finding of his in 1864 which he considered definitive, < blockquote >Never will the doctrine of spontaneous generation recover from the mortal blow struck by this simple experiment.<ref>{{harvnb|Oparin|1953|p=196}}</ref><ref name="Tyndall Fragments2">{{harvnb|Tyndall|1905|loc=IV, XII (1876), XIII (1878)}}</ref> < /blockquote >gave a mechanism by which life diversified from a few simple organisms to a variety of to complex forms. Today, scientists agree that all current life descends from earlier life, which has become progressively more complex and diverse through [[Charles Darwin]]'s mechanism of [[evolution]] by [[natural selection]].

By the middle of the 19th century, biogenesis had accumulated so much evidence in support that the alternative theory of spontaneous generation had been effectively disproven. [[Louis Pasteur|Pasteur]] remarked, about a finding of his in 1864 which he considered definitive, < blockquote >Never will the doctrine of spontaneous generation recover from the mortal blow struck by this simple experiment.<ref>{{harvnb|Oparin|1953|p=196}}</ref><ref name="Tyndall Fragments2">{{harvnb|Tyndall|1905|loc=IV, XII (1876), XIII (1878)}}</ref> < /blockquote >gave a mechanism by which life diversified from a few simple organisms to a variety of to complex forms. Today, scientists agree that all current life descends from earlier life, which has become progressively more complex and diverse through [[Charles Darwin]]'s mechanism of [[evolution]] by [[natural selection]].

Darwin wrote to Hooker in 1863 stating that, < blockquote >It is mere rubbish, thinking at present of the origin of life; one might as well think of the origin of matter.< /blockquote > In ''[[On the Origin of Species]]'', he had referred to life having been "created", by which he "really meant 'appeared' by some wholly unknown process", but had soon regretted using the Old Testament term "creation".{{Citation needed|date=July 2020}}

Darwin wrote to Hooker in 1863 stating that, < blockquote >It is mere rubbish, thinking at present of the origin of life; one might as well think of the origin of matter.< /blockquote > In ''[[On the Origin of Species]]'', he had referred to life having been "created", by which he "really meant 'appeared' by some wholly unknown process", but had soon regretted using the Old Testament term "creation".{{Citation needed|date=July 2020}}

< blockquote >

< blockquote >

< blockquote >

< blockquote >

< blockquote >

< blockquote >

< blockquote >

< blockquote >

在《物种起源》中，他曾提到生命是 "被创造的"，他说生命是“被创造出来的”，“实际上是指通过某种完全未知的过程‘出现’”，但很快就后悔使用旧约中的“创造”一词但很快就后悔使用《旧约》中的 "创造 "一词。

在《物种起源》中，他曾提到生命是 "被创造的"，他说生命是“被创造出来的”，“实际上是指通过某种完全未知的过程‘出现’”，但很快就后悔使用《旧约》中的“创造”一词。

==== Etymology of biogenesis and abiogenesis====

==== Etymology of biogenesis and abiogenesis====

<!--This section is the for topic in general, so the following timeline of specific molecule discovery seems out of place:

<!--This section is the for topic in general, so the following timeline of specific molecule discovery seems out of place:

< ! ——这一部分是一般的主题，所以下面的具体分子发现时间表似乎不合适:

< ! ——这一部分是一般的主题，所以下面的具体分子发现时间线似乎不合适:

{{Main|Biogenesis}}

{{Main|Biogenesis}}

The term ''biogenesis'' is usually credited to either [[Henry Charlton Bastian|Henry Bastian]] or to [[Thomas Henry Huxley|Thomas Huxley]].<ref name="eohtBiogenesis">{{cite encyclopedia |encyclopedia=Hmolpedia |title=Biogenesis |url=http://www.eoht.info/page/Biogenesis |accessdate=2014-05-19 |publisher=WikiFoundry, Inc. |location=Ancaster, Ontario, Canada |url-status=live |archiveurl=https://web.archive.org/web/20140520001148/http://www.eoht.info/page/Biogenesis |archivedate=20 May 2014}}</ref> Bastian used the term around 1869 in an unpublished exchange with [[John Tyndall]] to mean "life-origination or commencement". In 1870, Huxley, as new president of the [[British Science Association|British Association for the Advancement of Science]], delivered an address entitled ''Biogenesis and Abiogenesis''.<ref name="Huxley 1968">{{harvnb|Huxley|1968}}</ref> In it he introduced the term ''biogenesis'' (with an opposite meaning to Bastian's) as well as ''abiogenesis'':

The term ''biogenesis'' is usually credited to either [[Henry Charlton Bastian|Henry Bastian]] or to [[Thomas Henry Huxley|Thomas Huxley]].<ref name="eohtBiogenesis">{{cite encyclopedia |encyclopedia=Hmolpedia |title=Biogenesis |url=http://www.eoht.info/page/Biogenesis |accessdate=2014-05-19 |publisher=WikiFoundry, Inc. |location=Ancaster, Ontario, Canada |url-status=live |archiveurl=https://web.archive.org/web/20140520001148/http://www.eoht.info/page/Biogenesis |archivedate=20 May 2014}}</ref> Bastian used the term around 1869 in an unpublished exchange with [[John Tyndall]] to mean "life-origination or commencement". In 1870, Huxley, as new president of the [[British Science Association|British Association for the Advancement of Science]], delivered an address entitled ''Biogenesis and Abiogenesis''.<ref name="Huxley 1968">{{harvnb|Huxley|1968}}</ref> In it he introduced the term ''biogenesis'' (with an opposite meaning to Bastian's) as well as ''abiogenesis'':

生物起源一词通常归功于亨利-巴斯蒂安Henry Bastian或托马斯-赫胥黎Thomas Huxley.。Bastian大约在1869年与约翰-廷德尔John Tyndall的一次未发表的交流中使用了这个词，意思是 "生命起源或开始"。1870年，Huxley作为英国科学促进会的新任主席，发表了题为《生物起源和非生物起源》的演讲。在演讲中，他介绍了生物起源（与Bastian的意思相反）以及非生物起源这个术语。

生物起源一词通常归功于亨利·巴斯蒂安Henry Bastian或托马斯·赫胥黎Thomas Huxley.。Bastian大约在1869年与约翰·廷德尔John Tyndall的一次未发表的交流中使用了这个词，意思是“生命-起源或开始”。1870年，Huxley作为英国科学促进会的新任主席，发表了题为《生物起源和非生物起源》的演讲。在演讲中，他介绍了“生物起源”（与Bastian的意思相反）以及“非生物起源”这个术语。

:And thus the hypothesis that living matter always arises by the agency of pre-existing living matter, took definite shape; and had, henceforward, a right to be considered and a claim to be refuted, in each particular case, before the production of living matter in any other way could be admitted by careful reasoners. It will be necessary for me to refer to this hypothesis so frequently, that, to save circumlocution, I shall call it the hypothesis of ''Biogenesis''; and I shall term the contrary doctrine—that living matter may be produced by not living matter—the hypothesis of ''Abiogenesis''.<ref name="Huxley 1968" />

:And thus the hypothesis that living matter always arises by the agency of pre-existing living matter, took definite shape; and had, henceforward, a right to be considered and a claim to be refuted, in each particular case, before the production of living matter in any other way could be admitted by careful reasoners. It will be necessary for me to refer to this hypothesis so frequently, that, to save circumlocution, I shall call it the hypothesis of ''Biogenesis''; and I shall term the contrary doctrine—that living matter may be produced by not living matter—the hypothesis of ''Abiogenesis''.<ref name="Huxley 1968" />

因此，关于生命物质总是由先前存在的生命物质的机构产生的假说，就有了明确的形式；并且，从今以后，在仔细的推理者能够承认以任何其他方式产生生命物质之前，在每一个特定的情况下，都有权利被考虑和被驳斥的主张。我有必要经常提到这个假说，所以，为了节省周折，我将把它称为生物起源论的假说；而我将把相反的学说--有生命的物质可能由无生命的物质产生--称为非生物起源论的假说。

因此，关于生命物质总是经由先前存在的生命物质产生的假说，就有了明确的形式；并且，从今以后，在仔细的推理者能够承认以任何其他方式产生生命物质之前，在每一个特定的情况下，都有被考虑和被驳斥的权利。我有必要经常提到这个假说，所以，为了节省周折，我将把它称为“生物起源论”的假说；而我将把相反的学说--有生命的物质可能由无生命的物质产生--称为“非生物起源论”的假说。

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Since the end of the nineteenth century, 'evolutive abiogenesis' means increasing complexity and evolution of matter from inert to living states.<ref>[https://link.springer.com/referenceworkentry/10.1007/978-3-642-27833-4_2-4 Abiogenesis – Definition]. 20 April 2015. ''Encyclopedia of Astrobiology''.  {{doi|10.1007/978-3-642-27833-4_2-4}}</ref>

Since the end of the nineteenth century, 'evolutive abiogenesis' means increasing complexity and evolution of matter from inert to living states.<ref>[https://link.springer.com/referenceworkentry/10.1007/978-3-642-27833-4_2-4 Abiogenesis – Definition]. 20 April 2015. ''Encyclopedia of Astrobiology''.  {{doi|10.1007/978-3-642-27833-4_2-4}}</ref>

关于新术语 "生命起源 "的引入，似乎有必要作一解释。我最初在未发表的著作中，采用了 "生物起源 "一词来表达同样的意思，即生命的起源或开始。但与此同时，生物起源这个词已经被一位杰出的生物学家Huxley独立地使用了，他希望使它具有完全不同的意义。他还介绍了生命起源这个词。然而，我从最权威的人士那里得知，这些词无论它们在自什么语言，都不应具有最近公开赋予它们的含义。为了避免一切不必要的混淆，我因此放弃了使用 "生物起源 "这个词，而且由于刚才所讲的原因，我无法采用另一个词，我不得不引入一个新词，以便指定生命物质被认为是独立于先前存在的生命物质而产生的过程。

关于新术语 "生物自生 "的引入，似乎有必要作一解释。我最初在未发表的著作中，采用了 "生物起源 "一词来表达同样的意思，即生命的起源或开始。但与此同时，“生物起源”这个词已经被一位杰出的生物学家Huxley独立地使用了，他希望使它具有完全不同的意义。他还介绍了“非生物起源”这个词。然而，我从最权威的人士那里得知，这些词无论它们来自什么语言，都不应具有最近公开赋予它们的含义。为了避免一切不必要的混淆，我因此放弃了使用 "生物起源 "这个词，而且由于刚才所讲的原因，我无法采用另一个词，我不得不引入一个新词，以便指定生命物质被认为是独立于先前存在的生命物质而产生的过程。

自19世纪末以来，'演化性非生物起源'是指物质从惰性状态到生命状态的复杂性和演化性的增加。

自19世纪末以来，'演化性非生物起源'是指物质从惰性状态到生命状态的复杂性和演化性的增加。

=== Oparin: Primordial soup hypothesis ===

=== Oparin: Primordial soup hypothesis ===

{{Main|Primordial soup}}

{{Main|Primordial soup}}

There is no single generally accepted model for the origin of life. Scientists have proposed several plausible hypotheses which share some common elements. While differing in details, these hypotheses are based on the framework laid out by [[Alexander Oparin]] (in 1924) and [[J. B. S. Haldane|John Haldane]] (in 1925), that the first molecules constituting the earliest cells < blockquote >. . . were synthesized under natural conditions by a slow process of molecular evolution, and these molecules then organized into the first molecular system with properties with biological order".<ref name="bah2">{{cite journal|last=Bahadur|first=Krishna|year=1973|title=Photochemical Formation of Self–sustaining Coacervates|url=http://www.dli.gov.in/rawdataupload/upload/insa/INSA_1/20005b73_455.pdf|url-status=dead|journal=Proceedings of the Indian National Science Academy|volume=39B|issue=4|pages=455–467|doi=10.1016/S0044-4057(75)80076-1|pmid=1242552|archiveurl=https://web.archive.org/web/20131019172800/http://www.dli.gov.in/rawdataupload/upload/insa/INSA_1/20005b73_455.pdf|archivedate=19 October 2013}}

There is no single generally accepted model for the origin of life. Scientists have proposed several plausible hypotheses which share some common elements. While differing in details, these hypotheses are based on the framework laid out by [[Alexander Oparin]] (in 1924) and [[J. B. S. Haldane|John Haldane]] (in 1925), that the first molecules constituting the earliest cells < blockquote >. . . were synthesized under natural conditions by a slow process of molecular evolution, and these molecules then organized into the first molecular system with properties with biological order".<ref name="bah2">{{cite journal|last=Bahadur|first=Krishna|year=1973|title=Photochemical Formation of Self–sustaining Coacervates|url=http://www.dli.gov.in/rawdataupload/upload/insa/INSA_1/20005b73_455.pdf|url-status=dead|journal=Proceedings of the Indian National Science Academy|volume=39B|issue=4|pages=455–467|doi=10.1016/S0044-4057(75)80076-1|pmid=1242552|archiveurl=https://web.archive.org/web/20131019172800/http://www.dli.gov.in/rawdataupload/upload/insa/INSA_1/20005b73_455.pdf|archivedate=19 October 2013}}

对于生命的起源，没有一个普遍接受的模式。科学家们提出了几种可信的假说，这些假说有一些共同的内容。这些假说虽然在细节上有所不同，但都是基于亚历山大-奥帕林Alexander Oparin(1924年)和约翰-霍尔丹John Haldane(1925年)提出的框架，即构成最早的细胞的第一批分子。

对于生命的起源，没有一个普遍接受的模式。科学家们提出了几种似乎可信的假说，这些假说有一些共同的内容。这些假说虽然在细节上有所不同，但都是基于亚历山大·奥帕林Alexander Oparin(1924年)和约翰·霍尔丹John Haldane(1925年)提出的框架，即构成最早的细胞的第一批分子。

< blockquote >

< blockquote >

* {{cite journal|last=Bahadur|first=Krishna|year=1975|title=Photochemical Formation of Self-Sustaining Coacervates|journal=[[Microbiological Research|Zentralblatt für Bakteriologie, Parasitenkunde, Infektionskrankheiten und Hygiene]]|volume=130|issue=3|pages=211–218|doi=10.1016/S0044-4057(75)80076-1|oclc=641018092|pmid=1242552}}</ref> < /blockquote >Oparin and Haldane suggested that the atmosphere of the early Earth may have been chemically reducing in nature, composed primarily of methane (CH₄), ammonia (NH₃), water (H₂O), hydrogen sulfide (H₂S), carbon dioxide (CO₂) or carbon monoxide (CO), and [[phosphate]] (PO₄³⁻), with molecular oxygen (O₂) and [[ozone]] (O₃) either rare or absent. According to later models, the atmosphere in the late Hadean period consisted largely of nitrogen (N₂) and carbon dioxide, with smaller amounts of carbon monoxide, hydrogen (H₂), and sulfur compounds;<ref>{{harvnb|Kasting|1993|p=922}}</ref> while it did lack molecular oxygen and ozone,<ref>{{harvnb|Kasting|1993|p=920}}</ref> it was not as chemically reducing as Oparin and Haldane supposed.

* {{cite journal|last=Bahadur|first=Krishna|year=1975|title=Photochemical Formation of Self-Sustaining Coacervates|journal=[[Microbiological Research|Zentralblatt für Bakteriologie, Parasitenkunde, Infektionskrankheiten und Hygiene]]|volume=130|issue=3|pages=211–218|doi=10.1016/S0044-4057(75)80076-1|oclc=641018092|pmid=1242552}}</ref> < /blockquote >Oparin and Haldane suggested that the atmosphere of the early Earth may have been chemically reducing in nature, composed primarily of methane (CH₄), ammonia (NH₃), water (H₂O), hydrogen sulfide (H₂S), carbon dioxide (CO₂) or carbon monoxide (CO), and [[phosphate]] (PO₄³⁻), with molecular oxygen (O₂) and [[ozone]] (O₃) either rare or absent. According to later models, the atmosphere in the late Hadean period consisted largely of nitrogen (N₂) and carbon dioxide, with smaller amounts of carbon monoxide, hydrogen (H₂), and sulfur compounds;<ref>{{harvnb|Kasting|1993|p=922}}</ref> while it did lack molecular oxygen and ozone,<ref>{{harvnb|Kasting|1993|p=920}}</ref> it was not as chemically reducing as Oparin and Haldane supposed.

Oparin和Haldane提出，早期地球的大气可能具有化学还原性，主要由甲烷(CH₄)、氨(NH₃)、水(H₂O)、硫化氢(H₂S、二氧化碳(CO₂)或一氧化碳(CO)和磷酸盐(PO₄³⁻)组成，氧气(O₂)和臭氧(O₃)很少或没有。根据后来的模型，冥古代晚期的大气主要由氮气(N₂)和二氧化碳组成，还有少量的一氧化碳、氢气(H₂)和硫磺化合物;虽然它确实缺乏分子氧和臭氧，但它并不像Oparin和Haldane所认为的那样具有化学还原性。

Oparin和Haldane提出，早期地球的大气可能具有化学还原性，主要由甲烷(CH₄)、氨(NH₃)、水(H₂O)、硫化氢(H₂S、二氧化碳(CO₂)或一氧化碳(CO)和磷酸盐(PO₄³⁻)组成，分子氧(O₂)和臭氧(O₃)很少或没有。根据后来的模型，冥古代晚期的大气主要由氮气(N₂)和二氧化碳组成，还有少量的一氧化碳、氢气(H₂)和硫磺化合物;虽然它确实缺乏分子氧和臭氧，但它并不像Oparin和Haldane所认为的那样具有化学还原性。

No new notable research or hypothesis on the subject appeared until 1924, when Oparin reasoned that atmospheric oxygen prevents the synthesis of certain organic compounds that are necessary building blocks for life. In his book ''The Origin of Life'',<ref>{{harvnb|Bernal|1967|loc=[http://www.valencia.edu/~orilife/textos/The%20Origin%20of%20Life.pdf ''The Origin of Life'' (A.I. Oparin, 1924), pp. 199–234]}}</ref><ref>{{harvnb|Oparin|1953}}</ref> he proposed (echoing Darwin) that the "spontaneous generation of life" that had been attacked by Pasteur did, in fact, occur once, but was now impossible because the conditions found on the early Earth had changed, and preexisting organisms would immediately consume any spontaneously generated organism. Oparin argued that a "primeval soup" of organic molecules could be created in an oxygenless atmosphere through the action of [[sunlight]]. These would combine in ever more complex ways until they formed [[coacervate]] droplets. These droplets would "[[cell growth|grow]]" by fusion with other droplets, and "[[reproduction|reproduce]]" through fission into daughter droplets, and so have a primitive [[metabolism]] in which factors that promote "cell integrity" survive, and those that do not become [[Extinction|extinct]]. Many modern theories of the origin of life still take Oparin's ideas as a starting point.

No new notable research or hypothesis on the subject appeared until 1924, when Oparin reasoned that atmospheric oxygen prevents the synthesis of certain organic compounds that are necessary building blocks for life. In his book ''The Origin of Life'',<ref>{{harvnb|Bernal|1967|loc=[http://www.valencia.edu/~orilife/textos/The%20Origin%20of%20Life.pdf ''The Origin of Life'' (A.I. Oparin, 1924), pp. 199–234]}}</ref><ref>{{harvnb|Oparin|1953}}</ref> he proposed (echoing Darwin) that the "spontaneous generation of life" that had been attacked by Pasteur did, in fact, occur once, but was now impossible because the conditions found on the early Earth had changed, and preexisting organisms would immediately consume any spontaneously generated organism. Oparin argued that a "primeval soup" of organic molecules could be created in an oxygenless atmosphere through the action of [[sunlight]]. These would combine in ever more complex ways until they formed [[coacervate]] droplets. These droplets would "[[cell growth|grow]]" by fusion with other droplets, and "[[reproduction|reproduce]]" through fission into daughter droplets, and so have a primitive [[metabolism]] in which factors that promote "cell integrity" survive, and those that do not become [[Extinction|extinct]]. Many modern theories of the origin of life still take Oparin's ideas as a starting point.

直到1924年，Oparin推理出大气中的氧气阻碍了某些有机化合物的合成，而这些有机化合物是生命的必要构件，才出现了关于这个问题的新的显著研究或假说。在他的《生命的起源》一书中，他提出(与Darwin相呼应)，被Pasteur抨击的 "生命的自然发生"事实上确实曾经发生过，但现在是不可能的，因为早期地球上发现的条件已经发生了变化，先前存在的生物体会立即消耗任何自发产生的生物体。Oparin认为，在无氧的大气中，通过太阳光的作用，可以产生有机分子的 "原始汤"。这些分子会以越来越复杂的方式结合在一起，直到形成共酸液滴。这些液滴会通过与其他液滴的融合而 "成长"，并通过裂变 "繁殖 "成子液滴，因此具有原始的新陈代谢，在这种新陈代谢中，能促进 "细胞完整性 "的因子得以生存，而不能生存的因子则会灭绝。现代许多关于生命起源的理论仍然以Oparin的思想为出发点。

直到1924年，才出现了关于这个问题的新的著名研究或假说，Oparin推理出大气中的氧气阻碍了某些有机化合物的合成，而这些有机化合物是生命的必要构件。在他的《生命的起源》一书中，他提出(与Darwin相呼应)，被Pasteur抨击的 "生命的自然发生"事实上确实曾经发生过，但现在是不可能的，因为早期地球上发现的条件已经发生了变化，先前存在的生物体会立即消耗任何自发产生的生物体。Oparin认为，在无氧的大气中，通过太阳光的作用，可以产生有机分子的 "原始汤"。这些分子会以越来越复杂的方式结合在一起，直到形成凝聚的液滴。这些液滴会通过与其他液滴的融合而"生长"，并通过裂变"繁殖"成子液滴，因此具有原始的新陈代谢，在这种新陈代谢中，能促进 "细胞完整性"的因子得以生存，而不能促进的因子则会灭绝。现代许多关于生命起源的理论仍然以Oparin的思想为出发点。

About this time, Haldane suggested that the Earth's prebiotic oceans (quite different from their modern counterparts) would have formed a "hot dilute soup" in which organic compounds could have formed. Bernal called this idea ''biopoiesis'' or ''biopoesis'', the process of living matter evolving from self-replicating but non-living molecules,<ref name="Bernal 1967" /><ref>{{harvnb|Bryson|2004|pp=300–302}}</ref> and proposed that biopoiesis passes through a number of intermediate stages.

About this time, Haldane suggested that the Earth's prebiotic oceans (quite different from their modern counterparts) would have formed a "hot dilute soup" in which organic compounds could have formed. Bernal called this idea ''biopoiesis'' or ''biopoesis'', the process of living matter evolving from self-replicating but non-living molecules,<ref name="Bernal 1967" /><ref>{{harvnb|Bryson|2004|pp=300–302}}</ref> and proposed that biopoiesis passes through a number of intermediate stages.

大约在这个时候，Haldane提出，地球上的前生物海洋（与现代的同类海洋截然不同）会形成一种 "热稀汤"，有机化合物可能在其中形成。Bernal将这一观点称为生物创建或生物创造，即有生命的物质从自我复制但无生命的分子中演化出来的过程，并提出生物创建经过一些中间阶段。

大约在这个时候，Haldane提出，地球上的前生物海洋（与现代的同类海洋截然不同）会形成一种 "热稀汤"，有机化合物可能在其中形成。Bernal将这一观点称为“生物创建”或“生物创造”，即有生命的物质从自我复制但无生命的分子中演化出来的过程，并提出生物创建经过许多中间阶段。

[[Robert Shapiro (chemist)|Robert Shapiro]] has summarized the "primordial soup" theory of Oparin and Haldane in its "mature form" as follows:<ref>{{harvnb|Shapiro|1987|p=110}}</ref>

[[Robert Shapiro (chemist)|Robert Shapiro]] has summarized the "primordial soup" theory of Oparin and Haldane in its "mature form" as follows:<ref>{{harvnb|Shapiro|1987|p=110}}</ref>

罗伯特-夏皮罗Robert Shapiro将Oparin和Haldane的 "原始汤 "理论的 "成熟形态 "总结如下：

罗伯特·夏皮罗Robert Shapiro将Oparin和Haldane的 "原始汤"理论的 "成熟形态 "总结如下：

# The early Earth had a chemically [[reducing atmosphere]].

# The early Earth had a chemically [[reducing atmosphere]].

John Bernal showed that based upon this and subsequent work there is no difficulty in principle in forming most of the molecules we recognize as the necessary molecules for life from their inorganic precursors. The underlying hypothesis held by Oparin, Haldane, Bernal, Miller and Urey, for instance, was that multiple conditions on the primeval Earth favoured chemical reactions that synthesized the same set of complex organic compounds from such simple precursors.  

John Bernal showed that based upon this and subsequent work there is no difficulty in principle in forming most of the molecules we recognize as the necessary molecules for life from their inorganic precursors. The underlying hypothesis held by Oparin, Haldane, Bernal, Miller and Urey, for instance, was that multiple conditions on the primeval Earth favoured chemical reactions that synthesized the same set of complex organic compounds from such simple precursors.  

John Bernal 表明，基于这一研究和随后的工作，从无机前体中形成我们所认识到的生命所必需的大部分分子原则上没有困难。例如，Oparin、Haldane、Bernal、Miller和Urey所持的基本假设是，原始地球上的多种条件有利于化学反应，从这种简单的前体合成同一组复杂的有机化合物。

John Bernal 表明，基于这一研究和随后的工作，从无机前体中形成我们所认识到的生命所必需的大部分分子原则上没有困难。例如，Oparin、Haldane、Bernal、Miller和Urey所持的基本假设是，原始地球上的多种条件有利于化学反应从这些简单的前体合成同一组复杂的有机化合物。

Bernal coined the term ''biopoiesis'' in 1949 to refer to the origin of life.<ref>{{harvnb|Bernal|1951}}</ref> In 1967, he suggested that it occurred in three "stages":

Bernal coined the term ''biopoiesis'' in 1949 to refer to the origin of life.<ref>{{harvnb|Bernal|1951}}</ref> In 1967, he suggested that it occurred in three "stages":

Bernal在1949年创造了生物创建这一术语，用来指代生命的起源。1967年，他提出生命的起源是分三个 "阶段 "发生的。

Bernal在1949年创造了“生物创建”这一术语，用来指代生命的起源。1967年，他提出生命的起源是分三个 "阶段 "发生的。

# the origin of biological monomers

# the origin of biological monomers

Bernal suggested that evolution commenced between stages 1 and 2. Bernal regarded the third stage, in which biological reactions were incorporated behind a cell's boundary, as the most difficult. Modern work on the way that [[cell membrane]]s self-assemble, and the work on micropores in various substrates, may be a key step towards understanding the development of independent free-living cells.<ref>{{cite journal |last= Martin |first= William F. |authorlink= William F. Martin |date= January 2003 |title= On the origins of cells: a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells |journal=Phil. Trans. R. Soc. Lond. A |volume= 358 |issue= 1429 |pages= 59–83 |doi= 10.1098/rstb.2002.1183 |pmid=12594918 |pmc=1693102}}</ref><ref>{{cite journal |last= Bernal |first= John Desmond |authorlink= John Desmond Bernal |date= September 1949 |title= The Physical Basis of Life |journal= Proceedings of the Physical Society, Section A |volume= 62 |issue= 9 |pages= 537–558 |bibcode= 1949PPSA...62..537B |doi= 10.1088/0370-1298/62/9/301 }}</ref><ref>{{harvnb|Kauffman|1995}}</ref>

Bernal suggested that evolution commenced between stages 1 and 2. Bernal regarded the third stage, in which biological reactions were incorporated behind a cell's boundary, as the most difficult. Modern work on the way that [[cell membrane]]s self-assemble, and the work on micropores in various substrates, may be a key step towards understanding the development of independent free-living cells.<ref>{{cite journal |last= Martin |first= William F. |authorlink= William F. Martin |date= January 2003 |title= On the origins of cells: a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells |journal=Phil. Trans. R. Soc. Lond. A |volume= 358 |issue= 1429 |pages= 59–83 |doi= 10.1098/rstb.2002.1183 |pmid=12594918 |pmc=1693102}}</ref><ref>{{cite journal |last= Bernal |first= John Desmond |authorlink= John Desmond Bernal |date= September 1949 |title= The Physical Basis of Life |journal= Proceedings of the Physical Society, Section A |volume= 62 |issue= 9 |pages= 537–558 |bibcode= 1949PPSA...62..537B |doi= 10.1088/0370-1298/62/9/301 }}</ref><ref>{{harvnb|Kauffman|1995}}</ref>

===Miller–Urey experiment===

===Miller–Urey experiment===

One of the most important pieces of experimental support for the "soup" theory came in 1952. [[Stanley L. Miller|Stanley Miller]] and [[Harold C. Urey|Harold Urey]] performed an experiment that demonstrated how organic molecules could have spontaneously formed from inorganic precursors under conditions like those posited by the Oparin-Haldane hypothesis. The now-famous [[Miller–Urey experiment]] used a highly reducing mixture of gases—[[methane]], [[ammonia]], and [[hydrogen gas|hydrogen]], as well as [[water vapor]]—to form simple organic monomers such as amino acids.<ref>{{cite journal |last=Miller |first=Stanley L. |authorlink=Stanley Miller |date=15 May 1953 |title=A Production of Amino Acids Under Possible Primitive Earth Conditions |journal=[[Science (journal)|Science]] |volume=117 |issue=3046 |pages=528–529 |bibcode=1953Sci...117..528M |doi=10.1126/science.117.3046.528 |pmid=13056598}}</ref> The mixture of gases was cycled through an apparatus that delivered electrical sparks to the mixture. After one week, it was found that about 10% to 15% of the carbon in the system was then in the form of a [[racemic mixture]] of organic compounds, including amino acids, which are the building blocks of [[protein]]s. This provided direct experimental support for the second point of the "soup" theory, and it is around the remaining two points of the theory that much of the debate now centers.

One of the most important pieces of experimental support for the "soup" theory came in 1952. [[Stanley L. Miller|Stanley Miller]] and [[Harold C. Urey|Harold Urey]] performed an experiment that demonstrated how organic molecules could have spontaneously formed from inorganic precursors under conditions like those posited by the Oparin-Haldane hypothesis. The now-famous [[Miller–Urey experiment]] used a highly reducing mixture of gases—[[methane]], [[ammonia]], and [[hydrogen gas|hydrogen]], as well as [[water vapor]]—to form simple organic monomers such as amino acids.<ref>{{cite journal |last=Miller |first=Stanley L. |authorlink=Stanley Miller |date=15 May 1953 |title=A Production of Amino Acids Under Possible Primitive Earth Conditions |journal=[[Science (journal)|Science]] |volume=117 |issue=3046 |pages=528–529 |bibcode=1953Sci...117..528M |doi=10.1126/science.117.3046.528 |pmid=13056598}}</ref> The mixture of gases was cycled through an apparatus that delivered electrical sparks to the mixture. After one week, it was found that about 10% to 15% of the carbon in the system was then in the form of a [[racemic mixture]] of organic compounds, including amino acids, which are the building blocks of [[protein]]s. This provided direct experimental support for the second point of the "soup" theory, and it is around the remaining two points of the theory that much of the debate now centers.

“汤 ”理论最重要的实验支持之一是在1952年。Stanley Miller和Harold Urey做了一个实验，证明了在类似Oparin-Haldane假说所提出的条件下，有机分子是如何从无机前体自发形成的。现在著名的Miller-Urey实验使用高度还原性的混合气体--甲烷、氨、氢以及水蒸气--形成简单的有机单体，如氨基酸。一周后，发现系统中约有10%至15%的碳以有机化合物的外消旋混合物的形式存在，其中包括氨基酸，而氨基酸是蛋白质的构件。这为 "汤 "理论的第二点提供了直接的实验支持，而现在很多争论的焦点正是围绕着该理论的其余两点。

“汤 ”理论最重要的实验支持之一是在1952年。Stanley Miller和Harold Urey做了一个实验，证明了在类似Oparin-Haldane假说所提出的条件下，有机分子是如何从无机前体自发形成的。现在著名的Miller-Urey实验使用高度还原性的混合气体--甲烷、氨、氢以及水蒸气—来形成简单的有机单体，如氨基酸。混合气体通过一个装置循环，将电火花传递到混合物中。一周后，发现系统中约有10%至15%的碳以有机化合物的外消旋混合物的形式存在，其中包括氨基酸，而氨基酸是蛋白质的构件。这为 "汤 "理论的第二点提供了直接的实验支持，而现在很多争论的焦点正是围绕着该理论的其余两点。

A 2011 reanalysis of the saved vials containing the original extracts that resulted from the Miller and Urey experiments, using current and more advanced analytical equipment and technology, has uncovered more biochemicals than originally discovered in the 1950s. One of the more important findings was 23 amino acids, far more than the five originally found.<ref name="pmid21422282">{{cite journal |last1=Parker |first1=Eric T. |last2=Cleaves |first2=Henderson J. |last3=Dworkin |first3=Jason P. |last4=Glavin |first4=Daniel P. |last5=Callahan |first5=Michael |last6=Aubrey |first6=Andrew |last7=Lazcano |first7=Antonio |last8=Bada |first8=Jeffrey L. |display-authors=3 |date=5 April 2011 |title=Primordial synthesis of amines and amino acids in a 1958 Miller H₂S-rich spark discharge experiment |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=108 |issue=14 |pages=5526–5531 |bibcode=2011PNAS..108.5526P |doi=10.1073/pnas.1019191108 |pmc=3078417 |pmid=21422282 }}</ref>

A 2011 reanalysis of the saved vials containing the original extracts that resulted from the Miller and Urey experiments, using current and more advanced analytical equipment and technology, has uncovered more biochemicals than originally discovered in the 1950s. One of the more important findings was 23 amino acids, far more than the five originally found.<ref name="pmid21422282">{{cite journal |last1=Parker |first1=Eric T. |last2=Cleaves |first2=Henderson J. |last3=Dworkin |first3=Jason P. |last4=Glavin |first4=Daniel P. |last5=Callahan |first5=Michael |last6=Aubrey |first6=Andrew |last7=Lazcano |first7=Antonio |last8=Bada |first8=Jeffrey L. |display-authors=3 |date=5 April 2011 |title=Primordial synthesis of amines and amino acids in a 1958 Miller H₂S-rich spark discharge experiment |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=108 |issue=14 |pages=5526–5531 |bibcode=2011PNAS..108.5526P |doi=10.1073/pnas.1019191108 |pmc=3078417 |pmid=21422282 }}</ref>

The [[Chemical element|elements]], except for hydrogen and helium, ultimately derive from [[stellar nucleosynthesis]]. In 2016, astronomers reported that the very basic chemical ingredients of [[life]]—the [[Carbon-hydrogen bond|carbon-hydrogen molecule]] (CH, or [[methylidyne radical]]), the carbon-hydrogen positive ion (CH+) and the carbon ion (C+)—are largely the result of [[ultraviolet light]] from stars, rather than other forms of radiation from [[supernovae]] and [[young star]]s, as thought earlier.<ref name="NASA-20161012">{{cite web |last=Landau |first=Elizabeth |title=Building Blocks of Life's Building Blocks Come From Starlight |url=http://www.jpl.nasa.gov/news/news.php?feature=6645 |date=12 October 2016 |work=[[NASA]] |accessdate=13 October 2016 |url-status=live |archiveurl=https://web.archive.org/web/20161013135018/http://www.jpl.nasa.gov/news/news.php?feature=6645 |archivedate=13 October 2016}}</ref> Complex molecules, including organic molecules, form naturally both in space and on planets.<ref name="Ehrenfreund2010" /> There are two possible sources of organic molecules on the early Earth:

The [[Chemical element|elements]], except for hydrogen and helium, ultimately derive from [[stellar nucleosynthesis]]. In 2016, astronomers reported that the very basic chemical ingredients of [[life]]—the [[Carbon-hydrogen bond|carbon-hydrogen molecule]] (CH, or [[methylidyne radical]]), the carbon-hydrogen positive ion (CH+) and the carbon ion (C+)—are largely the result of [[ultraviolet light]] from stars, rather than other forms of radiation from [[supernovae]] and [[young star]]s, as thought earlier.<ref name="NASA-20161012">{{cite web |last=Landau |first=Elizabeth |title=Building Blocks of Life's Building Blocks Come From Starlight |url=http://www.jpl.nasa.gov/news/news.php?feature=6645 |date=12 October 2016 |work=[[NASA]] |accessdate=13 October 2016 |url-status=live |archiveurl=https://web.archive.org/web/20161013135018/http://www.jpl.nasa.gov/news/news.php?feature=6645 |archivedate=13 October 2016}}</ref> Complex molecules, including organic molecules, form naturally both in space and on planets.<ref name="Ehrenfreund2010" /> There are two possible sources of organic molecules on the early Earth:

生物前的早期地球的化学过程称为化学进化。除氢和氦外，其他元素最终都来自于恒星核合成。2016年，天文学家报告说，生命的非常基本的化学成分--碳氢分子（CH，或称甲基炔基）、碳氢正离子（CH+）和碳离子（C+）--主要是来自恒星的紫外线的结果，而不是之前认为的来自超新星和年轻恒星的其他辐射形式。复杂的分子，包括有机分子，在太空和行星上自然形成。早期地球上的有机分子有两种可能的来源：

生物前的早期地球的化学过程称为“化学进化”。除氢和氦外，其他元素最终都来自于恒星核合成。2016年，天文学家报告说，生命的非常基本的化学成分--碳氢分子（CH，或称次甲基自由基）、碳氢正离子（CH+）和碳离子（C+）--主要是来自恒星的紫外线的结果，而不是之前认为的来自超新星和年轻恒星的其他辐射形式。复杂的分子，包括有机分子，在太空和行星上自然形成。早期地球上的有机分子有两种可能的来源：

# Terrestrial origins – organic molecule synthesis driven by impact shocks or by other energy sources (such as UV light, [[Organic redox reaction|redox]] coupling, or electrical discharges; e.g., Miller's experiments)

# Terrestrial origins – organic molecule synthesis driven by impact shocks or by other energy sources (such as UV light, [[Organic redox reaction|redox]] coupling, or electrical discharges; e.g., Miller's experiments)

地面起源 -- -- 撞击冲击或其他能量源(如紫外光、氧化还原耦合或放电；如米勒的实验)驱动的有机分子合成。

地球起源 -- -- 撞击冲击或其他能量源(如紫外光、氧化还原耦合或放电；如，Miller的实验)驱动的有机分子合成。

# Extraterrestrial origins – formation of organic molecules in [[Interstellar cloud|interstellar dust clouds]], which rain down on planets.<ref name="Gawlowicz 2011">{{cite news |last=Gawlowicz |first=Susan |date=6 November 2011 |title=Carbon-based organic 'carriers' in interstellar dust clouds? Newly discovered diffuse interstellar bands |url=https://www.sciencedaily.com/releases/2011/11/111102161149.htm |work=[[Science Daily]] |location=Rockville, MD |publisher=ScienceDaily, LLC |accessdate=2015-06-08 |url-status=live |archiveurl=https://web.archive.org/web/20150711114643/https://www.sciencedaily.com/releases/2011/11/111102161149.htm |archivedate=11 July 2015}} Post is reprinted from materials provided by the [[Rochester Institute of Technology]].

# Extraterrestrial origins – formation of organic molecules in [[Interstellar cloud|interstellar dust clouds]], which rain down on planets.<ref name="Gawlowicz 2011">{{cite news |last=Gawlowicz |first=Susan |date=6 November 2011 |title=Carbon-based organic 'carriers' in interstellar dust clouds? Newly discovered diffuse interstellar bands |url=https://www.sciencedaily.com/releases/2011/11/111102161149.htm |work=[[Science Daily]] |location=Rockville, MD |publisher=ScienceDaily, LLC |accessdate=2015-06-08 |url-status=live |archiveurl=https://web.archive.org/web/20150711114643/https://www.sciencedaily.com/releases/2011/11/111102161149.htm |archivedate=11 July 2015}} Post is reprinted from materials provided by the [[Rochester Institute of Technology]].

=== Observed extraterrestrial organic molecules ===

=== Observed extraterrestrial organic molecules ===

{{See also|List of interstellar and circumstellar molecules|Panspermia#Pseudo-panspermia}}

{{See also|List of interstellar and circumstellar molecules|Panspermia#Pseudo-panspermia}}

An organic compound is any member of a large class of gaseous, liquid, or solid chemicals whose molecules contain carbon. Carbon is the [[Abundance of the chemical elements|fourth most abundant element in the Universe by mass]] after hydrogen, [[helium]], and oxygen.<ref>{{cite encyclopedia |encyclopedia=Encyclopedia of Science |title=biological abundance of elements |url=http://www.daviddarling.info/encyclopedia/E/elbio.html |publisher=David Darling Enterprises |location=Dundee, Scotland |accessdate=2008-10-09 |url-status=live |archiveurl=https://web.archive.org/web/20120204033420/http://www.daviddarling.info/encyclopedia/E/elbio.html |archivedate=4 February 2012}}</ref> Carbon is abundant in the Sun, stars, comets, and in the [[Celestial body's atmosphere|atmospheres]] of most planets.<ref name="NASA-20140221">{{cite web |url=http://www.nasa.gov/ames/need-to-track-organic-nano-particles-across-the-universe-nasas-got-an-app-for-that/ |title=Need to Track Organic Nano-Particles Across the Universe? NASA's Got an App for That |last=Hoover |first=Rachel |date=21 February 2014 |website=[[Ames Research Center]] |publisher=NASA |location=Mountain View, CA |accessdate=2015-06-22 |url-status=live |archiveurl=https://web.archive.org/web/20150906061428/http://www.nasa.gov/ames/need-to-track-organic-nano-particles-across-the-universe-nasas-got-an-app-for-that/ |archivedate=6 September 2015}}</ref> Organic compounds are relatively common in space, formed by "factories of complex molecular synthesis" which occur in [[molecular cloud]]s and [[circumstellar envelope]]s, and chemically evolve after reactions are initiated mostly by [[ionizing radiation]].<ref name="Ehrenfreund2010">{{cite journal |last1=Ehrenfreund |first1=Pascale |last2=Cami |first2=Jan |date=December 2010 |title=Cosmic carbon chemistry: from the interstellar medium to the early Earth. |journal=Cold Spring Harbor Perspectives in Biology |volume=2 |issue=12 |page=a002097 |doi=10.1101/cshperspect.a002097 |pmc=2982172 |pmid=20554702}}</ref><ref name="FromADistantComet">{{cite news |last=Chang |first=Kenneth |date=18 August 2009 |title=From a Distant Comet, a Clue to Life |url=https://www.nytimes.com/2009/08/19/science/space/19comet.html |newspaper=The New York Times |location=New York |page=A18 |accessdate=2015-06-22 |url-status=live |archiveurl=https://web.archive.org/web/20150623005046/http://www.nytimes.com/2009/08/19/science/space/19comet.html |archivedate=23 June 2015}}</ref><ref>{{cite journal |last1=Goncharuk |first1=Vladislav V. |last2=Zui |first2=O. V. |date=February 2015 |title=Water and carbon dioxide as the main precursors of organic matter on Earth and in space |journal=Journal of Water Chemistry and Technology |volume=37 |issue=1 |pages=2–3 |doi=10.3103/S1063455X15010026 |s2cid=97965067 }}</ref><ref>{{cite journal |last1=Abou Mrad |first1=Ninette |last2=Vinogradoff |first2=Vassilissa |last3=Duvernay |first3=Fabrice |last4=Danger |first4=Grégoire |last5=Theulé |first5=Patrice |last6=Borget |first6=Fabien |last7=Chiavassa |first7=Thierry |display-authors=3 |year=2015 |title=Laboratory experimental simulations: Chemical evolution of the organic matter from interstellar and cometary ice analogs |url=http://popups.ulg.ac.be/0037-9565/index.php?id=4621&file=1|journal=Bulletin de la Société Royale des Sciences de Liège |volume=84 |pages=21–32 |bibcode=2015BSRSL..84...21A  |accessdate=2015-04-06 |url-status=live |archiveurl=https://web.archive.org/web/20150413050621/http://popups.ulg.ac.be/0037-9565/index.php?id=4621&file=1 |archivedate=13 April 2015}}</ref> Based on [[computer simulation|computer model studies]], the complex organic molecules necessary for life may have formed on dust grains in the protoplanetary disk surrounding the Sun before the formation of the Earth.<ref name="Space-20120329" /> According to the computer studies, this same process may also occur around other stars that acquire planets.<ref name="Space-20120329" />

An organic compound is any member of a large class of gaseous, liquid, or solid chemicals whose molecules contain carbon. Carbon is the [[Abundance of the chemical elements|fourth most abundant element in the Universe by mass]] after hydrogen, [[helium]], and oxygen.<ref>{{cite encyclopedia |encyclopedia=Encyclopedia of Science |title=biological abundance of elements |url=http://www.daviddarling.info/encyclopedia/E/elbio.html |publisher=David Darling Enterprises |location=Dundee, Scotland |accessdate=2008-10-09 |url-status=live |archiveurl=https://web.archive.org/web/20120204033420/http://www.daviddarling.info/encyclopedia/E/elbio.html |archivedate=4 February 2012}}</ref> Carbon is abundant in the Sun, stars, comets, and in the [[Celestial body's atmosphere|atmospheres]] of most planets.<ref name="NASA-20140221">{{cite web |url=http://www.nasa.gov/ames/need-to-track-organic-nano-particles-across-the-universe-nasas-got-an-app-for-that/ |title=Need to Track Organic Nano-Particles Across the Universe? NASA's Got an App for That |last=Hoover |first=Rachel |date=21 February 2014 |website=[[Ames Research Center]] |publisher=NASA |location=Mountain View, CA |accessdate=2015-06-22 |url-status=live |archiveurl=https://web.archive.org/web/20150906061428/http://www.nasa.gov/ames/need-to-track-organic-nano-particles-across-the-universe-nasas-got-an-app-for-that/ |archivedate=6 September 2015}}</ref> Organic compounds are relatively common in space, formed by "factories of complex molecular synthesis" which occur in [[molecular cloud]]s and [[circumstellar envelope]]s, and chemically evolve after reactions are initiated mostly by [[ionizing radiation]].<ref name="Ehrenfreund2010">{{cite journal |last1=Ehrenfreund |first1=Pascale |last2=Cami |first2=Jan |date=December 2010 |title=Cosmic carbon chemistry: from the interstellar medium to the early Earth. |journal=Cold Spring Harbor Perspectives in Biology |volume=2 |issue=12 |page=a002097 |doi=10.1101/cshperspect.a002097 |pmc=2982172 |pmid=20554702}}</ref><ref name="FromADistantComet">{{cite news |last=Chang |first=Kenneth |date=18 August 2009 |title=From a Distant Comet, a Clue to Life |url=https://www.nytimes.com/2009/08/19/science/space/19comet.html |newspaper=The New York Times |location=New York |page=A18 |accessdate=2015-06-22 |url-status=live |archiveurl=https://web.archive.org/web/20150623005046/http://www.nytimes.com/2009/08/19/science/space/19comet.html |archivedate=23 June 2015}}</ref><ref>{{cite journal |last1=Goncharuk |first1=Vladislav V. |last2=Zui |first2=O. V. |date=February 2015 |title=Water and carbon dioxide as the main precursors of organic matter on Earth and in space |journal=Journal of Water Chemistry and Technology |volume=37 |issue=1 |pages=2–3 |doi=10.3103/S1063455X15010026 |s2cid=97965067 }}</ref><ref>{{cite journal |last1=Abou Mrad |first1=Ninette |last2=Vinogradoff |first2=Vassilissa |last3=Duvernay |first3=Fabrice |last4=Danger |first4=Grégoire |last5=Theulé |first5=Patrice |last6=Borget |first6=Fabien |last7=Chiavassa |first7=Thierry |display-authors=3 |year=2015 |title=Laboratory experimental simulations: Chemical evolution of the organic matter from interstellar and cometary ice analogs |url=http://popups.ulg.ac.be/0037-9565/index.php?id=4621&file=1|journal=Bulletin de la Société Royale des Sciences de Liège |volume=84 |pages=21–32 |bibcode=2015BSRSL..84...21A  |accessdate=2015-04-06 |url-status=live |archiveurl=https://web.archive.org/web/20150413050621/http://popups.ulg.ac.be/0037-9565/index.php?id=4621&file=1 |archivedate=13 April 2015}}</ref> Based on [[computer simulation|computer model studies]], the complex organic molecules necessary for life may have formed on dust grains in the protoplanetary disk surrounding the Sun before the formation of the Earth.<ref name="Space-20120329" /> According to the computer studies, this same process may also occur around other stars that acquire planets.<ref name="Space-20120329" />

有机化合物是指分子中含有碳的一大类气态、液态或固态化学品的任何成员。按质量计算，碳是宇宙中仅次于氢、氦和氧的第四大丰富元素。碳在太阳、恒星、彗星和大多数行星的大气层中含量丰富。有机化合物在太空中比较常见，是由分子云和环星包层中出现的 "复杂分子合成工厂 "形成的，主要由电离辐射引发反应后发生化学演变。 根据计算机模型研究，在地球形成之前，生命所需的复杂有机分子可能已经在太阳周围原行星盘的尘粒上形成。根据计算机研究，这一过程也可能发生在其他获得行星的恒星周围。

有机化合物是指分子中含有碳的一大类气态、液态或固态化学物质的任何成员。按质量计算，碳是宇宙中仅次于氢、氦和氧的第四大丰富元素。碳在太阳、恒星、彗星和大多数行星的大气层中含量丰富。有机化合物在太空中比较常见，是由分子云和环星包层中出现的 "复杂分子合成工厂"形成的，主要由电离辐射引发反应后发生化学演变。 根据计算机模型研究，在地球形成之前，生命所需的复杂有机分子可能已经在太阳周围原行星盘的尘粒上形成。根据计算机研究，这一过程也可能发生在其他获得行星的恒星周围。

====Amino acids====

====Amino acids====

NASA announced in 2009 that scientists had identified another fundamental chemical building block of life in a comet for the first time, glycine, an amino acid, which was detected in material ejected from comet [[81P/Wild|Wild 2]] in 2004 and grabbed by NASA's [[Stardust (spacecraft)|''Stardust'']] probe. Glycine has been detected in meteorites before. Carl Pilcher, who leads the [[NASA Astrobiology Institute]] commented that < blockquote >The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare.<ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |date=18 August 2009 |title='Life chemical' detected in comet |url=http://news.bbc.co.uk/2/hi/science/nature/8208307.stm |work=BBC News |location=London |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150525071228/http://news.bbc.co.uk/2/hi/science/nature/8208307.stm |archivedate=25 May 2015}}</ref>< /blockquote > Comets are encrusted with outer layers of dark material, thought to be a [[tar]]-like substance composed of complex organic material formed from simple carbon compounds after reactions initiated mostly by ionizing radiation. It is possible that a rain of material from comets could have brought significant quantities of such complex organic molecules to Earth.<ref>{{cite journal |last1=Thompson |first1=William Reid |last2=Murray |first2=B. G. |last3=Khare |first3=Bishun Narain |authorlink3=Bishun Khare |last4=Sagan |first4=Carl |date=30 December 1987 |title=Coloration and darkening of methane clathrate and other ices by charged particle irradiation: Applications to the outer solar system |journal=[[Journal of Geophysical Research]] |volume=92 |issue=A13 |pages=14933–14947 |bibcode=1987JGR....9214933T |doi=10.1029/JA092iA13p14933 |pmid=11542127}}</ref><ref>{{cite web |url=https://www.llnl.gov/news/life-earth-shockingly-comes-out-world |title=Life on Earth shockingly comes from out of this world |last=Stark |first=Anne M. |date=5 June 2013 |publisher=[[Lawrence Livermore National Laboratory]] |location=Livermore, CA |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150916135630/https://www.llnl.gov/news/life-earth-shockingly-comes-out-world |archivedate=16 September 2015}}</ref><ref>{{cite journal |last1=Goldman |first1=Nir |last2=Tamblyn |first2=Isaac |date=20 June 2013 |title=Prebiotic Chemistry within a Simple Impacting Icy Mixture |journal=[[Journal of Physical Chemistry A]] |volume=117 |issue=24 |pages=5124–5131 |doi=10.1021/jp402976n |pmid=23639050|bibcode=2013JPCA..117.5124G |url=http://nparc.nrc-cnrc.gc.ca/eng/view/fulltext/?id=e89d2ac7-4cf8-40e0-bcc9-3c53f68ed70a }}</ref> Amino acids which were formed extraterrestrially may also have arrived on Earth via comets.<ref name="Follmann2009" /> It is estimated that during the Late Heavy Bombardment, meteorites may have delivered up to five million [[ton]]s of organic prebiotic elements to Earth per year.<ref name="Follmann2009" />

NASA announced in 2009 that scientists had identified another fundamental chemical building block of life in a comet for the first time, glycine, an amino acid, which was detected in material ejected from comet [[81P/Wild|Wild 2]] in 2004 and grabbed by NASA's [[Stardust (spacecraft)|''Stardust'']] probe. Glycine has been detected in meteorites before. Carl Pilcher, who leads the [[NASA Astrobiology Institute]] commented that < blockquote >The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare.<ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |date=18 August 2009 |title='Life chemical' detected in comet |url=http://news.bbc.co.uk/2/hi/science/nature/8208307.stm |work=BBC News |location=London |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150525071228/http://news.bbc.co.uk/2/hi/science/nature/8208307.stm |archivedate=25 May 2015}}</ref>< /blockquote > Comets are encrusted with outer layers of dark material, thought to be a [[tar]]-like substance composed of complex organic material formed from simple carbon compounds after reactions initiated mostly by ionizing radiation. It is possible that a rain of material from comets could have brought significant quantities of such complex organic molecules to Earth.<ref>{{cite journal |last1=Thompson |first1=William Reid |last2=Murray |first2=B. G. |last3=Khare |first3=Bishun Narain |authorlink3=Bishun Khare |last4=Sagan |first4=Carl |date=30 December 1987 |title=Coloration and darkening of methane clathrate and other ices by charged particle irradiation: Applications to the outer solar system |journal=[[Journal of Geophysical Research]] |volume=92 |issue=A13 |pages=14933–14947 |bibcode=1987JGR....9214933T |doi=10.1029/JA092iA13p14933 |pmid=11542127}}</ref><ref>{{cite web |url=https://www.llnl.gov/news/life-earth-shockingly-comes-out-world |title=Life on Earth shockingly comes from out of this world |last=Stark |first=Anne M. |date=5 June 2013 |publisher=[[Lawrence Livermore National Laboratory]] |location=Livermore, CA |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150916135630/https://www.llnl.gov/news/life-earth-shockingly-comes-out-world |archivedate=16 September 2015}}</ref><ref>{{cite journal |last1=Goldman |first1=Nir |last2=Tamblyn |first2=Isaac |date=20 June 2013 |title=Prebiotic Chemistry within a Simple Impacting Icy Mixture |journal=[[Journal of Physical Chemistry A]] |volume=117 |issue=24 |pages=5124–5131 |doi=10.1021/jp402976n |pmid=23639050|bibcode=2013JPCA..117.5124G |url=http://nparc.nrc-cnrc.gc.ca/eng/view/fulltext/?id=e89d2ac7-4cf8-40e0-bcc9-3c53f68ed70a }}</ref> Amino acids which were formed extraterrestrially may also have arrived on Earth via comets.<ref name="Follmann2009" /> It is estimated that during the Late Heavy Bombardment, meteorites may have delivered up to five million [[ton]]s of organic prebiotic elements to Earth per year.<ref name="Follmann2009" />

美国宇航局在2009年宣布，科学家们首次在彗星中发现了生命的另一个基本化学构件--甘氨酸，这是一种氨基酸，在2004年从彗星野2号喷出的物质中检测到，并被美国宇航局的 "星尘 "探测器抓取。甘氨酸此前也曾在陨石中被检测到。领导美国宇航局天体生物学研究所的卡尔-皮尔彻Carl Pilcher说。

美国宇航局在2009年宣布，科学家们首次在彗星中发现了生命的另一个基本化学构件--甘氨酸，这是一种氨基酸，在2004年从荒野2号彗星喷出的物质中检测到，并被美国宇航局的 "星尘 "探测器抓取。甘氨酸此前也曾在陨石中被检测到。领导美国宇航局天体生物学研究所的卡尔·皮尔彻Carl Pilcher说。

==== PAH world hypothesis ====

==== PAH world hypothesis ====

[[File:PIA22568-CatsPawNebula-Spitzer-20181023.jpg|thumb|upright=1.3|The [[Cat's Paw Nebula]] lies inside the [[Milky Way Galaxy]] and is located in the [[constellation]] [[Scorpius]].<br>Green areas show regions where radiation from hot stars collided with large molecules and small dust grains called "[[polycyclic aromatic hydrocarbon]]s" (PAHs), causing them to [[fluoresce]].<br>([[Spitzer space telescope]], 2018)]]

[[File:PIA22568-CatsPawNebula-Spitzer-20181023.jpg|thumb|upright=1.3|The [[Cat's Paw Nebula]] lies inside the [[Milky Way Galaxy]] and is located in the [[constellation]] [[Scorpius]].<br>Green areas show regions where radiation from hot stars collided with large molecules and small dust grains called "[[polycyclic aromatic hydrocarbon]]s" (PAHs), causing them to [[fluoresce]].<br>([[Spitzer space telescope]], 2018)]]

（斯皮策太空望远镜，2018）

（斯皮策太空望远镜，2018）

Other sources of complex molecules have been postulated, including extraterrestrial stellar or interstellar origin. For example, from spectral analyses, organic molecules are known to be present in comets and meteorites. In 2004, a team detected traces of PAHs in a nebula.<ref>{{cite conference |last1=Witt |first1=Adolf N. |last2=Vijh |first2=Uma P. |last3=Gordon |first3=Karl D. |date=January 2004 |title=Discovery of Blue Fluorescence by Polycyclic Aromatic Hydrocarbon Molecules in the Red Rectangle |url=https://aas.org/archives/BAAS/v35n5/aas203/189.htm |publisher=[[American Astronomical Society]] |bibcode=2003AAS...20311017W |archiveurl=https://web.archive.org/web/20031219175322/http://www.aas.org/publications/baas/v35n5/aas203/189.htm |archivedate=19 December 2003 |url-status=dead |conference=American Astronomical Society Meeting 203 |location=Atlanta, GA |access-date=16 January 2019 }}</ref> In 2010, another team also detected PAHs, along with fullerenes, in nebulae.<ref name="AJL-20101120" /> The use of PAHs has also been proposed as a precursor to the RNA world in the PAH world hypothesis.<ref>{{Cite journal|last1=d'Ischia|first1=Marco|last2=Manini|first2=Paola|last3=Moracci|first3=Marco|last4=Saladino|first4=Raffaele|last5=Ball|first5=Vincent|last6=Thissen|first6=Helmut|last7=Evans|first7=Richard A.|last8=Puzzarini|first8=Cristina|last9=Barone|first9=Vincenzo|date=2019-08-21|title=Astrochemistry and Astrobiology: Materials Science in Wonderland?|journal=International Journal of Molecular Sciences|volume=20|issue=17|pages=4079|doi=10.3390/ijms20174079|issn=1422-0067|pmc=6747172|pmid=31438518}}</ref> The [[Spitzer Space Telescope]] has detected a star, HH 46-IR, which is forming by a process similar to that by which the Sun formed. In the disk of material surrounding the star, there is a very large range of molecules, including cyanide compounds, [[hydrocarbon]]s, and carbon monoxide. In 2012, NASA scientists reported that PAHs, subjected to interstellar medium conditions, are transformed, through [[hydrogenation]], [[Oxygenate|oxygenation]] and [[hydroxylation]], to more complex organics—"a step along the path toward amino acids and nucleotides, the raw materials of proteins and DNA, respectively."<ref name="Space-20120920">{{cite web |url= http://www.space.com/17681-life-building-blocks-nasa-organic-molecules.html |title= NASA Cooks Up Icy Organics to Mimic Life's Origins |date= 20 September 2012 |website= Space.com |location= Ogden, UT |publisher= Purch |accessdate= 2015-06-26 |url-status= live |archiveurl= https://web.archive.org/web/20150625035023/http://www.space.com/17681-life-building-blocks-nasa-organic-molecules.html |archivedate= 25 June 2015}}</ref><ref name="AJL-20120901">{{cite journal |last1=Gudipati |first1=Murthy S. |author2=Rui Yang |date=1 September 2012 |title=In-situ Probing of Radiation-induced Processing of Organics in Astrophysical Ice Analogs – Novel Laser Desorption Laser Ionization Time-of-flight Mass Spectroscopic Studies |journal=The Astrophysical Journal Letters |volume=756 |issue=1 |bibcode=2012ApJ...756L..24G |doi=10.1088/2041-8205/756/1/L24 |pages=L24}}</ref> Further, as a result of these transformations, the PAHs lose their [[Spectroscopy|spectroscopic signature]] which could be one of the reasons "for the lack of PAH detection in [[interstellar ice]] grains, particularly the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks."<ref name="Space-20120920" /><ref name="AJL-20120901" />

Other sources of complex molecules have been postulated, including extraterrestrial stellar or interstellar origin. For example, from spectral analyses, organic molecules are known to be present in comets and meteorites. In 2004, a team detected traces of PAHs in a nebula.<ref>{{cite conference |last1=Witt |first1=Adolf N. |last2=Vijh |first2=Uma P. |last3=Gordon |first3=Karl D. |date=January 2004 |title=Discovery of Blue Fluorescence by Polycyclic Aromatic Hydrocarbon Molecules in the Red Rectangle |url=https://aas.org/archives/BAAS/v35n5/aas203/189.htm |publisher=[[American Astronomical Society]] |bibcode=2003AAS...20311017W |archiveurl=https://web.archive.org/web/20031219175322/http://www.aas.org/publications/baas/v35n5/aas203/189.htm |archivedate=19 December 2003 |url-status=dead |conference=American Astronomical Society Meeting 203 |location=Atlanta, GA |access-date=16 January 2019 }}</ref> In 2010, another team also detected PAHs, along with fullerenes, in nebulae.<ref name="AJL-20101120" /> The use of PAHs has also been proposed as a precursor to the RNA world in the PAH world hypothesis.<ref>{{Cite journal|last1=d'Ischia|first1=Marco|last2=Manini|first2=Paola|last3=Moracci|first3=Marco|last4=Saladino|first4=Raffaele|last5=Ball|first5=Vincent|last6=Thissen|first6=Helmut|last7=Evans|first7=Richard A.|last8=Puzzarini|first8=Cristina|last9=Barone|first9=Vincenzo|date=2019-08-21|title=Astrochemistry and Astrobiology: Materials Science in Wonderland?|journal=International Journal of Molecular Sciences|volume=20|issue=17|pages=4079|doi=10.3390/ijms20174079|issn=1422-0067|pmc=6747172|pmid=31438518}}</ref> The [[Spitzer Space Telescope]] has detected a star, HH 46-IR, which is forming by a process similar to that by which the Sun formed. In the disk of material surrounding the star, there is a very large range of molecules, including cyanide compounds, [[hydrocarbon]]s, and carbon monoxide. In 2012, NASA scientists reported that PAHs, subjected to interstellar medium conditions, are transformed, through [[hydrogenation]], [[Oxygenate|oxygenation]] and [[hydroxylation]], to more complex organics—"a step along the path toward amino acids and nucleotides, the raw materials of proteins and DNA, respectively."<ref name="Space-20120920">{{cite web |url= http://www.space.com/17681-life-building-blocks-nasa-organic-molecules.html |title= NASA Cooks Up Icy Organics to Mimic Life's Origins |date= 20 September 2012 |website= Space.com |location= Ogden, UT |publisher= Purch |accessdate= 2015-06-26 |url-status= live |archiveurl= https://web.archive.org/web/20150625035023/http://www.space.com/17681-life-building-blocks-nasa-organic-molecules.html |archivedate= 25 June 2015}}</ref><ref name="AJL-20120901">{{cite journal |last1=Gudipati |first1=Murthy S. |author2=Rui Yang |date=1 September 2012 |title=In-situ Probing of Radiation-induced Processing of Organics in Astrophysical Ice Analogs – Novel Laser Desorption Laser Ionization Time-of-flight Mass Spectroscopic Studies |journal=The Astrophysical Journal Letters |volume=756 |issue=1 |bibcode=2012ApJ...756L..24G |doi=10.1088/2041-8205/756/1/L24 |pages=L24}}</ref> Further, as a result of these transformations, the PAHs lose their [[Spectroscopy|spectroscopic signature]] which could be one of the reasons "for the lack of PAH detection in [[interstellar ice]] grains, particularly the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks."<ref name="Space-20120920" /><ref name="AJL-20120901" />

复杂分子的其他来源也被推测出来，包括地外恒星或星际起源。例如，根据光谱分析，已知有机分子存在于彗星和陨石中。2004年，一个团队在一个星云中检测到了多环芳烃的痕迹。2010年，另一个团队也在星云中检测到了多环芳烃以及富勒烯。"多环芳烃世界 "假说中还提出将多环芳烃作为RNA世界的前兆。斯皮策太空望远镜探测到一颗恒星HH 46-IR，它的形成过程与太阳的形成过程相似。在恒星周围的物质盘中，有非常多的分子，包括氰化物、碳氢化合物和一氧化碳。2012年，美国宇航局的科学家报告说，多环芳烃在星际介质条件下，通过氢化、氧化和羟基化，转化为更复杂的有机物--"分别是向氨基酸和核苷酸（蛋白质和DNA的原料）迈进的一步。 "此外，由于这些转化，多环芳烃失去了它们的光谱特征，这可能是 "星际冰粒中缺乏多环芳烃检测的原因之一，特别是寒冷的稠密云的外部区域或原行星盘的上层分子层。"

复杂分子的其他来源也被推测出来，包括地外恒星或星际起源。例如，根据光谱分析，已知有机分子存在于彗星和陨石中。2004年，一个团队在一个星云中检测到了多环芳烃的痕迹。2010年，另一个团队也在星云中检测到了多环芳烃以及富勒烯。"多环芳烃世界"假说中还提出将多环芳烃作为RNA世界的前导。斯皮策太空望远镜探测到一颗恒星HH 46-IR，它的形成过程与太阳的形成过程相似。在恒星周围的物质盘中，有非常多的分子，包括氰化合物、碳氢化合物和一氧化碳。2012年，美国宇航局的科学家报告说，多环芳烃在星际介质条件下，通过氢化、氧化和羟基化，转化为更复杂的有机物--"分别是向氨基酸和核苷酸（蛋白质和DNA的原料）道路上迈进的一步。 "此外，由于这些转化，多环芳烃失去了它们的光谱特征，这可能是 "星际冰粒，特别是寒冷的稠密云的外部区域或原行星盘的上层分子层中，缺乏检测到多环芳烃的原因之一。"

NASA maintains a database for tracking PAHs in the universe.<ref name="NASA-20140221" /><ref>{{cite web |url=http://www.astrochem.org/pahdb/ |title=NASA Ames PAH IR Spectroscopic Database |publisher=NASA |accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150629185734/http://www.astrochem.org/pahdb/ |archivedate=29 June 2015}}</ref> More than 20% of the carbon in the universe may be associated with PAHs,<ref name="NASA-20140221" /><ref name="NASA-20140221" /> possible starting materials for the formation of life. PAHs seem to have been formed shortly after the Big Bang, are widespread throughout the universe,<ref name="SP-20051018" /><ref name="AJ-20051010" /><ref name="NASA-20110413" /> and are associated with [[Star formation|new stars]] and [[exoplanet]]s.<ref name="NASA-20140221" />

NASA maintains a database for tracking PAHs in the universe.<ref name="NASA-20140221" /><ref>{{cite web |url=http://www.astrochem.org/pahdb/ |title=NASA Ames PAH IR Spectroscopic Database |publisher=NASA |accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150629185734/http://www.astrochem.org/pahdb/ |archivedate=29 June 2015}}</ref> More than 20% of the carbon in the universe may be associated with PAHs,<ref name="NASA-20140221" /><ref name="NASA-20140221" /> possible starting materials for the formation of life. PAHs seem to have been formed shortly after the Big Bang, are widespread throughout the universe,<ref name="SP-20051018" /><ref name="AJ-20051010" /><ref name="NASA-20110413" /> and are associated with [[Star formation|new stars]] and [[exoplanet]]s.<ref name="NASA-20140221" />

美国宇航局维护着一个追踪宇宙中多环芳烃的数据库.宇宙中超过20%的碳可能与多环芳烃有关，可能是生命形成的起始材料。多环芳烃似乎是在宇宙大爆炸后不久形成的，在宇宙中广泛存在，并与新的恒星和系外行星有关。

美国宇航局维护着一个追踪宇宙中多环芳烃的数据库。宇宙中超过20%的碳可能与多环芳烃有关，可能是生命形成的起始材料。多环芳烃似乎是在宇宙大爆炸后不久形成的，在宇宙中广泛存在，并与新的恒星和系外行星有关。

====Nucleobases====

====Nucleobases====

Observations suggest that the majority of organic compounds introduced on Earth by interstellar dust particles are considered principal agents in the formation of complex molecules, thanks to their peculiar [[catalysis|surface-catalytic]] activities.<ref name="Lincei">{{cite journal |last=Gallori |first=Enzo |title=Astrochemistry and the origin of genetic material |journal=Rendiconti Lincei |date=June 2011 |volume=22 |issue=2 |pages=113–118 |doi=10.1007/s12210-011-0118-4 |s2cid=96659714 }} "Paper presented at the Symposium 'Astrochemistry: molecules in space and time' (Rome, 4–5 November 2010), sponsored by Fondazione 'Guido Donegani', Accademia Nazionale dei Lincei."</ref><ref>{{cite journal |last=Martins |first=Zita |authorlink=Zita Martins |date=February 2011 |title=Organic Chemistry of Carbonaceous Meteorites |journal=[[Elements (journal)|Elements]] |volume=7 |issue=1 |pages=35–40 |doi=10.2113/gselements.7.1.35 }}</ref> Studies reported in 2008, based on ¹²C/¹³C [[Natural abundance|isotopic ratios]] of organic compounds found in the Murchison meteorite, suggested that the RNA component uracil and related molecules, including [[xanthine]], were formed extraterrestrially.<ref name="Murch_base">{{cite journal |last1=Martins |first1=Zita |last2=Botta |first2=Oliver |last3=Fogel |first3=Marilyn L. |last4=Sephton |first4=Mark A. |last5=Glavin |first5=Daniel P. |last6=Watson |first6=Jonathan S. |last7=Dworkin |first7=Jason P. |last8=Schwartz |first8=Alan W. |last9=Ehrenfreund |first9=Pascale |display-authors=3 |date=15 June 2008 |title=Extraterrestrial nucleobases in the Murchison meteorite |journal=Earth and Planetary Science Letters |volume=270 |issue=1–2 |pages=130–136 |bibcode=2008E&PSL.270..130M |arxiv=0806.2286 |doi=10.1016/j.epsl.2008.03.026 |s2cid=14309508 }}</ref><ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |date=14 June 2008 |title=We may all be space aliens: study |url=http://www.abc.net.au/news/2008-06-14/we-may-all-be-space-aliens-study/2471434 |location=Sydney |publisher=[[Australian Broadcasting Corporation]] |agency=[[Agence France-Presse]] |accessdate=2015-06-22 |url-status=live |archiveurl=https://web.archive.org/web/20150623073332/http://www.abc.net.au/news/2008-06-14/we-may-all-be-space-aliens-study/2471434 |archivedate=23 June 2015}}</ref> In 2011, a report based on [[NASA]] studies of meteorites found on Earth was published suggesting DNA components (adenine, guanine and related organic molecules) were made in outer space.<ref name="Lincei" /><ref name="Callahan">{{cite journal |last1=Callahan |first1=Michael P. |last2=Smith |first2=Karen E. |last3=Cleaves |first3=H. James, II |last4=Ruzica |first4=Josef |last5=Stern |first5=Jennifer C. |last6=Glavin |first6=Daniel P. |last7=House |first7=Christopher H. |last8=Dworkin |first8=Jason P. |display-authors=3 |date=23 August 2011 |title=Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=108 |issue=34 |pages=13995–13998 |bibcode=2011PNAS..10813995C |doi=10.1073/pnas.1106493108 |pmc=3161613 |pmid=21836052}}</ref><ref name="Steigerwald">{{cite web |url=http://www.nasa.gov/topics/solarsystem/features/dna-meteorites.html |title=NASA Researchers: DNA Building Blocks Can Be Made in Space |last=Steigerwald |first=John |date=8 August 2011 |work=[[Goddard Space Flight Center]] |publisher=NASA |location=Greenbelt, MD |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150623004556/http://www.nasa.gov/topics/solarsystem/features/dna-meteorites.html |archivedate=23 June 2015}}</ref> Scientists also found that the [[cosmic dust]] permeating the universe contains complex organics ("amorphous organic solids with a mixed [[Aromaticity|aromatic]]–[[Aliphatic compound|aliphatic]] structure") that could be created naturally, and rapidly, by stars.<ref name="Space-20111026">{{cite news |last= Chow |first= Denise |date= 26 October 2011 |title= Discovery: Cosmic Dust Contains Organic Matter from Stars |url= http://www.space.com/13401-cosmic-star-dust-complex-organic-compounds.html |website= Space.com |location= Ogden, UT |publisher= Purch |accessdate= 2015-06-23 |url-status= live |archiveurl= https://web.archive.org/web/20150714084901/http://www.space.com/13401-cosmic-star-dust-complex-organic-compounds.html |archivedate= 14 July 2015}}</ref><ref name="ScienceDaily-20111026">{{cite news |author=The University of Hong Kong |date=27 October 2011 |title=Astronomers discover complex organic matter exists throughout the universe |url=https://www.sciencedaily.com/releases/2011/10/111026143721.htm |location=Rockville, MD |publisher= ScienceDaily, LLC |url-status=live |archiveurl=https://web.archive.org/web/20150703185252/https://www.sciencedaily.com/releases/2011/10/111026143721.htm |archivedate=3 July 2015|author-link=University of Hong Kong }}</ref><ref name="Nature-20111026">{{cite journal |author1=Sun Kwok |authorlink1=Sun Kwok |author2=Yong Zhang |date=3 November 2011 |title=Mixed aromatic–aliphatic organic nanoparticles as carriers of unidentified infrared emission features |journal=Nature |volume=479 |issue=7371 |pages=80–83 |bibcode=2011Natur.479...80K |doi=10.1038/nature10542 |pmid=22031328|s2cid=4419859 }}</ref> [[Sun Kwok]] of [[University of Hong Kong|The University of Hong Kong]] suggested that these compounds may have been related to the development of life on Earth said that "If this is the case, life on Earth may have had an easier time getting started as these organics can serve as basic ingredients for life."<ref name="Space-20111026" />

Observations suggest that the majority of organic compounds introduced on Earth by interstellar dust particles are considered principal agents in the formation of complex molecules, thanks to their peculiar [[catalysis|surface-catalytic]] activities.<ref name="Lincei">{{cite journal |last=Gallori |first=Enzo |title=Astrochemistry and the origin of genetic material |journal=Rendiconti Lincei |date=June 2011 |volume=22 |issue=2 |pages=113–118 |doi=10.1007/s12210-011-0118-4 |s2cid=96659714 }} "Paper presented at the Symposium 'Astrochemistry: molecules in space and time' (Rome, 4–5 November 2010), sponsored by Fondazione 'Guido Donegani', Accademia Nazionale dei Lincei."</ref><ref>{{cite journal |last=Martins |first=Zita |authorlink=Zita Martins |date=February 2011 |title=Organic Chemistry of Carbonaceous Meteorites |journal=[[Elements (journal)|Elements]] |volume=7 |issue=1 |pages=35–40 |doi=10.2113/gselements.7.1.35 }}</ref> Studies reported in 2008, based on ¹²C/¹³C [[Natural abundance|isotopic ratios]] of organic compounds found in the Murchison meteorite, suggested that the RNA component uracil and related molecules, including [[xanthine]], were formed extraterrestrially.<ref name="Murch_base">{{cite journal |last1=Martins |first1=Zita |last2=Botta |first2=Oliver |last3=Fogel |first3=Marilyn L. |last4=Sephton |first4=Mark A. |last5=Glavin |first5=Daniel P. |last6=Watson |first6=Jonathan S. |last7=Dworkin |first7=Jason P. |last8=Schwartz |first8=Alan W. |last9=Ehrenfreund |first9=Pascale |display-authors=3 |date=15 June 2008 |title=Extraterrestrial nucleobases in the Murchison meteorite |journal=Earth and Planetary Science Letters |volume=270 |issue=1–2 |pages=130–136 |bibcode=2008E&PSL.270..130M |arxiv=0806.2286 |doi=10.1016/j.epsl.2008.03.026 |s2cid=14309508 }}</ref><ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |date=14 June 2008 |title=We may all be space aliens: study |url=http://www.abc.net.au/news/2008-06-14/we-may-all-be-space-aliens-study/2471434 |location=Sydney |publisher=[[Australian Broadcasting Corporation]] |agency=[[Agence France-Presse]] |accessdate=2015-06-22 |url-status=live |archiveurl=https://web.archive.org/web/20150623073332/http://www.abc.net.au/news/2008-06-14/we-may-all-be-space-aliens-study/2471434 |archivedate=23 June 2015}}</ref> In 2011, a report based on [[NASA]] studies of meteorites found on Earth was published suggesting DNA components (adenine, guanine and related organic molecules) were made in outer space.<ref name="Lincei" /><ref name="Callahan">{{cite journal |last1=Callahan |first1=Michael P. |last2=Smith |first2=Karen E. |last3=Cleaves |first3=H. James, II |last4=Ruzica |first4=Josef |last5=Stern |first5=Jennifer C. |last6=Glavin |first6=Daniel P. |last7=House |first7=Christopher H. |last8=Dworkin |first8=Jason P. |display-authors=3 |date=23 August 2011 |title=Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=108 |issue=34 |pages=13995–13998 |bibcode=2011PNAS..10813995C |doi=10.1073/pnas.1106493108 |pmc=3161613 |pmid=21836052}}</ref><ref name="Steigerwald">{{cite web |url=http://www.nasa.gov/topics/solarsystem/features/dna-meteorites.html |title=NASA Researchers: DNA Building Blocks Can Be Made in Space |last=Steigerwald |first=John |date=8 August 2011 |work=[[Goddard Space Flight Center]] |publisher=NASA |location=Greenbelt, MD |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150623004556/http://www.nasa.gov/topics/solarsystem/features/dna-meteorites.html |archivedate=23 June 2015}}</ref> Scientists also found that the [[cosmic dust]] permeating the universe contains complex organics ("amorphous organic solids with a mixed [[Aromaticity|aromatic]]–[[Aliphatic compound|aliphatic]] structure") that could be created naturally, and rapidly, by stars.<ref name="Space-20111026">{{cite news |last= Chow |first= Denise |date= 26 October 2011 |title= Discovery: Cosmic Dust Contains Organic Matter from Stars |url= http://www.space.com/13401-cosmic-star-dust-complex-organic-compounds.html |website= Space.com |location= Ogden, UT |publisher= Purch |accessdate= 2015-06-23 |url-status= live |archiveurl= https://web.archive.org/web/20150714084901/http://www.space.com/13401-cosmic-star-dust-complex-organic-compounds.html |archivedate= 14 July 2015}}</ref><ref name="ScienceDaily-20111026">{{cite news |author=The University of Hong Kong |date=27 October 2011 |title=Astronomers discover complex organic matter exists throughout the universe |url=https://www.sciencedaily.com/releases/2011/10/111026143721.htm |location=Rockville, MD |publisher= ScienceDaily, LLC |url-status=live |archiveurl=https://web.archive.org/web/20150703185252/https://www.sciencedaily.com/releases/2011/10/111026143721.htm |archivedate=3 July 2015|author-link=University of Hong Kong }}</ref><ref name="Nature-20111026">{{cite journal |author1=Sun Kwok |authorlink1=Sun Kwok |author2=Yong Zhang |date=3 November 2011 |title=Mixed aromatic–aliphatic organic nanoparticles as carriers of unidentified infrared emission features |journal=Nature |volume=479 |issue=7371 |pages=80–83 |bibcode=2011Natur.479...80K |doi=10.1038/nature10542 |pmid=22031328|s2cid=4419859 }}</ref> [[Sun Kwok]] of [[University of Hong Kong|The University of Hong Kong]] suggested that these compounds may have been related to the development of life on Earth said that "If this is the case, life on Earth may have had an easier time getting started as these organics can serve as basic ingredients for life."<ref name="Space-20111026" />

观测结果表明，星际尘埃颗粒引入地球的大多数有机化合物被认为是形成复杂分子的主要媒介，这是因为它们具有特殊的表面催化活性。2008年报告的研究基于在默奇森陨石中发现的有机化合物的12C/13C同位素比率，表明RNA成分尿嘧啶和相关分子，包括黄嘌呤，是在外星形成的。 2011年，发表了一份基于美国宇航局对在地球上发现的陨石的研究的报告，表明DNA成分（腺嘌呤、鸟嘌呤和相关有机分子）是在外太空制造的。 科学家们还发现，弥漫在宇宙中的宇宙尘埃中含有复杂的有机物（"具有芳香族-脂肪族混合结构的无定形有机固体"），这些有机物可能是由恒星自然地、迅速地创造出来的。香港大学的Sun Kwok提出，这些化合物可能与地球上生命的发展有关，他说："如果是这样的话，地球上的生命可能更容易开始，因为这些有机物可以作为生命的基本成分。"

观测结果表明，星际尘埃颗粒引入地球的大多数有机化合物被认为是形成复杂分子的主要媒介，这是因为它们具有特殊的表面催化活性。2008年报告的研究基于在默奇森陨石中发现的有机化合物的¹²C/¹³C同位素比率，表明RNA成分尿嘧啶和相关分子，包括黄嘌呤，是在外星形成的。 2011年，发表了一份基于美国宇航局对在地球上发现的陨石的研究的报告，表明DNA成分（腺嘌呤、鸟嘌呤和相关有机分子）是在外太空制造的。 科学家们还发现，弥漫在宇宙中的宇宙尘埃中含有复杂的有机物（"具有芳香族-脂肪族混合结构的无定形有机固体"），这些有机物可能是由恒星自然地、迅速地创造出来的。香港大学的郭新 Sun Kwok提出，这些化合物可能与地球上生命的发展有关，他说："如果是这样的话，地球上的生命可能更容易开始，因为这些有机物可以作为生命的基本原料。"

====The sugar glycolaldehyde====

====The sugar glycolaldehyde====

[[File:Formation of Glycolaldehyde in star dust.png|thumb|Formation of [[glycolaldehyde]] in [[Cosmic dust|stardust]]]]

[[File:Formation of Glycolaldehyde in star dust.png|thumb|Formation of [[glycolaldehyde]] in [[Cosmic dust|stardust]]]]

Glycolaldehyde, the first example of an interstellar sugar molecule, was detected in the star-forming region near the centre of our galaxy. It was discovered in 2000 by Jes Jørgensen and Jan Hollis.<ref name=Hollis>{{cite web |url=http://www.nasa.gov/vision/universe/starsgalaxies/interstellar_sugar.html |title=Space Sugar's a Sweet Find |first1=Lara |last1=Clemence |last2=Cohen |first2=Jarrett |date=7 February 2005 |work=Goddard Space Flight Center |publisher=NASA |location=Greenbelt, MD |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20160305002758/http://www.nasa.gov/vision/universe/starsgalaxies/interstellar_sugar.html |archivedate=5 March 2016}}</ref> In 2012, Jørgensen's team reported the detection of glycolaldehyde in a distant star system. The molecule was found around the [[protostar|protostellar]] binary [[IRAS 16293-2422]] 400 [[Light-year|light years]] from Earth.<ref name="NG-20120829">{{cite news |last=Than |first=Ker |date=30 August 2012 |title=Sugar Found in Space: A Sign of Life? |url=http://news.nationalgeographic.com/news/2012/08/120829-sugar-space-planets-science-life/ |work=National Geographic News |location=Washington, D.C. |publisher=[[National Geographic Society]] |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150714073830/http://news.nationalgeographic.com/news/2012/08/120829-sugar-space-planets-science-life/ |archivedate=14 July 2015}}</ref><ref name="AP-20120829">{{cite news |author=<!--Staff writer(s); no by-line.--> |date=29 August 2012 |title=Sweet! Astronomers spot sugar molecule near star |url=http://apnews.excite.com/article/20120829/DA0V31D80.html |work=[[Excite]] |location=Yonkers, NY |publisher=[[Mindspark Interactive Network]] |agency=[[Associated Press]] |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150714101929/http://apnews.excite.com/article/20120829/DA0V31D80.html |archivedate=14 July 2015}}</ref><ref>{{cite web |url=http://www.news.leiden.edu/news-2012/building-blocks-for-life-found-on-young-star.html |title=Building blocks of life found around young star |author=<!--Staff writer(s); no by-line.--> |date=30 September 2012 |website=News & Events |publisher=[[Leiden University]] |location=Leiden, the Netherlands |accessdate=2013-12-11 |url-status=live |archiveurl=https://web.archive.org/web/20131213135815/http://www.news.leiden.edu/news-2012/building-blocks-for-life-found-on-young-star.html |archivedate=13 December 2013}}</ref> Glycolaldehyde is needed to form RNA, which is similar in function to DNA. These findings suggest that complex organic molecules may form in stellar systems prior to the formation of planets, eventually arriving on young planets early in their formation.<ref>{{cite journal |last1=Jørgensen |first1=Jes K. |last2=Favre |first2=Cécile |last3=Bisschop |first3=Suzanne E. |last4=Bourke |first4=Tyler L. |last5=van Dishoeck |first5=Ewine F. |authorlink5=Ewine van Dishoeck |last6=Schmalzl |first6=Markus |display-authors=3 |date=2012 |title=Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA |url=http://www.eso.org/public/archives/releases/sciencepapers/eso1234/eso1234a.pdf |journal=The Astrophysical Journal Letters |volume=757 |issue=1 |arxiv=1208.5498 |bibcode=2012ApJ...757L...4J |doi=10.1088/2041-8205/757/1/L4 |accessdate=2015-06-23 |pages=L4 |s2cid=14205612 |url-status=live |archiveurl=https://web.archive.org/web/20150924021240/http://www.eso.org/public/archives/releases/sciencepapers/eso1234/eso1234a.pdf |archivedate=24 September 2015}}</ref><ref name="PNAS-20191113">{{Cite journal|last1=Furukawa|first1=Yoshihiro|last2=Chikaraishi|first2=Yoshito|last3=Ohkouchi|first3=Naohiko|last4=Ogawa|first4=Nanako O.|last5=Glavin|first5=Daniel P.|last6=Dworkin|first6=Jason P.|last7=Abe|first7=Chiaki|last8=Nakamura|first8=Tomoki|date=2019-11-13|title=Extraterrestrial ribose and other sugars in primitive meteorites|journal=Proceedings of the National Academy of Sciences|volume=116|issue=49|pages=24440–24445|language=en|doi=10.1073/pnas.1907169116|issn=0027-8424|pmid=31740594|pmc=6900709|bibcode=2019PNAS..11624440F}}</ref> Because sugars are associated with both metabolism and the [[genetic code]], two of the most basic aspects of life, it is thought the discovery of extraterrestrial sugar increases the likelihood that life may exist elsewhere in our galaxy.<ref name="Hollis" />

Glycolaldehyde, the first example of an interstellar sugar molecule, was detected in the star-forming region near the centre of our galaxy. It was discovered in 2000 by Jes Jørgensen and Jan Hollis.<ref name=Hollis>{{cite web |url=http://www.nasa.gov/vision/universe/starsgalaxies/interstellar_sugar.html |title=Space Sugar's a Sweet Find |first1=Lara |last1=Clemence |last2=Cohen |first2=Jarrett |date=7 February 2005 |work=Goddard Space Flight Center |publisher=NASA |location=Greenbelt, MD |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20160305002758/http://www.nasa.gov/vision/universe/starsgalaxies/interstellar_sugar.html |archivedate=5 March 2016}}</ref> In 2012, Jørgensen's team reported the detection of glycolaldehyde in a distant star system. The molecule was found around the [[protostar|protostellar]] binary [[IRAS 16293-2422]] 400 [[Light-year|light years]] from Earth.<ref name="NG-20120829">{{cite news |last=Than |first=Ker |date=30 August 2012 |title=Sugar Found in Space: A Sign of Life? |url=http://news.nationalgeographic.com/news/2012/08/120829-sugar-space-planets-science-life/ |work=National Geographic News |location=Washington, D.C. |publisher=[[National Geographic Society]] |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150714073830/http://news.nationalgeographic.com/news/2012/08/120829-sugar-space-planets-science-life/ |archivedate=14 July 2015}}</ref><ref name="AP-20120829">{{cite news |author=<!--Staff writer(s); no by-line.--> |date=29 August 2012 |title=Sweet! Astronomers spot sugar molecule near star |url=http://apnews.excite.com/article/20120829/DA0V31D80.html |work=[[Excite]] |location=Yonkers, NY |publisher=[[Mindspark Interactive Network]] |agency=[[Associated Press]] |accessdate=2015-06-23 |url-status=live |archiveurl=https://web.archive.org/web/20150714101929/http://apnews.excite.com/article/20120829/DA0V31D80.html |archivedate=14 July 2015}}</ref><ref>{{cite web |url=http://www.news.leiden.edu/news-2012/building-blocks-for-life-found-on-young-star.html |title=Building blocks of life found around young star |author=<!--Staff writer(s); no by-line.--> |date=30 September 2012 |website=News & Events |publisher=[[Leiden University]] |location=Leiden, the Netherlands |accessdate=2013-12-11 |url-status=live |archiveurl=https://web.archive.org/web/20131213135815/http://www.news.leiden.edu/news-2012/building-blocks-for-life-found-on-young-star.html |archivedate=13 December 2013}}</ref> Glycolaldehyde is needed to form RNA, which is similar in function to DNA. These findings suggest that complex organic molecules may form in stellar systems prior to the formation of planets, eventually arriving on young planets early in their formation.<ref>{{cite journal |last1=Jørgensen |first1=Jes K. |last2=Favre |first2=Cécile |last3=Bisschop |first3=Suzanne E. |last4=Bourke |first4=Tyler L. |last5=van Dishoeck |first5=Ewine F. |authorlink5=Ewine van Dishoeck |last6=Schmalzl |first6=Markus |display-authors=3 |date=2012 |title=Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA |url=http://www.eso.org/public/archives/releases/sciencepapers/eso1234/eso1234a.pdf |journal=The Astrophysical Journal Letters |volume=757 |issue=1 |arxiv=1208.5498 |bibcode=2012ApJ...757L...4J |doi=10.1088/2041-8205/757/1/L4 |accessdate=2015-06-23 |pages=L4 |s2cid=14205612 |url-status=live |archiveurl=https://web.archive.org/web/20150924021240/http://www.eso.org/public/archives/releases/sciencepapers/eso1234/eso1234a.pdf |archivedate=24 September 2015}}</ref><ref name="PNAS-20191113">{{Cite journal|last1=Furukawa|first1=Yoshihiro|last2=Chikaraishi|first2=Yoshito|last3=Ohkouchi|first3=Naohiko|last4=Ogawa|first4=Nanako O.|last5=Glavin|first5=Daniel P.|last6=Dworkin|first6=Jason P.|last7=Abe|first7=Chiaki|last8=Nakamura|first8=Tomoki|date=2019-11-13|title=Extraterrestrial ribose and other sugars in primitive meteorites|journal=Proceedings of the National Academy of Sciences|volume=116|issue=49|pages=24440–24445|language=en|doi=10.1073/pnas.1907169116|issn=0027-8424|pmid=31740594|pmc=6900709|bibcode=2019PNAS..11624440F}}</ref> Because sugars are associated with both metabolism and the [[genetic code]], two of the most basic aspects of life, it is thought the discovery of extraterrestrial sugar increases the likelihood that life may exist elsewhere in our galaxy.<ref name="Hollis" />

乙二醇醛是星际糖分子的第一个例子，在银河系中心附近的恒星形成区被发现。它是由Jes Jørgensen和Jan Hollis在2000年发现的。2012年，Jørgensen的团队报告了在一个遥远的恒星系统中发现乙醛。该分子是在距离地球400光年的原恒星双星IRAS 16293-2422周围发现的。乙醛是形成RNA所需要的，其功能与DNA相似。这些发现表明，复杂的有机分子可能在行星形成之前就在恒星系统中形成，最终在行星形成的早期到达年轻行星上。由于糖类与新陈代谢和遗传密码这两个生命最基本的方面有关，因此认为发现地外糖类增加了银河系其他地方可能存在生命的可能性。

羟乙醛是星际糖分子的第一个例子，在银河系中心附近的恒星形成区被发现。它是由詹斯·约根森 Jes Jørgensen和简·霍利斯 Jan Hollis在2000年发现的。2012年，Jørgensen的团队报告了在一个遥远的恒星系统中发现羟乙醛。该分子是在距离地球400光年的原恒星双星IRAS 16293-2422周围发现的。羟乙醛是形成RNA所需要的，RNA的功能与DNA相似。这些发现表明，复杂的有机分子可能在行星形成之前就在恒星系统中形成，最终在行星形成的早期到达年轻行星上。由于糖类与新陈代谢和遗传密码这两个生命最基本的方面有关，因此认为发现地外糖类增加了银河系其他地方可能存在生命的可能性。

==== Polyphosphates ====

==== Polyphosphates ====

A problem in most scenarios of abiogenesis is that the thermodynamic equilibrium of amino acid versus peptides is in the direction of separate amino acids. What has been missing is some force that drives polymerization. The resolution of this problem may well be in the properties of [[polyphosphate]]s.<ref>{{cite journal |last1=Brown |first1=Michael R. W. |last2=Kornberg |first2=Arthur |authorlink2=Arthur Kornberg |date=16 November 2004 |title=Inorganic polyphosphate in the origin and survival of species |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=101 |issue=46 |pages=16085–16087 |bibcode=2004PNAS..10116085B |doi=10.1073/pnas.0406909101|pmc=528972 |pmid=15520374}}</ref><ref>{{cite web |url=http://www.science.siu.edu/microbiology/micr425/425Notes/14-OriginLife.html |title=The Origin of Life |last=Clark |first=David P. |date=3 August 1999 |website=Microbiology 425: Biochemistry and Physiology of Microorganism |publisher=College of Science; [[Southern Illinois University Carbondale]] |location=Carbondale, IL |type=Lecture |archiveurl=https://web.archive.org/web/20001002142750/http://www.science.siu.edu/microbiology/micr425/425Notes/14-OriginLife.html |archivedate=2000-10-02 |url-status=dead |accessdate=2015-06-26}}</ref> Polyphosphates are formed by polymerization of ordinary monophosphate ions PO₄^3-. Several mechanisms of organic molecule synthesis have been investigated. Polyphosphates cause polymerization of amino acids into peptides. They are also logical precursors in the synthesis of such key biochemical compounds as [[adenosine triphosphate]] (ATP). A key issue seems to be that calcium reacts with soluble phosphate to form insoluble [[calcium phosphate]] ([[apatite]]), so some plausible mechanism must be found to keep calcium ions from causing precipitation of phosphate. There has been much work on this topic over the years, but an interesting new idea is that meteorites may have introduced reactive phosphorus species on the early Earth.<ref>{{cite journal |last=Pasek |first=Matthew A. |date=22 January 2008 |title=Rethinking early Earth phosphorus geochemistry |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=105 |issue=3 |pages=853–858 |bibcode=2008PNAS..105..853P |doi=10.1073/pnas.0708205105 |pmc=2242691 |pmid=18195373}}</ref>

A problem in most scenarios of abiogenesis is that the thermodynamic equilibrium of amino acid versus peptides is in the direction of separate amino acids. What has been missing is some force that drives polymerization. The resolution of this problem may well be in the properties of [[polyphosphate]]s.<ref>{{cite journal |last1=Brown |first1=Michael R. W. |last2=Kornberg |first2=Arthur |authorlink2=Arthur Kornberg |date=16 November 2004 |title=Inorganic polyphosphate in the origin and survival of species |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=101 |issue=46 |pages=16085–16087 |bibcode=2004PNAS..10116085B |doi=10.1073/pnas.0406909101|pmc=528972 |pmid=15520374}}</ref><ref>{{cite web |url=http://www.science.siu.edu/microbiology/micr425/425Notes/14-OriginLife.html |title=The Origin of Life |last=Clark |first=David P. |date=3 August 1999 |website=Microbiology 425: Biochemistry and Physiology of Microorganism |publisher=College of Science; [[Southern Illinois University Carbondale]] |location=Carbondale, IL |type=Lecture |archiveurl=https://web.archive.org/web/20001002142750/http://www.science.siu.edu/microbiology/micr425/425Notes/14-OriginLife.html |archivedate=2000-10-02 |url-status=dead |accessdate=2015-06-26}}</ref> Polyphosphates are formed by polymerization of ordinary monophosphate ions PO₄^3-. Several mechanisms of organic molecule synthesis have been investigated. Polyphosphates cause polymerization of amino acids into peptides. They are also logical precursors in the synthesis of such key biochemical compounds as [[adenosine triphosphate]] (ATP). A key issue seems to be that calcium reacts with soluble phosphate to form insoluble [[calcium phosphate]] ([[apatite]]), so some plausible mechanism must be found to keep calcium ions from causing precipitation of phosphate. There has been much work on this topic over the years, but an interesting new idea is that meteorites may have introduced reactive phosphorus species on the early Earth.<ref>{{cite journal |last=Pasek |first=Matthew A. |date=22 January 2008 |title=Rethinking early Earth phosphorus geochemistry |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=105 |issue=3 |pages=853–858 |bibcode=2008PNAS..105..853P |doi=10.1073/pnas.0708205105 |pmc=2242691 |pmid=18195373}}</ref>

Based on recent [[computer simulation|computer model studies]], the [[organic compound|complex organic molecules]] necessary for life may have formed in the [[protoplanetary disk]] of [[cosmic dust|dust grains]] surrounding the [[Sun]] before the formation of the Earth.<ref name="Space-20120329">{{cite news |last=Moskowitz |first=Clara |date=29 March 2012 |title=Life's Building Blocks May Have Formed in Dust Around Young Sun |url=http://www.space.com/15089-life-building-blocks-young-sun-dust.html |website=[[Space.com]] |location=Salt Lake City, UT |publisher=[[Purch]] |accessdate=2012-03-30 |url-status=live |archiveurl=https://web.archive.org/web/20120814205056/http://www.space.com/15089-life-building-blocks-young-sun-dust.html |archivedate=14 August 2012}}</ref><ref>{{cite journal|last1=Ciesla|first1=F.J.|last2=Sandford|first2=S.A.|title=Organic Synthesis via Irradiation and Warming of Ice Grains in the Solar Nebula|journal=Science|date=29 March 2012|volume=336|issue=6080|pages=452–454|doi=10.1126/science.1217291|pmid=22461502|bibcode=2012Sci...336..452C|hdl=2060/20120011864|s2cid=25454671|hdl-access=free}}</ref> According to the computer studies, this same process may also occur around other [[star]]s that acquire [[planet]]s. (Also see [[#Extraterrestrial organic molecules|Extraterrestrial organic molecules]]).

Based on recent [[computer simulation|computer model studies]], the [[organic compound|complex organic molecules]] necessary for life may have formed in the [[protoplanetary disk]] of [[cosmic dust|dust grains]] surrounding the [[Sun]] before the formation of the Earth.<ref name="Space-20120329">{{cite news |last=Moskowitz |first=Clara |date=29 March 2012 |title=Life's Building Blocks May Have Formed in Dust Around Young Sun |url=http://www.space.com/15089-life-building-blocks-young-sun-dust.html |website=[[Space.com]] |location=Salt Lake City, UT |publisher=[[Purch]] |accessdate=2012-03-30 |url-status=live |archiveurl=https://web.archive.org/web/20120814205056/http://www.space.com/15089-life-building-blocks-young-sun-dust.html |archivedate=14 August 2012}}</ref><ref>{{cite journal|last1=Ciesla|first1=F.J.|last2=Sandford|first2=S.A.|title=Organic Synthesis via Irradiation and Warming of Ice Grains in the Solar Nebula|journal=Science|date=29 March 2012|volume=336|issue=6080|pages=452–454|doi=10.1126/science.1217291|pmid=22461502|bibcode=2012Sci...336..452C|hdl=2060/20120011864|s2cid=25454671|hdl-access=free}}</ref> According to the computer studies, this same process may also occur around other [[star]]s that acquire [[planet]]s. (Also see [[#Extraterrestrial organic molecules|Extraterrestrial organic molecules]]).

在大多数非生物发生的情况下，一个问题是氨基酸与肽的热力学平衡是向着分离氨基酸的方向发展的。一直以来，缺少的是某种推动聚合的力量。这个问题的解决很可能在于聚磷酸盐的特性。聚磷酸盐是由普通的单磷酸离子PO43-聚合而成。目前已经研究了几种有机分子合成的机制。多磷酸盐能使氨基酸聚合成肽。它们也是合成三磷酸腺苷(ATP)等关键生化化合物的逻辑前体。一个关键的问题似乎是，钙与可溶性磷酸盐反应形成不溶性的磷酸钙（磷灰石），所以必须找到一些合理的机制来防止钙离子引起磷酸盐的沉淀。多年来，关于这个主题的工作很多，但一个有趣的新想法是，陨石可能在早期地球上引入了活性磷物种。根据最近的计算机模型研究，在地球形成之前，生命所必需的复杂有机分子可能已经在太阳周围的尘粒原行星盘中形成.根据计算机研究，这个相同的过程也可能发生在其他获得行星的恒星周围。

在大多数非生物发生的情况下，一个问题是氨基酸与肽的热力学平衡是向着分离氨基酸的方向发展的。一直以来，缺少的是某种推动聚合的力量。这个问题的解决很可能在于多聚磷酸盐的特性。聚磷酸盐是由普通的单磷酸离子PO₄^3-聚合而成。目前已经研究了几种有机分子合成的机制。多聚磷酸盐能使氨基酸聚合成肽。它们也是合成三磷酸腺苷(ATP)等关键生化化合物的逻辑前体。一个关键的问题似乎是，钙与可溶性磷酸盐反应形成不溶性的磷酸钙（磷灰石），所以必须找到一些似合理的机制来防止钙离子引起磷酸盐的沉淀。多年来，关于这个主题的工作很多，但一个有趣的新想法是，陨石可能在早期地球上引入了活性磷物种。根据最近的计算机模型研究，在地球形成之前，生命所必需的复杂有机分子可能已经在太阳周围的尘粒的原行星盘中形成了。根据计算机研究，这个相同的过程也可能发生在其他获得行星的恒星周围。

The accumulation and concentration of organic molecules on a planetary surface is also considered an essential early step for the origin of life.<ref name="NASA strategy 2015"/> Identifying and understanding the mechanisms that led to the production of prebiotic molecules in various environments is critical for establishing the inventory of ingredients from which life originated on Earth, assuming that the abiotic production of molecules ultimately influenced the selection of molecules from which life emerged.<ref name="NASA strategy 2015"/>

The accumulation and concentration of organic molecules on a planetary surface is also considered an essential early step for the origin of life.<ref name="NASA strategy 2015"/> Identifying and understanding the mechanisms that led to the production of prebiotic molecules in various environments is critical for establishing the inventory of ingredients from which life originated on Earth, assuming that the abiotic production of molecules ultimately influenced the selection of molecules from which life emerged.<ref name="NASA strategy 2015"/>

In 2019, scientists reported detecting, for the first time, [[Sugar|sugar molecules]], including [[ribose]], in [[meteorite]]s, suggesting that chemical processes on [[asteroid]]s can produce some fundamentally essential bio-ingredients important to [[life]], and supporting the notion of an [[RNA world]] prior to a DNA-based origin of life on Earth, and possibly, as well, the notion of [[panspermia]].<ref name="NASA-20191118">{{cite news |last1=Steigerwald |first1=Bill |last2=Jones |first2=Nancy |last3=Furukawa |first3=Yoshihiro |title=First Detection of Sugars in Meteorites Gives Clues to Origin of Life |url=https://www.nasa.gov/press-release/goddard/2019/sugars-in-meteorites |date=18 November 2019 |work=[[NASA]] |accessdate=18 November 2019 }}</ref><ref name="PNAS-20191113" />

In 2019, scientists reported detecting, for the first time, [[Sugar|sugar molecules]], including [[ribose]], in [[meteorite]]s, suggesting that chemical processes on [[asteroid]]s can produce some fundamentally essential bio-ingredients important to [[life]], and supporting the notion of an [[RNA world]] prior to a DNA-based origin of life on Earth, and possibly, as well, the notion of [[panspermia]].<ref name="NASA-20191118">{{cite news |last1=Steigerwald |first1=Bill |last2=Jones |first2=Nancy |last3=Furukawa |first3=Yoshihiro |title=First Detection of Sugars in Meteorites Gives Clues to Origin of Life |url=https://www.nasa.gov/press-release/goddard/2019/sugars-in-meteorites |date=18 November 2019 |work=[[NASA]] |accessdate=18 November 2019 }}</ref><ref name="PNAS-20191113" />

=== Chemical synthesis in the laboratory===

=== Chemical synthesis in the laboratory===

In trying to uncover the intermediate stages of abiogenesis mentioned by Bernal, [[Sidney W. Fox|Sidney Fox]] in the 1950s and 1960s studied the spontaneous formation of [[peptide]] structures (small chains of amino acids) under conditions that might plausibly have existed early in Earth's history. In one of his experiments, he allowed amino acids to dry out as if puddled in a warm, dry spot in prebiotic conditions: In an experiment to set suitable conditions for life to form, Fox collected volcanic material from a [[cinder cone]] in [[Hawaii]]. He discovered that the temperature was over 100 C just {{convert|4|in}} beneath the surface of the cinder cone, and suggested that this might have been the environment in which life was created—molecules could have formed and then been washed through the loose volcanic ash into the sea. He placed lumps of lava over amino acids derived from methane, ammonia and water, sterilized all materials, and baked the lava over the amino acids for a few hours in a glass oven. A brown, sticky substance formed over the surface, and when the lava was drenched in sterilized water, a thick, brown liquid leached out. He found that, as they dried, the amino acids formed long, often cross-linked, thread-like, submicroscopic [[Peptide|polypeptide]] molecules.<ref name="foxexp"/>

In trying to uncover the intermediate stages of abiogenesis mentioned by Bernal, [[Sidney W. Fox|Sidney Fox]] in the 1950s and 1960s studied the spontaneous formation of [[peptide]] structures (small chains of amino acids) under conditions that might plausibly have existed early in Earth's history. In one of his experiments, he allowed amino acids to dry out as if puddled in a warm, dry spot in prebiotic conditions: In an experiment to set suitable conditions for life to form, Fox collected volcanic material from a [[cinder cone]] in [[Hawaii]]. He discovered that the temperature was over 100 C just {{convert|4|in}} beneath the surface of the cinder cone, and suggested that this might have been the environment in which life was created—molecules could have formed and then been washed through the loose volcanic ash into the sea. He placed lumps of lava over amino acids derived from methane, ammonia and water, sterilized all materials, and baked the lava over the amino acids for a few hours in a glass oven. A brown, sticky substance formed over the surface, and when the lava was drenched in sterilized water, a thick, brown liquid leached out. He found that, as they dried, the amino acids formed long, often cross-linked, thread-like, submicroscopic [[Peptide|polypeptide]] molecules.<ref name="foxexp"/>

在试图发现Bernal提到的非生物发生的中间阶段时，西德尼-福克斯Sidney Fox在20世纪50年代和60年代研究了在地球历史早期可能存在的条件下自发形成的肽结构（氨基酸小链）。在他的一个实验中，他让氨基酸在前生物条件下，像在温暖干燥的地方布丁一样干燥。在一个为生命的形成设置合适条件的实验中，Fox从夏威夷的一个煤渣堆中收集了火山材料。他发现煤渣锥表面下4英寸（100毫米）的温度就超过了100摄氏度，并认为这可能是创造生命的环境--分子可能已经形成，然后通过松散的火山灰被冲入海中。他将块状熔岩放在由甲烷、氨和水衍生的氨基酸上，对所有材料进行消毒，并将熔岩放在氨基酸上，在玻璃炉中烘烤几个小时。在表面形成了一种棕色的粘性物质，当把熔岩浸泡在消毒水中时，就会有浓稠的棕色液体渗出。他发现，随着它们的干燥，氨基酸形成了长长的、常常是交联的、线状的、亚显微的多肽分子。

在试图发现Bernal提到的非生物发生的中间阶段时，西德尼·福克斯Sidney Fox在20世纪50年代和60年代研究了在地球历史早期可能存在的条件下自发形成的肽结构（小的氨基酸链）。在他的一个实验中，他让氨基酸在前生物条件下，像在温暖干燥的地方搅拌一样变干燥。在一个为生命的形成设置合适条件的实验中，Fox从夏威夷的一个火山灰烬锥状物中收集了火山材料。他发现火山灰烬锥状物表面下4英寸（100毫米）的温度就超过了100 C，并认为这可能是生命诞生的环境--分子可能已经形成，然后通过松散的火山灰被冲入海中。他将一块块的熔岩放在由甲烷、氨和水产生的氨基酸上，对所有材料进行灭菌，并将熔岩放在氨基酸上，在玻璃炉中烘烤几个小时。在表面形成了一种棕色的粘性物质，当把熔岩浸泡在消毒水中时，就会有浓稠的棕色液体渗出。他发现，随着它们的干燥，氨基酸形成了长长的、常常是交联的、线状的、亚显微的多肽分子。

====Sugars====

====Sugars====

In particular, experiments by [[Alexander Butlerov|Butlerov]] (the [[formose reaction]]) showed that tetroses, pentoses, and hexoses are produced when formaldehyde is heated under basic conditions with divalent metal ions like calcium.  The reaction was scrutinized and subsequently proposed to be autocatalytic by Breslow in 1959.

In particular, experiments by [[Alexander Butlerov|Butlerov]] (the [[formose reaction]]) showed that tetroses, pentoses, and hexoses are produced when formaldehyde is heated under basic conditions with divalent metal ions like calcium.  The reaction was scrutinized and subsequently proposed to be autocatalytic by Breslow in 1959.

特别是Butlerov的实验(甲酸糖反应)表明，当甲醛在碱性条件下与钙等二价金属离子加热时，会产生四糖、五糖和六糖。1959年，Breslow对该反应进行了仔细研究，随后提出该反应是自催化反应。

特别是布列特洛夫Butlerov的实验(甲醛聚糖反应)表明，当甲醛在碱性条件下与钙等二价金属离子加热时，会产生四糖、五糖和六糖。1959年，布雷斯洛 Breslow对该反应进行了仔细研究，随后提出该反应是自催化反应。

====Nucleobases====

====Nucleobases====

类似的实验(见下文)表明，像鸟嘌呤和腺嘌呤这样的核酸碱基可以从简单的碳和氮源如氰化氢和氨合成。

类似的实验(见下文)表明，像鸟嘌呤和腺嘌呤这样的核酸碱基可以从简单的碳和氮源如氰化氢和氨合成。

 

[[Formamide]] produces all four ribonucleotides and other biological molecules when warmed in the presence of various terrestrial minerals. Formamide is ubiquitous in the Universe, produced by the reaction of water and [[hydrogen cyanide]] (HCN). It has several advantages as a biotic precursor, including the ability to easily become concentrated through the evaporation of water.<ref name="Saladino2012">{{cite journal |last1=Saladino |first1=Raffaele |last2=Crestini |first2=Claudia |last3=Pino |first3=Samanta |last4=Costanzo |first4=Giovanna |last5=Di Mauro |first5=Ernesto |display-authors=3 |date=March 2012 |title=Formamide and the origin of life. |journal=[[Physics of Life Reviews]] |volume=9 |issue=1 |pages=84–104 |bibcode=2012PhLRv...9...84S |doi=10.1016/j.plrev.2011.12.002 |pmid=22196896|hdl=2108/85168 |url=https://art.torvergata.it/bitstream/2108/85168/1/PoLRev%202012.pdf }}</ref><ref name="Saladino2012b">{{cite journal |last1=Saladino |first1=Raffaele |last2=Botta |first2=Giorgia |last3=Pino |first3=Samanta |last4=Costanzo |first4=Giovanna |last5=Di Mauro |first5=Ernesto |display-authors=3 |date=July 2012 |title=From the one-carbon amide formamide to RNA all the steps are prebiotically possible |journal=[[Biochimie]] |volume=94 |issue=7 |pages=1451–1456 |doi=10.1016/j.biochi.2012.02.018 |pmid=22738728}}</ref> Although HCN is poisonous, it only affects [[aerobic organism]]s ([[eukaryote]]s and aerobic bacteria), which did not yet exist. It can play roles in other chemical processes as well, such as the synthesis of the amino acid [[glycine]].<ref name="Follmann2009" />

[[Formamide]] produces all four ribonucleotides and other biological molecules when warmed in the presence of various terrestrial minerals. Formamide is ubiquitous in the Universe, produced by the reaction of water and [[hydrogen cyanide]] (HCN). It has several advantages as a biotic precursor, including the ability to easily become concentrated through the evaporation of water.<ref name="Saladino2012">{{cite journal |last1=Saladino |first1=Raffaele |last2=Crestini |first2=Claudia |last3=Pino |first3=Samanta |last4=Costanzo |first4=Giovanna |last5=Di Mauro |first5=Ernesto |display-authors=3 |date=March 2012 |title=Formamide and the origin of life. |journal=[[Physics of Life Reviews]] |volume=9 |issue=1 |pages=84–104 |bibcode=2012PhLRv...9...84S |doi=10.1016/j.plrev.2011.12.002 |pmid=22196896|hdl=2108/85168 |url=https://art.torvergata.it/bitstream/2108/85168/1/PoLRev%202012.pdf }}</ref><ref name="Saladino2012b">{{cite journal |last1=Saladino |first1=Raffaele |last2=Botta |first2=Giorgia |last3=Pino |first3=Samanta |last4=Costanzo |first4=Giovanna |last5=Di Mauro |first5=Ernesto |display-authors=3 |date=July 2012 |title=From the one-carbon amide formamide to RNA all the steps are prebiotically possible |journal=[[Biochimie]] |volume=94 |issue=7 |pages=1451–1456 |doi=10.1016/j.biochi.2012.02.018 |pmid=22738728}}</ref> Although HCN is poisonous, it only affects [[aerobic organism]]s ([[eukaryote]]s and aerobic bacteria), which did not yet exist. It can play roles in other chemical processes as well, such as the synthesis of the amino acid [[glycine]].<ref name="Follmann2009" />

In March 2015, NASA scientists reported that, for the first time, complex DNA and RNA organic compounds of life, including uracil, cytosine and [[thymine]], have been formed in the laboratory under outer space conditions, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like PAHs, the most carbon-rich chemical found in the Universe, may have been formed in [[red giant]] stars or in interstellar dust and gas clouds.<ref name="NASA-20150303">{{cite web |url=http://www.nasa.gov/content/nasa-ames-reproduces-the-building-blocks-of-life-in-laboratory |title=NASA Ames Reproduces the Building Blocks of Life in Laboratory |editor-last=Marlaire |editor-first=Ruth |date=3 March 2015 |work=Ames Research Center |publisher=NASA |location=Moffett Field, CA |accessdate=2015-03-05 |url-status=live |archiveurl=https://web.archive.org/web/20150305083306/http://www.nasa.gov/content/nasa-ames-reproduces-the-building-blocks-of-life-in-laboratory/ |archivedate=5 March 2015}}</ref> A group of Czech scientists reported that all four RNA-bases may be synthesized from formamide in the course of high-energy density events like extraterrestrial impacts.<ref>{{cite journal | last1 = Ferus | first1 = Martin | last2 = Nesvorný | first2 = David | last3 = Šponer | first3 = Jiří | last4 = Kubelík | first4 = Petr | last5 = Michalčíková | first5 = Regina | last6 = Shestivská | first6 = Violetta | last7 = Šponer | first7 = Judit E. | last8 = Civiš | first8 = Svatopluk | year = 2015 | title = High-energy chemistry of formamide: A unified mechanism of nucleobase formation | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 112 | issue = 3| pages = 657–662 | doi = 10.1073/pnas.1412072111 | pmid = 25489115 | bibcode = 2015PNAS..112..657F | pmc = 4311869 }}</ref>

In March 2015, NASA scientists reported that, for the first time, complex DNA and RNA organic compounds of life, including uracil, cytosine and [[thymine]], have been formed in the laboratory under outer space conditions, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like PAHs, the most carbon-rich chemical found in the Universe, may have been formed in [[red giant]] stars or in interstellar dust and gas clouds.<ref name="NASA-20150303">{{cite web |url=http://www.nasa.gov/content/nasa-ames-reproduces-the-building-blocks-of-life-in-laboratory |title=NASA Ames Reproduces the Building Blocks of Life in Laboratory |editor-last=Marlaire |editor-first=Ruth |date=3 March 2015 |work=Ames Research Center |publisher=NASA |location=Moffett Field, CA |accessdate=2015-03-05 |url-status=live |archiveurl=https://web.archive.org/web/20150305083306/http://www.nasa.gov/content/nasa-ames-reproduces-the-building-blocks-of-life-in-laboratory/ |archivedate=5 March 2015}}</ref> A group of Czech scientists reported that all four RNA-bases may be synthesized from formamide in the course of high-energy density events like extraterrestrial impacts.<ref>{{cite journal | last1 = Ferus | first1 = Martin | last2 = Nesvorný | first2 = David | last3 = Šponer | first3 = Jiří | last4 = Kubelík | first4 = Petr | last5 = Michalčíková | first5 = Regina | last6 = Shestivská | first6 = Violetta | last7 = Šponer | first7 = Judit E. | last8 = Civiš | first8 = Svatopluk | year = 2015 | title = High-energy chemistry of formamide: A unified mechanism of nucleobase formation | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 112 | issue = 3| pages = 657–662 | doi = 10.1073/pnas.1412072111 | pmid = 25489115 | bibcode = 2015PNAS..112..657F | pmc = 4311869 }}</ref>

====Use of high temperature====

====Use of high temperature====

In 1961, it was shown that the nucleic acid [[purine]] base [[adenine]] can be formed by heating aqueous [[ammonium cyanide]] solutions.<ref>{{cite journal |last=Oró |first=Joan |authorlink=Joan Oró |date=16 September 1961 |title=Mechanism of Synthesis of Adenine from Hydrogen Cyanide under Possible Primitive Earth Conditions |journal=Nature |volume=191 |issue=4794 |pages=1193–1194 |bibcode=1961Natur.191.1193O |doi=10.1038/1911193a0 |pmid=13731264|s2cid=4276712 }}</ref>

In 1961, it was shown that the nucleic acid [[purine]] base [[adenine]] can be formed by heating aqueous [[ammonium cyanide]] solutions.<ref>{{cite journal |last=Oró |first=Joan |authorlink=Joan Oró |date=16 September 1961 |title=Mechanism of Synthesis of Adenine from Hydrogen Cyanide under Possible Primitive Earth Conditions |journal=Nature |volume=191 |issue=4794 |pages=1193–1194 |bibcode=1961Natur.191.1193O |doi=10.1038/1911193a0 |pmid=13731264|s2cid=4276712 }}</ref>

====Use of low (freezing) temperature====

====Use of low (freezing) temperature====

Other pathways for synthesizing bases from inorganic materials were also reported.<ref name="Basile1984">{{cite journal |last1=Basile |first1=Brenda |last2=Lazcano |first2=Antonio |authorlink2=Antonio Lazcano |last3=Oró |first3=Joan |year=1984 |title=Prebiotic syntheses of purines and pyrimidines |journal=[[Advances in Space Research]] |volume=4 |issue=12 |pages=125–131 |bibcode=1984AdSpR...4..125B |doi=10.1016/0273-1177(84)90554-4 |pmid=11537766}}</ref> Orgel and colleagues have shown that freezing temperatures are advantageous for the synthesis of purines, due to the concentrating effect for key precursors such as hydrogen cyanide.<ref>{{cite journal |last=Orgel |first=Leslie E. |date=August 2004 |title=Prebiotic Adenine Revisited: Eutectics and Photochemistry |journal=Origins of Life and Evolution of Biospheres |volume=34 |issue=4 |pages=361–369 |bibcode=2004OLEB...34..361O |doi=10.1023/B:ORIG.0000029882.52156.c2 |pmid=15279171|s2cid=4998122 }}</ref> Research by Miller and colleagues suggested that while adenine and [[guanine]] require freezing conditions for synthesis, [[cytosine]] and [[uracil]] may require boiling temperatures.<ref>{{cite journal |last1=Robertson |first1=Michael P. |last2=Miller |first2=Stanley L. |date=29 June 1995 |title=An efficient prebiotic synthesis of cytosine and uracil |journal=Nature |volume=375 |issue=6534 |pages=772–774 |bibcode=1995Natur.375..772R |doi=10.1038/375772a0 |pmid=7596408|s2cid=4351012 }}</ref> Research by the Miller group notes the formation of seven different amino acids and 11 types of [[nucleobase]]s in ice when ammonia and [[cyanide]] were left in a freezer from 1972 to 1997.<ref>{{cite journal |last=Fox |first=Douglas |date=February 2008 |url=http://discovermagazine.com/2008/feb/did-life-evolve-in-ice |title=Did Life Evolve in Ice? |journal=[[Discover (magazine)|Discover]] |accessdate=2008-07-03 |url-status=live |archiveurl=https://web.archive.org/web/20080630043228/http://discovermagazine.com/2008/feb/did-life-evolve-in-ice |archivedate=30 June 2008}}</ref><ref>{{cite journal |last1=Levy |first1=Matthew |last2=Miller |first2=Stanley L. |last3=Brinton |first3=Karen |last4=Bada |first4=Jeffrey L. |authorlink4=Jeffrey L. Bada |date=June 2000 |title=Prebiotic Synthesis of Adenine and Amino Acids Under Europa-like Conditions |journal=[[Icarus (journal)|Icarus]] |volume=145 |issue=2 |pages=609–613 |bibcode=2000Icar..145..609L |doi=10.1006/icar.2000.6365 |pmid=11543508}}</ref> Other work demonstrated the formation of s-[[triazine]]s (alternative nucleobases), [[pyrimidine]]s (including cytosine and uracil), and adenine from urea solutions subjected to freeze-thaw cycles under a reductive atmosphere (with spark discharges as an energy source).<ref>{{cite journal |last1=Menor-Salván |first1=César |last2=Ruiz-Bermejo |first2=Marta |last3=Guzmán |first3=Marcelo I. |last4=Osuna-Esteban |first4=Susana |last5=Veintemillas-Verdaguer |first5=Sabino |date=20 April 2009 |title=Synthesis of Pyrimidines and Triazines in Ice: Implications for the Prebiotic Chemistry of Nucleobases |journal=[[Chemistry: A European Journal]] |volume=15 |issue=17 |pages=4411–4418 |doi=10.1002/chem.200802656 |pmid=19288488}}</ref> The explanation given for the unusual speed of these reactions at such a low temperature is [[Eutectic system|eutectic freezing]]. As an ice crystal forms, it stays pure: only molecules of water join the growing crystal, while impurities like salt or cyanide are excluded. These impurities become crowded in microscopic pockets of liquid within the ice, and this crowding causes the molecules to collide more often. Mechanistic exploration using quantum chemical methods provide a more detailed understanding of some of the chemical processes involved in chemical evolution, and a partial answer to the fundamental question of molecular biogenesis.<ref>{{cite journal |last1=Roy |first1=Debjani |last2=Najafian |first2=Katayoun |last3=von Ragué Schleyer |first3=Paul |authorlink3=Paul von Ragué Schleyer |date=30 October 2007 |title=Chemical evolution: The mechanism of the formation of adenine under prebiotic conditions |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=104 |issue=44 |pages=17272–17277 |bibcode=2007PNAS..10417272R |doi=10.1073/pnas.0708434104|pmc=2077245 |pmid=17951429}}</ref>

Other pathways for synthesizing bases from inorganic materials were also reported.<ref name="Basile1984">{{cite journal |last1=Basile |first1=Brenda |last2=Lazcano |first2=Antonio |authorlink2=Antonio Lazcano |last3=Oró |first3=Joan |year=1984 |title=Prebiotic syntheses of purines and pyrimidines |journal=[[Advances in Space Research]] |volume=4 |issue=12 |pages=125–131 |bibcode=1984AdSpR...4..125B |doi=10.1016/0273-1177(84)90554-4 |pmid=11537766}}</ref> Orgel and colleagues have shown that freezing temperatures are advantageous for the synthesis of purines, due to the concentrating effect for key precursors such as hydrogen cyanide.<ref>{{cite journal |last=Orgel |first=Leslie E. |date=August 2004 |title=Prebiotic Adenine Revisited: Eutectics and Photochemistry |journal=Origins of Life and Evolution of Biospheres |volume=34 |issue=4 |pages=361–369 |bibcode=2004OLEB...34..361O |doi=10.1023/B:ORIG.0000029882.52156.c2 |pmid=15279171|s2cid=4998122 }}</ref> Research by Miller and colleagues suggested that while adenine and [[guanine]] require freezing conditions for synthesis, [[cytosine]] and [[uracil]] may require boiling temperatures.<ref>{{cite journal |last1=Robertson |first1=Michael P. |last2=Miller |first2=Stanley L. |date=29 June 1995 |title=An efficient prebiotic synthesis of cytosine and uracil |journal=Nature |volume=375 |issue=6534 |pages=772–774 |bibcode=1995Natur.375..772R |doi=10.1038/375772a0 |pmid=7596408|s2cid=4351012 }}</ref> Research by the Miller group notes the formation of seven different amino acids and 11 types of [[nucleobase]]s in ice when ammonia and [[cyanide]] were left in a freezer from 1972 to 1997.<ref>{{cite journal |last=Fox |first=Douglas |date=February 2008 |url=http://discovermagazine.com/2008/feb/did-life-evolve-in-ice |title=Did Life Evolve in Ice? |journal=[[Discover (magazine)|Discover]] |accessdate=2008-07-03 |url-status=live |archiveurl=https://web.archive.org/web/20080630043228/http://discovermagazine.com/2008/feb/did-life-evolve-in-ice |archivedate=30 June 2008}}</ref><ref>{{cite journal |last1=Levy |first1=Matthew |last2=Miller |first2=Stanley L. |last3=Brinton |first3=Karen |last4=Bada |first4=Jeffrey L. |authorlink4=Jeffrey L. Bada |date=June 2000 |title=Prebiotic Synthesis of Adenine and Amino Acids Under Europa-like Conditions |journal=[[Icarus (journal)|Icarus]] |volume=145 |issue=2 |pages=609–613 |bibcode=2000Icar..145..609L |doi=10.1006/icar.2000.6365 |pmid=11543508}}</ref> Other work demonstrated the formation of s-[[triazine]]s (alternative nucleobases), [[pyrimidine]]s (including cytosine and uracil), and adenine from urea solutions subjected to freeze-thaw cycles under a reductive atmosphere (with spark discharges as an energy source).<ref>{{cite journal |last1=Menor-Salván |first1=César |last2=Ruiz-Bermejo |first2=Marta |last3=Guzmán |first3=Marcelo I. |last4=Osuna-Esteban |first4=Susana |last5=Veintemillas-Verdaguer |first5=Sabino |date=20 April 2009 |title=Synthesis of Pyrimidines and Triazines in Ice: Implications for the Prebiotic Chemistry of Nucleobases |journal=[[Chemistry: A European Journal]] |volume=15 |issue=17 |pages=4411–4418 |doi=10.1002/chem.200802656 |pmid=19288488}}</ref> The explanation given for the unusual speed of these reactions at such a low temperature is [[Eutectic system|eutectic freezing]]. As an ice crystal forms, it stays pure: only molecules of water join the growing crystal, while impurities like salt or cyanide are excluded. These impurities become crowded in microscopic pockets of liquid within the ice, and this crowding causes the molecules to collide more often. Mechanistic exploration using quantum chemical methods provide a more detailed understanding of some of the chemical processes involved in chemical evolution, and a partial answer to the fundamental question of molecular biogenesis.<ref>{{cite journal |last1=Roy |first1=Debjani |last2=Najafian |first2=Katayoun |last3=von Ragué Schleyer |first3=Paul |authorlink3=Paul von Ragué Schleyer |date=30 October 2007 |title=Chemical evolution: The mechanism of the formation of adenine under prebiotic conditions |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=104 |issue=44 |pages=17272–17277 |bibcode=2007PNAS..10417272R |doi=10.1073/pnas.0708434104|pmc=2077245 |pmid=17951429}}</ref>

还有人报道了从无机材料合成碱的其他途径。Orgel及其同事的研究表明，由于氰化氢等关键前体的浓缩作用，冷冻温度对嘌呤的合成是有利的。Miller及其同事的研究表明，腺嘌呤和鸟嘌呤的合成需要冷冻条件，而胞嘧啶和尿嘧啶可能需要沸腾的温度.Miller小组的研究指出，从1972年到1997年，当氨和氰化氢被放置在冰柜中时，在冰中形成了7种不同的氨基酸和11种核碱。其他研究证明了s-三嗪(替代核碱基)、嘧啶(包括胞嘧啶和尿嘧啶)和腺嘌呤从尿素溶液在还原性气氛下(以火花放电为能源)进行冻融循环形成。对于这些反应在如此低的温度下的异常速度，给出的解释是共晶冻结。当冰晶形成时，它保持纯净：只有水分子加入生长的晶体，而盐或氰化物等杂质被排除在外。这些杂质在冰内变得拥挤在微观的液体口袋中，这种拥挤导致分子更频繁地碰撞。利用量子化学方法进行机理探索，可以更详细地了解化学演化中的一些化学过程，并对分子生物发生的基本问题做出部分回答。

还有人报道了从无机材料合成碱基的其他途径。奥格尔Orgel及其同事的研究表明，由于氰化氢等关键前体的浓缩作用，冷冻温度对嘌呤的合成是有利的。Miller及其同事的研究表明，腺嘌呤和鸟嘌呤的合成需要冷冻条件，而胞嘧啶和尿嘧啶可能需要沸腾的温度。Miller课题组的研究指出，从1972年到1997年，当氨和氰化物被放置在冰柜中时，在冰中形成了7种不同的氨基酸和11种核酸碱基。其他研究证明了s-三嗪(替代核酸碱基)、嘧啶(包括胞嘧啶和尿嘧啶)和腺嘌呤从尿素溶液在还原性气氛下(以火花放电为能量来源)经过冻融循环形成。对于这些反应在如此低的温度下的异常速度，给出的解释是共晶凝固。当冰晶形成时，它保持纯净：只有水分子加入生长的晶体，而盐或氰化物等杂质被排除在外。这些杂质在冰内变得拥挤在微观的液体口袋中，这种拥挤导致分子更频繁地碰撞。利用量子化学方法进行机理探索，可以更详细地了解化学演化中的一些化学过程，并对分子生物发生的基本问题做出部分回答。

====Use of less-reducing gas in Miller–Urey experiment====

====Use of less-reducing gas in Miller–Urey experiment====

A research project completed in 2015 by [[John Sutherland (chemist)|John Sutherland]] and others found that a network of reactions beginning with hydrogen cyanide and hydrogen sulfide, in streams of water irradiated by UV light, could produce the chemical components of proteins and lipids, as well as those of RNA,<ref>{{cite news |last=Service |first=Robert F. |date=16 March 2015 |title=Researchers may have solved origin-of-life conundrum |url=http://news.sciencemag.org/biology/2015/03/researchers-may-have-solved-origin-life-conundrum |work=Science |type=News |location=Washington, D.C. |publisher=American Association for the Advancement of Science |accessdate=2015-07-26 |url-status=live |archiveurl=https://web.archive.org/web/20150812103559/http://news.sciencemag.org/biology/2015/03/researchers-may-have-solved-origin-life-conundrum |archivedate=12 August 2015}}</ref><ref name="patel">{{cite journal |last1=Patel |first1=Bhavesh H.|last2=Percivalle |first2=Claudia |last3=Ritson |first3=Dougal J. |last4=Duffy |first4=Colm D. |last5=Sutherland |first5=John D. |authorlink5=John Sutherland (chemist) |date=April 2015 |title=Common origins of RNA, protein and lipid precursors in a cyanosulfidic protometabolism |journal=[[Nature Chemistry]] |volume=7 |issue=4 |pages=301–307 |bibcode=2015NatCh...7..301P |doi=10.1038/nchem.2202 |pmid=25803468 |ref=harv |pmc=4568310}}</ref> while not producing a wide range of other compounds.<ref>{{harvnb|Patel|Percivalle|Ritson|Duffy|2015|p=302}}</ref> The researchers used the term "cyanosulfidic" to describe this network of reactions.<ref name="patel" />

A research project completed in 2015 by [[John Sutherland (chemist)|John Sutherland]] and others found that a network of reactions beginning with hydrogen cyanide and hydrogen sulfide, in streams of water irradiated by UV light, could produce the chemical components of proteins and lipids, as well as those of RNA,<ref>{{cite news |last=Service |first=Robert F. |date=16 March 2015 |title=Researchers may have solved origin-of-life conundrum |url=http://news.sciencemag.org/biology/2015/03/researchers-may-have-solved-origin-life-conundrum |work=Science |type=News |location=Washington, D.C. |publisher=American Association for the Advancement of Science |accessdate=2015-07-26 |url-status=live |archiveurl=https://web.archive.org/web/20150812103559/http://news.sciencemag.org/biology/2015/03/researchers-may-have-solved-origin-life-conundrum |archivedate=12 August 2015}}</ref><ref name="patel">{{cite journal |last1=Patel |first1=Bhavesh H.|last2=Percivalle |first2=Claudia |last3=Ritson |first3=Dougal J. |last4=Duffy |first4=Colm D. |last5=Sutherland |first5=John D. |authorlink5=John Sutherland (chemist) |date=April 2015 |title=Common origins of RNA, protein and lipid precursors in a cyanosulfidic protometabolism |journal=[[Nature Chemistry]] |volume=7 |issue=4 |pages=301–307 |bibcode=2015NatCh...7..301P |doi=10.1038/nchem.2202 |pmid=25803468 |ref=harv |pmc=4568310}}</ref> while not producing a wide range of other compounds.<ref>{{harvnb|Patel|Percivalle|Ritson|Duffy|2015|p=302}}</ref> The researchers used the term "cyanosulfidic" to describe this network of reactions.<ref name="patel" />

约翰-萨瑟兰John Sutherland 等人在2015年完成的一个研究项目发现，在紫外线照射的水流中，一个以氰化氢和硫化氢为起点的反应网络，可以产生蛋白质和脂类的化学成分，以及RNA的化学成分，同时不产生其他多种化合物。研究人员用 "氰基硫化物 "一词来描述这个反应网络。

约翰·萨瑟兰John Sutherland 等人在2015年完成的一个研究项目发现，在紫外线照射的水流中，一个以氰化氢和硫化氢为起点的反应网络，可以产生蛋白质和脂类的化学成分，以及RNA的化学成分，同时不产生其他多种化合物。研究人员用 "氰基硫化物 "一词来描述这个反应网络。

====Issues during laboratory synthesis====

====Issues during laboratory synthesis====

The spontaneous formation of complex polymers from abiotically generated monomers under the conditions posited by the "soup" theory is not at all a straightforward process. Besides the necessary basic organic monomers, compounds that would have prohibited the formation of polymers were also formed in high concentration during the Miller–Urey and [[Joan Oró]] experiments.<ref>{{cite journal |last1=Oró |first1=Joan |last2=Kimball |first2=Aubrey P. |date=February 1962 |title=Synthesis of purines under possible primitive earth conditions: II. Purine intermediates from hydrogen cyanide |journal=[[Archives of Biochemistry and Biophysics]] |volume=96 |issue=2 |pages=293–313 |doi=10.1016/0003-9861(62)90412-5 |pmid=14482339}}</ref> The Miller–Urey experiment, for example, produces many substances that would react with the amino acids or terminate their coupling into peptide chains.<ref>{{cite book |editor-last=Ahuja |editor-first=Mukesh |year=2006 |chapter=Origin of Life |chapterurl=https://books.google.com/books?id=VJF12TlT58kC&pg=PA11 |title=Life Science |volume=1 |location=Delhi |publisher=Isha Books |page=11 |isbn=978-81-8205-386-1 |oclc=297208106 |ref=harv}}{{Unreliable source?|reason=What material is Ahuja editing? Further, see use of Ahuja material in the Iron-sulfur world section in this WP article, among others. See also: Wikipedia talk:Noticeboard for India-related topics/Archive 42#Problem with ISHA books as references|date=June 2015}}</ref>

The spontaneous formation of complex polymers from abiotically generated monomers under the conditions posited by the "soup" theory is not at all a straightforward process. Besides the necessary basic organic monomers, compounds that would have prohibited the formation of polymers were also formed in high concentration during the Miller–Urey and [[Joan Oró]] experiments.<ref>{{cite journal |last1=Oró |first1=Joan |last2=Kimball |first2=Aubrey P. |date=February 1962 |title=Synthesis of purines under possible primitive earth conditions: II. Purine intermediates from hydrogen cyanide |journal=[[Archives of Biochemistry and Biophysics]] |volume=96 |issue=2 |pages=293–313 |doi=10.1016/0003-9861(62)90412-5 |pmid=14482339}}</ref> The Miller–Urey experiment, for example, produces many substances that would react with the amino acids or terminate their coupling into peptide chains.<ref>{{cite book |editor-last=Ahuja |editor-first=Mukesh |year=2006 |chapter=Origin of Life |chapterurl=https://books.google.com/books?id=VJF12TlT58kC&pg=PA11 |title=Life Science |volume=1 |location=Delhi |publisher=Isha Books |page=11 |isbn=978-81-8205-386-1 |oclc=297208106 |ref=harv}}{{Unreliable source?|reason=What material is Ahuja editing? Further, see use of Ahuja material in the Iron-sulfur world section in this WP article, among others. See also: Wikipedia talk:Noticeboard for India-related topics/Archive 42#Problem with ISHA books as references|date=June 2015}}</ref>

在 "汤 "理论提出的条件下，由非生物生成的单体自发形成复杂的聚合物，根本不是一个简单的过程。除了必要的基本有机单体外，在Miller-Urey和Joan Oró实验过程中，还形成了高浓度的禁止聚合物形成的化合物.例如，Miller-Urey实验会产生许多与氨基酸反应或终止其偶联成肽链的物质。

在"汤"理论提出的条件下，由非生物生成的单体自发形成复杂的聚合物，根本不是一个简单的过程。除了必要的基本有机单体外，在Miller-Urey和琼·奥罗 Joan Oró实验过程中，还形成了高浓度的禁止聚合物形成的化合物。例如，Miller-Urey实验会产生许多与氨基酸反应或终止其偶联成肽链的物质。

 

=== Autocatalysis ===

=== Autocatalysis ===

[[Autocatalysis|Autocatalysts]] are substances that catalyze the production of themselves and therefore are "molecular replicators." The simplest self-replicating chemical systems are autocatalytic, and typically contain three components: a product molecule and two precursor molecules. The product molecule joins together the precursor molecules, which in turn produce more product molecules from more precursor molecules. The product molecule catalyzes the reaction by providing a complementary template that binds to the precursors, thus bringing them together. Such systems have been demonstrated both in biological [[macromolecule]]s and in small organic molecules.<ref name="Paul2004">{{cite journal |last1=Paul |first1=Natasha |last2=Joyce |first2=Gerald F. |date=December 2004 |title=Minimal self-replicating systems |journal=Current Opinion in Chemical Biology |volume=8 |issue=6 |pages=634–639 |doi=10.1016/j.cbpa.2004.09.005|pmid=15556408}}</ref><ref name="Bissette2013">{{cite journal |last1=Bissette |first1=Andrew J. |last2=Fletcher |first2=Stephen P. |date=2 December 2013 |title=Mechanisms of Autocatalysis |journal=Angewandte Chemie International Edition |volume=52 |issue=49 |pages=12800–12826 |doi=10.1002/anie.201303822 |pmid=24127341}}</ref> Systems that do not proceed by template mechanisms, such as the self-reproduction of [[micelle]]s and [[Vesicle (biology and chemistry)|vesicles]], have also been observed.<ref name="Bissette2013" />

[[Autocatalysis|Autocatalysts]] are substances that catalyze the production of themselves and therefore are "molecular replicators." The simplest self-replicating chemical systems are autocatalytic, and typically contain three components: a product molecule and two precursor molecules. The product molecule joins together the precursor molecules, which in turn produce more product molecules from more precursor molecules. The product molecule catalyzes the reaction by providing a complementary template that binds to the precursors, thus bringing them together. Such systems have been demonstrated both in biological [[macromolecule]]s and in small organic molecules.<ref name="Paul2004">{{cite journal |last1=Paul |first1=Natasha |last2=Joyce |first2=Gerald F. |date=December 2004 |title=Minimal self-replicating systems |journal=Current Opinion in Chemical Biology |volume=8 |issue=6 |pages=634–639 |doi=10.1016/j.cbpa.2004.09.005|pmid=15556408}}</ref><ref name="Bissette2013">{{cite journal |last1=Bissette |first1=Andrew J. |last2=Fletcher |first2=Stephen P. |date=2 December 2013 |title=Mechanisms of Autocatalysis |journal=Angewandte Chemie International Edition |volume=52 |issue=49 |pages=12800–12826 |doi=10.1002/anie.201303822 |pmid=24127341}}</ref> Systems that do not proceed by template mechanisms, such as the self-reproduction of [[micelle]]s and [[Vesicle (biology and chemistry)|vesicles]], have also been observed.<ref name="Bissette2013" />

自催化剂是指能催化自身生产的物质，因此是 "分子复制器"。最简单的自我复制化学体系是自催化的，通常包含三个组成部分：一个产物分子和两个前体分子。产品分子将前体分子连接在一起，再由更多的前体分子产生更多的产品分子。产物分子通过提供一个互补的模板来催化反应，该模板与前体结合，从而使它们结合在一起。这样的系统在生物大分子和小有机分子中都得到了证明.也观察到了不通过模板机制进行的系统，如胶束和囊泡的自我再生。

自催化剂是指能催化生产自身的物质，因此是 "分子复制器"。最简单的自我复制化学体系是自催化的，通常包含三个组成部分：一个产物分子和两个前体分子。产物分子将前体分子们连接在一起，反过来由更多的前体分子产生更多的产物分子。产物分子通过提供一个互补的模板来催化反应，该模板与前体结合，从而使它们结合在一起。这样的系统在生物大分子和有机小分子中都得到了证明。也观察到了不通过模板机制进行的系统，如胶束和囊泡的自我再生。

It has been proposed that life initially arose as autocatalytic chemical networks.<ref>{{harvnb|Kauffman|1993|loc=chpt. 7}}</ref> British [[ethologist]] [[Richard Dawkins]] wrote about autocatalysis as a potential explanation for the origin of life in his 2004 book ''[[The Ancestor's Tale]]''.<ref>{{harvnb|Dawkins|2004}}</ref> In his book, Dawkins cites experiments performed by [[Julius Rebek]] and his colleagues in which they combined amino adenosine and [[pentafluorophenyl esters]] with the autocatalyst amino adenosine triacid ester (AATE). One product was a variant of AATE, which catalyzed the synthesis of themselves. This experiment demonstrated the possibility that autocatalysts could exhibit competition within a population of entities with heredity, which could be interpreted as a rudimentary form of natural selection.<ref>{{cite journal |last1=Tjivikua |first1=T. |last2=Ballester |first2=Pablo |last3=Rebek |first3=Julius Jr. |authorlink3=Julius Rebek |date=January 1990 |title=Self-replicating system |journal=[[Journal of the American Chemical Society]] |volume=112 |issue=3 |pages=1249–1250 |doi=10.1021/ja00159a057 }}</ref><ref>{{cite news |last=Browne |first=Malcolm W. |authorlink=Malcolm Browne |date=30 October 1990 |title=Chemists Make Molecule With Hint of Life |url=https://www.nytimes.com/1990/10/30/science/chemists-make-molecule-with-hint-of-life.html |newspaper=The New York Times |location=New York |accessdate=2015-07-14 |url-status=live |archiveurl=https://web.archive.org/web/20150721135740/http://www.nytimes.com/1990/10/30/science/chemists-make-molecule-with-hint-of-life.html |archivedate=21 July 2015}}</ref>

It has been proposed that life initially arose as autocatalytic chemical networks.<ref>{{harvnb|Kauffman|1993|loc=chpt. 7}}</ref> British [[ethologist]] [[Richard Dawkins]] wrote about autocatalysis as a potential explanation for the origin of life in his 2004 book ''[[The Ancestor's Tale]]''.<ref>{{harvnb|Dawkins|2004}}</ref> In his book, Dawkins cites experiments performed by [[Julius Rebek]] and his colleagues in which they combined amino adenosine and [[pentafluorophenyl esters]] with the autocatalyst amino adenosine triacid ester (AATE). One product was a variant of AATE, which catalyzed the synthesis of themselves. This experiment demonstrated the possibility that autocatalysts could exhibit competition within a population of entities with heredity, which could be interpreted as a rudimentary form of natural selection.<ref>{{cite journal |last1=Tjivikua |first1=T. |last2=Ballester |first2=Pablo |last3=Rebek |first3=Julius Jr. |authorlink3=Julius Rebek |date=January 1990 |title=Self-replicating system |journal=[[Journal of the American Chemical Society]] |volume=112 |issue=3 |pages=1249–1250 |doi=10.1021/ja00159a057 }}</ref><ref>{{cite news |last=Browne |first=Malcolm W. |authorlink=Malcolm Browne |date=30 October 1990 |title=Chemists Make Molecule With Hint of Life |url=https://www.nytimes.com/1990/10/30/science/chemists-make-molecule-with-hint-of-life.html |newspaper=The New York Times |location=New York |accessdate=2015-07-14 |url-status=live |archiveurl=https://web.archive.org/web/20150721135740/http://www.nytimes.com/1990/10/30/science/chemists-make-molecule-with-hint-of-life.html |archivedate=21 July 2015}}</ref>

有人提出，生命最初是以自催化化学网络的形式产生的。英国伦理学家理查德-道金斯（Richard Dawkins）在2004年出版的《祖先的故事》（The Ancestor's Tale）一书中写道，自催化是生命起源的一种潜在解释。在书中，道金斯引用了朱利叶斯-雷贝克（Julius Rebek）和他的同事所做的实验，他们将氨基腺苷和五氟苯基酯与自催化剂氨基腺苷三酸酯（AATE）相结合。其中一种产物是AATE的变体，它能催化自身的合成。这一实验表明，自催化剂有可能在具有遗传性的实体种群中表现出竞争，这可以被解释为自然选择的一种基本形式。

有人提出，生命最初是以自催化的化学网络产生的。英国伦理学家理查德·道金斯 Richard Dawkins在2004年出版的《祖先的故事》（The Ancestor's Tale）一书中写道，自催化是生命起源的一种可能的解释。在书中，Dawkins引用了朱利叶斯·雷贝克 Julius Rebek和他的同事所做的实验，他们将氨基腺苷和五氟苯基酯与自催化剂氨基腺苷三酸酯（AATE）相结合。其中一种产物是AATE的变体，它能催化自身的合成。这一实验表明，自催化剂有可能在具有遗传性的实体种群中表现出竞争，这可以被解释为自然选择的一种基本形式。

== Encapsulation: morphology ==

== Encapsulation: morphology ==

Researchers Tony Jia and Kuhan Chandru<ref>{{cite journal |last1=Jia |first1=Tony Z. |last2=Chandru |first2=Kuhan |last3=Hongo |first3=Yayoi |last4=Afrin |first4=Rehana |last5=Usui |first5=Tomohiro |last6=Myojo |first6=Kunihiro |last7=Cleaves |first7=H. James |title=Membraneless polyester microdroplets as primordial compartments at the origins of life |journal=Proceedings of the National Academy of Sciences |volume=116 |issue=32 |date=22 July 2019 |pages=15830–15835 |doi=10.1073/pnas.1902336116|pmid=31332006 |pmc=6690027 }}</ref> have proposed that membraneless polyesters droplets could have been significant in the Origins of Life.<ref>{{Cite journal|last1=Chandru|first1=Kuhan|last2=Mamajanov|first2=Irena|last3=Cleaves|first3=H. James|last4=Jia|first4=Tony Z.|date=January 2020|title=Polyesters as a Model System for Building Primitive Biologies from Non-Biological Prebiotic Chemistry|journal=Life|language=en|volume=10|issue=1|pages=6|doi=10.3390/life10010006|pmc=7175156|pmid=31963928}}</ref> Given the "messy" nature of prebiotic chemistry,<ref>{{cite web |last1=Marc |first1=Kaufman |title=NASA Astrobiology |url=https://astrobiology.nasa.gov/news/messy-chemistry-a-new-way-to-approach-the-origins-of-life/|date = 18 July 2019 |website=astrobiology.nasa.gov |language=en-EN}}</ref><ref>{{cite journal |last1=Guttenberg |first1=Nicholas |last2=Virgo |first2=Nathaniel |last3=Chandru |first3=Kuhan |last4=Scharf |first4=Caleb |last5=Mamajanov |first5=Irena |title=Bulk measurements of messy chemistries are needed for a theory of the origins of life |journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |date=13 November 2017 |volume=375 |issue=2109 |pages=20160347 |doi=10.1098/rsta.2016.0347|pmid=29133446 |pmc=5686404 |bibcode=2017RSPTA.37560347G }}</ref> the spontaneous generation of these combinatorial droplets may have played a role in early cellularization before the innovation of lipid vesicles. Protein function within and RNA function in the presence of certain polyester droplets was shown to be preserved within the droplets. Additionally, the droplets have scaffolding ability, by allowing lipids to assemble around them that may have prevented leakage of genetic materials.

Researchers Tony Jia and Kuhan Chandru<ref>{{cite journal |last1=Jia |first1=Tony Z. |last2=Chandru |first2=Kuhan |last3=Hongo |first3=Yayoi |last4=Afrin |first4=Rehana |last5=Usui |first5=Tomohiro |last6=Myojo |first6=Kunihiro |last7=Cleaves |first7=H. James |title=Membraneless polyester microdroplets as primordial compartments at the origins of life |journal=Proceedings of the National Academy of Sciences |volume=116 |issue=32 |date=22 July 2019 |pages=15830–15835 |doi=10.1073/pnas.1902336116|pmid=31332006 |pmc=6690027 }}</ref> have proposed that membraneless polyesters droplets could have been significant in the Origins of Life.<ref>{{Cite journal|last1=Chandru|first1=Kuhan|last2=Mamajanov|first2=Irena|last3=Cleaves|first3=H. James|last4=Jia|first4=Tony Z.|date=January 2020|title=Polyesters as a Model System for Building Primitive Biologies from Non-Biological Prebiotic Chemistry|journal=Life|language=en|volume=10|issue=1|pages=6|doi=10.3390/life10010006|pmc=7175156|pmid=31963928}}</ref> Given the "messy" nature of prebiotic chemistry,<ref>{{cite web |last1=Marc |first1=Kaufman |title=NASA Astrobiology |url=https://astrobiology.nasa.gov/news/messy-chemistry-a-new-way-to-approach-the-origins-of-life/|date = 18 July 2019 |website=astrobiology.nasa.gov |language=en-EN}}</ref><ref>{{cite journal |last1=Guttenberg |first1=Nicholas |last2=Virgo |first2=Nathaniel |last3=Chandru |first3=Kuhan |last4=Scharf |first4=Caleb |last5=Mamajanov |first5=Irena |title=Bulk measurements of messy chemistries are needed for a theory of the origins of life |journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |date=13 November 2017 |volume=375 |issue=2109 |pages=20160347 |doi=10.1098/rsta.2016.0347|pmid=29133446 |pmc=5686404 |bibcode=2017RSPTA.37560347G }}</ref> the spontaneous generation of these combinatorial droplets may have played a role in early cellularization before the innovation of lipid vesicles. Protein function within and RNA function in the presence of certain polyester droplets was shown to be preserved within the droplets. Additionally, the droplets have scaffolding ability, by allowing lipids to assemble around them that may have prevented leakage of genetic materials.

研究人员Tony Jia和Kuhan Chandruhave提出，无膜聚酯液滴可能在生命起源中发挥了重要作用。鉴于前生物化学的 "混乱 "性质，这些组合液滴的自然发生可能在脂质小泡革新之前的早期细胞化中发挥了作用。研究表明，在某些聚酯液滴的存在下，液滴内的蛋白质功能和RNA功能得以保存。此外，该液滴具有支架能力，通过允许脂质在其周围组装，可能防止了遗传物质的泄漏。

研究人员托尼·贾 Tony Jia和库罕·尚德吕 Kuhan Chandru提出，无膜聚酯液滴可能在生命起源中发挥了重要作用。鉴于生命起源以前的化学的 "混乱 "性质，这些组合液滴的自然发生可能在脂质小泡革新之前的早期细胞化中发挥了作用。研究表明，在某些聚酯液滴的存在下，液滴内的蛋白质功能和RNA功能得以保存。此外，该液滴具有支架能力，通过允许脂质在其周围组装，可能防止了遗传物质的泄漏。

=== Proteinoid microspheres ===

=== Proteinoid microspheres ===

Fox observed in the 1960s that the proteinoids that he had synthesized could form cell-like structures that have been named "[[Proteinoid|proteinoid microspheres]]".<ref name="foxexp">{{cite web |url=http://nitro.biosci.arizona.edu/courses/EEB105/lectures/Origins_of_Life/origins.html |title=Part 4: Experimental studies of the origins of life |last=Walsh |first=J. Bruce |year=1995 |work=Origins of life |publisher=[[University of Arizona]] |location=Tucson, AZ |type=Lecture notes |archiveurl=https://web.archive.org/web/20080113152408/http://nitro.biosci.arizona.edu/courses/EEB105/lectures/Origins_of_Life/origins.html |archivedate=2008-01-13 |accessdate=2015-06-08}}</ref>

Fox observed in the 1960s that the proteinoids that he had synthesized could form cell-like structures that have been named "[[Proteinoid|proteinoid microspheres]]".<ref name="foxexp">{{cite web |url=http://nitro.biosci.arizona.edu/courses/EEB105/lectures/Origins_of_Life/origins.html |title=Part 4: Experimental studies of the origins of life |last=Walsh |first=J. Bruce |year=1995 |work=Origins of life |publisher=[[University of Arizona]] |location=Tucson, AZ |type=Lecture notes |archiveurl=https://web.archive.org/web/20080113152408/http://nitro.biosci.arizona.edu/courses/EEB105/lectures/Origins_of_Life/origins.html |archivedate=2008-01-13 |accessdate=2015-06-08}}</ref>

Fox在20世纪60年代观察到，他合成的蛋白素可以形成细胞状结构，被命名为 "类蛋白微球体"。

Fox在20世纪60年代观察到，他合成的类蛋白可以形成细胞状结构，被命名为 "类蛋白微球体"。

The amino acids had combined to form [[proteinoid]]s, and the proteinoids had combined to form small globules that Fox called "microspheres". His proteinoids were not cells, although they formed clumps and chains reminiscent of [[cyanobacteria]], but they contained no functional [[nucleic acid]]s or any encoded information. Based upon such experiments, [[Colin Pittendrigh]] stated in 1967 that "laboratories will be creating a living cell within ten years," a remark that reflected the typical contemporary naivety about the complexity of cell structures.<ref>{{harvnb|Woodward|1969|p=287}}</ref>

The amino acids had combined to form [[proteinoid]]s, and the proteinoids had combined to form small globules that Fox called "microspheres". His proteinoids were not cells, although they formed clumps and chains reminiscent of [[cyanobacteria]], but they contained no functional [[nucleic acid]]s or any encoded information. Based upon such experiments, [[Colin Pittendrigh]] stated in 1967 that "laboratories will be creating a living cell within ten years," a remark that reflected the typical contemporary naivety about the complexity of cell structures.<ref>{{harvnb|Woodward|1969|p=287}}</ref>

氨基酸组合成类蛋白，而类蛋白组合成小球，福克斯称之为 "微球体"。他的类蛋白不是细胞，虽然它们形成的团块和链子让人联想到蓝藻，但它们不含任何功能性核酸或任何编码信息。基于这样的实验，Colin Pittendrigh在1967年说："实验室将在十年内创造出一个活细胞。"这句话反映了当代人对细胞结构复杂性的典型天真。

氨基酸组合形成类蛋白，而类蛋白组合成小球，福克斯称之为 "微球体"。他的类蛋白不是细胞，虽然它们形成的团块和链子让人联想到蓝藻，但它们不含任何功能性核酸或任何编码信息。基于这样的实验，科林·布里斯顿 Colin Pittendrigh在1967年说："实验室将在十年内创造出一个活细胞。"这句话反映了当代人对细胞结构复杂性的典型天真。

=== Lipid world ===

=== Lipid world ===

The [[Gard model|lipid world]] theory postulates that the first self-replicating object was [[lipid]]-like.<ref>{{cite web |url=http://www.weizmann.ac.il/molgen/Lancet/research/prebiotic-evolution |title=Systems Prebiology-Studies of the origin of Life |last=Lancet |first=Doron |date=30 December 2014 |website=The Lancet Lab |publisher=Department of Molecular Genetics; [[Weizmann Institute of Science]] |location=Rehovot, Israel |accessdate=2015-06-26 |url-status=live |archiveurl=https://web.archive.org/web/20150626180507/http://www.weizmann.ac.il/molgen/Lancet/research/prebiotic-evolution |archivedate=26 June 2015}}</ref><ref>{{cite journal |last1=Segré |first1=Daniel |last2=Ben-Eli |first2=Dafna |last3=Deamer |first3=David W. |last4=Lancet |first4=Doron |date=February 2001 |title=The Lipid World |url=http://www.weizmann.ac.il/molgen/Lancet/sites/molgen.Lancet/files/uploads/segre_lipid_world.pdf |journal=Origins of Life and Evolution of the Biosphere |volume=31 |issue=1–2 |pages=119–145 |doi=10.1023/A:1006746807104 |pmid=11296516 |bibcode=2001OLEB...31..119S |s2cid=10959497 |accessdate=2008-09-11 |url-status=live |archiveurl=https://web.archive.org/web/20150626225745/http://www.weizmann.ac.il/molgen/Lancet/sites/molgen.Lancet/files/uploads/segre_lipid_world.pdf |archivedate=26 June 2015}}</ref> It is known that phospholipids form [[lipid bilayer]]s in water while under agitation—the same structure as in cell membranes. These molecules were not present on early Earth, but other [[Amphiphile|amphiphilic]] long-chain molecules also form membranes. Furthermore, these bodies may expand (by insertion of additional lipids), and under excessive expansion may undergo spontaneous splitting which preserves the same size and composition of lipids in the two [[Offspring|progenies]]. The main idea in this theory is that the molecular composition of the lipid bodies is the preliminary way for information storage, and evolution led to the appearance of polymer entities such as RNA or DNA that may store information favourably. Studies on vesicles from potentially prebiotic amphiphiles have so far been limited to systems containing one or two types of amphiphiles. This in contrast to the output of simulated prebiotic chemical reactions, which typically produce very heterogeneous mixtures of compounds.<ref name="Chen 2010" />

The [[Gard model|lipid world]] theory postulates that the first self-replicating object was [[lipid]]-like.<ref>{{cite web |url=http://www.weizmann.ac.il/molgen/Lancet/research/prebiotic-evolution |title=Systems Prebiology-Studies of the origin of Life |last=Lancet |first=Doron |date=30 December 2014 |website=The Lancet Lab |publisher=Department of Molecular Genetics; [[Weizmann Institute of Science]] |location=Rehovot, Israel |accessdate=2015-06-26 |url-status=live |archiveurl=https://web.archive.org/web/20150626180507/http://www.weizmann.ac.il/molgen/Lancet/research/prebiotic-evolution |archivedate=26 June 2015}}</ref><ref>{{cite journal |last1=Segré |first1=Daniel |last2=Ben-Eli |first2=Dafna |last3=Deamer |first3=David W. |last4=Lancet |first4=Doron |date=February 2001 |title=The Lipid World |url=http://www.weizmann.ac.il/molgen/Lancet/sites/molgen.Lancet/files/uploads/segre_lipid_world.pdf |journal=Origins of Life and Evolution of the Biosphere |volume=31 |issue=1–2 |pages=119–145 |doi=10.1023/A:1006746807104 |pmid=11296516 |bibcode=2001OLEB...31..119S |s2cid=10959497 |accessdate=2008-09-11 |url-status=live |archiveurl=https://web.archive.org/web/20150626225745/http://www.weizmann.ac.il/molgen/Lancet/sites/molgen.Lancet/files/uploads/segre_lipid_world.pdf |archivedate=26 June 2015}}</ref> It is known that phospholipids form [[lipid bilayer]]s in water while under agitation—the same structure as in cell membranes. These molecules were not present on early Earth, but other [[Amphiphile|amphiphilic]] long-chain molecules also form membranes. Furthermore, these bodies may expand (by insertion of additional lipids), and under excessive expansion may undergo spontaneous splitting which preserves the same size and composition of lipids in the two [[Offspring|progenies]]. The main idea in this theory is that the molecular composition of the lipid bodies is the preliminary way for information storage, and evolution led to the appearance of polymer entities such as RNA or DNA that may store information favourably. Studies on vesicles from potentially prebiotic amphiphiles have so far been limited to systems containing one or two types of amphiphiles. This in contrast to the output of simulated prebiotic chemical reactions, which typically produce very heterogeneous mixtures of compounds.<ref name="Chen 2010" />

脂质世界理论认为，第一个自我复制的物体是类脂质的。众所周知，磷脂在水中搅拌时形成脂质双层--与细胞膜的结构相同。这些分子在早期地球上并不存在，但其他两亲长链分子也会形成膜。此外，这些脂质体可能会膨胀（通过插入额外的脂质），在过度膨胀下可能会发生自发的分裂，从而在两个后代中保留了相同的大小和脂质的组成。这一理论的主要观点是，脂质体的分子组成是信息储存的初步方式，进化导致了RNA或DNA等聚合物实体的出现，它们可能有利地储存信息。迄今为止，对潜在的前生物两栖动物的囊泡的研究还仅限于含有一两种两栖动物的系统。这与模拟的前生物化学反应的输出形成鲜明对比，前生物化学反应通常会产生非常异质的化合物混合物。

脂质世界理论认为，第一个自我复制的物体是类脂质的。众所周知，磷脂在水中搅拌时形成脂质双层--与细胞膜的结构相同。这些分子在早期地球上并不存在，但其他两亲性质的长链分子也会形成膜。此外，这些脂质体可能会膨胀（通过插入额外的脂质），在过度膨胀下可能会发生自发的分裂，从而在两个后代中保留了相同的大小和脂质的组成。这一理论的主要观点是，脂质体的分子组成是信息储存的初步方式，进化导致了如RNA或DNA等聚合物实体的出现，它们可能有利地储存信息。迄今为止，对来自潜在的前生物两亲化合物的囊泡的研究还仅限于含有一两种两亲化合物的系统。这与模拟的前生物化学反应的产出形成鲜明对比，前生物化学反应通常会产生非常异质的化合物的混合物。

Within the hypothesis of a lipid bilayer membrane composed of a mixture of various distinct amphiphilic compounds there is the opportunity of a huge number of theoretically possible combinations in the arrangements of these amphiphiles in the membrane. Among all these potential combinations, a specific local arrangement of the membrane would have favoured the constitution of a hypercycle,<ref>{{cite journal |last1=Eigen |first1=Manfred |authorlink1=Manfred Eigen |last2=Schuster |first2=Peter |authorlink2=Peter Schuster |date=November 1977 |title=The Hypercycle. A Principle of Natural Self-Organization. Part A: Emergence of the Hypercycle |url=http://jaguar.biologie.hu-berlin.de/~wolfram/pages/seminar_theoretische_biologie_2007/literatur/schaber/Eigen1977Naturwissenschaften64.pdf |journal=Naturwissenschaften |volume=64 |issue=11 |pages=541–65|bibcode=1977NW.....64..541E |doi=10.1007/bf00450633 |pmid=593400 |accessdate=2015-06-13 |url-status=dead |archiveurl=https://web.archive.org/web/20160303194728/http://jaguar.biologie.hu-berlin.de/~wolfram/pages/seminar_theoretische_biologie_2007/literatur/schaber/Eigen1977Naturwissenschaften64.pdf |archivedate=3 March 2016}}

Within the hypothesis of a lipid bilayer membrane composed of a mixture of various distinct amphiphilic compounds there is the opportunity of a huge number of theoretically possible combinations in the arrangements of these amphiphiles in the membrane. Among all these potential combinations, a specific local arrangement of the membrane would have favoured the constitution of a hypercycle,<ref>{{cite journal |last1=Eigen |first1=Manfred |authorlink1=Manfred Eigen |last2=Schuster |first2=Peter |authorlink2=Peter Schuster |date=November 1977 |title=The Hypercycle. A Principle of Natural Self-Organization. Part A: Emergence of the Hypercycle |url=http://jaguar.biologie.hu-berlin.de/~wolfram/pages/seminar_theoretische_biologie_2007/literatur/schaber/Eigen1977Naturwissenschaften64.pdf |journal=Naturwissenschaften |volume=64 |issue=11 |pages=541–65|bibcode=1977NW.....64..541E |doi=10.1007/bf00450633 |pmid=593400 |accessdate=2015-06-13 |url-status=dead |archiveurl=https://web.archive.org/web/20160303194728/http://jaguar.biologie.hu-berlin.de/~wolfram/pages/seminar_theoretische_biologie_2007/literatur/schaber/Eigen1977Naturwissenschaften64.pdf |archivedate=3 March 2016}}

* {{cite journal |last1=Eigen |first1=Manfred |last2=Schuster |first2=Peter |date=July 1978 |title=The Hypercycle. A Principle of Natural Self-Organization. Part C: The Realistic Hypercycle |url=http://jaguar.biologie.hu-berlin.de/~wolfram/pages/seminar_theoretische_biologie_2007/literatur/schaber/Eigen1978Naturwissenschaften65b.pdf |journal=Naturwissenschaften |volume=65 |issue=7 |pages=341–369 |bibcode=1978NW.....65..341E |doi=10.1007/bf00439699 |s2cid=13825356 |accessdate=2015-06-13 |url-status=dead |archiveurl=https://web.archive.org/web/20160616180402/http://jaguar.biologie.hu-berlin.de/~wolfram/pages/seminar_theoretische_biologie_2007/literatur/schaber/Eigen1978Naturwissenschaften65b.pdf |archivedate=16 June 2016}}</ref><ref>{{cite journal |last1=Markovitch |first1=Omer |last2=Lancet |first2=Doron |date=Summer 2012 |title=Excess Mutual Catalysis Is Required for Effective Evolvability |journal=[[Artificial Life (journal)|Artificial Life]] |volume=18 |issue=3 |pages=243–266 |doi=10.1162/artl_a_00064|pmid=22662913 |s2cid=5236043 }}</ref> actually a positive [[feedback]] composed of two mutual catalysts represented by a membrane site and a specific compound trapped in the vesicle. Such site/compound pairs are transmissible to the daughter vesicles leading to the emergence of distinct [[Lineage (evolution)|lineages]] of vesicles which would have allowed Darwinian natural selection.<ref>{{cite journal |last=Tessera |first=Marc |year=2011 |title=Origin of Evolution ''versus'' Origin of Life: A Shift of Paradigm |journal=[[International Journal of Molecular Sciences]] |volume=12 |issue=6 |pages=3445–3458 |doi=10.3390/ijms12063445 |pmc=3131571 |pmid=21747687}} Special Issue: "Origin of Life 2011"</ref>

* {{cite journal |last1=Eigen |first1=Manfred |last2=Schuster |first2=Peter |date=July 1978 |title=The Hypercycle. A Principle of Natural Self-Organization. Part C: The Realistic Hypercycle |url=http://jaguar.biologie.hu-berlin.de/~wolfram/pages/seminar_theoretische_biologie_2007/literatur/schaber/Eigen1978Naturwissenschaften65b.pdf |journal=Naturwissenschaften |volume=65 |issue=7 |pages=341–369 |bibcode=1978NW.....65..341E |doi=10.1007/bf00439699 |s2cid=13825356 |accessdate=2015-06-13 |url-status=dead |archiveurl=https://web.archive.org/web/20160616180402/http://jaguar.biologie.hu-berlin.de/~wolfram/pages/seminar_theoretische_biologie_2007/literatur/schaber/Eigen1978Naturwissenschaften65b.pdf |archivedate=16 June 2016}}</ref><ref>{{cite journal |last1=Markovitch |first1=Omer |last2=Lancet |first2=Doron |date=Summer 2012 |title=Excess Mutual Catalysis Is Required for Effective Evolvability |journal=[[Artificial Life (journal)|Artificial Life]] |volume=18 |issue=3 |pages=243–266 |doi=10.1162/artl_a_00064|pmid=22662913 |s2cid=5236043 }}</ref> actually a positive [[feedback]] composed of two mutual catalysts represented by a membrane site and a specific compound trapped in the vesicle. Such site/compound pairs are transmissible to the daughter vesicles leading to the emergence of distinct [[Lineage (evolution)|lineages]] of vesicles which would have allowed Darwinian natural selection.<ref>{{cite journal |last=Tessera |first=Marc |year=2011 |title=Origin of Evolution ''versus'' Origin of Life: A Shift of Paradigm |journal=[[International Journal of Molecular Sciences]] |volume=12 |issue=6 |pages=3445–3458 |doi=10.3390/ijms12063445 |pmc=3131571 |pmid=21747687}} Special Issue: "Origin of Life 2011"</ref>

实际上是由两个相互的催化剂组成的正反馈，由一个膜位和一个被困在囊泡中的特定化合物代表。这样的位点/化合物对可以传递给子囊泡，从而导致不同的囊泡品系的出现，这将遵循达尔文的自然选择。

实际上是由两个相互的催化剂组成的正反馈，由一个膜位点和一个被困在囊泡中的特定化合物代表。这样的位点/化合物对可以传递给子囊泡，从而导致不同的囊泡谱系的出现，这将允许达尔文的自然选择。

 

=== Protocells ===

=== Protocells ===

原始细胞

原始细胞

[[File:Phospholipids aqueous solution structures.svg|thumb|upright|The three main structures [[phospholipid]]s form spontaneously in solution: the [[liposome]] (a closed bilayer), the [[micelle]] and the bilayer.]]

[[File:Phospholipids aqueous solution structures.svg|thumb|upright|The three main structures [[phospholipid]]s form spontaneously in solution: the [[liposome]] (a closed bilayer), the [[micelle]] and the bilayer.]]

A protocell is a self-organized, self-ordered, spherical collection of [[lipid]]s proposed as a stepping-stone to the origin of life.<ref name="Chen 2010">{{cite journal |first1=Irene A. |last1=Chen |first2=Peter |last2=Walde |title=From Self-Assembled Vesicles to Protocells |journal=Cold Spring Harbor Perspectives in Biology |date=July 2010 |volume=2 |issue=7 |page=a002170 |doi=10.1101/cshperspect.a002170 |pmc=2890201 |pmid=20519344}}</ref> A central question in evolution is how simple protocells first arose and differed in reproductive contribution to the following generation driving the evolution of life. Although a functional protocell has not yet been achieved in a laboratory setting, there are scientists who think the goal is well within reach.<ref name="Exploring">{{cite web |url=http://exploringorigins.org/protocells.html |title=Exploring Life's Origins: Protocells |website=Exploring Life's Origins: A Virtual Exhibit |publisher=National Science Foundation |location=Arlington County, VA |accessdate=2014-03-18 |url-status=live |archiveurl=https://web.archive.org/web/20140228083459/http://exploringorigins.org/protocells.html |archivedate=28 February 2014}}</ref><ref name="Chen 2006">{{cite journal |last=Chen |first=Irene A. |date=8 December 2006 |title=The Emergence of Cells During the Origin of Life |journal=Science |volume=314 |issue=5805 |pages=1558–1559 |doi=10.1126/science.1137541 |pmid=17158315 |doi-access=free }}</ref><ref name="Discover 2004">{{cite journal |last=Zimmer |first=Carl |authorlink=Carl Zimmer |date=26 June 2004 |title=What Came Before DNA? |url=http://discovermagazine.com/2004/jun/cover |journal=Discover  |url-status=live |archiveurl=https://web.archive.org/web/20140319001351/http://discovermagazine.com/2004/jun/cover |archivedate=19 March 2014}}</ref>

A protocell is a self-organized, self-ordered, spherical collection of [[lipid]]s proposed as a stepping-stone to the origin of life.<ref name="Chen 2010">{{cite journal |first1=Irene A. |last1=Chen |first2=Peter |last2=Walde |title=From Self-Assembled Vesicles to Protocells |journal=Cold Spring Harbor Perspectives in Biology |date=July 2010 |volume=2 |issue=7 |page=a002170 |doi=10.1101/cshperspect.a002170 |pmc=2890201 |pmid=20519344}}</ref> A central question in evolution is how simple protocells first arose and differed in reproductive contribution to the following generation driving the evolution of life. Although a functional protocell has not yet been achieved in a laboratory setting, there are scientists who think the goal is well within reach.<ref name="Exploring">{{cite web |url=http://exploringorigins.org/protocells.html |title=Exploring Life's Origins: Protocells |website=Exploring Life's Origins: A Virtual Exhibit |publisher=National Science Foundation |location=Arlington County, VA |accessdate=2014-03-18 |url-status=live |archiveurl=https://web.archive.org/web/20140228083459/http://exploringorigins.org/protocells.html |archivedate=28 February 2014}}</ref><ref name="Chen 2006">{{cite journal |last=Chen |first=Irene A. |date=8 December 2006 |title=The Emergence of Cells During the Origin of Life |journal=Science |volume=314 |issue=5805 |pages=1558–1559 |doi=10.1126/science.1137541 |pmid=17158315 |doi-access=free }}</ref><ref name="Discover 2004">{{cite journal |last=Zimmer |first=Carl |authorlink=Carl Zimmer |date=26 June 2004 |title=What Came Before DNA? |url=http://discovermagazine.com/2004/jun/cover |journal=Discover  |url-status=live |archiveurl=https://web.archive.org/web/20140319001351/http://discovermagazine.com/2004/jun/cover |archivedate=19 March 2014}}</ref>

Self-assembled [[Vesicle (biology and chemistry)|vesicles]] are essential components of primitive cells.<ref name="Chen 2010" /> The [[second law of thermodynamics]] requires that the universe move in a direction in which [[entropy]] increases, yet life is distinguished by its great degree of organization. Therefore, a boundary is needed to separate [[Metabolism|life processes]] from non-living matter.<ref name="SciAm 2007">{{cite journal |last=Shapiro |first=Robert |authorlink=Robert Shapiro (chemist) |date=June 2007 |title=A Simpler Origin for Life |url=http://www.scientificamerican.com/article/a-simpler-origin-for-life/ |journal=Scientific American |volume=296 |issue=6 |pages=46–53 |doi=10.1038/scientificamerican0607-46 |pmid=17663224 |accessdate=2015-06-15 |bibcode=2007SciAm.296f..46S |url-status=live |archiveurl=https://web.archive.org/web/20150614000643/http://www.scientificamerican.com/article/a-simpler-origin-for-life/ |archivedate=14 June 2015}}</ref> Researchers Irene Chen and Szostak amongst others, suggest that simple physicochemical properties of elementary protocells can give rise to essential cellular behaviours, including primitive forms of differential reproduction competition and energy storage. Such cooperative interactions between the membrane and its encapsulated contents could greatly simplify the transition from simple replicating molecules to true cells.<ref name="Chen 2006" /> Furthermore, competition for membrane molecules would favour stabilized membranes, suggesting a selective advantage for the evolution of cross-linked fatty acids and even the [[phospholipid]]s of today.<ref name="Chen 2006" /> Such [[micro-encapsulation]] would allow for metabolism within the membrane, the exchange of small molecules but the prevention of passage of large substances across it.<ref>{{harvnb|Chang|2007}}</ref> The main advantages of encapsulation include the increased [[solubility]] of the contained cargo within the capsule and the storage of energy in the form of an [[electrochemical gradient]].

Self-assembled [[Vesicle (biology and chemistry)|vesicles]] are essential components of primitive cells.<ref name="Chen 2010" /> The [[second law of thermodynamics]] requires that the universe move in a direction in which [[entropy]] increases, yet life is distinguished by its great degree of organization. Therefore, a boundary is needed to separate [[Metabolism|life processes]] from non-living matter.<ref name="SciAm 2007">{{cite journal |last=Shapiro |first=Robert |authorlink=Robert Shapiro (chemist) |date=June 2007 |title=A Simpler Origin for Life |url=http://www.scientificamerican.com/article/a-simpler-origin-for-life/ |journal=Scientific American |volume=296 |issue=6 |pages=46–53 |doi=10.1038/scientificamerican0607-46 |pmid=17663224 |accessdate=2015-06-15 |bibcode=2007SciAm.296f..46S |url-status=live |archiveurl=https://web.archive.org/web/20150614000643/http://www.scientificamerican.com/article/a-simpler-origin-for-life/ |archivedate=14 June 2015}}</ref> Researchers Irene Chen and Szostak amongst others, suggest that simple physicochemical properties of elementary protocells can give rise to essential cellular behaviours, including primitive forms of differential reproduction competition and energy storage. Such cooperative interactions between the membrane and its encapsulated contents could greatly simplify the transition from simple replicating molecules to true cells.<ref name="Chen 2006" /> Furthermore, competition for membrane molecules would favour stabilized membranes, suggesting a selective advantage for the evolution of cross-linked fatty acids and even the [[phospholipid]]s of today.<ref name="Chen 2006" /> Such [[micro-encapsulation]] would allow for metabolism within the membrane, the exchange of small molecules but the prevention of passage of large substances across it.<ref>{{harvnb|Chang|2007}}</ref> The main advantages of encapsulation include the increased [[solubility]] of the contained cargo within the capsule and the storage of energy in the form of an [[electrochemical gradient]].

A 2012 study led by Mulkidjanian of the [[University of Osnabrück]], suggests that inland pools of condensed and cooled geothermal vapor have the ideal characteristics for the origin of life.<ref name="Switek 2012">{{cite news |last=Switek |first=Brian |date=13 February 2012 |title=Debate bubbles over the origin of life |work=Nature |location=London |publisher=Nature Publishing Group |doi=10.1038/nature.2012.10024}}</ref> Scientists confirmed in 2002 that by adding a [[montmorillonite]] clay to a solution of fatty acid micelles (lipid spheres), the clay sped up the rate of vesicles formation 100-fold.<ref name="Discover 2004" /> Furthermore, recent studies have found that the repeated actions of dehydration and rehydration trapped biomolecules like RNA inside the lipid protocells found within hot springs and providing the necessary preconditions for evolution by natural selection.<ref>{{Cite web|last=z3530495|date=2020-05-05|title='When chemistry became biology': looking for the origins of life in hot springs|url=https://newsroom.unsw.edu.au/news/science-tech/when-chemistry-became-biology-looking-origins-life-hot-springs|access-date=2020-10-12|website=UNSW Newsroom}}</ref>

A 2012 study led by Mulkidjanian of the [[University of Osnabrück]], suggests that inland pools of condensed and cooled geothermal vapor have the ideal characteristics for the origin of life.<ref name="Switek 2012">{{cite news |last=Switek |first=Brian |date=13 February 2012 |title=Debate bubbles over the origin of life |work=Nature |location=London |publisher=Nature Publishing Group |doi=10.1038/nature.2012.10024}}</ref> Scientists confirmed in 2002 that by adding a [[montmorillonite]] clay to a solution of fatty acid micelles (lipid spheres), the clay sped up the rate of vesicles formation 100-fold.<ref name="Discover 2004" /> Furthermore, recent studies have found that the repeated actions of dehydration and rehydration trapped biomolecules like RNA inside the lipid protocells found within hot springs and providing the necessary preconditions for evolution by natural selection.<ref>{{Cite web|last=z3530495|date=2020-05-05|title='When chemistry became biology': looking for the origins of life in hot springs|url=https://newsroom.unsw.edu.au/news/science-tech/when-chemistry-became-biology-looking-origins-life-hot-springs|access-date=2020-10-12|website=UNSW Newsroom}}</ref>

=== Lipid vesicles formation in fresh water ===

=== Lipid vesicles formation in fresh water ===

[[Bruce Damer]] and [[David Deamer]] have come to the conclusion that [[cell membrane]]s cannot be formed in salty [[seawater]], and must therefore have originated in freshwater. Before the continents formed, the only dry land on Earth would be volcanic islands, where rainwater would form ponds where lipids could form the first stages towards cell membranes. These predecessors of true cells are assumed to have behaved more like a [[superorganism]] rather than individual structures, where the porous membranes would house molecules which would leak out and enter other protocells. Only when true cells had evolved would they gradually adapt to saltier environments and enter the ocean.<ref>{{cite journal |last1=Damer |first1=Bruce |last2=Deamer |first2=David |date=13 March 2015 |title=Coupled Phases and Combinatorial Selection in Fluctuating Hydrothermal Pools: A Scenario to Guide Experimental Approaches to the Origin of Cellular Life |journal=Life |volume=5 |issue=1 |pages=872–887 |doi=10.3390/life5010872 |pmc=4390883 |pmid=25780958}}</ref>

[[Bruce Damer]] and [[David Deamer]] have come to the conclusion that [[cell membrane]]s cannot be formed in salty [[seawater]], and must therefore have originated in freshwater. Before the continents formed, the only dry land on Earth would be volcanic islands, where rainwater would form ponds where lipids could form the first stages towards cell membranes. These predecessors of true cells are assumed to have behaved more like a [[superorganism]] rather than individual structures, where the porous membranes would house molecules which would leak out and enter other protocells. Only when true cells had evolved would they gradually adapt to saltier environments and enter the ocean.<ref>{{cite journal |last1=Damer |first1=Bruce |last2=Deamer |first2=David |date=13 March 2015 |title=Coupled Phases and Combinatorial Selection in Fluctuating Hydrothermal Pools: A Scenario to Guide Experimental Approaches to the Origin of Cellular Life |journal=Life |volume=5 |issue=1 |pages=872–887 |doi=10.3390/life5010872 |pmc=4390883 |pmid=25780958}}</ref>

=== Vesicles consisting of mixtures of RNA-like biochemicals ===

=== Vesicles consisting of mixtures of RNA-like biochemicals ===

William Martin and [[Michael Russell (scientist)|Michael Russell]] have suggested < blockquote >. . . . that life evolved in structured iron monosulphide precipitates in a seepage site hydrothermal mound at a redox, pH, and temperature gradient between sulphide-rich hydrothermal fluid and iron(II)-containing waters of the Hadean ocean floor. The naturally arising, three-dimensional compartmentation observed within fossilized seepage-site metal sulphide precipitates indicates that these inorganic compartments were the precursors of cell walls and membranes found in free-living prokaryotes. The known capability of FeS and NiS to catalyze the synthesis of the acetyl-methylsulphide from carbon monoxide and methylsulphide, constituents of hydrothermal fluid, indicates that pre-biotic syntheses occurred at the inner surfaces of these metal-sulphide-walled compartments,..."<ref name="Martin2003">{{cite journal |last1=Martin |first1=William |authorlink1=William F. Martin |last2=Russell |first2=Michael J. |date=29 January 2003 |title=On the origins of cells: a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells |journal=Philosophical Transactions of the Royal Society B |volume=358 |issue=1429 |pages=59–83; discussion 83–85 |doi=10.1098/rstb.2002.1183|pmid=12594918 |pmc=1693102}}</ref> < /blockquote >

William Martin and [[Michael Russell (scientist)|Michael Russell]] have suggested < blockquote >. . . . that life evolved in structured iron monosulphide precipitates in a seepage site hydrothermal mound at a redox, pH, and temperature gradient between sulphide-rich hydrothermal fluid and iron(II)-containing waters of the Hadean ocean floor. The naturally arising, three-dimensional compartmentation observed within fossilized seepage-site metal sulphide precipitates indicates that these inorganic compartments were the precursors of cell walls and membranes found in free-living prokaryotes. The known capability of FeS and NiS to catalyze the synthesis of the acetyl-methylsulphide from carbon monoxide and methylsulphide, constituents of hydrothermal fluid, indicates that pre-biotic syntheses occurred at the inner surfaces of these metal-sulphide-walled compartments,..."<ref name="Martin2003">{{cite journal |last1=Martin |first1=William |authorlink1=William F. Martin |last2=Russell |first2=Michael J. |date=29 January 2003 |title=On the origins of cells: a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells |journal=Philosophical Transactions of the Royal Society B |volume=358 |issue=1429 |pages=59–83; discussion 83–85 |doi=10.1098/rstb.2002.1183|pmid=12594918 |pmc=1693102}}</ref> < /blockquote >

William Martin和Michael Russell说

威廉·马丁 William Martin和迈克尔·拉塞尔 Michael Russell说

     ......生命是在一个渗漏点热液丘中的结构化单硫化铁沉淀物中演化出来的，其氧化还原、pH值和温度梯度介于富含硫化物的热液和冥古代洋底的含铁(II)水之间。在化石渗出地金属硫化物沉淀物中观察到的自然生成的三维分层表明，这些无机分层是在自由生活的原核生物中发现的细胞壁和细胞膜的前身。已知FeS和NiS能够催化一氧化碳和甲基硫化物（热液的成分）合成乙酰-甲基硫化物，这表明生物前的合成发生在这些金属硫化物壁室的内表面，......"

     ......生命是在一个渗流点热液丘中的结构化一硫化铁沉淀物中演化出来的，其氧化还原、pH值和温度梯度介于富含硫化物的热液和冥古代洋底的含铁(II)水之间。在渗透点金属硫化物沉淀物化石中观察到的自然生成的三维分隔表明，这些无机分隔是在自由生活的原核生物中发现的细胞壁和细胞膜的前身。已知FeS和NiS能够催化一氧化碳和甲基硫化物（热液的成分）合成乙酰-甲基硫化物，这表明前生物合成发生在这些金属硫化物壁隔室的内表面，......"

== Pertinent geological environments ==

== Pertinent geological environments ==

An early concept, that life originated from non-living matter in slow stages, appeared in [[Herbert Spencer]]'s 1864–1867 book ''Principles of Biology''. In 1879 [[William Turner Thiselton-Dyer]] referred to this in a paper "On spontaneous generation and evolution". On 1 February 1871 [[Charles Darwin]] wrote about these publications to [[Joseph Dalton Hooker|Joseph Hooker]], and set out his own speculation,<ref name="Darwin DCP-LETT-7471">{{cite web | title=Letter no. 7471, Charles Darwin to Joseph Dalton Hooker, 1 February (1871) | website=Darwin Correspondence Project | date= | url=https://www.darwinproject.ac.uk/letter/DCP-LETT-7471.xml | access-date=7 July 2020}}</ref><ref>{{cite web|url=https://www.nsf.gov/news/special_reports/darwin/textonly/polar_essay1.jsp|title=Origin and Evolution of Life on a Frozen Earth|last=Priscu|first=John C.|authorlink=John Charles Priscu|publisher=[[National Science Foundation]]|location=Arlington County, VA|archiveurl=https://web.archive.org/web/20131218070241/http://www.nsf.gov/news/special_reports/darwin/textonly/polar_essay1.jsp|archivedate=18 December 2013|url-status=live|accessdate=2014-03-01}}</ref> suggesting that the original spark of life may have begun in a < blockquote >warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, {{sic|hide=y|&c.}}, present, that a {{sic|hide=y|[[protein]]e}} compound was chemically formed ready to undergo still more complex changes.< /blockquote > He went on to explain that < blockquote >at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed.< /blockquote >

An early concept, that life originated from non-living matter in slow stages, appeared in [[Herbert Spencer]]'s 1864–1867 book ''Principles of Biology''. In 1879 [[William Turner Thiselton-Dyer]] referred to this in a paper "On spontaneous generation and evolution". On 1 February 1871 [[Charles Darwin]] wrote about these publications to [[Joseph Dalton Hooker|Joseph Hooker]], and set out his own speculation,<ref name="Darwin DCP-LETT-7471">{{cite web | title=Letter no. 7471, Charles Darwin to Joseph Dalton Hooker, 1 February (1871) | website=Darwin Correspondence Project | date= | url=https://www.darwinproject.ac.uk/letter/DCP-LETT-7471.xml | access-date=7 July 2020}}</ref><ref>{{cite web|url=https://www.nsf.gov/news/special_reports/darwin/textonly/polar_essay1.jsp|title=Origin and Evolution of Life on a Frozen Earth|last=Priscu|first=John C.|authorlink=John Charles Priscu|publisher=[[National Science Foundation]]|location=Arlington County, VA|archiveurl=https://web.archive.org/web/20131218070241/http://www.nsf.gov/news/special_reports/darwin/textonly/polar_essay1.jsp|archivedate=18 December 2013|url-status=live|accessdate=2014-03-01}}</ref> suggesting that the original spark of life may have begun in a < blockquote >warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, {{sic|hide=y|&c.}}, present, that a {{sic|hide=y|[[protein]]e}} compound was chemically formed ready to undergo still more complex changes.< /blockquote > He went on to explain that < blockquote >at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed.< /blockquote >

一个早期的概念，即生命起源于非生命物质的缓慢阶段，出现在Herbert Spencer 1864-1867年的《生物学原理》一书中。1879年William Turner Thiselton-Dyer在 "论自然发生和进化 "一文中提到了这一点。1871年2月1日，Charles Darwin将这些出版物写信给Joseph Hooker，并提出了自己的推测，认为生命的最初火花可能是始于

一个早期的概念，即生命在缓慢的阶段中起源于非生命物质，出现在赫伯特·斯宾塞 Herbert Spencer 1864-1867年的《生物学原理》一书中。1879年威廉·特纳·希塞尔顿-代尔 William Turner Thiselton-Dyer在论文"论自然发生和演化"中提到了这一点。1871年2月1日，Charles Darwin将这些出版物写信给约瑟夫·胡克 Joseph Hooker，并提出了自己的推测，认为生命的最初火花可能是始于

It is often said that all the conditions for the first production of a living organism are now present, which could ever have been present. But if (and oh! what a big if!) we could conceive in some warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, {{sic|&c.|hide=y}}, present, that a {{sic|[[protein]]e|hide=y}} compound was chemically formed ready to undergo still more complex changes, at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed.

It is often said that all the conditions for the first production of a living organism are now present, which could ever have been present. But if (and oh! what a big if!) we could conceive in some warm little pond, with all sorts of ammonia and phosphoric salts, light, heat, electricity, {{sic|&c.|hide=y}}, present, that a {{sic|[[protein]]e|hide=y}} compound was chemically formed ready to undergo still more complex changes, at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed.

— Darwin, 1 February 1871

— Darwin, 1 February 1871

More recent studies, in 2017, support the notion that life may have begun right after the Earth was formed as RNA molecules emerging from "warm little ponds".<ref name="IND-20171002">{{cite web |last=Johnston |first=Ian |title=Life first emerged in 'warm little ponds' almost as old as the Earth itself – Darwin's famous idea backed by new scientific study |url=https://www.independent.co.uk/news/science/origins-life-ponds-organisms-earth-age-study-a7978906.html |date=2 October 2017 |work=[[The Independent]] |accessdate=2 October 2017 |url-status=live |archiveurl=https://web.archive.org/web/20171003003027/http://www.independent.co.uk/news/science/origins-life-ponds-organisms-earth-age-study-a7978906.html |archivedate=3 October 2017}}</ref>

More recent studies, in 2017, support the notion that life may have begun right after the Earth was formed as RNA molecules emerging from "warm little ponds".<ref name="IND-20171002">{{cite web |last=Johnston |first=Ian |title=Life first emerged in 'warm little ponds' almost as old as the Earth itself – Darwin's famous idea backed by new scientific study |url=https://www.independent.co.uk/news/science/origins-life-ponds-organisms-earth-age-study-a7978906.html |date=2 October 2017 |work=[[The Independent]] |accessdate=2 October 2017 |url-status=live |archiveurl=https://web.archive.org/web/20171003003027/http://www.independent.co.uk/news/science/origins-life-ponds-organisms-earth-age-study-a7978906.html |archivedate=3 October 2017}}</ref>

2017年，更多的最新研究支持这样的观点：生命可能在地球形成后就开始了，因为RNA分子从 "温暖的小池塘 "中出现。

2017年的最新研究支持这样的观点：生命可能在地球形成后就开始了，因为RNA分子从"温暖的小池塘"中出现。

===Volcanic hot springs and hydrothermal vents, shallow or deep===

===Volcanic hot springs and hydrothermal vents, shallow or deep===

M.D> Brasier (2012), "Secret Chambers: The Inside Story of Cells and Complex Life" (Oxford Uni Press), p.298</ref> Another analysis of the conventional threefold tree of life shows thermophilic and hyperthermophilic [[bacteria]] and [[archaea]] are closest to the root, suggesting that life may have evolved in a hot environment.<ref>Ward, Peter & Kirschvink, Joe, op cit, p. 42</ref>

M.D> Brasier (2012), "Secret Chambers: The Inside Story of Cells and Complex Life" (Oxford Uni Press), p.298</ref> Another analysis of the conventional threefold tree of life shows thermophilic and hyperthermophilic [[bacteria]] and [[archaea]] are closest to the root, suggesting that life may have evolved in a hot environment.<ref>Ward, Peter & Kirschvink, Joe, op cit, p. 42</ref>

===Deep sea hydrothermal vents===

===Deep sea hydrothermal vents===

[[File:Blacksmoker in Atlantic Ocean.jpg|thumb|upright|Deep-sea hydrothermal vent or [[black smoker]]]]

[[File:Blacksmoker in Atlantic Ocean.jpg|thumb|upright|Deep-sea hydrothermal vent or [[black smoker]]]]

The deep sea vent, or alkaline [[hydrothermal vent]], theory posits that life may have begun at submarine hydrothermal vents,<ref name=":1">{{Cite journal|author1=Colín-García, M.|author2=A. Heredia|author3=G. Cordero|author4=A. Camprubí|author5=A. Negrón-Mendoza|author6=F. Ortega-Gutiérrez|author7=H. Berald|author8=S. Ramos-Bernal|year=2016|title=Hydrothermal vents and prebiotic chemistry: a review|url=http://boletinsgm.igeolcu.unam.mx/bsgm/index.php/component/content/article/309-sitio/articulos/cuarta-epoca/6803/1620-6803-13-colin|journal=Boletín de la Sociedad Geológica Mexicana|volume=68|issue=3|pages=599–620|url-status=live|archiveurl=https://web.archive.org/web/20170818175803/http://boletinsgm.igeolcu.unam.mx/bsgm/index.php/component/content/article/309-sitio/articulos/cuarta-epoca/6803/1620-6803-13-colin|archivedate=18 August 2017|doi=10.18268/BSGM2016v68n3a13|doi-access=free}}</ref><ref name="hydrothermal vents NASA 2014">{{cite web|url=https://astrobiology.nasa.gov/articles/2014/6/24/hydrothermal-vents-could-explain-chemical-precursors-to-life/ |title=Hydrothermal Vents Could Explain Chemical Precursors to Life |last=Schirber |first=Michael |date=24 June 2014 |website=NASA Astrobiology: Life in the Universe |publisher=NASA |accessdate=2015-06-19 |url-status=dead |archiveurl=https://web.archive.org/web/20141129051724/http://astrobiology.nasa.gov/articles/2014/6/24/hydrothermal-vents-could-explain-chemical-precursors-to-life/ |archivedate=29 November 2014}}</ref>  Martin and Russell have suggested < blockquote >that life evolved in structured iron monosulphide precipitates in a seepage site hydrothermal mound at a redox, pH, and temperature gradient between sulphide-rich hydrothermal fluid and iron(II)-containing waters of the Hadean ocean floor. The naturally arising, three-dimensional compartmentation observed within fossilized seepage-site metal sulphide precipitates indicates that these inorganic compartments were the precursors of cell walls and membranes found in free-living prokaryotes. The known capability of FeS and NiS to catalyze the synthesis of the acetyl-methylsulphide from carbon monoxide and methylsulphide, constituents of hydrothermal fluid, indicates that pre-biotic syntheses occurred at the inner surfaces of these metal-sulphide-walled compartments,...<ref name="Martin2003" />< /blockquote > These form where hydrogen-rich fluids emerge from below the sea floor, as a result of [[Serpentinite|serpentinization]] of ultra-[[mafic]] [[olivine]] with seawater and a pH interface with carbon dioxide-rich ocean water. The vents form a sustained chemical energy source derived from redox reactions, in which electron donors (molecular hydrogen) react with electron acceptors (carbon dioxide); see [[Iron–sulfur world theory]]. These are highly [[exothermic reaction]]s.<ref name=":1" />{{efn|The reactions are:<br />

The deep sea vent, or alkaline [[hydrothermal vent]], theory posits that life may have begun at submarine hydrothermal vents,<ref name=":1">{{Cite journal|author1=Colín-García, M.|author2=A. Heredia|author3=G. Cordero|author4=A. Camprubí|author5=A. Negrón-Mendoza|author6=F. Ortega-Gutiérrez|author7=H. Berald|author8=S. Ramos-Bernal|year=2016|title=Hydrothermal vents and prebiotic chemistry: a review|url=http://boletinsgm.igeolcu.unam.mx/bsgm/index.php/component/content/article/309-sitio/articulos/cuarta-epoca/6803/1620-6803-13-colin|journal=Boletín de la Sociedad Geológica Mexicana|volume=68|issue=3|pages=599–620|url-status=live|archiveurl=https://web.archive.org/web/20170818175803/http://boletinsgm.igeolcu.unam.mx/bsgm/index.php/component/content/article/309-sitio/articulos/cuarta-epoca/6803/1620-6803-13-colin|archivedate=18 August 2017|doi=10.18268/BSGM2016v68n3a13|doi-access=free}}</ref><ref name="hydrothermal vents NASA 2014">{{cite web|url=https://astrobiology.nasa.gov/articles/2014/6/24/hydrothermal-vents-could-explain-chemical-precursors-to-life/ |title=Hydrothermal Vents Could Explain Chemical Precursors to Life |last=Schirber |first=Michael |date=24 June 2014 |website=NASA Astrobiology: Life in the Universe |publisher=NASA |accessdate=2015-06-19 |url-status=dead |archiveurl=https://web.archive.org/web/20141129051724/http://astrobiology.nasa.gov/articles/2014/6/24/hydrothermal-vents-could-explain-chemical-precursors-to-life/ |archivedate=29 November 2014}}</ref>  Martin and Russell have suggested < blockquote >that life evolved in structured iron monosulphide precipitates in a seepage site hydrothermal mound at a redox, pH, and temperature gradient between sulphide-rich hydrothermal fluid and iron(II)-containing waters of the Hadean ocean floor. The naturally arising, three-dimensional compartmentation observed within fossilized seepage-site metal sulphide precipitates indicates that these inorganic compartments were the precursors of cell walls and membranes found in free-living prokaryotes. The known capability of FeS and NiS to catalyze the synthesis of the acetyl-methylsulphide from carbon monoxide and methylsulphide, constituents of hydrothermal fluid, indicates that pre-biotic syntheses occurred at the inner surfaces of these metal-sulphide-walled compartments,...<ref name="Martin2003" />< /blockquote > These form where hydrogen-rich fluids emerge from below the sea floor, as a result of [[Serpentinite|serpentinization]] of ultra-[[mafic]] [[olivine]] with seawater and a pH interface with carbon dioxide-rich ocean water. The vents form a sustained chemical energy source derived from redox reactions, in which electron donors (molecular hydrogen) react with electron acceptors (carbon dioxide); see [[Iron–sulfur world theory]]. These are highly [[exothermic reaction]]s.<ref name=":1" />{{efn|The reactions are:<br />

< blockquote >

< blockquote >

生命是在一个渗漏点热液丘中的结构化单硫化铁沉淀物中演化出来的，其氧化还原、pH值和温度梯度介于富含硫化物的热液和哈丹洋底的含铁(II)水之间。在化石渗出地金属硫化物沉淀物中观察到的自然生成的三维分层表明，这些无机分层是自由生活的原核生物中发现的细胞壁和膜的前体。已知FeS和NiS能够催化一氧化碳和甲基硫化物（热液的成分）合成乙酰-甲基硫化物，这表明生物前的合成发生在这些金属硫化物壁隔室的内表面，

生命是在一个渗流点热液丘中的结构化一硫化铁沉淀物中演化出来的，其氧化还原、pH值和温度梯度介于富含硫化物的热液和冥古代洋底的含铁(II)水之间。在渗流点金属硫化物沉淀物化石中观察到的自然生成的三维分隔表明，这些无机分隔是自由生活的原核生物中发现的细胞壁和膜的前体。已知FeS和NiS能够催化一氧化碳和甲基硫化物（热液的成分）合成乙酰-甲基硫化物，这表明前生物合成发生在这些金属硫化物壁隔室的内表面，

< blockquote >

< blockquote >

这些喷口形成于富氢流体从海底下冒出的地方，是超基性橄榄石与海水发生蛇纹石化以及与富含二氧化碳的海水发生pH值界面的结果。这些喷口形成了一个来自氧化还原反应的持续化学能源，其中电子供体(分子氢)与电子受体(二氧化碳)发生反应；见铁-硫世界理论。这些都是高度放热的反应。

这些喷口形成于海底富氢液体渗出的地方，是超镁铁质橄榄石与海水发生蛇纹石化以及与富含二氧化碳的海水的pH值界面的结果。这些喷口形成了一个来自氧化还原反应的持续化学能源，其中电子供体（分子氢）与电子受体（二氧化碳）发生反应；见铁-硫世界理论。这些都是高度放热的反应。

Russell demonstrated that alkaline vents created an abiogenic [[Proton electromotive force|proton motive force]] (PMF) [[Chemiosmosis|chemiosmotic]] gradient,<ref name="Martin2003" /> in which conditions are ideal for an abiogenic hatchery for life. Their microscopic compartments "provide a natural means of concentrating organic molecules," composed of iron-sulfur minerals such as [[mackinawite]], endowed these mineral cells with the catalytic properties envisaged by [[Günter Wächtershäuser]].<ref name="Lane 2009" /> This movement of ions across the membrane depends on a combination of two factors:

Russell demonstrated that alkaline vents created an abiogenic [[Proton electromotive force|proton motive force]] (PMF) [[Chemiosmosis|chemiosmotic]] gradient,<ref name="Martin2003" /> in which conditions are ideal for an abiogenic hatchery for life. Their microscopic compartments "provide a natural means of concentrating organic molecules," composed of iron-sulfur minerals such as [[mackinawite]], endowed these mineral cells with the catalytic properties envisaged by [[Günter Wächtershäuser]].<ref name="Lane 2009" /> This movement of ions across the membrane depends on a combination of two factors:

Russell证明，碱性喷口创造了一个非生物质质子动力（PMF）化生梯度，其中的条件是理想的非生物生命孵化器。它们的微观隔间 "提供了集中有机分子的天然手段"，由铁硫矿物组成，如麦饭石，赋予这些矿物细胞以金特·沃特肖泽 Günter Wächtershäuser设想的催化特性。这种离子在膜上的运动取决于两个因素的组合：

Russell证明，碱性喷口创造了一个非生物质子动力（PMF）化学渗透的梯度，其中的条件是理想的非生物生命孵化器。它们的微观隔间"提供了集中有机分子的天然手段"，由铁硫矿物组成，如马基诺矿，赋予这些矿物小室以金特·沃特肖泽 Günter Wächtershäuser设想的催化特性。这种离子在膜上的运动取决于两个因素的组合：

# [[Diffusion]] force caused by concentration gradient—all particles including ions tend to diffuse from higher concentration to lower.

# [[Diffusion]] force caused by concentration gradient—all particles including ions tend to diffuse from higher concentration to lower.

# Electrostatic force caused by electrical potential gradient—[[cations]] like [[proton]]s H⁺ tend to diffuse down the electrical potential, [[anions]] in the opposite direction.

# Electrostatic force caused by electrical potential gradient—[[cations]] like [[proton]]s H⁺ tend to diffuse down the electrical potential, [[anions]] in the opposite direction.

电位梯度引起的静电力--质子H+等阳离子倾向于顺着电位扩散，阴离子则相反。

电位梯度引起的静电力--质子H⁺等阳离子倾向于顺着电位扩散，阴离子则相反。

These two gradients taken together can be expressed as an [[electrochemical gradient]], providing energy for abiogenic synthesis. The proton motive force can be described as the measure of the potential energy stored as a combination of proton and voltage gradients across a membrane (differences in proton concentration and electrical potential).

These two gradients taken together can be expressed as an [[electrochemical gradient]], providing energy for abiogenic synthesis. The proton motive force can be described as the measure of the potential energy stored as a combination of proton and voltage gradients across a membrane (differences in proton concentration and electrical potential).

Szostak suggested that geothermal activity provides greater opportunities for the origination of life in open lakes where there is a buildup of minerals. In 2010, based on spectral analysis of sea and hot mineral water, Ignat Ignatov and Oleg Mosin demonstrated that life may have predominantly originated in hot mineral water. The hot mineral water that contains [[bicarbonate]] and [[calcium]] ions has the most optimal range.<ref>{{cite journal |last1=Ignatov |first1=Ignat |last2=Mosin |first2=Oleg V. |year=2013 |title=Possible Processes for Origin of Life and Living Matter with modeling of Physiological Processes of Bacterium ''Bacillus Subtilis'' in Heavy Water as Model System |journal=Journal of Natural Sciences Research |volume=3 |issue=9 |pages=65–76}}</ref> This case is similar to the origin of life in hydrothermal vents, but with bicarbonate and calcium ions in hot water. This water has a pH of 9–11 and is possible to have the reactions in seawater. According to [[Melvin Calvin]], certain reactions of condensation-dehydration of amino acids and nucleotides in individual blocks of peptides and nucleic acids can take place in the primary hydrosphere with pH 9–11 at a later evolutionary stage.<ref>{{harvnb|Calvin|1969}}</ref> Some of these compounds like [[Hydrogen cyanide|hydrocyanic acid]] (HCN) have been proven in the experiments of Miller. This is the environment in which the [[stromatolite]]s have been created. David Ward of [[Montana State University]] described the formation of stromatolites in hot mineral water at the [[Yellowstone National Park]]. Stromatolites survive in hot mineral water and in proximity to areas with volcanic activity.<ref>{{cite journal |last=Schirber |first=Michael |date=1 March 2010 |title=First Fossil-Makers in Hot Water |url=http://www.astrobio.net/news-exclusive/first-fossil-makers-in-hot-water/ |journal=[[Astrobiology Magazine]] |accessdate=2015-06-19 |url-status=live |archiveurl=https://web.archive.org/web/20150714085640/http://www.astrobio.net/news-exclusive/first-fossil-makers-in-hot-water/ |archivedate=14 July 2015}}</ref> Processes have evolved in the sea near geysers of hot mineral water.  

Szostak suggested that geothermal activity provides greater opportunities for the origination of life in open lakes where there is a buildup of minerals. In 2010, based on spectral analysis of sea and hot mineral water, Ignat Ignatov and Oleg Mosin demonstrated that life may have predominantly originated in hot mineral water. The hot mineral water that contains [[bicarbonate]] and [[calcium]] ions has the most optimal range.<ref>{{cite journal |last1=Ignatov |first1=Ignat |last2=Mosin |first2=Oleg V. |year=2013 |title=Possible Processes for Origin of Life and Living Matter with modeling of Physiological Processes of Bacterium ''Bacillus Subtilis'' in Heavy Water as Model System |journal=Journal of Natural Sciences Research |volume=3 |issue=9 |pages=65–76}}</ref> This case is similar to the origin of life in hydrothermal vents, but with bicarbonate and calcium ions in hot water. This water has a pH of 9–11 and is possible to have the reactions in seawater. According to [[Melvin Calvin]], certain reactions of condensation-dehydration of amino acids and nucleotides in individual blocks of peptides and nucleic acids can take place in the primary hydrosphere with pH 9–11 at a later evolutionary stage.<ref>{{harvnb|Calvin|1969}}</ref> Some of these compounds like [[Hydrogen cyanide|hydrocyanic acid]] (HCN) have been proven in the experiments of Miller. This is the environment in which the [[stromatolite]]s have been created. David Ward of [[Montana State University]] described the formation of stromatolites in hot mineral water at the [[Yellowstone National Park]]. Stromatolites survive in hot mineral water and in proximity to areas with volcanic activity.<ref>{{cite journal |last=Schirber |first=Michael |date=1 March 2010 |title=First Fossil-Makers in Hot Water |url=http://www.astrobio.net/news-exclusive/first-fossil-makers-in-hot-water/ |journal=[[Astrobiology Magazine]] |accessdate=2015-06-19 |url-status=live |archiveurl=https://web.archive.org/web/20150714085640/http://www.astrobio.net/news-exclusive/first-fossil-makers-in-hot-water/ |archivedate=14 July 2015}}</ref> Processes have evolved in the sea near geysers of hot mineral water.  

Szostak提出，在有矿物质堆积的开放湖泊中，地热活动为生命的起源提供了更大的机会。2010年，Ignat Ignatov伊格纳特-伊格纳托夫和Oleg Mosin奥列格-莫辛根据对海水和热矿泉水的光谱分析，证明生命可能主要起源于热矿泉水。含有碳酸氢盐和钙离子的热矿泉水具有最理想的范围。这种情况类似于热液喷口中的生命起源，但热水中含有碳酸氢盐和钙离子。这种水的pH值为9-11，有可能在海水中发生反应。根据Melvin Calvin梅尔文-卡尔文的观点，在以后的进化阶段，在pH值为9-11的原生水球中，可以发生某些氨基酸和核苷酸单个区块的缩合-脱水反应.其中一些化合物如氢氰酸(HCN)已经在米勒的实验中得到证明。这就是产生气相石的环境。蒙大拿州立大学的David Ward描述了黄石国家公园的热矿泉水中形成的叠层石。叠层石生存在热矿泉水中和靠近火山活动的地区。在热矿泉水的喷泉附近的海中也有演化过程。2011年，东京大学的Tadashi Sugawara在热水中创造了一个原生细胞。

Szostak提出，在有矿物质堆积的开放湖泊中，地热活动为生命的起源提供了更大的机会。2010年，伊格纳特·伊格纳托夫 Ignat Ignatov和奥列格·莫辛Oleg Mosin根据对海水和热矿泉水的光谱分析，证明生命可能主要起源于热矿泉水。含有碳酸氢盐和钙离子的热矿泉水具有最理想的范围。这种情况类似于热液喷口中的生命起源，但热水中含有碳酸氢盐和钙离子。这种水的pH值为9-11，有可能在海水中发生反应。根据梅尔文·卡尔文 Melvin Calvin的观点，在更后的进化阶段，在pH值为9-11的原生水球中，可能发生某些氨基酸和核苷酸在多肽和核酸各个区段中的脱水-缩合反应。其中一些化合物如氢氰酸（HCN）已经在Miller的实验中得到证明。这就是产生叠层石的环境。蒙大拿州立大学的大卫·沃德 David Ward描述了黄石国家公园的热矿泉水中的叠层石的形成。叠层石存在于热矿泉水中和靠近火山活动的地区。这些过程是在热矿泉水的间歇泉附近的海中演化的。***2011年，东京大学的Tadashi Sugawara在热水中创造了一个原生细胞。***缺乏对应英文

Experimental research and computer modelling suggest that the surfaces of mineral particles inside hydrothermal vents have catalytic properties similar to those of enzymes and are able to create simple organic molecules, such as [[methanol]] (CH₃OH) and [[Formic acid|formic]], [[Acetic acid|acetic]] and [[Pyruvic acid|pyruvic]] acid out of the dissolved CO₂ in the water.<ref name="organics">{{cite press release |last=Usher |first=Oli |date=27 April 2015 |title=Chemistry of seabed's hot vents could explain emergence of life |url=https://www.ucl.ac.uk/silva/mathematical-physical-sciences/maps-news-publication/maps1526 |publisher=[[University College London]] |accessdate=2015-06-19 |archive-url=https://web.archive.org/web/20150620012231/https://www.ucl.ac.uk/silva/mathematical-physical-sciences/maps-news-publication/maps1526 |archive-date=20 June 2015 |url-status=dead}}</ref><ref>{{cite journal |last1=Roldan |first1=Alberto |last2=Hollingsworth |first2=Nathan |last3=Roffey |first3=Anna |last4=Islam |first4=Husn-Ubayda |last5=Goodall |first5=Josephine B. M. |last6=Catlow |first6=C. Richard A. |authorlink6=Richard Catlow |last7=Darr |first7=Jawwad A. |last8=Bras |first8=Wim |last9=Sankar |first9=Gopinathan |last10=Holt |first10=Katherine B. |last11=Hogarth |first11=Graeme |last12=de Leeuw |first12=Nora Henriette |display-authors=4 |date=May 2015 |title=Bio-inspired CO2 conversion by iron sulfide catalysts under sustainable conditions |url=http://pubs.rsc.org/en/content/articlepdf/2015/cc/c5cc02078f|journal=Chemical Communications |volume=51 |issue=35 |pages=7501–7504 |doi=10.1039/C5CC02078F |pmid=25835242 |accessdate=2015-06-19 |url-status=live |archiveurl=https://web.archive.org/web/20150620003943/http://pubs.rsc.org/en/content/articlepdf/2015/cc/c5cc02078f |archivedate=20 June 2015|doi-access=free }}</ref>

Experimental research and computer modelling suggest that the surfaces of mineral particles inside hydrothermal vents have catalytic properties similar to those of enzymes and are able to create simple organic molecules, such as [[methanol]] (CH₃OH) and [[Formic acid|formic]], [[Acetic acid|acetic]] and [[Pyruvic acid|pyruvic]] acid out of the dissolved CO₂ in the water.<ref name="organics">{{cite press release |last=Usher |first=Oli |date=27 April 2015 |title=Chemistry of seabed's hot vents could explain emergence of life |url=https://www.ucl.ac.uk/silva/mathematical-physical-sciences/maps-news-publication/maps1526 |publisher=[[University College London]] |accessdate=2015-06-19 |archive-url=https://web.archive.org/web/20150620012231/https://www.ucl.ac.uk/silva/mathematical-physical-sciences/maps-news-publication/maps1526 |archive-date=20 June 2015 |url-status=dead}}</ref><ref>{{cite journal |last1=Roldan |first1=Alberto |last2=Hollingsworth |first2=Nathan |last3=Roffey |first3=Anna |last4=Islam |first4=Husn-Ubayda |last5=Goodall |first5=Josephine B. M. |last6=Catlow |first6=C. Richard A. |authorlink6=Richard Catlow |last7=Darr |first7=Jawwad A. |last8=Bras |first8=Wim |last9=Sankar |first9=Gopinathan |last10=Holt |first10=Katherine B. |last11=Hogarth |first11=Graeme |last12=de Leeuw |first12=Nora Henriette |display-authors=4 |date=May 2015 |title=Bio-inspired CO2 conversion by iron sulfide catalysts under sustainable conditions |url=http://pubs.rsc.org/en/content/articlepdf/2015/cc/c5cc02078f|journal=Chemical Communications |volume=51 |issue=35 |pages=7501–7504 |doi=10.1039/C5CC02078F |pmid=25835242 |accessdate=2015-06-19 |url-status=live |archiveurl=https://web.archive.org/web/20150620003943/http://pubs.rsc.org/en/content/articlepdf/2015/cc/c5cc02078f |archivedate=20 June 2015|doi-access=free }}</ref>

The research reported above by Martin in 2016 supports the thesis that life arose at hydrothermal vents,<ref>{{cite journal | last1 = Baross | first1 = J.A. | last2 = Hoffman | first2 = S.E. | year = 1985 | title = Submarine hydrothermal vents and associated gradient environments as sites for the origin and evolution of life | journal = Origins LifeEvol. B | volume = 15 | issue = 4 | pages = 327–345 | doi=10.1007/bf01808177| bibcode = 1985OrLi...15..327B | s2cid = 4613918 }}</ref><ref>{{cite journal | last1 = Russell | first1 = M.J. | last2 = Hall | first2 = A.J. | year = 1997 | title = The emergence of life from iron monosulphide bubbles at a submarine hydrothermal redox and pH front | journal = Journal of the Geological Society| volume = 154 | issue = 3 | pages = 377–402 | doi=10.1144/gsjgs.154.3.0377| pmid = 11541234 | bibcode = 1997JGSoc.154..377R | s2cid = 24792282 }}</ref> that spontaneous chemistry in the Earth's crust driven by rock–water interactions at disequilibrium thermodynamically underpinned life's origin<ref>{{cite journal | last1 = Amend | first1 = J.P. | last2 = LaRowe | first2 = D.E. | last3 = McCollom | first3 = T.M. | last4 = Shock | first4 = E.L. | year = 2013 | title = The energetics of organic synthesis inside and outside the cell | journal = Phil. Trans. R. Soc. Lond. B | volume = 368 | issue = 1622 | page = 20120255 | doi=10.1098/rstb.2012.0255| pmid = 23754809 | pmc = 3685458 }}</ref><ref>{{cite journal | last1 = Shock | first1 = E.L. | last2 = Boyd | first2 = E.S. | year = 2015 | title = Geomicrobiology and microbial geochemistry:principles of geobiochemistry | journal = Elements | volume = 11 | pages = 389–394 | doi = 10.2113/gselements.11.6.395 }}</ref> and that the founding lineages of the archaea and bacteria were H2-dependent autotrophs that used CO2 as their terminal acceptor in energy metabolism.<ref>{{cite journal | last1 = Martin | first1 = W. | last2 = Russell | first2 = M.J. | year = 2007 | title = On the origin of biochemistry at an alkaline hydrothermal vent | journal = Phil. Trans. R. Soc. Lond. B | volume = 362 | issue = 1486 | pages = 1887–1925 | doi = 10.1098/rstb.2006.1881 | pmid = 17255002 | pmc = 2442388 }}</ref> Martin suggests, based upon this evidence that [[LUCA]] "may have depended heavily on the geothermal energy of the vent to survive".<ref>Nature, Vol 535, 28 July 2016. p.468</ref>

The research reported above by Martin in 2016 supports the thesis that life arose at hydrothermal vents,<ref>{{cite journal | last1 = Baross | first1 = J.A. | last2 = Hoffman | first2 = S.E. | year = 1985 | title = Submarine hydrothermal vents and associated gradient environments as sites for the origin and evolution of life | journal = Origins LifeEvol. B | volume = 15 | issue = 4 | pages = 327–345 | doi=10.1007/bf01808177| bibcode = 1985OrLi...15..327B | s2cid = 4613918 }}</ref><ref>{{cite journal | last1 = Russell | first1 = M.J. | last2 = Hall | first2 = A.J. | year = 1997 | title = The emergence of life from iron monosulphide bubbles at a submarine hydrothermal redox and pH front | journal = Journal of the Geological Society| volume = 154 | issue = 3 | pages = 377–402 | doi=10.1144/gsjgs.154.3.0377| pmid = 11541234 | bibcode = 1997JGSoc.154..377R | s2cid = 24792282 }}</ref> that spontaneous chemistry in the Earth's crust driven by rock–water interactions at disequilibrium thermodynamically underpinned life's origin<ref>{{cite journal | last1 = Amend | first1 = J.P. | last2 = LaRowe | first2 = D.E. | last3 = McCollom | first3 = T.M. | last4 = Shock | first4 = E.L. | year = 2013 | title = The energetics of organic synthesis inside and outside the cell | journal = Phil. Trans. R. Soc. Lond. B | volume = 368 | issue = 1622 | page = 20120255 | doi=10.1098/rstb.2012.0255| pmid = 23754809 | pmc = 3685458 }}</ref><ref>{{cite journal | last1 = Shock | first1 = E.L. | last2 = Boyd | first2 = E.S. | year = 2015 | title = Geomicrobiology and microbial geochemistry:principles of geobiochemistry | journal = Elements | volume = 11 | pages = 389–394 | doi = 10.2113/gselements.11.6.395 }}</ref> and that the founding lineages of the archaea and bacteria were H2-dependent autotrophs that used CO2 as their terminal acceptor in energy metabolism.<ref>{{cite journal | last1 = Martin | first1 = W. | last2 = Russell | first2 = M.J. | year = 2007 | title = On the origin of biochemistry at an alkaline hydrothermal vent | journal = Phil. Trans. R. Soc. Lond. B | volume = 362 | issue = 1486 | pages = 1887–1925 | doi = 10.1098/rstb.2006.1881 | pmid = 17255002 | pmc = 2442388 }}</ref> Martin suggests, based upon this evidence that [[LUCA]] "may have depended heavily on the geothermal energy of the vent to survive".<ref>Nature, Vol 535, 28 July 2016. p.468</ref>

Martin在2016年报告的上述研究支持这样的论点，即生命产生于热液喷口,地壳中由岩石-水相互作用驱动的非平衡热力学自发化学作用是生命起源的基础，古菌和细菌的创始系是依赖H2的自养生物，它们在能量代谢中使用CO2作为终端接受体。Martin根据这些证据提出，LUCA "可能严重依赖喷口的地热能而生存"。

Martin在2016年报告的上述研究支持这样的论点，即生命产生于热液喷口,地壳中由岩石-水相互作用驱动的非平衡热力学自发化学作用是生命起源的基础，古细菌和细菌的创始系是依赖H2的自养生物，它们在能量代谢中使用CO2作为终端接受体。Martin根据这些证据提出，LUCA "可能严重依赖喷口的地热能而生存"。

=== Fluctuating hydrothermal pools on volcanic islands or proto-continents ===

=== Fluctuating hydrothermal pools on volcanic islands or proto-continents ===

Mulkidjanian and co-authors think that the marine environments did not provide the ionic balance and composition universally found in cells, as well as of ions required by essential proteins and ribozymes found in virtually all living organisms, especially with respect to K⁺/Na⁺ ratio, Mn²⁺, Zn²⁺ and phosphate concentrations. The only known environments that mimic the needed conditions on Earth are found in terrestrial hydrothermal pools fed by steam vents.<ref name=":1" /> Additionally, mineral deposits in these environments under an anoxic atmosphere would have suitable pH (as opposed to current pools in an oxygenated atmosphere), contain precipitates of sulfide minerals that block harmful UV radiation, have wetting/drying cycles that concentrate substrate solutions to concentrations amenable to spontaneous formation of polymers of nucleic acids, polyesters<ref>{{cite journal |last1=Chandru |first1=Kuhan |last2=Guttenberg |first2=Nicholas |last3=Giri |first3=Chaitanya |last4=Hongo |first4=Yayoi |last5=Butch |first5=Christopher |last6=Mamajanov |first6=Irena |last7=Cleaves |first7=H. James |title=Simple prebiotic synthesis of high diversity dynamic combinatorial polyester libraries |journal=Communications Chemistry |date=31 May 2018 |volume=1 |issue=1 |doi=10.1038/s42004-018-0031-1 |doi-access=free }}</ref> and depsipeptides,<ref>{{cite journal |last1=Forsythe |first1=Jay G |last2=Yu |first2=Sheng-Sheng |last3=Mamajanov |first3=Irena |last4=Grover |first4=Martha A |last5=Krishnamurthy |first5=Ramanarayanan |last6=Fernández |first6=Facundo M |last7=Hud |first7=Nicholas V |title=Ester-Mediated Amide Bond Formation Driven by Wet–Dry Cycles: A Possible Path to Polypeptides on the Prebiotic Earth |journal=Angewandte Chemie (International ed. In English) |date=17 August 2015 |volume=54 |issue=34 |pages=9871–9875 |doi=10.1002/anie.201503792 |pmid=26201989 |pmc=4678426 }}</ref> both by chemical reactions in the hydrothermal environment, as well as by exposure to [[UV light]] during transport from vents to adjacent pools. Their hypothesized pre-biotic environments are similar to the deep-oceanic vent environments most commonly hypothesized, but add additional components that help explain peculiarities found in reconstructions of the [[Last Universal Common Ancestor]] (LUCA) of all living organisms.<ref>{{cite journal |last1=Mulkidjanian |first1=Armid |last2=Bychkov |first2=Andrew |last3=Dibrova |first3=Daria |last4=Galperin |first4=Michael |last5=Koonin |first5=Eugene |date=3 April 2012 |title=Origin of first cells at terrestrial, anoxic geothermal fields |journal=PNAS |volume=109 |issue=14 |pages=E821–E830 |doi=10.1073/pnas.1117774109 |pmid=22331915 |pmc=3325685|bibcode=2012PNAS..109E.821M }}</ref>

Mulkidjanian and co-authors think that the marine environments did not provide the ionic balance and composition universally found in cells, as well as of ions required by essential proteins and ribozymes found in virtually all living organisms, especially with respect to K⁺/Na⁺ ratio, Mn²⁺, Zn²⁺ and phosphate concentrations. The only known environments that mimic the needed conditions on Earth are found in terrestrial hydrothermal pools fed by steam vents.<ref name=":1" /> Additionally, mineral deposits in these environments under an anoxic atmosphere would have suitable pH (as opposed to current pools in an oxygenated atmosphere), contain precipitates of sulfide minerals that block harmful UV radiation, have wetting/drying cycles that concentrate substrate solutions to concentrations amenable to spontaneous formation of polymers of nucleic acids, polyesters<ref>{{cite journal |last1=Chandru |first1=Kuhan |last2=Guttenberg |first2=Nicholas |last3=Giri |first3=Chaitanya |last4=Hongo |first4=Yayoi |last5=Butch |first5=Christopher |last6=Mamajanov |first6=Irena |last7=Cleaves |first7=H. James |title=Simple prebiotic synthesis of high diversity dynamic combinatorial polyester libraries |journal=Communications Chemistry |date=31 May 2018 |volume=1 |issue=1 |doi=10.1038/s42004-018-0031-1 |doi-access=free }}</ref> and depsipeptides,<ref>{{cite journal |last1=Forsythe |first1=Jay G |last2=Yu |first2=Sheng-Sheng |last3=Mamajanov |first3=Irena |last4=Grover |first4=Martha A |last5=Krishnamurthy |first5=Ramanarayanan |last6=Fernández |first6=Facundo M |last7=Hud |first7=Nicholas V |title=Ester-Mediated Amide Bond Formation Driven by Wet–Dry Cycles: A Possible Path to Polypeptides on the Prebiotic Earth |journal=Angewandte Chemie (International ed. In English) |date=17 August 2015 |volume=54 |issue=34 |pages=9871–9875 |doi=10.1002/anie.201503792 |pmid=26201989 |pmc=4678426 }}</ref> both by chemical reactions in the hydrothermal environment, as well as by exposure to [[UV light]] during transport from vents to adjacent pools. Their hypothesized pre-biotic environments are similar to the deep-oceanic vent environments most commonly hypothesized, but add additional components that help explain peculiarities found in reconstructions of the [[Last Universal Common Ancestor]] (LUCA) of all living organisms.<ref>{{cite journal |last1=Mulkidjanian |first1=Armid |last2=Bychkov |first2=Andrew |last3=Dibrova |first3=Daria |last4=Galperin |first4=Michael |last5=Koonin |first5=Eugene |date=3 April 2012 |title=Origin of first cells at terrestrial, anoxic geothermal fields |journal=PNAS |volume=109 |issue=14 |pages=E821–E830 |doi=10.1073/pnas.1117774109 |pmid=22331915 |pmc=3325685|bibcode=2012PNAS..109E.821M }}</ref>

Mulkidjanian和其合著者认为，海洋环境没有提供细胞中普遍存在的离子平衡和组成，也没有提供几乎所有生物体中基本蛋白质和核糖体所需的离子，特别是K+/Na+比率、Mn2+、Zn2+和磷酸盐浓度。唯一已知的模拟地球上所需条件的环境是在由蒸汽喷口供给的陆地热液池中发现的。此外，这些环境中的矿藏在缺氧气氛下会有合适的pH值(而不是目前在含氧气氛下的池子)，含有能阻挡有害紫外线辐射的硫化物矿物质沉淀物，有湿润/干燥循环，能将基质溶液浓缩到适合自发形成核酸、聚酯和去肽的聚合物的浓度，这些都是通过热液环境中的化学反应，以及通过从喷口向相邻池子运输过程中暴露在紫外线下形成的。他们推测的生物前环境与通常推测的深海喷口环境相似，但增加了额外的成分，有助于解释在重建所有生物的最后普遍共同祖先(LUCA)中发现的奇特之处。

Mulkidjanian和其合著者认为，海洋环境没有提供细胞中普遍存在的离子平衡和组成，也没有提供几乎所有生物体中基本蛋白质和核酶所需的离子，特别是K⁺/Na⁺比率、Mn²⁺、Zn²⁺和磷酸盐浓度。唯一已知的模拟地球上所需条件的环境是在由蒸汽喷口供给的陆地热液池中发现的。此外，这些环境中的矿藏在缺氧大气下会有合适的pH值(而不是目前在含氧大气下的池子)，含有能阻挡有害紫外线辐射的硫化物矿物质沉淀物，有湿润/干燥循环，能将基质溶液浓缩到适合自发形成多聚核酸、聚酯和缩肽的浓度，这些都是通过热液环境中的化学反应，以及通过从喷口向相邻池子运输过程中暴露在紫外线下形成的。他们推测的前生物环境与通常推测的深海喷口环境相似，但增加了额外的成分，有助于解释在重建所有生物的最后普遍共同祖先(LUCA)中发现的奇特之处。

Colín-García ''et al.'' (2016) discuss the advantages and disadvantages of hydrothermal vents as primitive environments.<ref name=":1"/> They mention the exergonic reactions in such systems could have been a source of free energy that promoted chemical reactions, additional to their high mineralogical diversity which implies the induction of important chemical gradients, thus favoring the interaction between electron donors and acceptors. Colín-García ''et al.'' (2016) also summarize a set of experiments proposed to test the role of hydrothermal vents in prebiotic synthesis.<ref name=":1"/>

Colín-García ''et al.'' (2016) discuss the advantages and disadvantages of hydrothermal vents as primitive environments.<ref name=":1"/> They mention the exergonic reactions in such systems could have been a source of free energy that promoted chemical reactions, additional to their high mineralogical diversity which implies the induction of important chemical gradients, thus favoring the interaction between electron donors and acceptors. Colín-García ''et al.'' (2016) also summarize a set of experiments proposed to test the role of hydrothermal vents in prebiotic synthesis.<ref name=":1"/>

Colín-García等人（2016）讨论了热液喷口作为原始环境的优势和劣势。他们提到，这种系统中的放能反应可能是促进化学反应的自由能量来源，此外，它们的矿物学多样性很高，这意味着重要的化学梯度的诱导，从而有利于电子供体和受体之间的相互作用。Colín-García等(2016)还总结了一组拟用于测试热液喷口在前生物合成中的作用的实验。

科林-加西亚 Colín-García“等人”（2016）讨论了热液喷口作为原始环境的优势和劣势。他们提到，这种系统中的放能反应可能是促进化学反应的一种自由能来源，此外，它们的矿物学多样性很高，这意味着重要的化学梯度的诱导，从而有利于电子供体和受体之间的相互作用。Colín-García等(2016)还总结了一组被提议用于测试热液喷口在前生物合成中的作用的实验。

===Volcanic ash in the ocean===

===Volcanic ash in the ocean===

[[Geoffrey W. Hoffmann]] has argued that a complex nucleation event as the origin of life involving both polypeptides and nucleic acid is compatible with the time and space available in the primitive oceans of Earth<ref>{{cite biorxiv|last1=Hoffmann|first1=Geoffrey William|title=A network theory of the origin of life|date=24 December 2016|biorxiv=10.1101/096701}}</ref> Hoffmann suggests that volcanic ash may provide the many random shapes needed in the postulated complex nucleation event. This aspect of the theory can be tested experimentally.

[[Geoffrey W. Hoffmann]] has argued that a complex nucleation event as the origin of life involving both polypeptides and nucleic acid is compatible with the time and space available in the primitive oceans of Earth<ref>{{cite biorxiv|last1=Hoffmann|first1=Geoffrey William|title=A network theory of the origin of life|date=24 December 2016|biorxiv=10.1101/096701}}</ref> Hoffmann suggests that volcanic ash may provide the many random shapes needed in the postulated complex nucleation event. This aspect of the theory can be tested experimentally.

Geoffrey W.Hoffmann认为，作为生命起源的复杂成核事件涉及多肽和核酸，与地球原始海洋中可用的时间和空间相适应Hoffmann认为，火山灰可能提供了假设的复杂成核事件中所需要的许多随机形状。这方面的理论可以通过实验来检验。

杰弗里·W.霍夫曼 Geoffrey W.Hoffmann认为，作为生命起源的复杂成核事件涉及多肽和核酸，与地球原始海洋中可用的时间和空间相适应。Hoffmann认为，火山灰可能提供了假设的复杂成核事件中所需要的许多随机形状。这方面的理论可以通过实验来检验。

=== Gold's deep-hot biosphere ===

=== Gold's deep-hot biosphere ===

黄金的深热生物圈    

戈德的深热生物圈    

In the 1970s, [[Thomas Gold]] proposed the theory that life first developed not on the surface of the Earth, but several kilometers below the surface. It is claimed that the discovery of microbial life below the surface of another body in our Solar System would lend significant credence to this theory. Gold also asserted that a trickle of food from a deep, unreachable, source is needed for survival because life arising in a puddle of organic material is likely to consume all of its food and become extinct. Gold's theory is that the flow of such food is due to out-gassing of primordial methane from the Earth's mantle; more conventional explanations of the food supply of deep microbes (away from sedimentary carbon compounds) is that the organisms [[Microbial metabolism#Hydrogen oxidation|subsist on hydrogen]] released by an interaction between water and (reduced) iron compounds in rocks.

In the 1970s, [[Thomas Gold]] proposed the theory that life first developed not on the surface of the Earth, but several kilometers below the surface. It is claimed that the discovery of microbial life below the surface of another body in our Solar System would lend significant credence to this theory. Gold also asserted that a trickle of food from a deep, unreachable, source is needed for survival because life arising in a puddle of organic material is likely to consume all of its food and become extinct. Gold's theory is that the flow of such food is due to out-gassing of primordial methane from the Earth's mantle; more conventional explanations of the food supply of deep microbes (away from sedimentary carbon compounds) is that the organisms [[Microbial metabolism#Hydrogen oxidation|subsist on hydrogen]] released by an interaction between water and (reduced) iron compounds in rocks.

=== Radioactive beach hypothesis ===

=== Radioactive beach hypothesis ===

Zachary Adam claims that tidal processes that occurred during a time when the Moon was much closer may have concentrated grains of [[uranium]] and other radioactive elements at the high-water mark on primordial beaches, where they may have been responsible for generating life's building blocks.<ref>{{cite journal |last=Dartnell |first=Lewis |date=12 January 2008 |title=Did life begin on a radioactive beach? |url=https://www.newscientist.com/article/mg19726384.000-did-life-begin-on-a-radioactive-beach.html |journal=New Scientist |issue=2638 |page=8 |accessdate=2015-06-26 |url-status=live |archiveurl=https://web.archive.org/web/20150627101858/http://www.newscientist.com/article/mg19726384.000-did-life-begin-on-a-radioactive-beach.html |archivedate=27 June 2015}}</ref> According to computer models,<ref>{{cite journal |last=Adam |first=Zachary |year=2007 |title=Actinides and Life's Origins |journal=Astrobiology |volume=7 |issue=6 |pages=852–872 |bibcode=2007AsBio...7..852A |doi=10.1089/ast.2006.0066|pmid=18163867}}</ref> a deposit of such radioactive materials could show the same [[Natural nuclear fission reactor|self-sustaining nuclear reaction]] as that found in the [[Oklo]] uranium ore seam in [[Gabon]]. Such radioactive beach sand might have provided sufficient energy to generate organic molecules, such as amino acids and sugars from [[acetonitrile]] in water. Radioactive [[monazite]] material also has released soluble phosphate into the regions between sand-grains, making it biologically "accessible." Thus amino acids, sugars, and soluble phosphates might have been produced simultaneously, according to Adam. Radioactive [[actinide]]s, left behind in some concentration by the reaction, might have formed part of [[Organometallic chemistry|organometallic complexes]]. These complexes could have been important early catalysts to living processes.

Zachary Adam claims that tidal processes that occurred during a time when the Moon was much closer may have concentrated grains of [[uranium]] and other radioactive elements at the high-water mark on primordial beaches, where they may have been responsible for generating life's building blocks.<ref>{{cite journal |last=Dartnell |first=Lewis |date=12 January 2008 |title=Did life begin on a radioactive beach? |url=https://www.newscientist.com/article/mg19726384.000-did-life-begin-on-a-radioactive-beach.html |journal=New Scientist |issue=2638 |page=8 |accessdate=2015-06-26 |url-status=live |archiveurl=https://web.archive.org/web/20150627101858/http://www.newscientist.com/article/mg19726384.000-did-life-begin-on-a-radioactive-beach.html |archivedate=27 June 2015}}</ref> According to computer models,<ref>{{cite journal |last=Adam |first=Zachary |year=2007 |title=Actinides and Life's Origins |journal=Astrobiology |volume=7 |issue=6 |pages=852–872 |bibcode=2007AsBio...7..852A |doi=10.1089/ast.2006.0066|pmid=18163867}}</ref> a deposit of such radioactive materials could show the same [[Natural nuclear fission reactor|self-sustaining nuclear reaction]] as that found in the [[Oklo]] uranium ore seam in [[Gabon]]. Such radioactive beach sand might have provided sufficient energy to generate organic molecules, such as amino acids and sugars from [[acetonitrile]] in water. Radioactive [[monazite]] material also has released soluble phosphate into the regions between sand-grains, making it biologically "accessible." Thus amino acids, sugars, and soluble phosphates might have been produced simultaneously, according to Adam. Radioactive [[actinide]]s, left behind in some concentration by the reaction, might have formed part of [[Organometallic chemistry|organometallic complexes]]. These complexes could have been important early catalysts to living processes.

扎卡里-亚当Zachary Adam声称，在月球更接近月球的时期发生的潮汐过程可能将铀和其他放射性元素的颗粒集中在原始海滩的高水位线上，在那里它们可能负责生成生命的构件。根据计算机模型，这种放射性物质的沉积可能显示出与加蓬奥克洛铀矿缝中发现的相同的自我维持的核反应。这种放射性海滩沙子可能提供了足够的能量来生成有机分子，如水中的乙腈生成氨基酸和糖类。放射性单晶石物质还将可溶性磷酸盐释放到沙粒之间的区域，使其成为生物上的 "可利用物质"。据Adam说，因此氨基酸、糖类和可溶性磷酸盐可能是同时产生的。放射性的锕系元素，在反应中留下了一定的浓度，可能已经形成了有机金属复合物的一部分。这些复合物可能是生命过程的重要早期催化剂。

扎卡里·亚当 Zachary Adam声称，在月球更接近的时期发生的潮汐过程可能将铀和其他放射性元素的颗粒集中在原始海滩的高水位线上，在那里它们可能负责生成生命的构件。根据计算机模型，这种放射性物质的沉积可能显示出与加蓬奥克洛铀矿缝中发现的相同的自我维持的核反应。这种放射性海滩沙子可能提供了足够的能量来生成有机分子，如水中的乙腈生成氨基酸和糖类。放射性独居石物质还将可溶性磷酸盐释放到沙粒之间的区域，使其成为生物上的 "可利用物质"。据Adam说，因此氨基酸、糖类和可溶性磷酸盐可能是同时产生的。放射性的锕系元素，在反应中留下了一定的浓度，可能已经形成了有机金属复合物的一部分。这些复合物可能是生命过程的重要早期催化剂。

John Parnell has suggested that such a process could provide part of the "crucible of life" in the early stages of any early wet rocky planet, so long as the planet is large enough to have generated a system of plate tectonics which brings radioactive minerals to the surface. As the early Earth is thought to have had many smaller plates, it might have provided a suitable environment for such processes.<ref>{{cite journal |last=Parnell |first=John |date=December 2004 |title=Mineral Radioactivity in Sands as a Mechanism for Fixation of Organic Carbon on the Early Earth |journal=Origins of Life and Evolution of Biospheres |volume=34 |issue=6 |pages=533–547 |bibcode=2004OLEB...34..533P |doi=10.1023/B:ORIG.0000043132.23966.a1 |pmid=15570707|citeseerx=10.1.1.456.8955 |s2cid=6067448 }}</ref>

John Parnell has suggested that such a process could provide part of the "crucible of life" in the early stages of any early wet rocky planet, so long as the planet is large enough to have generated a system of plate tectonics which brings radioactive minerals to the surface. As the early Earth is thought to have had many smaller plates, it might have provided a suitable environment for such processes.<ref>{{cite journal |last=Parnell |first=John |date=December 2004 |title=Mineral Radioactivity in Sands as a Mechanism for Fixation of Organic Carbon on the Early Earth |journal=Origins of Life and Evolution of Biospheres |volume=34 |issue=6 |pages=533–547 |bibcode=2004OLEB...34..533P |doi=10.1023/B:ORIG.0000043132.23966.a1 |pmid=15570707|citeseerx=10.1.1.456.8955 |s2cid=6067448 }}</ref>

约翰-帕内尔John Parnell认为，在任何早期湿岩行星的早期阶段，这种过程都可能提供部分 "生命的坩埚"，只要该行星足够大，产生了板块构造系统，将放射性矿物带到地表。由于早期地球被认为有许多较小的板块，它可能为这种过程提供了合适的环境。

约翰·帕内尔 John Parnell认为，在任何早期潮湿的岩石行星的早期阶段，这种过程都可能提供部分 "生命的坩埚"，只要该行星足够大，产生了板块构造系统，将放射性矿物带到地表。由于早期地球被认为有许多较小的板块，它可能为这种过程提供了合适的环境。

== Origin of metabolism: physiology ==

== Origin of metabolism: physiology ==

Different forms of life with variable origin processes may have appeared quasi-simultaneously in the early [[history of Earth]].<ref>{{cite journal |last=Davies |first=Paul |authorlink=Paul Davies |date=December 2007 |title=Are Aliens Among Us? |url=http://www.zo.utexas.edu/courses/kalthoff/bio301c/readings/07Davies.pdf |journal=Scientific American |volume=297 |issue=6 |pages=62–69 |doi=10.1038/scientificamerican1207-62 |accessdate=2015-07-16 |quote=...if life does emerge readily under terrestrial conditions, then perhaps it formed many times on our home planet. To pursue this possibility, deserts, lakes and other extreme or isolated environments have been searched for evidence of "alien" life-forms—organisms that would differ fundamentally from known organisms because they arose independently. |bibcode=2007SciAm.297f..62D |url-status=live |archiveurl=https://web.archive.org/web/20160304185832/http://www.zo.utexas.edu/courses/kalthoff/bio301c/readings/07Davies.pdf |archivedate=4 March 2016}}</ref> The other forms may be extinct (having left distinctive fossils through their different biochemistry—e.g., [[hypothetical types of biochemistry]]). It has been proposed that:

Different forms of life with variable origin processes may have appeared quasi-simultaneously in the early [[history of Earth]].<ref>{{cite journal |last=Davies |first=Paul |authorlink=Paul Davies |date=December 2007 |title=Are Aliens Among Us? |url=http://www.zo.utexas.edu/courses/kalthoff/bio301c/readings/07Davies.pdf |journal=Scientific American |volume=297 |issue=6 |pages=62–69 |doi=10.1038/scientificamerican1207-62 |accessdate=2015-07-16 |quote=...if life does emerge readily under terrestrial conditions, then perhaps it formed many times on our home planet. To pursue this possibility, deserts, lakes and other extreme or isolated environments have been searched for evidence of "alien" life-forms—organisms that would differ fundamentally from known organisms because they arose independently. |bibcode=2007SciAm.297f..62D |url-status=live |archiveurl=https://web.archive.org/web/20160304185832/http://www.zo.utexas.edu/courses/kalthoff/bio301c/readings/07Davies.pdf |archivedate=4 March 2016}}</ref> The other forms may be extinct (having left distinctive fossils through their different biochemistry—e.g., [[hypothetical types of biochemistry]]). It has been proposed that:

在地球的早期历史中，具有不同起源过程的不同生命形式可能同时出现。其他形式可能已经灭绝(通过其不同的生物化学--如假设的生物化学类型--留下了独特的化石)。有人提出：

在早期的地球历史中，具有不同起源过程的不同生命形式可能准同时出现。其他形式可能已经灭绝(通过其不同的生物化学--如假设的生物化学类型--留下了独特的化石)。有人提出：

< blockquote >The first organisms were self-replicating iron-rich clays which fixed carbon dioxide into oxalic and other [[dicarboxylic acid]]s. This system of replicating clays and their metabolic phenotype then evolved into the sulfide rich region of the hotspring acquiring the ability to fix nitrogen. Finally phosphate was incorporated into the evolving system which allowed the synthesis of nucleotides and phospholipids. If biosynthesis recapitulates biopoiesis, then the synthesis of amino acids preceded the synthesis of the purine and pyrimidine bases. Furthermore, the polymerization of the amino acid thioesters into polypeptides preceded the directed polymerization of amino acid esters by polynucleotides.<ref>{{cite journal |last=Hartman |first=Hyman |date=1998 |title=Photosynthesis and the Origin of Life |journal=Origins of Life and Evolution of Biospheres |volume=28 |issue=4–6 |pages=515–521 |bibcode=1998OLEB...28..515H |doi=10.1023/A:1006548904157 |pmid=11536891|s2cid=2464 }}</ref>< /blockquote >

< blockquote >The first organisms were self-replicating iron-rich clays which fixed carbon dioxide into oxalic and other [[dicarboxylic acid]]s. This system of replicating clays and their metabolic phenotype then evolved into the sulfide rich region of the hotspring acquiring the ability to fix nitrogen. Finally phosphate was incorporated into the evolving system which allowed the synthesis of nucleotides and phospholipids. If biosynthesis recapitulates biopoiesis, then the synthesis of amino acids preceded the synthesis of the purine and pyrimidine bases. Furthermore, the polymerization of the amino acid thioesters into polypeptides preceded the directed polymerization of amino acid esters by polynucleotides.<ref>{{cite journal |last=Hartman |first=Hyman |date=1998 |title=Photosynthesis and the Origin of Life |journal=Origins of Life and Evolution of Biospheres |volume=28 |issue=4–6 |pages=515–521 |bibcode=1998OLEB...28..515H |doi=10.1023/A:1006548904157 |pmid=11536891|s2cid=2464 }}</ref>< /blockquote >

< blockquote >

< blockquote >

Metabolism-like reactions could have occurred naturally in early oceans, before the first organisms evolved.<ref name="Ralser 2014" /><ref name="Metabolism 2014">{{cite press release |last=Senthilingam |first=Meera |date=25 April 2014 |title=Metabolism May Have Started in Early Oceans Before the Origin of Life |url=http://www.eurekalert.org/pub_releases/2014-04/wt-mmh042314.php |publisher=[[Wellcome Trust]] |agency=[[American Association for the Advancement of Science|EurekAlert!]] |accessdate=2015-06-16 |url-status=live |archiveurl=https://web.archive.org/web/20150617102656/http://www.eurekalert.org/pub_releases/2014-04/wt-mmh042314.php |archivedate=17 June 2015}}</ref> Metabolism may predate the origin of life, which may have evolved from the chemical conditions in the earliest oceans. Reconstructions in laboratories show that some of these reactions can produce RNA, and some others resemble two essential reaction cascades of metabolism: [[glycolysis]] and the [[pentose phosphate pathway]], that provide essential precursors for nucleic acids, amino acids and lipids.<ref name="Metabolism 2014" />

Metabolism-like reactions could have occurred naturally in early oceans, before the first organisms evolved.<ref name="Ralser 2014" /><ref name="Metabolism 2014">{{cite press release |last=Senthilingam |first=Meera |date=25 April 2014 |title=Metabolism May Have Started in Early Oceans Before the Origin of Life |url=http://www.eurekalert.org/pub_releases/2014-04/wt-mmh042314.php |publisher=[[Wellcome Trust]] |agency=[[American Association for the Advancement of Science|EurekAlert!]] |accessdate=2015-06-16 |url-status=live |archiveurl=https://web.archive.org/web/20150617102656/http://www.eurekalert.org/pub_releases/2014-04/wt-mmh042314.php |archivedate=17 June 2015}}</ref> Metabolism may predate the origin of life, which may have evolved from the chemical conditions in the earliest oceans. Reconstructions in laboratories show that some of these reactions can produce RNA, and some others resemble two essential reaction cascades of metabolism: [[glycolysis]] and the [[pentose phosphate pathway]], that provide essential precursors for nucleic acids, amino acids and lipids.<ref name="Metabolism 2014" />

=== Clay hypothesis ===

=== Clay hypothesis ===

[[Montmorillonite]], an abundant [[clay]], is a catalyst for the polymerization of RNA and for the formation of membranes from lipids.<ref>{{cite press release |last=Perry |first=Caroline |date=7 February 2011 |title=Clay-armored bubbles may have formed first protocells |url=http://www.eurekalert.org/pub_releases/2011-02/hu-cbm020411.php |location=Cambridge, MA |publisher=[[Harvard University]] |agency=EurekAlert! |accessdate=2015-06-20 |url-status=live |archiveurl=https://web.archive.org/web/20150714101638/http://www.eurekalert.org/pub_releases/2011-02/hu-cbm020411.php |archivedate=14 July 2015}}</ref> A model for the origin of life using clay was forwarded by Alexander Cairns-Smith in 1985 and explored as a plausible mechanism by several scientists.<ref>{{harvnb|Dawkins|1996|pp=148–161}}</ref> The clay hypothesis postulates that complex organic molecules arose gradually on pre-existing, non-organic replication surfaces of silicate crystals in solution.

[[Montmorillonite]], an abundant [[clay]], is a catalyst for the polymerization of RNA and for the formation of membranes from lipids.<ref>{{cite press release |last=Perry |first=Caroline |date=7 February 2011 |title=Clay-armored bubbles may have formed first protocells |url=http://www.eurekalert.org/pub_releases/2011-02/hu-cbm020411.php |location=Cambridge, MA |publisher=[[Harvard University]] |agency=EurekAlert! |accessdate=2015-06-20 |url-status=live |archiveurl=https://web.archive.org/web/20150714101638/http://www.eurekalert.org/pub_releases/2011-02/hu-cbm020411.php |archivedate=14 July 2015}}</ref> A model for the origin of life using clay was forwarded by Alexander Cairns-Smith in 1985 and explored as a plausible mechanism by several scientists.<ref>{{harvnb|Dawkins|1996|pp=148–161}}</ref> The clay hypothesis postulates that complex organic molecules arose gradually on pre-existing, non-organic replication surfaces of silicate crystals in solution.

蒙脱石是一种丰富的粘土，是RNA聚合和脂质形成膜的催化剂。1985年，亚历山大-凯恩斯-史密斯Alexander Cairns-Smith提出了一个利用粘土进行生命起源的模型，并被一些科学家作为一种可信的机制进行了探讨。粘土假说假定复杂的有机分子是在溶液中的硅酸盐晶体预先存在的非有机复制表面上逐渐产生的。

蒙脱石是一种丰富的粘土，是RNA聚合和脂质形成膜的催化剂。1985年，亚历山大·凯恩斯-史密斯 Alexander Cairns-Smith提出了一个利用粘土进行生命起源的模型，并被一些科学家作为一种似可信的机制进行了探索。粘土假说假定复杂的有机分子是在溶液中的硅酸盐晶体预先存在的非有机重复表面上逐渐产生的。

At the [[Rensselaer Polytechnic Institute]], James Ferris' studies have also confirmed that montmorillonite clay minerals catalyze the formation of RNA in aqueous solution, by joining nucleotides to form longer chains.<ref>{{cite journal |author1=Wenhua Huang |last2=Ferris |first2=James P. |date=12 July 2006 |title=One-Step, Regioselective Synthesis of up to 50-mers of RNA Oligomers by Montmorillonite Catalysis |journal=Journal of the American Chemical Society |volume=128 |issue=27 |pages=8914–8919 |doi=10.1021/ja061782k |pmid=16819887}}</ref>

At the [[Rensselaer Polytechnic Institute]], James Ferris' studies have also confirmed that montmorillonite clay minerals catalyze the formation of RNA in aqueous solution, by joining nucleotides to form longer chains.<ref>{{cite journal |author1=Wenhua Huang |last2=Ferris |first2=James P. |date=12 July 2006 |title=One-Step, Regioselective Synthesis of up to 50-mers of RNA Oligomers by Montmorillonite Catalysis |journal=Journal of the American Chemical Society |volume=128 |issue=27 |pages=8914–8919 |doi=10.1021/ja061782k |pmid=16819887}}</ref>

在伦斯勒理工学院，James Ferris的研究也证实，蒙脱石粘土矿物在水溶液中催化RNA的形成，通过连接核苷酸形成较长的链。

在伦斯勒理工学院，詹姆斯·费里斯 James Ferris的研究也证实，蒙脱石粘土矿物在水溶液中催化RNA的形成，通过连接核苷酸形成较长的链。

In 2007, Bart Kahr from the [[University of Washington]] and colleagues reported their experiments that tested the idea that crystals can act as a source of transferable information, using crystals of [[potassium hydrogen phthalate]]. "Mother" crystals with imperfections were cleaved and used as seeds to grow "daughter" crystals from solution. They then examined the distribution of imperfections in the new crystals and found that the imperfections in the mother crystals were reproduced in the daughters, but the daughter crystals also had many additional imperfections. For gene-like behavior to be observed, the quantity of inheritance of these imperfections should have exceeded that of the mutations in the successive generations, but it did not. Thus Kahr concluded that the crystals "were not faithful enough to store and transfer information from one generation to the next."<ref>{{cite journal |last=Moore |first=Caroline |date=16 July 2007 |title=Crystals as genes? |url=http://www.rsc.org/Publishing/ChemScience/Volume/2007/08/Crystals_as_genes.asp |journal=Highlights in Chemical Science |accessdate=2015-06-21 |url-status=live |archiveurl=https://web.archive.org/web/20150714094855/http://www.rsc.org/Publishing/ChemScience/Volume/2007/08/Crystals_as_genes.asp |archivedate=14 July 2015}}

In 2007, Bart Kahr from the [[University of Washington]] and colleagues reported their experiments that tested the idea that crystals can act as a source of transferable information, using crystals of [[potassium hydrogen phthalate]]. "Mother" crystals with imperfections were cleaved and used as seeds to grow "daughter" crystals from solution. They then examined the distribution of imperfections in the new crystals and found that the imperfections in the mother crystals were reproduced in the daughters, but the daughter crystals also had many additional imperfections. For gene-like behavior to be observed, the quantity of inheritance of these imperfections should have exceeded that of the mutations in the successive generations, but it did not. Thus Kahr concluded that the crystals "were not faithful enough to store and transfer information from one generation to the next."<ref>{{cite journal |last=Moore |first=Caroline |date=16 July 2007 |title=Crystals as genes? |url=http://www.rsc.org/Publishing/ChemScience/Volume/2007/08/Crystals_as_genes.asp |journal=Highlights in Chemical Science |accessdate=2015-06-21 |url-status=live |archiveurl=https://web.archive.org/web/20150714094855/http://www.rsc.org/Publishing/ChemScience/Volume/2007/08/Crystals_as_genes.asp |archivedate=14 July 2015}}

* {{cite journal |last1=Bullard |first1=Theresa |last2=Freudenthal |first2=John |last3=Avagyan |first3=Serine |last4=Kahr |first4=Bart |display-authors=3 |year=2007 |title=Test of Cairns-Smith's 'crystals-as-genes' hypothesis |journal=[[Faraday Discussions]] |volume=136 |pages=231–245 |bibcode=2007FaDi..136..231B |doi=10.1039/b616612c |pmid=17955812 }}</ref>

* {{cite journal |last1=Bullard |first1=Theresa |last2=Freudenthal |first2=John |last3=Avagyan |first3=Serine |last4=Kahr |first4=Bart |display-authors=3 |year=2007 |title=Test of Cairns-Smith's 'crystals-as-genes' hypothesis |journal=[[Faraday Discussions]] |volume=136 |pages=231–245 |bibcode=2007FaDi..136..231B |doi=10.1039/b616612c |pmid=17955812 }}</ref>

2007年，来自华盛顿大学的巴特-卡尔Bart Kahr 及其同事报告了他们的实验，利用邻苯二甲酸氢钾的晶体，检验了晶体可以作为可转移信息的来源的观点。切割有缺陷的 "母 "晶体，作为种子以从溶液中生长出 "子体"晶体。然后，他们检查了新晶体中的缺陷分布，发现母晶体中的缺陷在子晶体中重现，但子晶体也有许多额外的缺陷。要想观察到类似基因的行为，这些缺陷的遗传量应该超过历代的突变量，但事实并非如此。因此Kahr 得出结论，这些晶体 "不够忠实，无法存储信息并将信息从一代传给下一代”。

2007年，来自华盛顿大学的巴特·卡尔Bart Kahr 及其同事报告了他们的实验，利用邻苯二甲酸氢钾的晶体，检验了晶体可以作为可转移信息的来源的想法。有缺陷的"母"晶体被切割用作种子以从溶液中生长出"子"晶体。然后，他们检查了新晶体中缺陷的分布，发现母晶体中的缺陷在子晶体中重现，但子晶体也有许多额外的缺陷。要想观察到类似基因的行为，这些缺陷的遗传的量应该超过连续几代中的突变的量，但事实并非如此。因此Kahr 得出结论，这些晶体 "不够忠实，无法存储信息并将信息从一代传给下一代”。

In the 1980s, Günter Wächtershäuser, encouraged and supported by [[Karl R. Popper|Karl Popper]],<ref>{{cite journal |last=Yue-Ching Ho |first=Eugene |date=July–September 1990 |title=Evolutionary Epistemology and Sir Karl Popper's Latest Intellectual Interest: A First-Hand Report |url=http://www.tkpw.net/hk-ies/n15/ |journal=Intellectus |volume=15 |pages=1–3 |oclc=26878740 |accessdate=2012-08-13 |url-status=live |archiveurl=https://web.archive.org/web/20120311074143/http://www.tkpw.net/hk-ies/n15/ |archivedate=11 March 2012}}</ref><ref>{{cite news |last=Wade |first=Nicholas |date=22 April 1997 |title=Amateur Shakes Up Ideas on Recipe for Life |url=https://www.nytimes.com/1997/04/22/science/amateur-shakes-up-ideas-on-recipe-for-life.html?src=pm&pagewanted=2&pagewanted=all |newspaper=The New York Times |location=New York  |accessdate=2015-06-16 |url-status=live |archiveurl=https://web.archive.org/web/20150617122450/http://www.nytimes.com/1997/04/22/science/amateur-shakes-up-ideas-on-recipe-for-life.html?src=pm&pagewanted=2&pagewanted=all |archivedate=17 June 2015}}</ref><ref>{{cite journal |last=Popper |first=Karl R. |authorlink=Karl Popper |date=29 March 1990 |title=Pyrite and the origin of life |journal=Nature |volume=344 |issue=6265 |page=387 |bibcode=1990Natur.344..387P |doi=10.1038/344387a0 |s2cid=4322774 }}</ref> postulated his iron–sulfur world, a theory of the evolution of pre-biotic chemical pathways as the starting point in the evolution of life. It systematically traces today's biochemistry to primordial reactions which provide alternative pathways to the synthesis of organic building blocks from simple gaseous compounds.

In the 1980s, Günter Wächtershäuser, encouraged and supported by [[Karl R. Popper|Karl Popper]],<ref>{{cite journal |last=Yue-Ching Ho |first=Eugene |date=July–September 1990 |title=Evolutionary Epistemology and Sir Karl Popper's Latest Intellectual Interest: A First-Hand Report |url=http://www.tkpw.net/hk-ies/n15/ |journal=Intellectus |volume=15 |pages=1–3 |oclc=26878740 |accessdate=2012-08-13 |url-status=live |archiveurl=https://web.archive.org/web/20120311074143/http://www.tkpw.net/hk-ies/n15/ |archivedate=11 March 2012}}</ref><ref>{{cite news |last=Wade |first=Nicholas |date=22 April 1997 |title=Amateur Shakes Up Ideas on Recipe for Life |url=https://www.nytimes.com/1997/04/22/science/amateur-shakes-up-ideas-on-recipe-for-life.html?src=pm&pagewanted=2&pagewanted=all |newspaper=The New York Times |location=New York  |accessdate=2015-06-16 |url-status=live |archiveurl=https://web.archive.org/web/20150617122450/http://www.nytimes.com/1997/04/22/science/amateur-shakes-up-ideas-on-recipe-for-life.html?src=pm&pagewanted=2&pagewanted=all |archivedate=17 June 2015}}</ref><ref>{{cite journal |last=Popper |first=Karl R. |authorlink=Karl Popper |date=29 March 1990 |title=Pyrite and the origin of life |journal=Nature |volume=344 |issue=6265 |page=387 |bibcode=1990Natur.344..387P |doi=10.1038/344387a0 |s2cid=4322774 }}</ref> postulated his iron–sulfur world, a theory of the evolution of pre-biotic chemical pathways as the starting point in the evolution of life. It systematically traces today's biochemistry to primordial reactions which provide alternative pathways to the synthesis of organic building blocks from simple gaseous compounds.

20世纪80年代，Günter Wächtershäuser在Karl Popper的鼓励和支持下，提出了他的铁-硫世界，这是一个关于生物前化学途径进化的理论，是生命进化的起点。它系统地将今天的生物化学追溯到原始反应，原始反应提供了从简单的气体化合物合成有机构件的替代途径。

20世纪80年代，Günter Wächtershäuser在卡尔·波普尔 Karl Popper的鼓励和支持下，提出了他的铁-硫世界，这是一个关于前生物化学途径进化的理论，是生命进化的起点。它系统地将今天的生物化学追溯到原始反应，原始反应提供了从简单的气体化合物合成有机构件的替代途径。

In contrast to the classical Miller experiments, which depend on external sources of energy (simulated lightning, ultraviolet [[irradiation]]), "Wächtershäuser systems" come with a built-in source of energy: [[sulfide]]s of iron (iron [[pyrite]]) and other minerals. The energy released from [[redox]] reactions of these metal sulfides is available for the synthesis of organic molecules, and such systems may have evolved into autocatalytic sets constituting self-replicating, metabolically active entities predating the life forms known today.<ref name="Ralser 2014" /><ref name="Metabolism 2014" /> Experiments with such sulfides in an aqueous environment at 100&nbsp;°C produced a relatively small yield of [[dipeptide]]s (0.4% to 12.4%) and a smaller yield of [[tripeptide]]s (0.10%) although under the same conditions, dipeptides were quickly broken down.<ref>{{cite journal |last1=Huber |first1=Claudia |last2=Wächtershäuser |first2=Günter |authorlink2=Günter Wächtershäuser |date=31 July 1998 |title=Peptides by Activation of Amino Acids with CO on (Ni,Fe)S Surfaces: Implications for the Origin of Life |journal=Science |volume=281 |issue=5377 |pages=670–672 |bibcode=1998Sci...281..670H |doi=10.1126/science.281.5377.670 |pmid=9685253}}</ref>

In contrast to the classical Miller experiments, which depend on external sources of energy (simulated lightning, ultraviolet [[irradiation]]), "Wächtershäuser systems" come with a built-in source of energy: [[sulfide]]s of iron (iron [[pyrite]]) and other minerals. The energy released from [[redox]] reactions of these metal sulfides is available for the synthesis of organic molecules, and such systems may have evolved into autocatalytic sets constituting self-replicating, metabolically active entities predating the life forms known today.<ref name="Ralser 2014" /><ref name="Metabolism 2014" /> Experiments with such sulfides in an aqueous environment at 100&nbsp;°C produced a relatively small yield of [[dipeptide]]s (0.4% to 12.4%) and a smaller yield of [[tripeptide]]s (0.10%) although under the same conditions, dipeptides were quickly broken down.<ref>{{cite journal |last1=Huber |first1=Claudia |last2=Wächtershäuser |first2=Günter |authorlink2=Günter Wächtershäuser |date=31 July 1998 |title=Peptides by Activation of Amino Acids with CO on (Ni,Fe)S Surfaces: Implications for the Origin of Life |journal=Science |volume=281 |issue=5377 |pages=670–672 |bibcode=1998Sci...281..670H |doi=10.1126/science.281.5377.670 |pmid=9685253}}</ref>

与经典的Miller实验依赖外部能量来源（模拟闪电、紫外线照射）不同，"韦氏系统 "自带内置能量来源：铁的硫化物（黄铁矿）和其他矿物。这些金属硫化物的氧化还原反应所释放的能量可用于有机分子的合成，这种系统可能已经演化成自催化组，构成自我复制、代谢活跃的实体，早于今天已知的生命形式.在100℃的水环境中用这种硫化物进行实验，产生了相对较小的二肽产量(0.4%～12.4%)和较小的三肽产量(0.10%)，尽管在相同的条件下，二肽很快被分解。

与经典的Miller实验依赖外部能量来源（模拟闪电、紫外线照射）不同，" Wächtershäuser系统 "自带内置能量来源：铁的硫化物（黄铁矿）和其他矿物。这些金属硫化物的氧化还原反应所释放的能量可用于有机分子的合成，这种系统可能已经演化成自催化组，构成自我复制、代谢活跃的实体，早于今天已知的生命形式。在100℃的水环境中用这种硫化物进行实验，产生了产量相对较小的二肽 (0.4%～12.4%)和更小产量的三肽 (0.10%)，尽管在相同的条件下，二肽很快被分解。

Several models reject the self-replication of a "naked-gene", postulating instead the emergence of a primitive metabolism providing a safe environment for the later emergence of RNA replication. The centrality of the [[Citric acid cycle|Krebs cycle]] (citric acid cycle) to energy production in aerobic organisms, and in drawing in carbon dioxide and hydrogen ions in biosynthesis of complex organic chemicals, suggests that it was one of the first parts of the metabolism to evolve.<ref name="Lane 2009">{{harvnb|Lane|2009}}</ref> Concordantly, [[Geochemistry|geochemist]] Russell has proposed that "the purpose of life is to hydrogenate carbon dioxide" (as part of a "metabolism-first," rather than a "genetics-first," scenario). <ref name="Musser">{{cite web |url=http://blogs.scientificamerican.com/observations/how-life-arose-on-earth-and-how-a-singularity-might-bring-it-down/ |title=How Life Arose on Earth, and How a Singularity Might Bring It Down |last=Musser |first=George |authorlink=George Musser |date=23 September 2011 |work=Observations |type=Blog  |accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150617211804/http://blogs.scientificamerican.com/observations/how-life-arose-on-earth-and-how-a-singularity-might-bring-it-down/ |archivedate=17 June 2015}}</ref><ref name="Carroll">{{cite web |url=http://blogs.discovermagazine.com/cosmicvariance/2010/03/10/free-energy-and-the-meaning-of-life/ |title=Free Energy and the Meaning of Life |last=Carroll |first=Sean |authorlink=Sean M. Carroll |date=10 March 2010 |work=Cosmic Variance |type=Blog |publisher=Discover|accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150714074327/http://blogs.discovermagazine.com/cosmicvariance/2010/03/10/free-energy-and-the-meaning-of-life/ |archivedate=14 July 2015}}</ref> [[Physicist]] [[Jeremy England]] has proposed that life was inevitable from general thermodynamic considerations: < blockquote >... when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life.<ref>{{cite journal |last=Wolchover |first=Natalie |date=22 January 2014 |title=A New Physics Theory of Life |url=https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/ |journal=Quanta Magazine |accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150613052830/https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/ |archivedate=13 June 2015}}</ref><ref>{{cite journal |last=England |first=Jeremy L. |authorlink=Jeremy England |date=28 September 2013 |title=Statistical physics of self-replication |url=http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsrep.pdf |journal=[[Journal of Chemical Physics]] |volume=139 |issue=12 |page=121923 |arxiv=1209.1179 |bibcode=2013JChPh.139l1923E |doi=10.1063/1.4818538 |pmid=24089735  |accessdate=2015-06-18 |url-status=live |archiveurl=https://web.archive.org/web/20150604131515/http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsrep.pdf |archivedate=4 June 2015|hdl=1721.1/90392 |s2cid=478964 }}</ref>< /blockquote >

Several models reject the self-replication of a "naked-gene", postulating instead the emergence of a primitive metabolism providing a safe environment for the later emergence of RNA replication. The centrality of the [[Citric acid cycle|Krebs cycle]] (citric acid cycle) to energy production in aerobic organisms, and in drawing in carbon dioxide and hydrogen ions in biosynthesis of complex organic chemicals, suggests that it was one of the first parts of the metabolism to evolve.<ref name="Lane 2009">{{harvnb|Lane|2009}}</ref> Concordantly, [[Geochemistry|geochemist]] Russell has proposed that "the purpose of life is to hydrogenate carbon dioxide" (as part of a "metabolism-first," rather than a "genetics-first," scenario). <ref name="Musser">{{cite web |url=http://blogs.scientificamerican.com/observations/how-life-arose-on-earth-and-how-a-singularity-might-bring-it-down/ |title=How Life Arose on Earth, and How a Singularity Might Bring It Down |last=Musser |first=George |authorlink=George Musser |date=23 September 2011 |work=Observations |type=Blog  |accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150617211804/http://blogs.scientificamerican.com/observations/how-life-arose-on-earth-and-how-a-singularity-might-bring-it-down/ |archivedate=17 June 2015}}</ref><ref name="Carroll">{{cite web |url=http://blogs.discovermagazine.com/cosmicvariance/2010/03/10/free-energy-and-the-meaning-of-life/ |title=Free Energy and the Meaning of Life |last=Carroll |first=Sean |authorlink=Sean M. Carroll |date=10 March 2010 |work=Cosmic Variance |type=Blog |publisher=Discover|accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150714074327/http://blogs.discovermagazine.com/cosmicvariance/2010/03/10/free-energy-and-the-meaning-of-life/ |archivedate=14 July 2015}}</ref> [[Physicist]] [[Jeremy England]] has proposed that life was inevitable from general thermodynamic considerations: < blockquote >... when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life.<ref>{{cite journal |last=Wolchover |first=Natalie |date=22 January 2014 |title=A New Physics Theory of Life |url=https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/ |journal=Quanta Magazine |accessdate=2015-06-17 |url-status=live |archiveurl=https://web.archive.org/web/20150613052830/https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/ |archivedate=13 June 2015}}</ref><ref>{{cite journal |last=England |first=Jeremy L. |authorlink=Jeremy England |date=28 September 2013 |title=Statistical physics of self-replication |url=http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsrep.pdf |journal=[[Journal of Chemical Physics]] |volume=139 |issue=12 |page=121923 |arxiv=1209.1179 |bibcode=2013JChPh.139l1923E |doi=10.1063/1.4818538 |pmid=24089735  |accessdate=2015-06-18 |url-status=live |archiveurl=https://web.archive.org/web/20150604131515/http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsrep.pdf |archivedate=4 June 2015|hdl=1721.1/90392 |s2cid=478964 }}</ref>< /blockquote >

有几个模型否定了 "裸基因 "的自我复制，而是假设出现了一种原始的新陈代谢，为后来出现的RNA复制提供了安全的环境。Krebs循环(柠檬酸循环)在好氧生物体内产生能量，以及在复杂有机化学物的生物合成中吸取二氧化碳和氢离子的中心地位，表明它是新陈代谢中最早进化的部分之一。 与此相一致的是，地球化学家Russell 罗素提出“生命的目的是使二氧化碳氢化”(这是“新陈代谢优先”而不是“基因优先”方案的一部分)。物理学家杰里米-英格兰Jeremy England提出，从一般的热力学考虑，生命是不可避免的：

有几个模型否定了"裸基因"的自我复制，而是假设出现了一种原始的新陈代谢，为后来出现的RNA复制提供了安全的环境。克雷布斯循环 Krebs cycle(柠檬酸循环)在需氧生物体内产生能量，以及在复杂有机化学物的生物合成中吸取二氧化碳和氢离子的中心地位，表明它是新陈代谢中最早进化的部分之一。与此相一致的是，地球化学家Russell提出“生命的目的是使二氧化碳氢化”(这是“新陈代谢优先”而不是“基因优先”情形的一部分)。物理学家杰里米·英格兰Jeremy England提出，从一般的热力学考虑，生命是不可避免的：

   ...当一组原子受到外部能量源(如太阳或化学燃料)的驱动，并被热浴(如海洋或大气层)所包围时，它往往会逐渐进行自我重组，以便散失越来越多的能量。这可能意味着，在某些条件下，物质不可避免地获得了与生命相关的关键物理属性。

   ...当一组原子受到外部能量源(如太阳或化学燃料)的驱动，并被热浴(如海洋或大气层)所包围时，它往往会逐渐重组自己，以耗散越来越多的能量。这可能意味着，在某些条件下，物质不可避免地获得了与生命相关的关键物理属性。

 

One of the earliest incarnations of this idea was put forward in 1924 with Oparin's notion of primitive self-replicating vesicles which predated the discovery of the structure of DNA. Variants in the 1980s and 1990s include Wächtershäuser's iron–sulfur world theory and models introduced by [[Christian de Duve]] based on the chemistry of [[thioester]]s. More abstract and theoretical arguments for the plausibility of the emergence of metabolism without the presence of genes include a mathematical model introduced by [[Freeman Dyson]] in the early 1980s and [[Stuart Kauffman]]'s notion of collectively autocatalytic sets, discussed later that decade.

One of the earliest incarnations of this idea was put forward in 1924 with Oparin's notion of primitive self-replicating vesicles which predated the discovery of the structure of DNA. Variants in the 1980s and 1990s include Wächtershäuser's iron–sulfur world theory and models introduced by [[Christian de Duve]] based on the chemistry of [[thioester]]s. More abstract and theoretical arguments for the plausibility of the emergence of metabolism without the presence of genes include a mathematical model introduced by [[Freeman Dyson]] in the early 1980s and [[Stuart Kauffman]]'s notion of collectively autocatalytic sets, discussed later that decade.

这一思想最早的化身之一是在1924年提出的Oparin的原始自我复制囊泡的概念，这比DNA结构的发现还要早。20世纪80年代和90年代的变体包括Wächtershäuser的铁硫世界理论和Christian de Duve提出的基于硫酯化学的模型。更加抽象和理论化的论证，认为新陈代谢在没有基因存在的情况下出现的合理性，包括弗里曼-戴森Freeman Dyson在20世纪80年代初提出的数学模型和斯图亚特-考夫曼Stuart Kauffman的集体自催化集的概念，该观点在随后的十年中进行了讨论。。

这一思想最早的化身之一是在1924年提出的Oparin的原始自复制囊泡的概念，这比DNA结构的发现还要早。20世纪80年代和90年代的变体包括Wächtershäuser的铁-硫世界理论和克里斯蒂安·德·杜夫 Christian de Duve提出的基于硫酯的化学的模型。对于在没有基因存在的情况下新陈代谢出现的合理性，更加抽象和理论化的论证，包括弗里曼·戴森Freeman Dyson在20世纪80年代初提出的数学模型和斯图亚特·考夫曼Stuart Kauffman的集体自催化集的概念，该观点在该十年晚些时候进行了讨论。

Orgel总结他的分析说，

Orgel总结他的分析说，

   目前没有理由期望多步循环，如还原性柠檬酸循环会在FeS/FeS2或其他一些矿物的表面自组织。"

   目前没有理由期望多步循环，如还原性柠檬酸循环会在FeS/ FeS₂或一些其他矿物的表面自组织。"

有可能在生命诞生之初就使用了另一种代谢途径。例如，"开放的 "乙酰-CoA途径（当今自然界公认的五种二氧化碳固定方式中的另一种）代替了还原性柠檬酸循环，就符合金属硫化物表面自组织的想法。该途径的关键酶--一氧化碳脱氢酶/乙酰-CoA合成酶，在其反应中心藏有镍-铁-硫混合簇，并在一个步骤中催化形成乙酰-CoA（类似乙酰-硫醇）。然而，越来越多的人担心，在热力学和动力学上，生命起源以前的硫醇化和硫酯化合物不利于在假定的生命起源以前的条件(即热液喷口)中积累。然而也有人提出，半胱氨酸和同型半胱氨酸可能已经与Stecker反应产生的亚硝酸盐反应，容易形成催化硫醇达到的弹力肽。

有可能在生命诞生之初就使用了另一种代谢通路。例如，"开放的"乙酰-辅酶A通路（当今公认的自然界中五种二氧化碳固定方式中的另一种）而不是还原性柠檬酸循环，会符合金属硫化物表面的自组织的想法。该通路的关键酶--一氧化碳脱氢酶/乙酰-辅酶A合成酶，在其反应中心藏有镍-铁-硫混合簇，并在一个步骤中催化形成乙酰-辅酶A（类似乙酰-硫醇）。然而，越来越多的人担心，在热力学和动力学上，生命起源以前的硫醇化和硫酯化合物不利于在假定的生命起源以前的条件(如，热液喷口)中积累。然而也有人提出，半胱氨酸和同型半胱氨酸可能已经与施特克反应 Stecker reaction产生的腈类反应，容易形成起催化作用的富硫醇的多肽。*** thiol-reach 应为thiol-rich，poplypeptodes应为polypeptides***

=== Zinc-world hypothesis ===

=== Zinc-world hypothesis ===

The zinc world (Zn-world) theory of Mulkidjanian<ref name="Mulkidjanian">{{cite journal |last=Mulkidjanian |first=Armen Y. |date=24 August 2009 |title=On the origin of life in the zinc world: 1. Photosynthesizing, porous edifices built of hydrothermally precipitated zinc sulfide as cradles of life on Earth |journal=Biology Direct |volume=4 |page=26 |doi=10.1186/1745-6150-4-26 |pmid=19703272 |pmc=3152778 }}</ref> is an extension of Wächtershäuser's pyrite hypothesis. Wächtershäuser based his theory of the initial chemical processes leading to informational molecules (RNA, peptides) on a regular mesh of electric charges at the surface of pyrite that may have facilitated the primeval [[polymerization]] by attracting reactants and arranging them appropriately relative to each other.<ref>{{cite journal |last=Wächtershäuser |first=Günter |date=December 1988 |title=Before Enzymes and Templates: Theory of Surface Metabolism |journal=[[Microbiology and Molecular Biology Reviews|Microbiological Reviews]] |volume=52 |pages=452–484 |issue=4 |pmc=373159 |pmid=3070320 |doi=10.1128/MMBR.52.4.452-484.1988 }}</ref> The Zn-world theory specifies and differentiates further.<ref name="Mulkidjanian" /><ref>{{cite journal |last1=Mulkidjanian |first1=Armen Y. |last2=Galperin |first2=Michael Y. |date=24 August 2009 |title=On the origin of life in the zinc world. 2. Validation of the hypothesis on the photosynthesizing zinc sulfide edifices as cradles of life on Earth |journal=Biology Direct |volume=4 |page=27 |doi=10.1186/1745-6150-4-27 |pmid=19703275 |pmc=2749021 }}</ref> Hydrothermal fluids rich in H₂S interacting with cold primordial ocean (or Darwin's "warm little pond") water leads to the precipitation of metal sulfide particles. Oceanic [[Hydrothermal vent|vent systems]] and other hydrothermal systems have a zonal structure reflected in ancient [[Volcanogenic massive sulfide ore deposit|volcanogenic massive sulfide deposits]] (VMS) of hydrothermal origin. They reach many kilometers in diameter and date back to the [[Archean]] Eon. Most abundant are pyrite (FeS₂), [[chalcopyrite]] (CuFeS₂), and [[sphalerite]] (ZnS), with additions of [[galena]] (PbS) and [[alabandite]] (MnS). ZnS and MnS have a unique ability to store radiation energy, e.g. from UV light. During the relevant time window of the origins of replicating molecules, the primordial atmospheric pressure was high enough (>100&nbsp;bar, about 100 atmospheres) to precipitate near the Earth's surface, and UV irradiation was 10 to 100 times more intense than now; hence the unique photosynthetic properties mediated by ZnS provided just the right energy conditions to energize the synthesis of informational and metabolic molecules and the selection of photostable nucleobases.

The zinc world (Zn-world) theory of Mulkidjanian<ref name="Mulkidjanian">{{cite journal |last=Mulkidjanian |first=Armen Y. |date=24 August 2009 |title=On the origin of life in the zinc world: 1. Photosynthesizing, porous edifices built of hydrothermally precipitated zinc sulfide as cradles of life on Earth |journal=Biology Direct |volume=4 |page=26 |doi=10.1186/1745-6150-4-26 |pmid=19703272 |pmc=3152778 }}</ref> is an extension of Wächtershäuser's pyrite hypothesis. Wächtershäuser based his theory of the initial chemical processes leading to informational molecules (RNA, peptides) on a regular mesh of electric charges at the surface of pyrite that may have facilitated the primeval [[polymerization]] by attracting reactants and arranging them appropriately relative to each other.<ref>{{cite journal |last=Wächtershäuser |first=Günter |date=December 1988 |title=Before Enzymes and Templates: Theory of Surface Metabolism |journal=[[Microbiology and Molecular Biology Reviews|Microbiological Reviews]] |volume=52 |pages=452–484 |issue=4 |pmc=373159 |pmid=3070320 |doi=10.1128/MMBR.52.4.452-484.1988 }}</ref> The Zn-world theory specifies and differentiates further.<ref name="Mulkidjanian" /><ref>{{cite journal |last1=Mulkidjanian |first1=Armen Y. |last2=Galperin |first2=Michael Y. |date=24 August 2009 |title=On the origin of life in the zinc world. 2. Validation of the hypothesis on the photosynthesizing zinc sulfide edifices as cradles of life on Earth |journal=Biology Direct |volume=4 |page=27 |doi=10.1186/1745-6150-4-27 |pmid=19703275 |pmc=2749021 }}</ref> Hydrothermal fluids rich in H₂S interacting with cold primordial ocean (or Darwin's "warm little pond") water leads to the precipitation of metal sulfide particles. Oceanic [[Hydrothermal vent|vent systems]] and other hydrothermal systems have a zonal structure reflected in ancient [[Volcanogenic massive sulfide ore deposit|volcanogenic massive sulfide deposits]] (VMS) of hydrothermal origin. They reach many kilometers in diameter and date back to the [[Archean]] Eon. Most abundant are pyrite (FeS₂), [[chalcopyrite]] (CuFeS₂), and [[sphalerite]] (ZnS), with additions of [[galena]] (PbS) and [[alabandite]] (MnS). ZnS and MnS have a unique ability to store radiation energy, e.g. from UV light. During the relevant time window of the origins of replicating molecules, the primordial atmospheric pressure was high enough (>100&nbsp;bar, about 100 atmospheres) to precipitate near the Earth's surface, and UV irradiation was 10 to 100 times more intense than now; hence the unique photosynthetic properties mediated by ZnS provided just the right energy conditions to energize the synthesis of informational and metabolic molecules and the selection of photostable nucleobases.

Mulkidjanian的锌世界（Zn-world）理论是Wächtershäuser的黄铁矿假说的延伸。Wächtershäuser根据他的理论，将导致信息分子（RNA、肽）的初始化学过程建立在黄铁矿表面有规律的电荷网状结构上，这种网状结构可能通过吸引反应物并将它们适当地相对排列，促进了原始聚合。"锌世界 "理论进一步明确和区分了富含H2S的热液与寒冷的原始海洋（或Darwin的 "温暖的小池塘"）水相互作用，导致金属硫化物颗粒的沉淀。大洋喷口系统和其他热液系统的区系结构反映在热液起源的古火山块状硫化物矿床（VMS）中。它们的直径达数千米，可追溯到考古纪元。最丰富的是黄铁矿(FeS₂)、黄铜矿(CuFeS₂)和闪锌矿(ZnS)，另外还有方铅矿(PbS)和铝钒矿(MnS)。ZnS和MnS具有独特的储存辐射能量的能力，例如来自紫外线的能量。在复制分子起源的相关时间窗内，原始大气压足够高(>100巴，约100个大气压)，可以在地球表面附近沉淀，紫外线照射强度是现在的10～100倍，因此，ZnS所介导的独特的光合作用特性正好为信息分子和代谢分子的合成以及光稳定核碱的选择提供了能量条件。

Mulkidjanian的锌世界（Zn-world）理论是Wächtershäuser的黄铁矿假说的延伸。Wächtershäuser根据他的导致信息分子（RNA、肽）的初始化学过程的理论建立在黄铁矿表面有规律的电荷网状结构上，这种网状结构可能通过吸引反应物并将它们适当地相对排列，促进了原始聚合。"锌世界 "理论进一步明确和区分了富含H₂S的热流与寒冷的原始海洋（或Darwin的"温暖的小池塘"）的水相互作用，导致金属硫化物颗粒的沉淀。大洋喷口系统和其他热液系统的区域结构反映在热液起源的古火山块状硫化物矿床（VMS）中。它们的直径达数千米，可追溯到太古宙。最丰富的是黄铁矿(FeS₂)、黄铜矿(CuFeS₂)和闪锌矿(ZnS)，另外还有方铅矿(PbS)和硫锰矿(MnS)。ZnS和MnS具有独特的储存辐射能量的能力，例如来自紫外线的能量。在复制分子起源的相关时间窗口内，原始大气压足够高(>100巴，约100个大气压)，可以在地球表面附近沉降，紫外线照射强度是现在的10～100倍，因此，ZnS所介导的独特的光合作用特性为供能信息分子和代谢分子的合成以及光稳定核酸碱基的选择提供了正好的能量条件。

The Zn-world theory has been further filled out with experimental and theoretical evidence for the ionic constitution of the interior of the first proto-cells before archaea, bacteria and [[Origin of eukaryotes|proto-eukaryotes]] evolved. [[Archibald Macallum]] noted the resemblance of body fluids such as blood and lymph to seawater;<ref>{{cite journal |last=Macallum |first=A. B. |authorlink=Archibald Macallum |date=1 April 1926 |title=The Paleochemistry of the body fluids and tissues |journal=[[Physiological Reviews]] |volume=6 |issue=2 |pages=316–357|doi=10.1152/physrev.1926.6.2.316 }}</ref> however, the inorganic composition of all cells differ from that of modern seawater, which led Mulkidjanian and colleagues to reconstruct the "hatcheries" of the first cells combining geochemical analysis with [[Phylogenomics|phylogenomic]] scrutiny of the inorganic ion requirements of universal components of modern cells. The authors conclude that ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K⁺, Zn²⁺, Mn²⁺, and {{chem|[PO|4|]|3−}}. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in what we today call marine settings but is compatible with emissions of vapor-dominated zones of what we today call inland geothermal systems. Under the oxygen depleted, CO₂-dominated primordial atmosphere, the chemistry of water condensates and exhalations near geothermal fields would resemble the internal milieu of modern cells. Therefore, the precellular stages of evolution may have taken place in shallow "Darwin ponds" lined with porous [[silicate minerals]] mixed with metal sulfides and enriched in K⁺, Zn²⁺, and phosphorus compounds.<ref>{{cite journal |last1=Mulkidjanian |first1=Armen Y. |last2=Bychkov |first2=Andrew Yu. |last3=Dibrova |first3=Daria V. |last4=Galperin |first4=Michael Y. |last5=Koonin |first5=Eugene V. |display-authors=3 |date=3 April 2012 |title=Origin of first cells at terrestrial, anoxic geothermal fields |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=109 |issue=14 |pages=E821–E830 |bibcode=2012PNAS..109E.821M |doi=10.1073/pnas.1117774109  |pmc=3325685 |pmid=22331915}}</ref><ref>For a deeper integrative version of this hypothesis, see in particular {{harvnb|Lankenau|2011|pp=225–286}}, interconnecting the "Two RNA worlds" concept and other detailed aspects; and {{cite journal |last1=Davidovich |first1=Chen |last2=Belousoff |first2=Matthew |last3=Bashan |first3=Anat |last4=Yonath |first4=Ada |authorlink4=Ada Yonath |date=September 2009 |title=The evolving ribosome: from non-coded peptide bond formation to sophisticated translation machinery |journal=Research in Microbiology |volume=160 |issue=7 |pages=487–492 |doi=10.1016/j.resmic.2009.07.004 |pmid=19619641}}</ref>

The Zn-world theory has been further filled out with experimental and theoretical evidence for the ionic constitution of the interior of the first proto-cells before archaea, bacteria and [[Origin of eukaryotes|proto-eukaryotes]] evolved. [[Archibald Macallum]] noted the resemblance of body fluids such as blood and lymph to seawater;<ref>{{cite journal |last=Macallum |first=A. B. |authorlink=Archibald Macallum |date=1 April 1926 |title=The Paleochemistry of the body fluids and tissues |journal=[[Physiological Reviews]] |volume=6 |issue=2 |pages=316–357|doi=10.1152/physrev.1926.6.2.316 }}</ref> however, the inorganic composition of all cells differ from that of modern seawater, which led Mulkidjanian and colleagues to reconstruct the "hatcheries" of the first cells combining geochemical analysis with [[Phylogenomics|phylogenomic]] scrutiny of the inorganic ion requirements of universal components of modern cells. The authors conclude that ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K⁺, Zn²⁺, Mn²⁺, and {{chem|[PO|4|]|3−}}. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in what we today call marine settings but is compatible with emissions of vapor-dominated zones of what we today call inland geothermal systems. Under the oxygen depleted, CO₂-dominated primordial atmosphere, the chemistry of water condensates and exhalations near geothermal fields would resemble the internal milieu of modern cells. Therefore, the precellular stages of evolution may have taken place in shallow "Darwin ponds" lined with porous [[silicate minerals]] mixed with metal sulfides and enriched in K⁺, Zn²⁺, and phosphorus compounds.<ref>{{cite journal |last1=Mulkidjanian |first1=Armen Y. |last2=Bychkov |first2=Andrew Yu. |last3=Dibrova |first3=Daria V. |last4=Galperin |first4=Michael Y. |last5=Koonin |first5=Eugene V. |display-authors=3 |date=3 April 2012 |title=Origin of first cells at terrestrial, anoxic geothermal fields |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=109 |issue=14 |pages=E821–E830 |bibcode=2012PNAS..109E.821M |doi=10.1073/pnas.1117774109  |pmc=3325685 |pmid=22331915}}</ref><ref>For a deeper integrative version of this hypothesis, see in particular {{harvnb|Lankenau|2011|pp=225–286}}, interconnecting the "Two RNA worlds" concept and other detailed aspects; and {{cite journal |last1=Davidovich |first1=Chen |last2=Belousoff |first2=Matthew |last3=Bashan |first3=Anat |last4=Yonath |first4=Ada |authorlink4=Ada Yonath |date=September 2009 |title=The evolving ribosome: from non-coded peptide bond formation to sophisticated translation machinery |journal=Research in Microbiology |volume=160 |issue=7 |pages=487–492 |doi=10.1016/j.resmic.2009.07.004 |pmid=19619641}}</ref>

在古生物、细菌和原真核生物进化之前，Zn-世界理论已经有了实验和理论上的证据，进一步充实了第一批原细胞内部的离子构成。Archibald Macallum注意到血液和淋巴等体液与海水的相似性;然而，所有细胞的无机成分与现代海水的无机成分不同，这使得Mulkidjanian及其同事结合地球化学分析和系统发育学审查现代细胞普遍成分的无机离子需求，重建了第一批细胞的 "孵化器"。作者认为，蛋白质和功能系统是普遍存在的，并通过原始的推断，显示出对K⁺, Zn²⁺, Mn²⁺和[PO4]3−的亲和性和功能需求。

锌世界理论已经被在古细菌、细菌和原真核生物演化之前的第一批原细胞内部的离子构成的实验和理论上的证据进一步充实了。阿奇博尔德·麦卡勒姆 Archibald Macallum注意到血液和淋巴等体液与海水的相似性；然而，所有细胞的无机成分与现代海水的无机成分不同，这使得Mulkidjanian及其同事结合地球化学分析和系统发育组学审查现代细胞普遍成分的无机离子需求，重建了第一批细胞的"孵化器"。作者得出的结论是，普遍存在的，并根据推断，原始的蛋白质和功能系统显示出对K⁺, Zn²⁺, Mn²⁺和[PO4]3−的亲和性和功能需求。

地球化学重建表明，有利于细胞起源的离子成分不可能存在于我们今天所说的海洋环境中，而是与我们今天所说的内陆地热系统的蒸汽主导区的排放相适应。在缺氧的、以二氧化碳为主的原始大气下，地热田附近的水凝结物和呼出物的化学性质会类似于现代细胞的内部环境。因此，进化的前阶段可能发生在浅层的 "达尔文池塘 "中，池塘内有多孔硅酸盐矿物与金属硫化物混合，富含K+、Zn2+和磷化合物。

地球化学重建表明，有利于细胞起源的离子成分不可能存在于我们今天所说的海洋环境中，而是与我们今天所说的内陆地热系统的蒸汽主导区的排放相符合。在缺氧的、以二氧化碳为主的原始大气下，地热场附近的水凝结物和蒸发物的化学性质会类似于现代细胞的内环境。因此，细胞前的进化阶段可能发生在浅层的"达尔文池塘"中，池塘内衬与金属硫化物混合的多孔硅酸盐矿物，富含K⁺, Zn²⁺和磷化合物。

==Other abiogenesis scenarios==

==Other abiogenesis scenarios==

We define a scenario as a set of related concepts pertinent to the origin of life that is or has been investigated. The concepts related to the Iron-Sulfur world can be considered as a scenario. We consider some other scenarios that may partially overlap with scenarios discussed above or with each other.

We define a scenario as a set of related concepts pertinent to the origin of life that is or has been investigated. The concepts related to the Iron-Sulfur world can be considered as a scenario. We consider some other scenarios that may partially overlap with scenarios discussed above or with each other.

===Chemical pathways described by computer===

===Chemical pathways described by computer===

In September 2020, chemists described, for the first time, possible chemical pathways from nonliving prebiotic chemicals to [[Biochemistry|complex biochemicals]] that could give rise to [[Earliest known life forms|living organisms]], based on a new computer program named ALLCHEMY.<ref name="SA-20200103">{{cite news |last=Starr |first=Michelle |title=A New Chemical 'Tree of The Origins of Life' Reveals Our Possible Molecular Evolution |url=https://www.sciencealert.com/a-new-chemical-tree-of-the-origins-of-life-reveals-our-possible-chemical-evolution |date=3 October 2020 |work=[[ScienceAlert]] |accessdate=3 October 2020 }}</ref><ref name="SCI-20200925">{{cite journal |author=Wolos, Agnieszka |display-authors=et al. |title=Synthetic connectivity, emergence, and self-regeneration in the network of prebiotic chemistry |url=https://science.sciencemag.org/content/369/6511/eaaw1955 |date=25 September 2020 |journal=[[Science (journal)|Science]] |volume=369 |issue=6511 |doi=10.1126/science.aaw1955 |doi-broken-date=10 October 2020 |pmid=32973002 |accessdate=3 October 2020 }}</ref>

In September 2020, chemists described, for the first time, possible chemical pathways from nonliving prebiotic chemicals to [[Biochemistry|complex biochemicals]] that could give rise to [[Earliest known life forms|living organisms]], based on a new computer program named ALLCHEMY.<ref name="SA-20200103">{{cite news |last=Starr |first=Michelle |title=A New Chemical 'Tree of The Origins of Life' Reveals Our Possible Molecular Evolution |url=https://www.sciencealert.com/a-new-chemical-tree-of-the-origins-of-life-reveals-our-possible-chemical-evolution |date=3 October 2020 |work=[[ScienceAlert]] |accessdate=3 October 2020 }}</ref><ref name="SCI-20200925">{{cite journal |author=Wolos, Agnieszka |display-authors=et al. |title=Synthetic connectivity, emergence, and self-regeneration in the network of prebiotic chemistry |url=https://science.sciencemag.org/content/369/6511/eaaw1955 |date=25 September 2020 |journal=[[Science (journal)|Science]] |volume=369 |issue=6511 |doi=10.1126/science.aaw1955 |doi-broken-date=10 October 2020 |pmid=32973002 |accessdate=3 October 2020 }}</ref>

In the early 1970s, Manfred Eigen and [[Peter Schuster]] examined the transient stages between the molecular chaos and a self-replicating [[Hypercycle (chemistry)|hypercycle]] in a prebiotic soup.<ref>{{harvnb|Eigen|Schuster|1979}}</ref> In a hypercycle, the [[information]] storing system (possibly RNA) produces an [[enzyme]], which catalyzes the formation of another information system, in sequence until the product of the last aids in the formation of the first information system. Mathematically treated, hypercycles could create [[Quasispecies model|quasispecies]], which through natural selection entered into a form of Darwinian evolution. A boost to hypercycle theory was the discovery of [[ribozyme]]s capable of catalyzing their own chemical reactions. The hypercycle theory requires the existence of complex biochemicals, such as nucleotides, which do not form under the conditions proposed by the Miller–Urey experiment.

In the early 1970s, Manfred Eigen and [[Peter Schuster]] examined the transient stages between the molecular chaos and a self-replicating [[Hypercycle (chemistry)|hypercycle]] in a prebiotic soup.<ref>{{harvnb|Eigen|Schuster|1979}}</ref> In a hypercycle, the [[information]] storing system (possibly RNA) produces an [[enzyme]], which catalyzes the formation of another information system, in sequence until the product of the last aids in the formation of the first information system. Mathematically treated, hypercycles could create [[Quasispecies model|quasispecies]], which through natural selection entered into a form of Darwinian evolution. A boost to hypercycle theory was the discovery of [[ribozyme]]s capable of catalyzing their own chemical reactions. The hypercycle theory requires the existence of complex biochemicals, such as nucleotides, which do not form under the conditions proposed by the Miller–Urey experiment.

In his "Thermodynamic Dissipation Theory of the Origin and Evolution of Life",<ref>{{cite journal |bibcode=2011ESD.....2...37M |title= Thermodynamic Origin of Life |journal=Earth System Dynamics |volume=0907 |issue=2011 |pages=37–51 |last1=Michaelian |first1=K |year=2009 |arxiv=0907.0042 |doi=10.5194/esd-2-37-2011 |s2cid= 14574109 }}</ref><ref name="Michaelian, K. 2011">{{cite journal |doi=10.5194/esd-2-37-2011 |title= Thermodynamic dissipation theory for the origin of life |journal=Earth System Dynamics |volume=2 |issue=1 |pages=37–51 |year=2011 |last1= Michaelian |first1=K |bibcode=2011ESD.....2...37M |arxiv=0907.0042 |s2cid= 14574109 }}</ref><ref name="Michaelian, K. 2017">{{cite journal |doi= 10.1016/j.heliyon.2017.e00424 |pmid=29062973 |pmc=5647473 |title=Microscopic dissipative structuring and proliferation at the origin of life |journal=Heliyon |volume=3 |issue=10 |pages=e00424 |year=2017 |last1=Michaelian |first1=Karo }}</ref> Karo Michaelian has taken the insight of Boltzmann and the work of Prigogine to its ultimate consequences regarding the origin of life. This theory postulates that the hallmark of the origin and evolution of life is the microscopic dissipative structuring of [[Biological pigment|organic pigments]] and their proliferation over the entire Earth surface.<ref name="Michaelian, K. 2017" /> Present day life augments the entropy production of Earth in its solar environment by dissipating [[ultraviolet]] and [[Visible spectrum|visible]] [[photon]]s into heat through organic pigments in water. This heat then catalyzes a host of secondary dissipative processes such as the [[water cycle]], [[Ocean current|ocean]] and [[wind]] currents, [[Tropical cyclone|hurricanes]], etc.<ref name="Michaelian, K. 2011"/><ref name="HESS Opinions 'Biological catalysis"/> Michaelian argues that if the thermodynamic function of life today is to produce entropy through photon dissipation in organic pigments, then this probably was its function at its very beginnings. It turns out that both [[RNA]] and [[DNA]] when in water solution are very strong absorbers and extremely rapid dissipaters of ultraviolet light within the 230–290&nbsp;nm wavelength (UV-C) region, which is a part of the Sun's spectrum that could have penetrated the prebiotic [[Atmosphere of Earth|atmosphere]].<ref>Sagan, C. (1973) Ultraviolet Selection Pressure on the Earliest Organisms, J. Theor. Biol., 39, 195–200.</ref> In fact, not only RNA and DNA, but many fundamental molecules of life (those common to all three [[Domain (biology)|domains]] of life) are also pigments that absorb in the UV-C, and many of these also have a chemical affinity to RNA and DNA.<ref>{{cite journal |doi=10.5194/bg-12-4913-2015 |title=Fundamental molecules of life are pigments which arose and co-evolved as a response to the thermodynamic imperative of dissipating the prevailing solar spectrum |journal=Biogeosciences |volume=12 |issue=16 |pages=4913–4937 |year=2015 |last1=Michaelian |first1=K |last2=Simeonov |first2=A |bibcode=2015BGeo...12.4913M |arxiv=1405.4059v2 }}</ref> [[Nucleic acid]]s may thus have acted as acceptor molecules to the UV-C photon [[Excited state|excited]] antenna pigment donor molecules by providing an [[Conical intersection|ultrafast channel]] for dissipation. Michaelian has shown using the formalism of non-linear irreversible thermodynamics that there would have existed during the [[Archean]] a thermodynamic imperative to the abiogenic UV-C [[Photochemistry|photochemical]] synthesis and proliferation of these pigments over the entire Earth surface if they acted as [[Catalysis|catalysts]] to augment the dissipation of the solar photons.<ref>{{cite journal |doi=10.1088/1742-6596/475/1/012010 |title=A non-linear irreversible thermodynamic perspective on organic pigment proliferation and biological evolution |journal= Journal of Physics: Conference Series |volume=475 |issue=1 |pages=012010 |year=2013 |last1=Michaelian |first1=K |bibcode= 2013JPhCS.475a2010M |arxiv=1307.5924 |s2cid=118564759 }}</ref> By the end of the Archean, with life-induced [[ozone]] dissipating UV-C light in the Earth's upper atmosphere, it would have become ever more improbable for a completely new life to emerge that did not rely on the complex metabolic pathways already existing since now the free energy in the photons arriving at Earth's surface would have been insufficient for direct breaking and remaking of [[covalent bond]]s. It has been suggested, however, that such changes in the surface flux of ultraviolet radiation due to geophysical events affecting the atmosphere could have been what promoted the development of complexity in life based on existing metabolic pathways, for example during the [[Cambrian explosion]]<ref>{{cite journal | last1 = Doglioni | first1 = C. | last2 = Pignatti | first2 = J. | last3 = Coleman | first3 = M. | year = 2016 | title = Why did life develop on the surface of the Earth in the Cambrian? | journal = Geoscience Frontiers | volume = 7 | issue = 6| pages = 865–873 | doi=10.1016/j.gsf.2016.02.001| url = https://iris.uniroma1.it/bitstream/11573/925124/1/Doglioni_Why_2016.pdf }}</ref>

In his "Thermodynamic Dissipation Theory of the Origin and Evolution of Life",<ref>{{cite journal |bibcode=2011ESD.....2...37M |title= Thermodynamic Origin of Life |journal=Earth System Dynamics |volume=0907 |issue=2011 |pages=37–51 |last1=Michaelian |first1=K |year=2009 |arxiv=0907.0042 |doi=10.5194/esd-2-37-2011 |s2cid= 14574109 }}</ref><ref name="Michaelian, K. 2011">{{cite journal |doi=10.5194/esd-2-37-2011 |title= Thermodynamic dissipation theory for the origin of life |journal=Earth System Dynamics |volume=2 |issue=1 |pages=37–51 |year=2011 |last1= Michaelian |first1=K |bibcode=2011ESD.....2...37M |arxiv=0907.0042 |s2cid= 14574109 }}</ref><ref name="Michaelian, K. 2017">{{cite journal |doi= 10.1016/j.heliyon.2017.e00424 |pmid=29062973 |pmc=5647473 |title=Microscopic dissipative structuring and proliferation at the origin of life |journal=Heliyon |volume=3 |issue=10 |pages=e00424 |year=2017 |last1=Michaelian |first1=Karo }}</ref> Karo Michaelian has taken the insight of Boltzmann and the work of Prigogine to its ultimate consequences regarding the origin of life. This theory postulates that the hallmark of the origin and evolution of life is the microscopic dissipative structuring of [[Biological pigment|organic pigments]] and their proliferation over the entire Earth surface.<ref name="Michaelian, K. 2017" /> Present day life augments the entropy production of Earth in its solar environment by dissipating [[ultraviolet]] and [[Visible spectrum|visible]] [[photon]]s into heat through organic pigments in water. This heat then catalyzes a host of secondary dissipative processes such as the [[water cycle]], [[Ocean current|ocean]] and [[wind]] currents, [[Tropical cyclone|hurricanes]], etc.<ref name="Michaelian, K. 2011"/><ref name="HESS Opinions 'Biological catalysis"/> Michaelian argues that if the thermodynamic function of life today is to produce entropy through photon dissipation in organic pigments, then this probably was its function at its very beginnings. It turns out that both [[RNA]] and [[DNA]] when in water solution are very strong absorbers and extremely rapid dissipaters of ultraviolet light within the 230–290&nbsp;nm wavelength (UV-C) region, which is a part of the Sun's spectrum that could have penetrated the prebiotic [[Atmosphere of Earth|atmosphere]].<ref>Sagan, C. (1973) Ultraviolet Selection Pressure on the Earliest Organisms, J. Theor. Biol., 39, 195–200.</ref> In fact, not only RNA and DNA, but many fundamental molecules of life (those common to all three [[Domain (biology)|domains]] of life) are also pigments that absorb in the UV-C, and many of these also have a chemical affinity to RNA and DNA.<ref>{{cite journal |doi=10.5194/bg-12-4913-2015 |title=Fundamental molecules of life are pigments which arose and co-evolved as a response to the thermodynamic imperative of dissipating the prevailing solar spectrum |journal=Biogeosciences |volume=12 |issue=16 |pages=4913–4937 |year=2015 |last1=Michaelian |first1=K |last2=Simeonov |first2=A |bibcode=2015BGeo...12.4913M |arxiv=1405.4059v2 }}</ref> [[Nucleic acid]]s may thus have acted as acceptor molecules to the UV-C photon [[Excited state|excited]] antenna pigment donor molecules by providing an [[Conical intersection|ultrafast channel]] for dissipation. Michaelian has shown using the formalism of non-linear irreversible thermodynamics that there would have existed during the [[Archean]] a thermodynamic imperative to the abiogenic UV-C [[Photochemistry|photochemical]] synthesis and proliferation of these pigments over the entire Earth surface if they acted as [[Catalysis|catalysts]] to augment the dissipation of the solar photons.<ref>{{cite journal |doi=10.1088/1742-6596/475/1/012010 |title=A non-linear irreversible thermodynamic perspective on organic pigment proliferation and biological evolution |journal= Journal of Physics: Conference Series |volume=475 |issue=1 |pages=012010 |year=2013 |last1=Michaelian |first1=K |bibcode= 2013JPhCS.475a2010M |arxiv=1307.5924 |s2cid=118564759 }}</ref> By the end of the Archean, with life-induced [[ozone]] dissipating UV-C light in the Earth's upper atmosphere, it would have become ever more improbable for a completely new life to emerge that did not rely on the complex metabolic pathways already existing since now the free energy in the photons arriving at Earth's surface would have been insufficient for direct breaking and remaking of [[covalent bond]]s. It has been suggested, however, that such changes in the surface flux of ultraviolet radiation due to geophysical events affecting the atmosphere could have been what promoted the development of complexity in life based on existing metabolic pathways, for example during the [[Cambrian explosion]]<ref>{{cite journal | last1 = Doglioni | first1 = C. | last2 = Pignatti | first2 = J. | last3 = Coleman | first3 = M. | year = 2016 | title = Why did life develop on the surface of the Earth in the Cambrian? | journal = Geoscience Frontiers | volume = 7 | issue = 6| pages = 865–873 | doi=10.1016/j.gsf.2016.02.001| url = https://iris.uniroma1.it/bitstream/11573/925124/1/Doglioni_Why_2016.pdf }}</ref>

在他的 "生命起源和进化的热力学耗散理论 "中，卡洛-米迦勒安Karo Michaelian将Boltzmann的见解和Prigogine的研究用于关于生命起源的最终结果。该理论假设生命起源和进化的标志是有机颜料的微观耗散结构及其在整个地球表面的扩散。现今的生命通过将紫外线和可见光子通过水中的有机颜料耗散成热能，增强了地球在太阳环境中的熵产。这种热量就会催化一系列的二次耗散过程，如水循环、洋流和风流、飓风等。Michaelian认为，如果说今天生命的热力学功能是通过有机颜料中的光子耗散产生熵，那么这可能是它在一开始就具有的功能。事实证明，RNA和DNA在水溶液中时，都是230-290nm波长（UV-C）区域内紫外线的极强吸收者和极快耗散者，这是太阳光谱中可能穿透前生物大气层的一部分。事实上，不仅是RNA和DNA，许多生命的基本分子（生命三大领域共同的分子）也是在UV-C中吸收的色素，其中许多也与RNA和DNA有化学亲和力。因此，核酸可能通过提供一个超快的消散通道，充当了UV-C光子激发的天线色素供体分子的接受分子。Michaelian用非线性不可逆热力学的形式论表明，在太古代，如果这些色素作为催化剂来增强太阳光子的耗散，那么这些色素的非生物UV-C光化学合成和增殖在整个地球表面就会存在一种热力学上的必然性。 到了太古代末期，随着生命诱导的臭氧使地球上层大气中的UV-C光消散，要想出现一个不依赖已有的复杂代谢途径的全新生命将变得越来越不可能，因为现在到达地球表面的光子中的自由能已经不足以直接破坏和重造共价键。然而，有人认为，由于影响大气层的地球物理事件造成的紫外线辐射表面通量的这种变化，可能是在现有代谢途径的基础上促进生命复杂性发展的原因，例如在寒武纪生命大爆发期间。

在他的 "生命起源和进化的热力学耗散理论 "中，卡洛·米迦勒安 Karo Michaelian将Boltzmann的洞见和Prigogine的工作用于关于生命起源的最终结果。该理论假设生命起源和进化的标志是有机颜料的微观耗散结构及其在整个地球表面的扩散。现今的生命通过将紫外线和可见光子通过水中的有机颜料耗散成热能，增强了地球在太阳环境中的熵产生。这种热量就会催化大量的二次耗散过程，如水循环、洋流和风流、飓风等。Michaelian认为，如果说今天生命的热力学功能是通过有机颜料中光子耗散产生熵，那么这可能是它在一开始就具有的功能。事实证明，RNA和DNA在水溶液中时，都是230-290nm波长（UV-C）区域内紫外线的极强吸收者和极快耗散者，这是太阳光谱中可能穿透生命起源以前大气层的一部分。事实上，不仅是RNA和DNA，许多生命的基本分子（生命所有三个域共同的分子）也是在UV-C中吸收的色素，其中许多也与RNA和DNA有化学亲和力。因此，核酸可能通过提供一个超快的耗散通道，充当了UV-C光子激发的天线色素供体分子的受体分子。Michaelian用非线性不可逆热力学的形式体系表明，在太古宙，如果这些色素作为催化剂来增强太阳光子的耗散，那么这些色素的生命起源前UV-C光化学合成和扩散在整个地球表面就会存在一种热力学上的必然性。到了太古宙末期，随着生命诱导的臭氧使地球上层大气中的UV-C光耗散，要想出现一种不依赖已有的复杂代谢通路的全新生命将变得越来越不可能，因为现在到达地球表面的光子中的自由能已经不足以直接破坏和重造共价键。然而，有人认为，由于影响大气层的地球物理事件造成的紫外线辐射的地表通量的这种变化，可能是在现有代谢通路的基础上促进生命复杂性发展的原因，例如在寒武纪生命大爆发期间。

 

Some of the most difficult problems concerning the origin of life, such as enzyme-less [[DNA replication|replication]] of RNA and DNA,<ref>{{cite journal |last1=Michaelian |first1=Karo |last2=Santillán |first2=Norberto |title=UVC photon-induced denaturing of DNA: A possible dissipative route to Archean enzyme-less replication |journal=Heliyon |date=June 2019 |volume=5 |issue=6 |page=e01902 |doi=10.1016/j.heliyon.2019.e01902|pmid=31249892 |pmc=6584779 }}</ref> [[homochirality]] of the fundamental molecules,<ref>{{cite journal |last1=Michaelian |first1=Karo |title=Homochirality through Photon-Induced Denaturing of RNA/DNA at the Origin of Life |journal=Life |date=June 2018 |volume=8 |issue=2 |page=21 |doi=10.3390/life8020021 |pmid=29882802 |pmc=6027432 }}</ref> and the origin of [[Genetic code|information encoding]] in RNA and DNA, also find an explanation within the same dissipative thermodynamic framework by considering the probable existence of a relation between primordial replication and UV-C photon dissipation. Michaelian suggests that it is erroneous to expect to describe the emergence, proliferation, or even evolution, of life without overwhelming reference to entropy production through the dissipation of a generalized thermodynamic potential, in particular, the prevailing solar photon flux.

Some of the most difficult problems concerning the origin of life, such as enzyme-less [[DNA replication|replication]] of RNA and DNA,<ref>{{cite journal |last1=Michaelian |first1=Karo |last2=Santillán |first2=Norberto |title=UVC photon-induced denaturing of DNA: A possible dissipative route to Archean enzyme-less replication |journal=Heliyon |date=June 2019 |volume=5 |issue=6 |page=e01902 |doi=10.1016/j.heliyon.2019.e01902|pmid=31249892 |pmc=6584779 }}</ref> [[homochirality]] of the fundamental molecules,<ref>{{cite journal |last1=Michaelian |first1=Karo |title=Homochirality through Photon-Induced Denaturing of RNA/DNA at the Origin of Life |journal=Life |date=June 2018 |volume=8 |issue=2 |page=21 |doi=10.3390/life8020021 |pmid=29882802 |pmc=6027432 }}</ref> and the origin of [[Genetic code|information encoding]] in RNA and DNA, also find an explanation within the same dissipative thermodynamic framework by considering the probable existence of a relation between primordial replication and UV-C photon dissipation. Michaelian suggests that it is erroneous to expect to describe the emergence, proliferation, or even evolution, of life without overwhelming reference to entropy production through the dissipation of a generalized thermodynamic potential, in particular, the prevailing solar photon flux.

关于生命起源的一些最困难的问题，如RNA和DNA的无酶复制，基本分子的同向性，以及RNA和DNA中信息编码的起源，也可以通过考虑原始复制和UV-C光子耗散之间可能存在的关系，在同一耗散热力学框架内找到解释。Michaelian认为，如果期望描述生命的出现、增殖甚至进化，而不大量提及通过耗散广义热力学势能，特别是普遍的太阳光子通量产生的熵，那是错误的。

关于生命起源的一些最困难的问题，如RNA和DNA的无酶复制，基本分子的同手型，以及RNA和DNA中信息编码的起源，也可以通过考虑原始复制和UV-C光子耗散之间可能存在的关系，在同一耗散热力学框架内找到解释。Michaelian认为，如果期望描述生命的涌现、增殖甚至进化，而不大量提及通过耗散广义热力学势能，特别是主流太阳光子通量产生的熵，那是错误的。

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Theories of abiogenesis seldom address the caveat raised by Harold Blum:<ref>Blum, H.F. (1957). On the origin of self-replicating systems. In Rhythmic and Synthetic Processes in Growth, ed. Rudnick, D., pp. 155–170. Princeton University Press, Princeton, NJ.</ref> if the key informational elements of life – proto-nucleic acid chains – spontaneously form duplex structures, then there is no way to dissociate them. < blockquote >Somewhere in this cycle work must be done, which means that free energy must be expended. If the parts assemble themselves on a template spontaneously, work has to be done to take the replica off; or, if the replica comes off the template of its own accord, work must be done to put the parts on in the first place.< /blockquote >

Theories of abiogenesis seldom address the caveat raised by Harold Blum:<ref>Blum, H.F. (1957). On the origin of self-replicating systems. In Rhythmic and Synthetic Processes in Growth, ed. Rudnick, D., pp. 155–170. Princeton University Press, Princeton, NJ.</ref> if the key informational elements of life – proto-nucleic acid chains – spontaneously form duplex structures, then there is no way to dissociate them. < blockquote >Somewhere in this cycle work must be done, which means that free energy must be expended. If the parts assemble themselves on a template spontaneously, work has to be done to take the replica off; or, if the replica comes off the template of its own accord, work must be done to put the parts on in the first place.< /blockquote >

   在这个循环的某个地方，必须做功，这意味着自由能必须被消耗。如果零件自发地在模板上组装起来，就必须做功才能把复制品取下来;或者，如果复制品自动从模板上脱落，必须先把零件装上。

   在这个循环的某个地方，必须做功，这意味着自由能必须被消耗。如果零件自发地在模板上组装起来，就必须做功才能把复制品取下来；或者，如果复制品自动从模板上脱落，首先一定要做功把这些零件装上。

The Oparin–Haldane conjecture addresses the formation, but not the dissociation, of nucleic acid polymers and duplexes. However, nucleic acids are unusual because, in the absence of counterions (low salt) to neutralize the high charges on opposing phosphate groups, the nucleic acid duplex dissociates into single chains.<ref name="ReferenceB">{{Cite journal |doi = 10.1016/j.icarus.2003.10.018|title = Fast tidal cycling and the origin of life|year = 2004|last1 = Lathe|first1 = Richard|journal = Icarus|volume = 168|issue = 1|pages = 18–22|bibcode = 2004Icar..168...18L}}</ref> Early tides, driven by a close moon, could have generated rapid cycles of dilution (high tide, low salt) and concentration (dry-down at low tide, high salt) that exclusively promoted the replication of nucleic acids<ref name="ReferenceB"/> through a process dubbed tidal chain reaction (TCR).<ref>{{Cite journal |doi = 10.1017/S1473550405002314|title = Tidal chain reaction and the origin of replicating biopolymers|year = 2005|last1 = Lathe|first1 = Richard|journal = International Journal of Astrobiology|volume = 4|issue = 1|pages = 19–31|bibcode = 2005IJAsB...4...19L}}</ref> This theory has been criticized on the grounds that early tides may not have been so rapid,<ref>{{Cite journal |doi = 10.1016/j.icarus.2005.04.022|title = Comment on the paper "Fast tidal cycling and the origin of life" by Richard Lathe|year = 2006|last1 = Varga|first1 = P.|last2 = Rybicki|first2 = K.|last3 = Denis|first3 = C.|journal = Icarus|volume = 180|issue = 1|pages = 274–276|bibcode = 2006Icar..180..274V}}</ref> although regression from current values requires an Earth–Moon juxtaposition at around two Ga, for which there is no evidence, and early tides may have been approximately every seven hours.<ref>{{Cite journal |doi = 10.1016/j.icarus.2005.08.019|title = Early tides: Response to Varga et al|year = 2006|last1 = Lathe|first1 = R.|journal = Icarus|volume = 180|issue = 1|pages = 277–280|bibcode = 2006Icar..180..277L}}</ref> Another critique is that only 2–3% of the Earth's crust may have been exposed above the sea until late in terrestrial evolution.<ref>{{Cite journal | doi=10.1016/j.epsl.2008.08.029| title=A case for late-Archaean continental emergence from thermal evolution models and hypsometry| year=2008| last1=Flament| first1=Nicolas| last2=Coltice| first2=Nicolas| last3=Rey| first3=Patrice F.| journal=Earth and Planetary Science Letters| volume=275| issue=3–4| pages=326–336| bibcode=2008E&PSL.275..326F}}</ref>

The Oparin–Haldane conjecture addresses the formation, but not the dissociation, of nucleic acid polymers and duplexes. However, nucleic acids are unusual because, in the absence of counterions (low salt) to neutralize the high charges on opposing phosphate groups, the nucleic acid duplex dissociates into single chains.<ref name="ReferenceB">{{Cite journal |doi = 10.1016/j.icarus.2003.10.018|title = Fast tidal cycling and the origin of life|year = 2004|last1 = Lathe|first1 = Richard|journal = Icarus|volume = 168|issue = 1|pages = 18–22|bibcode = 2004Icar..168...18L}}</ref> Early tides, driven by a close moon, could have generated rapid cycles of dilution (high tide, low salt) and concentration (dry-down at low tide, high salt) that exclusively promoted the replication of nucleic acids<ref name="ReferenceB"/> through a process dubbed tidal chain reaction (TCR).<ref>{{Cite journal |doi = 10.1017/S1473550405002314|title = Tidal chain reaction and the origin of replicating biopolymers|year = 2005|last1 = Lathe|first1 = Richard|journal = International Journal of Astrobiology|volume = 4|issue = 1|pages = 19–31|bibcode = 2005IJAsB...4...19L}}</ref> This theory has been criticized on the grounds that early tides may not have been so rapid,<ref>{{Cite journal |doi = 10.1016/j.icarus.2005.04.022|title = Comment on the paper "Fast tidal cycling and the origin of life" by Richard Lathe|year = 2006|last1 = Varga|first1 = P.|last2 = Rybicki|first2 = K.|last3 = Denis|first3 = C.|journal = Icarus|volume = 180|issue = 1|pages = 274–276|bibcode = 2006Icar..180..274V}}</ref> although regression from current values requires an Earth–Moon juxtaposition at around two Ga, for which there is no evidence, and early tides may have been approximately every seven hours.<ref>{{Cite journal |doi = 10.1016/j.icarus.2005.08.019|title = Early tides: Response to Varga et al|year = 2006|last1 = Lathe|first1 = R.|journal = Icarus|volume = 180|issue = 1|pages = 277–280|bibcode = 2006Icar..180..277L}}</ref> Another critique is that only 2–3% of the Earth's crust may have been exposed above the sea until late in terrestrial evolution.<ref>{{Cite journal | doi=10.1016/j.epsl.2008.08.029| title=A case for late-Archaean continental emergence from thermal evolution models and hypsometry| year=2008| last1=Flament| first1=Nicolas| last2=Coltice| first2=Nicolas| last3=Rey| first3=Patrice F.| journal=Earth and Planetary Science Letters| volume=275| issue=3–4| pages=326–336| bibcode=2008E&PSL.275..326F}}</ref>

Oparin-Haldane猜想解决的是核酸聚合物和双联体的形成，但不是解离。然而，核酸是不寻常的，因为在没有反离子（低盐）中和对立的磷酸基团上的高电荷时，核酸双联会解离成单链.早期的潮汐，在近月的驱动下，可能产生了快速的稀释（高潮、低盐）和浓缩（低潮、高盐时干涸）循环，通过被称为潮汐链式反应（TCR）的过程，专门促进核酸的复制。 这一理论受到了批评，理由是早期的潮汐可能并不那么快，尽管从目前的数值回归需要在两个Ga左右的地月并置，但没有证据表明这一点，而且早期的潮汐可能大约是每7个小时一次。另一种批评认为，在陆地演化的晚期，只有2-3%的地壳可能暴露在海面上。

Oparin-Haldane猜想解决的是核酸聚合物和双螺旋的形成，而不是解离。然而，核酸是不寻常的，因为在没有反离子（低盐）中和对立的磷酸基团上的高电荷时，核酸双螺旋会解离成单链。早期的潮汐，在近月的驱动下，可能产生了快速的稀释（高潮、低盐）和浓缩（低潮、高盐时干涸）循环，通过被称为潮汐链式反应（TCR）的过程，专门促进核酸的复制。 这一理论受到了批评，理由是早期的潮汐可能并不那么快，英文翻译不确定***尽管从目前数值的回归需要在二十亿年左右的地月毗邻***，但没有证据表明这一点，而且早期的潮汐可能大约是每7个小时一次。另一种批评认为，直到陆地演化的晚期，只有2-3%的地壳可能暴露在海面上。

The TCR (tidal chain reaction) theory has mechanistic advantages over thermal association/dissociation at deep-sea vents because TCR requires that chain assembly (template-driven polymerization) takes place during the dry-down phase, when precursors are most concentrated, whereas thermal cycling needs polymerization to take place during the cold phase, when the rate of chain assembly is lowest and precursors are likely to be more dilute.

The TCR (tidal chain reaction) theory has mechanistic advantages over thermal association/dissociation at deep-sea vents because TCR requires that chain assembly (template-driven polymerization) takes place during the dry-down phase, when precursors are most concentrated, whereas thermal cycling needs polymerization to take place during the cold phase, when the rate of chain assembly is lowest and precursors are likely to be more dilute.

在深海喷口，潮汐链式反应(TCR)理论与热联合/解离相比，在力学上具有优势，因为潮汐链式反应要求链的组装(模板驱动的聚合)发生在干涸阶段，即前体最集中的时候，而热循环则需要聚合发生在冷阶段，即链的组装速度最低，前体可能更稀薄的时候。

在深海喷口， TCR (潮汐链式反应)理论与热联合/解离相比，在力学上具有优势，因为潮汐链式反应要求链的组装(模板驱动的聚合)发生在干涸阶段，即前体最集中的时候，而热循环则需要聚合发生在冷阶段，即链的组装速度最低，前体可能更稀薄的时候。

[[File:ConvectionCells.svg|thumb|upright=1.25|Convection cells in fluid placed in a gravity field are selforganizing and enable thermal cycling of the suspended contents in the fluid such as protocells containing protoenzymes that work on thermal cycling.]]

[[File:ConvectionCells.svg|thumb|upright=1.25|Convection cells in fluid placed in a gravity field are selforganizing and enable thermal cycling of the suspended contents in the fluid such as protocells containing protoenzymes that work on thermal cycling.]]

'''Emergence of chemiosmotic machinery''' Today's bioenergetic process of [[fermentation]] is carried out by either the aforementioned citric acid cycle or the Acetyl-CoA pathway, both of which have been connected to the primordial Iron–sulfur world.

'''Emergence of chemiosmotic machinery''' Today's bioenergetic process of [[fermentation]] is carried out by either the aforementioned citric acid cycle or the Acetyl-CoA pathway, both of which have been connected to the primordial Iron–sulfur world.

化学渗透机制的出现

化学渗透机制的出现

今天发酵的生物能过程是由上述柠檬酸循环或乙酰-CoA途径进行的，这两种途径都与原始的铁-硫世界有关。

今天发酵的生物能过程是由上述柠檬酸循环或乙酰-辅酶A通路进行的，这两种通路都与原始的铁-硫世界有关。

In a different approach, the thermosynthesis hypothesis considers the bioenergetic process of [[chemiosmosis]], which plays an essential role in [[cellular respiration]] and photosynthesis, more basal than fermentation: the [[ATP synthase]] enzyme, which sustains chemiosmosis, is proposed as the currently extant enzyme most closely related to the first metabolic process.<ref>{{cite journal |last=Muller |first=Anthonie W. J. |date=7 August 1985 |pages=429–453 |title=Thermosynthesis by biomembranes: Energy gain from cyclic temperature changes |journal=[[Journal of Theoretical Biology]] |volume=115 |issue=3 |doi=10.1016/S0022-5193(85)80202-2 |pmid=3162066}}</ref><ref>{{cite journal |last=Muller |first=Anthonie W. J. |year=1995 |title=Were the first organisms heat engines? A new model for biogenesis and the early evolution of biological energy conversion |journal=Progress in Biophysics and Molecular Biology |volume=63 |issue=2 |pages=193–231 |doi=10.1016/0079-6107(95)00004-7 |pmid=7542789}}</ref>

In a different approach, the thermosynthesis hypothesis considers the bioenergetic process of [[chemiosmosis]], which plays an essential role in [[cellular respiration]] and photosynthesis, more basal than fermentation: the [[ATP synthase]] enzyme, which sustains chemiosmosis, is proposed as the currently extant enzyme most closely related to the first metabolic process.<ref>{{cite journal |last=Muller |first=Anthonie W. J. |date=7 August 1985 |pages=429–453 |title=Thermosynthesis by biomembranes: Energy gain from cyclic temperature changes |journal=[[Journal of Theoretical Biology]] |volume=115 |issue=3 |doi=10.1016/S0022-5193(85)80202-2 |pmid=3162066}}</ref><ref>{{cite journal |last=Muller |first=Anthonie W. J. |year=1995 |title=Were the first organisms heat engines? A new model for biogenesis and the early evolution of biological energy conversion |journal=Progress in Biophysics and Molecular Biology |volume=63 |issue=2 |pages=193–231 |doi=10.1016/0079-6107(95)00004-7 |pmid=7542789}}</ref>

First life needed an energy source to bring about the condensation reaction that yielded the peptide bonds of proteins and the [[phosphodiester bond]]s of RNA. In a generalization and thermal variation of the [[ATP synthase#Binding model|binding change mechanism]] of today's ATP synthase, the "first protein" would have bound substrates (peptides, phosphate, nucleosides, RNA 'monomers') and condensed them to a reaction product that remained bound until it was released after a temperature change by a thermal unfolding. The primordial '''first protein''' would therefore have strongly resembled the beta subunits of the [[ATP synthase alpha/beta subunits]] of today's F₁ moiety in the F_oF₁ [[ATP synthase]]. Note however that today's enzymes function during isothermal conditions, whereas the hypothetical first protein worked on and during thermal cycling.

First life needed an energy source to bring about the condensation reaction that yielded the peptide bonds of proteins and the [[phosphodiester bond]]s of RNA. In a generalization and thermal variation of the [[ATP synthase#Binding model|binding change mechanism]] of today's ATP synthase, the "first protein" would have bound substrates (peptides, phosphate, nucleosides, RNA 'monomers') and condensed them to a reaction product that remained bound until it was released after a temperature change by a thermal unfolding. The primordial '''first protein''' would therefore have strongly resembled the beta subunits of the [[ATP synthase alpha/beta subunits]] of today's F₁ moiety in the F_oF₁ [[ATP synthase]]. Note however that today's enzymes function during isothermal conditions, whereas the hypothetical first protein worked on and during thermal cycling.

第一个生命需要一个能量源来实现缩合反应，产生蛋白质的肽键和RNA的磷酸二酯键。在今天ATP合成酶的结合变化机制的概括和热变化中，"第一蛋白 "应该是结合了底物（肽、磷酸盐、核苷、RNA "单体"），并将它们缩合成反应产物，这种产物一直保持结合，直到温度变化后通过热展开释放出来。因此，原始的第一个蛋白质应该与今天FoF1 ATP合成酶中的α/β亚基的β亚基非常相似。但请注意，今天的酶是在等温条件下工作的，而假设的第一个蛋白质则是在和热循环下工作的。

第一个生命需要一个能量源来实现缩合反应，产生蛋白质的肽键和RNA的磷酸二酯键。在今天ATP合成酶的结合变化机制的概括和热变化中，"第一种蛋白质"应该是结合了底物（肽、磷酸盐、核苷、RNA"单体"），并将它们缩合成一种反应产物，这种产物一直保持结合，直到温度变化后通过热诱导去折叠被释放。因此，原始的“第一种蛋白质”应该会与今天的F_oF₁ ATP合成酶中的F₁部分的ATP合成酶的α/β亚基的β亚基非常相似。但请注意，今天的酶是在等温条件下发挥功能的，而假设的第一种蛋白质则是在热循环中工作的。

The energy source under the thermosynthesis hypothesis was thermal cycling, the result of suspension of protocells in a [[convection]] current, as is plausible in a volcanic hot spring; the convection accounts for the self-organization and [[Dissipative system|dissipative structure]] required in any origin of life model. The still ubiquitous role of thermal cycling in germination and cell division is considered a relic of primordial thermosynthesis.

The energy source under the thermosynthesis hypothesis was thermal cycling, the result of suspension of protocells in a [[convection]] current, as is plausible in a volcanic hot spring; the convection accounts for the self-organization and [[Dissipative system|dissipative structure]] required in any origin of life model. The still ubiquitous role of thermal cycling in germination and cell division is considered a relic of primordial thermosynthesis.

By [[Phosphorylation|phosphorylating]] cell membrane lipids, this '''first protein''' gave a selective advantage to the lipid protocell that contained the protein. This protein also synthesized a library of many proteins, of which only a minute fraction had thermosynthesis capabilities. As proposed by Dyson,<ref name="Dyson 1999" /> it propagated functionally: it made daughters with similar capabilities, but it did not copy itself. Functioning daughters consisted of different amino acid sequences.

By [[Phosphorylation|phosphorylating]] cell membrane lipids, this '''first protein''' gave a selective advantage to the lipid protocell that contained the protein. This protein also synthesized a library of many proteins, of which only a minute fraction had thermosynthesis capabilities. As proposed by Dyson,<ref name="Dyson 1999" /> it propagated functionally: it made daughters with similar capabilities, but it did not copy itself. Functioning daughters consisted of different amino acid sequences.

Whereas the iron–sulfur world identifies a circular pathway as the most simple, the thermosynthesis hypothesis does not even invoke a pathway: [[ATP synthase#Binding model|ATP synthase's binding change mechanism]] resembles a physical adsorption process that yields free energy,<ref>{{cite journal |last1=Muller |first1=Anthonie W. J. |last2=Schulze-Makuch |first2=Dirk |authorlink2=Dirk Schulze-Makuch |date=1 April 2006 |title=Sorption heat engines: Simple inanimate negative entropy generators |journal=[[Physica (journal)#Physica A: Statistical Mechanics and its Applications|Physica A: Statistical Mechanics and its Applications]] |volume=362 |issue=2 |pages=369–381 |arxiv=physics/0507173 |bibcode=2006PhyA..362..369M |doi=10.1016/j.physa.2005.12.003 |s2cid=96186464 }}</ref> rather than a regular enzyme's mechanism, which decreases the free energy.

Whereas the iron–sulfur world identifies a circular pathway as the most simple, the thermosynthesis hypothesis does not even invoke a pathway: [[ATP synthase#Binding model|ATP synthase's binding change mechanism]] resembles a physical adsorption process that yields free energy,<ref>{{cite journal |last1=Muller |first1=Anthonie W. J. |last2=Schulze-Makuch |first2=Dirk |authorlink2=Dirk Schulze-Makuch |date=1 April 2006 |title=Sorption heat engines: Simple inanimate negative entropy generators |journal=[[Physica (journal)#Physica A: Statistical Mechanics and its Applications|Physica A: Statistical Mechanics and its Applications]] |volume=362 |issue=2 |pages=369–381 |arxiv=physics/0507173 |bibcode=2006PhyA..362..369M |doi=10.1016/j.physa.2005.12.003 |s2cid=96186464 }}</ref> rather than a regular enzyme's mechanism, which decreases the free energy.

The described first protein may be simple in the sense that is requires only a short sequence of conserved amino acid residues,  a sequent sufficient for the appropriate catalytic cleft. In contrast, it has been claimed that the emergence of cyclic systems of protein catalysts such as required by fermentation is implausible because of the length of many required sequences.<ref>{{harvnb|Orgel|1987|pp=9–16}}</ref>

The described first protein may be simple in the sense that is requires only a short sequence of conserved amino acid residues,  a sequent sufficient for the appropriate catalytic cleft. In contrast, it has been claimed that the emergence of cyclic systems of protein catalysts such as required by fermentation is implausible because of the length of many required sequences.<ref>{{harvnb|Orgel|1987|pp=9–16}}</ref>

=== Pre-RNA world: The ribose issue and its bypass ===

=== Pre-RNA world: The ribose issue and its bypass ===

It is possible that a different type of nucleic acid, such as peptide nucleic acid, threose nucleic acid or glycol nucleic acid, was the first to emerge as a self-reproducing molecule, only later replaced by RNA. Larralde et al., say that < blockquote >the generally accepted prebiotic synthesis of ribose, the formose reaction, yields numerous sugars without any selectivity.< /blockquote > and they conclude that their < blockquote >results suggest that the backbone of the first genetic material could not have contained ribose or other sugars because of their instability.< /blockquote > The ester linkage of ribose and phosphoric acid in RNA is known to be prone to hydrolysis.

It is possible that a different type of nucleic acid, such as peptide nucleic acid, threose nucleic acid or glycol nucleic acid, was the first to emerge as a self-reproducing molecule, only later replaced by RNA. Larralde et al., say that < blockquote >the generally accepted prebiotic synthesis of ribose, the formose reaction, yields numerous sugars without any selectivity.< /blockquote > and they conclude that their < blockquote >results suggest that the backbone of the first genetic material could not have contained ribose or other sugars because of their instability.< /blockquote > The ester linkage of ribose and phosphoric acid in RNA is known to be prone to hydrolysis.

有可能是一种不同类型的核酸，如肽核酸、苏糖核酸或 乙二醇核酸，最先以自我繁殖分子的形式出现，只是后来被 RNA 所取代。Larralde 等人说，

有可能一种不同类型的核酸，如肽核酸、苏糖核酸或乙二醇核酸，最先以自再生分子的形式出现，只是后来被RNA所取代。拉腊尔德 Larralde 等人说，

< blockquote >

< blockquote >

他们得出结论，他们的

他们得出结论，他们的

< blockquote >

< blockquote >

已知RNA中核糖和磷酸的酯连接容易发生水解。

已知RNA中核糖和磷酸的酯连接容易发生水解。

Pyrimidine ribonucleosides and their respective nucleotides have been prebiotically synthesized by a sequence of reactions which by-pass the free sugars, and are assembled in a stepwise fashion by using nitrogenous or oxygenous chemistries. Sutherland has demonstrated high yielding routes to cytidine and uridine ribonucleotides built from small 2 and 3 carbon fragments such as glycolaldehyde, glyceraldehyde or glyceraldehyde-3-phosphate, cyanamide and cyanoacetylene. One of the steps in this sequence allows the isolation of enantiopure ribose aminooxazoline if the enantiomeric excess of glyceraldehyde is 60% or greater. This can be viewed as a prebiotic purification step, where the said compound spontaneously crystallized out from a mixture of the other pentose aminooxazolines. Ribose aminooxazoline can then react with cyanoacetylene in a mild and highly efficient manner to give the alpha cytidine ribonucleotide. Photoanomerization with UV light allows for inversion about the 1' anomeric centre to give the correct beta stereochemistry. In 2009 they showed that the same simple building blocks allow access, via phosphate controlled nucleobase elaboration, to 2',3'-cyclic pyrimidine nucleotides directly, which are known to be able to polymerize into RNA. This paper also highlights the possibility for the photo-sanitization of the pyrimidine-2',3'-cyclic phosphates.

Pyrimidine ribonucleosides and their respective nucleotides have been prebiotically synthesized by a sequence of reactions which by-pass the free sugars, and are assembled in a stepwise fashion by using nitrogenous or oxygenous chemistries. Sutherland has demonstrated high yielding routes to cytidine and uridine ribonucleotides built from small 2 and 3 carbon fragments such as glycolaldehyde, glyceraldehyde or glyceraldehyde-3-phosphate, cyanamide and cyanoacetylene. One of the steps in this sequence allows the isolation of enantiopure ribose aminooxazoline if the enantiomeric excess of glyceraldehyde is 60% or greater. This can be viewed as a prebiotic purification step, where the said compound spontaneously crystallized out from a mixture of the other pentose aminooxazolines. Ribose aminooxazoline can then react with cyanoacetylene in a mild and highly efficient manner to give the alpha cytidine ribonucleotide. Photoanomerization with UV light allows for inversion about the 1' anomeric centre to give the correct beta stereochemistry. In 2009 they showed that the same simple building blocks allow access, via phosphate controlled nucleobase elaboration, to 2',3'-cyclic pyrimidine nucleotides directly, which are known to be able to polymerize into RNA. This paper also highlights the possibility for the photo-sanitization of the pyrimidine-2',3'-cyclic phosphates.

嘧啶核苷及其各自的核苷酸已经通过一连串的反应，绕过游离的糖类，利用含氮或含氧的化学反应，一步步地组装起来，进行了生物起源以前的合成。Sutherland已经证明了由小的2和3个碳片段如乙醛、甘油醛或甘油醛-3-磷酸、氰胺和氰基乙炔构建的胞苷和尿苷核苷酸的高产路线。该序列中的一个步骤允许分离出对映纯的核糖氨基噁唑啉，如果甘油醛的对映体过量为大于或等于60％。这可以看作是一个生物起源以前的纯化步骤，所述化合物自发地从其他戊糖氨基恶唑啉的混合物中结晶出来。然后，核糖氨基恶唑啉可以以温和和高效的方式与氰基乙炔反应，给出α胞嘧啶核苷酸。用紫外光进行光异构化，可以实现关于1'异构中心的倒置，从而给出正确的β立体化学。2009年，他们表明，同样的简单构件允许通过磷酸控制的核碱基阐释，直接获得2',3'-环状嘧啶核苷酸，已知这些核苷酸能够聚合成RNA。本文还强调了嘧啶-2',3'-环状磷酸盐光致消毒的可能性。

嘧啶核糖核苷及其各自的核苷酸已经通过一连串的反应，绕过游离的糖类，利用含氮或含氧的化学反应，一步步地组装起来，进行了生物起源以前的合成。Sutherland已经证明了由小的2和3个碳片段如羟乙醛、甘油醛或甘油醛-3-磷酸、氰胺和氰基乙炔构建胞嘧啶和尿嘧啶核糖核苷酸的高产路线。该序列中的一个步骤允许分离出对映纯的核糖氨基噁唑啉，如果甘油醛的对映体过量为大于或等于60％。这可以看作是一个生物起源以前的纯化步骤，所述化合物自发地从其他戊糖氨基恶唑啉的混合物中结晶出来。然后，核糖氨基恶唑啉可以以温和和高效的方式与氰基乙炔反应，给出α胞嘧啶核糖核苷酸。用紫外光进行光异构化，可以实现关于1'异构中心的倒置，从而给出正确的β立体化学。2009年，他们表明，同样的简单构件允许通过磷酸盐控制的核碱基加工，直接获得2',3'-环状嘧啶核苷酸，已知这些核苷酸能够聚合成RNA。这篇文章还强调了嘧啶-2',3'-环状磷酸盐的光致消毒的可能性。

 

===RNA structure===

===RNA structure===

RNA结构

RNA结构

While features of self-organization and self-replication are often considered the hallmark of living systems, there are many instances of abiotic molecules exhibiting such characteristics under proper conditions. Stan Palasek suggested based on a theoretical model that self-assembly of ribonucleic acid (RNA) molecules can occur spontaneously due to physical factors in hydrothermal vents. Virus self-assembly within host cells has implications for the study of the origin of life, as it lends further credence to the hypothesis that life could have started as self-assembling organic molecules.

While features of self-organization and self-replication are often considered the hallmark of living systems, there are many instances of abiotic molecules exhibiting such characteristics under proper conditions. Stan Palasek suggested based on a theoretical model that self-assembly of ribonucleic acid (RNA) molecules can occur spontaneously due to physical factors in hydrothermal vents. Virus self-assembly within host cells has implications for the study of the origin of life, as it lends further credence to the hypothesis that life could have started as self-assembling organic molecules.

===Viral origin===

===Viral origin===

Recent evidence for a "virus first" hypothesis, which may support theories of the RNA world, has been suggested. One of the difficulties for the study of the origins of viruses is their high rate of mutation; this is particularly the case in RNA retroviruses like HIV. A 2015 study compared protein fold structures across different branches of the tree of life, where researchers can reconstruct the evolutionary histories of the folds and of the organisms whose genomes code for those folds. They argue that protein folds are better markers of ancient events as their three-dimensional structures can be maintained even as the sequences that code for those begin to change. Thus, the viral protein repertoire retain traces of ancient evolutionary history that can be recovered using advanced bioinformatics approaches. Those researchers think that "the prolonged pressure of genome and particle size reduction eventually reduced virocells into modern viruses (identified by the complete loss of cellular makeup), meanwhile other coexisting cellular lineages diversified into modern cells." The data suggest that viruses originated from ancient cells that co-existed with the ancestors of modern cells. These ancient cells likely contained segmented RNA genomes.

Recent evidence for a "virus first" hypothesis, which may support theories of the RNA world, has been suggested. One of the difficulties for the study of the origins of viruses is their high rate of mutation; this is particularly the case in RNA retroviruses like HIV. A 2015 study compared protein fold structures across different branches of the tree of life, where researchers can reconstruct the evolutionary histories of the folds and of the organisms whose genomes code for those folds. They argue that protein folds are better markers of ancient events as their three-dimensional structures can be maintained even as the sequences that code for those begin to change. Thus, the viral protein repertoire retain traces of ancient evolutionary history that can be recovered using advanced bioinformatics approaches. Those researchers think that "the prolonged pressure of genome and particle size reduction eventually reduced virocells into modern viruses (identified by the complete loss of cellular makeup), meanwhile other coexisting cellular lineages diversified into modern cells." The data suggest that viruses originated from ancient cells that co-existed with the ancestors of modern cells. These ancient cells likely contained segmented RNA genomes.

最近有人提出了 "病毒优先”假说的证据，这可能支持RNA世界的理论。研究病毒起源的困难之一是它们的高突变率;尤其是像HIV这样的RNA逆转录病毒。2015年的一项研究比较了生命树不同分支的蛋白质褶皱结构，研究人员可以重建褶皱和基因组编码这些褶皱的生物体的进化史。他们认为，蛋白质褶皱是古代事件的更好标志，因为即使编码这些褶皱的序列开始发生变化，它们的三维结构也能保持不变。因此，病毒蛋白库保留了古代进化史的痕迹，可以使用先进的生物信息学方法来恢复。这些研究人员认为，"基因组和颗粒大小减少的长期压力最终将病毒细胞还原成现代病毒（通过细胞组成的完全丧失来识别），同时其他共存的细胞系也多样化成了现代细胞。"这些数据表明，病毒起源于与现代细胞的祖先共存的古细胞。这些古细胞很可能包含分段的RNA基因组。

最近有人提出了"病毒优先”假说的证据，这可能支持RNA世界的理论。研究病毒起源的困难之一是它们的高突变率;尤其是像HIV这样的RNA逆转录病毒。2015年的一项研究比较了生命树不同分支的蛋白质折叠结构，研究人员可以重建折叠和基因组编码这些折叠的生物体的进化史。他们认为，蛋白质折叠是古代事件的更好标志，因为即使编码那些折叠的序列开始变化，它们的三维结构也能保持不变。因此，病毒蛋白库保留了古代进化史的痕迹，可以使用先进的生物信息学方法来恢复。那些研究人员认为，"基因组和颗粒大小减少的长期压力最终将病毒细胞缩减成现代病毒（通过细胞组成的完全丧失来识别），同时其他共存的细胞系也多样化成了现代细胞。"数据表明，病毒起源于与现代细胞的祖先共存的古细胞。这些古细胞很可能包含分段的RNA基因组。

 

A computational model (2015) has shown that virus capsids may have originated in the RNA world and that they served as a means of horizontal transfer between replicator communities since these communities could not survive if the number of gene parasites  increased, with certain genes being responsible for the formation of these structures and those that favored the survival of self-replicating communities. The displacement of these ancestral genes between cellular organisms could favor the appearance of new viruses during evolution. Viruses retain a replication module inherited from the prebiotic stage since it is absent in cells. So this is evidence that viruses could originate from the RNA world and could also emerge several times in evolution through genetic escape in cells.

A computational model (2015) has shown that virus capsids may have originated in the RNA world and that they served as a means of horizontal transfer between replicator communities since these communities could not survive if the number of gene parasites  increased, with certain genes being responsible for the formation of these structures and those that favored the survival of self-replicating communities. The displacement of these ancestral genes between cellular organisms could favor the appearance of new viruses during evolution. Viruses retain a replication module inherited from the prebiotic stage since it is absent in cells. So this is evidence that viruses could originate from the RNA world and could also emerge several times in evolution through genetic escape in cells.

 

=== RNA world ===

=== RNA world ===

RNA世界

RNA世界

[[File:Jack-szostak.jpg|thumb|upright|Jack Szostak]]

[[File:Jack-szostak.jpg|thumb|upright|Jack Szostak]]

杰克·索斯塔克（Jack Szostak）

杰克·绍斯塔克（Jack Szostak）

A number of hypotheses of formation of RNA have been put forward. {{As of|1994}}, there were difficulties in the explanation of the abiotic synthesis of the nucleotides cytosine and uracil.<ref>{{cite journal |last=Orgel |first=Leslie E. |date=October 1994 |title=The origin of life on Earth|journal=Scientific American |volume=271 |issue=4 |pages=76–83 |doi=10.1038/scientificamerican1094-76 |pmid=7524147|bibcode=1994SciAm.271d..76O }}</ref> Subsequent research has shown possible routes of synthesis; for example, formamide produces all four ribonucleotides and other biological molecules when warmed in the presence of various terrestrial minerals.<ref name="Saladino2012" /><ref name="Saladino2012b" /> Early cell membranes could have formed spontaneously from proteinoids, which are protein-like molecules produced when amino acid solutions are heated while in the correct concentration of aqueous solution. These are seen to form micro-spheres which are observed to behave similarly to membrane-enclosed compartments. Other possible means of producing more complicated organic molecules include chemical reactions that take place on [[clay]] substrates or on the surface of the mineral [[pyrite]].

A number of hypotheses of formation of RNA have been put forward. {{As of|1994}}, there were difficulties in the explanation of the abiotic synthesis of the nucleotides cytosine and uracil.<ref>{{cite journal |last=Orgel |first=Leslie E. |date=October 1994 |title=The origin of life on Earth|journal=Scientific American |volume=271 |issue=4 |pages=76–83 |doi=10.1038/scientificamerican1094-76 |pmid=7524147|bibcode=1994SciAm.271d..76O }}</ref> Subsequent research has shown possible routes of synthesis; for example, formamide produces all four ribonucleotides and other biological molecules when warmed in the presence of various terrestrial minerals.<ref name="Saladino2012" /><ref name="Saladino2012b" /> Early cell membranes could have formed spontaneously from proteinoids, which are protein-like molecules produced when amino acid solutions are heated while in the correct concentration of aqueous solution. These are seen to form micro-spheres which are observed to behave similarly to membrane-enclosed compartments. Other possible means of producing more complicated organic molecules include chemical reactions that take place on [[clay]] substrates or on the surface of the mineral [[pyrite]].

Factors supporting an important role for RNA in early life include its ability to act both to store information and to catalyze chemical reactions (as a ribozyme); its many important roles as an intermediate in the expression of and maintenance of the genetic information (in the form of DNA) in modern organisms; and the ease of chemical synthesis of at least the components of the RNA molecule under the conditions that approximated the early Earth.<ref>{{cite journal |last1=Camprubí |first1=E. |last2=de Leeuw|first2=J.W. |last3=House |first3=C.H. |last4=Raulin |first4=F. |last5=Russell |first5=M.J. |last6=Spang|first6=A. | last7=Tirumalai|first7=M.R. |last8=Westall|first8=F. |date=12 December 2019|title=Emergence of Life |journal=Space Sci Rev.|volume=215 |issue=56 |page=56 |doi=10.1007/s11214-019-0624-8 |bibcode=2019SSRv..215...56C |doi-access=free }}</ref>

Factors supporting an important role for RNA in early life include its ability to act both to store information and to catalyze chemical reactions (as a ribozyme); its many important roles as an intermediate in the expression of and maintenance of the genetic information (in the form of DNA) in modern organisms; and the ease of chemical synthesis of at least the components of the RNA molecule under the conditions that approximated the early Earth.<ref>{{cite journal |last1=Camprubí |first1=E. |last2=de Leeuw|first2=J.W. |last3=House |first3=C.H. |last4=Raulin |first4=F. |last5=Russell |first5=M.J. |last6=Spang|first6=A. | last7=Tirumalai|first7=M.R. |last8=Westall|first8=F. |date=12 December 2019|title=Emergence of Life |journal=Space Sci Rev.|volume=215 |issue=56 |page=56 |doi=10.1007/s11214-019-0624-8 |bibcode=2019SSRv..215...56C |doi-access=free }}</ref>

Relatively short RNA molecules have been synthesized, capable of replication.<ref>{{cite journal |last1=Johnston |first1=Wendy K. |last2=Unrau |first2=Peter J. |last3=Lawrence |first3=Michael S. |last4=Glasner |first4=Margaret E. |last5=Bartel |first5=David P. |authorlink5=David Bartel |display-authors=3 |date=18 May 2001 |title=RNA-Catalyzed RNA Polymerization: Accurate and General RNA-Templated Primer Extension |journal=Science |volume=292 |issue=5520 |pages=1319–1325 |bibcode=2001Sci...292.1319J |doi=10.1126/science.1060786 |pmid=11358999|citeseerx=10.1.1.70.5439 |s2cid=14174984 }}</ref> Such replicase RNA, which functions as both code and catalyst provides its own template upon which copying can occur. Szostak has shown that certain catalytic RNAs can join smaller RNA sequences together, creating the potential for self-replication. If these conditions were present, Darwinian natural selection would favour the proliferation of such [[autocatalytic set]]s, to which further functionalities could be added.<ref>{{cite web |url=http://www.hhmi.org/research/origins-cellular-life |title=The Origins of Function in Biological Nucleic Acids, Proteins, and Membranes |last=Szostak |first=Jack W. |authorlink=Jack W. Szostak |date=5 February 2015 |publisher=[[Howard Hughes Medical Institute]] |location=Chevy Chase (CDP), MD |accessdate=2015-06-16 |url-status=live |archiveurl=https://web.archive.org/web/20150714092225/http://www.hhmi.org/research/origins-cellular-life |archivedate=14 July 2015}}</ref> Such autocatalytic systems of RNA capable of self-sustained replication have been identified.<ref>{{cite journal |last1=Lincoln |first1=Tracey A. |last2=Joyce |first2=Gerald F. |date=27 February 2009 |title=Self-Sustained Replication of an RNA Enzyme |journal=Science |volume=323 |issue=5918 |pages=1229–1232 |bibcode=2009Sci...323.1229L |doi=10.1126/science.1167856 |pmc=2652413 |pmid=19131595}}</ref> The RNA replication systems, which include two ribozymes that catalyze each other's synthesis, showed a doubling time of the product of about one hour, and were subject to natural selection under the conditions that existed in the experiment.<ref name="Joyce2009" /> In evolutionary competition experiments, this led to the emergence of new systems which replicated more efficiently.<ref name="Robertson2012" /> This was the first demonstration of evolutionary adaptation occurring in a molecular genetic system.<ref name="Joyce2009">{{cite journal |last=Joyce |first=Gerald F. |year=2009 |title=Evolution in an RNA world |journal=Cold Spring Harbor Perspectives in Biology |volume=74 |issue=Evolution: The Molecular Landscape |pages=17–23 |doi=10.1101/sqb.2009.74.004 |pmc=2891321 |pmid=19667013 }}</ref>

Relatively short RNA molecules have been synthesized, capable of replication.<ref>{{cite journal |last1=Johnston |first1=Wendy K. |last2=Unrau |first2=Peter J. |last3=Lawrence |first3=Michael S. |last4=Glasner |first4=Margaret E. |last5=Bartel |first5=David P. |authorlink5=David Bartel |display-authors=3 |date=18 May 2001 |title=RNA-Catalyzed RNA Polymerization: Accurate and General RNA-Templated Primer Extension |journal=Science |volume=292 |issue=5520 |pages=1319–1325 |bibcode=2001Sci...292.1319J |doi=10.1126/science.1060786 |pmid=11358999|citeseerx=10.1.1.70.5439 |s2cid=14174984 }}</ref> Such replicase RNA, which functions as both code and catalyst provides its own template upon which copying can occur. Szostak has shown that certain catalytic RNAs can join smaller RNA sequences together, creating the potential for self-replication. If these conditions were present, Darwinian natural selection would favour the proliferation of such [[autocatalytic set]]s, to which further functionalities could be added.<ref>{{cite web |url=http://www.hhmi.org/research/origins-cellular-life |title=The Origins of Function in Biological Nucleic Acids, Proteins, and Membranes |last=Szostak |first=Jack W. |authorlink=Jack W. Szostak |date=5 February 2015 |publisher=[[Howard Hughes Medical Institute]] |location=Chevy Chase (CDP), MD |accessdate=2015-06-16 |url-status=live |archiveurl=https://web.archive.org/web/20150714092225/http://www.hhmi.org/research/origins-cellular-life |archivedate=14 July 2015}}</ref> Such autocatalytic systems of RNA capable of self-sustained replication have been identified.<ref>{{cite journal |last1=Lincoln |first1=Tracey A. |last2=Joyce |first2=Gerald F. |date=27 February 2009 |title=Self-Sustained Replication of an RNA Enzyme |journal=Science |volume=323 |issue=5918 |pages=1229–1232 |bibcode=2009Sci...323.1229L |doi=10.1126/science.1167856 |pmc=2652413 |pmid=19131595}}</ref> The RNA replication systems, which include two ribozymes that catalyze each other's synthesis, showed a doubling time of the product of about one hour, and were subject to natural selection under the conditions that existed in the experiment.<ref name="Joyce2009" /> In evolutionary competition experiments, this led to the emergence of new systems which replicated more efficiently.<ref name="Robertson2012" /> This was the first demonstration of evolutionary adaptation occurring in a molecular genetic system.<ref name="Joyce2009">{{cite journal |last=Joyce |first=Gerald F. |year=2009 |title=Evolution in an RNA world |journal=Cold Spring Harbor Perspectives in Biology |volume=74 |issue=Evolution: The Molecular Landscape |pages=17–23 |doi=10.1101/sqb.2009.74.004 |pmc=2891321 |pmid=19667013 }}</ref>

 

Depending on the definition, life started when RNA chains began to self-replicate, initiating the three mechanisms of Darwinian selection: [[heritability]], variation of type, and differential reproductive output. The fitness of an RNA replicator (its per capita rate of increase) would likely be a function of its intrinsic adaptive capacities, determined by its nucleotide sequence, and the availability of resources.<ref name="Bernstein">{{cite journal |last1=Bernstein |first1=Harris |last2=Byerly |first2=Henry C. |last3=Hopf |first3=Frederick A. |last4=Michod |first4=Richard A. |last5=Vemulapalli |first5=G. Krishna |display-authors=3 |date=June 1983 |title=The Darwinian Dynamic |journal=[[The Quarterly Review of Biology]] |volume=58 |issue=2 |pages=185–207 |doi=10.1086/413216 |jstor=2828805}}</ref><ref name="Michod 1999">{{harvnb|Michod|1999}}</ref> The three primary adaptive capacities may have been: (1) replication with moderate fidelity, giving rise to both heritability while allowing variation of type, (2) resistance to decay, and (3) acquisition of process resources.<ref name="Bernstein" /><ref name="Michod 1999" /> These capacities would have functioned by means of the folded configurations of the RNA replicators resulting from their nucleotide sequences.

Depending on the definition, life started when RNA chains began to self-replicate, initiating the three mechanisms of Darwinian selection: [[heritability]], variation of type, and differential reproductive output. The fitness of an RNA replicator (its per capita rate of increase) would likely be a function of its intrinsic adaptive capacities, determined by its nucleotide sequence, and the availability of resources.<ref name="Bernstein">{{cite journal |last1=Bernstein |first1=Harris |last2=Byerly |first2=Henry C. |last3=Hopf |first3=Frederick A. |last4=Michod |first4=Richard A. |last5=Vemulapalli |first5=G. Krishna |display-authors=3 |date=June 1983 |title=The Darwinian Dynamic |journal=[[The Quarterly Review of Biology]] |volume=58 |issue=2 |pages=185–207 |doi=10.1086/413216 |jstor=2828805}}</ref><ref name="Michod 1999">{{harvnb|Michod|1999}}</ref> The three primary adaptive capacities may have been: (1) replication with moderate fidelity, giving rise to both heritability while allowing variation of type, (2) resistance to decay, and (3) acquisition of process resources.<ref name="Bernstein" /><ref name="Michod 1999" /> These capacities would have functioned by means of the folded configurations of the RNA replicators resulting from their nucleotide sequences.

根据定义，当RNA链开始自我复制时，生命就开始了，启动了达尔文选择的三种机制：遗传性、类型的变异和生殖输出差异。一个RNA复制因子的适应性(其人均增长率)很可能是其内在适应能力的函数，由其核苷酸序列以及资源的可用性决定。三种主要的适应能力可能是。(1) 中等保真度的复制，在允许类型变异的同增加生遗传性；(2) 抗衰变能力；(3) 获得加工资源。 这些能力将通过核苷酸序列产生的RNA复制因子的褶皱构型来发挥作用。

根据定义，当RNA链开始自复制时，生命就开始了，启动了达尔文选择的三种机制：遗传性、类型的变异和生殖输出差异。一个RNA复制因子的适应性（其人均增长率）很可能是其内在适应能力的函数，由其核苷酸序列以及资源的可用性决定。三种主要的适应能力可能是：(1) 中等保真度的复制，在允许类型变异的同时增加遗传性；(2) 抗衰减能力；(3) 加工资源的获取。 这些能力将通过核苷酸序列产生的RNA复制因子的折叠构型来发挥作用。

==Experiments on the origin of life==

==Experiments on the origin of life==

Both Eigen and [[Sol Spiegelman]] demonstrated that evolution, including replication, variation, and [[natural selection]], can occur in populations of molecules as well as in organisms.<ref name="Follmann2009">{{cite journal |last1= Follmann |first1= Hartmut |last2= Brownson |first2= Carol |date= November 2009 |title= Darwin's warm little pond revisited: from molecules to the origin of life |journal= [[Naturwissenschaften]] |volume= 96 |issue= 11 |pages= 1265–1292 |bibcode= 2009NW.....96.1265F |pmid= 19760276 |doi= 10.1007/s00114-009-0602-1|s2cid= 23259886 }}</ref> Following on from chemical evolution came the initiation of [[Evolution|biological evolution]], which led to the first cells.<ref name="Follmann2009" /> No one has yet synthesized a "[[protocell]]" using simple components with the necessary properties of life (the so-called "[[Top-down and bottom-up design|bottom-up-approach]]"). Without such a proof-of-principle, explanations have tended to focus on [[chemosynthesis]].<ref>{{cite press release |last1= McCollom |first1= Thomas |last2= Mayhew |first2= Lisa |last3= Scott |first3= Jim |date= 7 October 2014 |title= NASA awards CU-Boulder-led team $7 million to study origins, evolution of life in universe |url= http://www.colorado.edu/news/releases/2014/10/07/nasa-awards-cu-boulder-led-team-7-million-study-origins-evolution-life |location= Boulder, CO |publisher= [[University of Colorado Boulder]] |accessdate= 2015-06-08 |url-status= dead |archiveurl= https://web.archive.org/web/20150731015530/http://www.colorado.edu/news/releases/2014/10/07/nasa-awards-cu-boulder-led-team-7-million-study-origins-evolution-life |archivedate= 31 July 2015}}</ref> However, some researchers work in this field, notably [[Steen Rasmussen (physicist)|Steen Rasmussen]] and  Szostak.

Both Eigen and [[Sol Spiegelman]] demonstrated that evolution, including replication, variation, and [[natural selection]], can occur in populations of molecules as well as in organisms.<ref name="Follmann2009">{{cite journal |last1= Follmann |first1= Hartmut |last2= Brownson |first2= Carol |date= November 2009 |title= Darwin's warm little pond revisited: from molecules to the origin of life |journal= [[Naturwissenschaften]] |volume= 96 |issue= 11 |pages= 1265–1292 |bibcode= 2009NW.....96.1265F |pmid= 19760276 |doi= 10.1007/s00114-009-0602-1|s2cid= 23259886 }}</ref> Following on from chemical evolution came the initiation of [[Evolution|biological evolution]], which led to the first cells.<ref name="Follmann2009" /> No one has yet synthesized a "[[protocell]]" using simple components with the necessary properties of life (the so-called "[[Top-down and bottom-up design|bottom-up-approach]]"). Without such a proof-of-principle, explanations have tended to focus on [[chemosynthesis]].<ref>{{cite press release |last1= McCollom |first1= Thomas |last2= Mayhew |first2= Lisa |last3= Scott |first3= Jim |date= 7 October 2014 |title= NASA awards CU-Boulder-led team $7 million to study origins, evolution of life in universe |url= http://www.colorado.edu/news/releases/2014/10/07/nasa-awards-cu-boulder-led-team-7-million-study-origins-evolution-life |location= Boulder, CO |publisher= [[University of Colorado Boulder]] |accessdate= 2015-06-08 |url-status= dead |archiveurl= https://web.archive.org/web/20150731015530/http://www.colorado.edu/news/releases/2014/10/07/nasa-awards-cu-boulder-led-team-7-million-study-origins-evolution-life |archivedate= 31 July 2015}}</ref> However, some researchers work in this field, notably [[Steen Rasmussen (physicist)|Steen Rasmussen]] and  Szostak.

Eigen和索尔-斯皮格尔曼Sol Spiegelman都证明了进化，包括复制、变异和自然选择，可以发生在分子群体中，也可以发生在生物体中。继化学进化之后，生物进化的开始，导致了第一个细胞的出现。目前还没有人用简单的成分合成一个具有生命必要特性的 "原始细胞"（所谓 "自下而上的方法"）。在没有这样的原理证明的情况下，解释往往集中在化学合成上。然而，一些研究者从事这一领域的研究，著名的有Steen Rasmussen和Szostak。

Eigen和索尔·斯皮格尔曼 Sol Spiegelman都证明了进化，包括复制、变异和自然选择，可以发生在分子群体中，也可以发生在生物群体中。继化学进化之后，是生物进化的开始，导致了第一个细胞的出现。目前还没有人用简单的成分合成一个具有必要生命特征的"原细胞"（所谓"自下而上的方法"）。在没有这样的原理证明的情况下，解释往往集中在化学合成上。然而，一些研究者从事这一领域的研究，著名的有斯蒂恩·拉斯穆森 Steen Rasmussen和Szostak。

Others have argued that a "[[Top-down and bottom-up design|top-down approach]]" is more feasible, starting with simple forms of current life. Spiegelman took advantage of natural selection to synthesize the [[Spiegelman Monster]], which had a genome with just 218 [[nucleotide]] bases, having deconstructively evolved from a 4500-base bacterial RNA. Eigen built on Spiegelman's work and produced a similar system further degraded to just 48 or 54 nucleotides—the minimum required for the binding of the replication enzyme.<ref name="EIG">{{cite journal|last1=Oehlenschläger|first1=Frank|last2=Eigen|first2=Manfred|authorlink2=Manfred Eigen|date=December 1997|title=30 Years Later – a New Approach to Sol Spiegelman's and Leslie Orgel's in vitro Evolutionary Studies Dedicated to Leslie Orgel on the occasion of his 70th birthday|journal=[[Origins of Life and Evolution of Biospheres]]|volume=27|issue=5–6|pages=437–457|doi=10.1023/A:1006501326129|pmid=9394469|bibcode=1997OLEB...27..437O|s2cid=26717033}}</ref> [[Craig Venter]] and others at [[J. Craig Venter Institute]] engineered existing prokaryotic cells with progressively fewer genes, attempting to discern at which point the most minimal requirements for life are reached.<ref>{{cite journal |last1= Gibson |first1= Daniel G.|last2= Glass |first2= John I. |last3= Lartigue |first3= Carole | last4 = Noskov | first4 = V.| last5 = Chuang | first5 = R.| last6 = Algire | first6 = M.| last7 = Benders | first7 = G.| last8 = Montague | first8 = M.| last9 = Ma | first9 = L.| last10 = Moodie | first10 = M.M.| last11 = Merryman | first11 = C.| last12 = Vashee | first12 = S.| last13 = Krishnakumar | first13 = R.| last14 = Assad-Garcia | first14 = N.| last15 = Andrews-Pfannkoch | first15 = C.| last16 = Denisova | first16 = E.A.| last17 = Young | first17 = L.| last18 = Qi | first18 = Z.-Q.| last19 = Segall-Shapiro | first19 = T.H.| last20 = Calvey | first20 = C.H.| last21 = Parmar | first21 = P.P.| last22 = Hutchison Ca | first22 = C.A.| last23 = Smith | first23 = H.O.| last24 = Venter | first24 = J.C. |display-authors= 3 |date= 2 July 2010 |title= Creation of a Bacterial Cell Controlled by a Chemically Synthesized Genome |journal= Science |volume= 329 |issue= 5987 |pages= 52–56 |bibcode= 2010Sci...329...52G |doi= 10.1126/science.1190719 |pmid= 20488990| citeseerx = 10.1.1.167.1455 |s2cid= 7320517}}</ref><ref>{{cite news |last= Swaby |first= Rachel |date= 20 May 2010 |title= Scientists Create First Self-Replicating Synthetic Life |url= https://www.wired.com/2010/05/scientists-create-first-self-replicating-synthetic-life-2/ |work= [[Wired (website)|Wired]] |location= New York |accessdate= 2015-06-08 |url-status= live |archiveurl= https://web.archive.org/web/20150617125555/http://www.wired.com/2010/05/scientists-create-first-self-replicating-synthetic-life-2/ |archivedate= 17 June 2015}}</ref><ref>Coughlan, Andy (2016) "Smallest ever genome comes to life: Humans built it but we don't know what a third of its genes actually do" (New Scientist 2 April 2016 No 3067)p.6</ref>

Others have argued that a "[[Top-down and bottom-up design|top-down approach]]" is more feasible, starting with simple forms of current life. Spiegelman took advantage of natural selection to synthesize the [[Spiegelman Monster]], which had a genome with just 218 [[nucleotide]] bases, having deconstructively evolved from a 4500-base bacterial RNA. Eigen built on Spiegelman's work and produced a similar system further degraded to just 48 or 54 nucleotides—the minimum required for the binding of the replication enzyme.<ref name="EIG">{{cite journal|last1=Oehlenschläger|first1=Frank|last2=Eigen|first2=Manfred|authorlink2=Manfred Eigen|date=December 1997|title=30 Years Later – a New Approach to Sol Spiegelman's and Leslie Orgel's in vitro Evolutionary Studies Dedicated to Leslie Orgel on the occasion of his 70th birthday|journal=[[Origins of Life and Evolution of Biospheres]]|volume=27|issue=5–6|pages=437–457|doi=10.1023/A:1006501326129|pmid=9394469|bibcode=1997OLEB...27..437O|s2cid=26717033}}</ref> [[Craig Venter]] and others at [[J. Craig Venter Institute]] engineered existing prokaryotic cells with progressively fewer genes, attempting to discern at which point the most minimal requirements for life are reached.<ref>{{cite journal |last1= Gibson |first1= Daniel G.|last2= Glass |first2= John I. |last3= Lartigue |first3= Carole | last4 = Noskov | first4 = V.| last5 = Chuang | first5 = R.| last6 = Algire | first6 = M.| last7 = Benders | first7 = G.| last8 = Montague | first8 = M.| last9 = Ma | first9 = L.| last10 = Moodie | first10 = M.M.| last11 = Merryman | first11 = C.| last12 = Vashee | first12 = S.| last13 = Krishnakumar | first13 = R.| last14 = Assad-Garcia | first14 = N.| last15 = Andrews-Pfannkoch | first15 = C.| last16 = Denisova | first16 = E.A.| last17 = Young | first17 = L.| last18 = Qi | first18 = Z.-Q.| last19 = Segall-Shapiro | first19 = T.H.| last20 = Calvey | first20 = C.H.| last21 = Parmar | first21 = P.P.| last22 = Hutchison Ca | first22 = C.A.| last23 = Smith | first23 = H.O.| last24 = Venter | first24 = J.C. |display-authors= 3 |date= 2 July 2010 |title= Creation of a Bacterial Cell Controlled by a Chemically Synthesized Genome |journal= Science |volume= 329 |issue= 5987 |pages= 52–56 |bibcode= 2010Sci...329...52G |doi= 10.1126/science.1190719 |pmid= 20488990| citeseerx = 10.1.1.167.1455 |s2cid= 7320517}}</ref><ref>{{cite news |last= Swaby |first= Rachel |date= 20 May 2010 |title= Scientists Create First Self-Replicating Synthetic Life |url= https://www.wired.com/2010/05/scientists-create-first-self-replicating-synthetic-life-2/ |work= [[Wired (website)|Wired]] |location= New York |accessdate= 2015-06-08 |url-status= live |archiveurl= https://web.archive.org/web/20150617125555/http://www.wired.com/2010/05/scientists-create-first-self-replicating-synthetic-life-2/ |archivedate= 17 June 2015}}</ref><ref>Coughlan, Andy (2016) "Smallest ever genome comes to life: Humans built it but we don't know what a third of its genes actually do" (New Scientist 2 April 2016 No 3067)p.6</ref>

另一些人则认为 "自上而下的方法 "更可行，从当前生命的简单形式开始。Spiegelman利用自然选择的优势合成了Spiegelman怪兽，它的基因组只有218个核苷酸碱基，是由4500个碱基的细菌RNA解构进化而来的。Eigen在Spiegelman的研究基础上，制造了一个类似的系统，该系统进一步降解为仅有48或54个核苷酸--这是复制酶结合所需的最低限度。J.Craig Venter研究所的Craig Venter等人对现有的原核细胞进行了基因逐渐减少的工程设计，试图分辨出在哪一点上达到了生命的最基本要求。

另一些人则认为"自上而下的方法"更可行，从当前生命的简单形式开始。Spiegelman利用自然选择的优势合成了Spiegelman怪兽，它的基因组只有218个核苷酸碱基，是由4500个碱基的细菌RNA解构进化而来的。Eigen在Spiegelman的研究基础上，制造了一个类似的系统，该系统进一步退化为仅有48或54个核苷酸——这是复制酶结合所需的最低限度。美国克雷格·文特尔研究所 J.Craig Venter研究所的克雷格·文特尔 Craig Venter等人对现有的原核细胞进行了基因逐渐减少的工程，试图分辨出在哪一点上达到了生命的最基本要求。

In October 2018, researchers at [[McMaster University]] announced the development of a new technology, called a ''[[Planet Simulator]]'', to help study the [[origin of life]] on planet [[Earth]] and beyond.<ref name="BW-20181004">{{cite news |last=Balch |first=Erica |title=Ground-breaking lab poised to unlock the mystery of the origins of life on Earth and beyond |url=https://brighterworld.mcmaster.ca/articles/ground-breaking-lab-poised-to-unlock-the-mystery-of-the-origins-of-life-on-earth-and-beyond/ |date=4 October 2018 |work=[[McMaster University]] |accessdate=4 October 2018 }}</ref><ref name="EA-20181004">{{cite news |author=Staff |title=Ground-breaking lab poised to unlock the mystery of the origins of life |url=https://www.eurekalert.org/pub_releases/2018-10/mu-glp100418.php |date=4 October 2018 |work=[[EurekAlert!]] |accessdate=14 October 2018 }}</ref><ref name="IVG-2018">{{cite web |author=Staff |title=Planet Simulator |url=https://www.intravisiongroup.com/planet-simulator |date=2018 |work=IntraVisionGroup.com |accessdate=14 October 2018 }}</ref><ref name="ES-209181014">{{cite web |last=Anderson |first=Paul Scott |title=New technology may help solve mystery of life's origins – How did life on Earth begin? A new technology, called Planet Simulator, might finally help solve the mystery. |url=http://earthsky.org/space/new-technology-solve-mystery-of-lifes-origins |date=14 October 2018 |work=[[EarthSky]] |accessdate=14 October 2018 }}</ref> It consists of a sophisticated climate chamber to study how the building blocks of life were assembled and how these prebiotic molecules transitioned into self-replicating RNA molecules.<ref name="BW-20181004"/>

In October 2018, researchers at [[McMaster University]] announced the development of a new technology, called a ''[[Planet Simulator]]'', to help study the [[origin of life]] on planet [[Earth]] and beyond.<ref name="BW-20181004">{{cite news |last=Balch |first=Erica |title=Ground-breaking lab poised to unlock the mystery of the origins of life on Earth and beyond |url=https://brighterworld.mcmaster.ca/articles/ground-breaking-lab-poised-to-unlock-the-mystery-of-the-origins-of-life-on-earth-and-beyond/ |date=4 October 2018 |work=[[McMaster University]] |accessdate=4 October 2018 }}</ref><ref name="EA-20181004">{{cite news |author=Staff |title=Ground-breaking lab poised to unlock the mystery of the origins of life |url=https://www.eurekalert.org/pub_releases/2018-10/mu-glp100418.php |date=4 October 2018 |work=[[EurekAlert!]] |accessdate=14 October 2018 }}</ref><ref name="IVG-2018">{{cite web |author=Staff |title=Planet Simulator |url=https://www.intravisiongroup.com/planet-simulator |date=2018 |work=IntraVisionGroup.com |accessdate=14 October 2018 }}</ref><ref name="ES-209181014">{{cite web |last=Anderson |first=Paul Scott |title=New technology may help solve mystery of life's origins – How did life on Earth begin? A new technology, called Planet Simulator, might finally help solve the mystery. |url=http://earthsky.org/space/new-technology-solve-mystery-of-lifes-origins |date=14 October 2018 |work=[[EarthSky]] |accessdate=14 October 2018 }}</ref> It consists of a sophisticated climate chamber to study how the building blocks of life were assembled and how these prebiotic molecules transitioned into self-replicating RNA molecules.<ref name="BW-20181004"/>

2018年10月，麦克马斯特大学的研究人员宣布开发出一种名为 "行星模拟器 "的新技术，以帮助研究地球及其他星球上生命的起源。它由一个复杂的气候室组成，以研究生命的构件是如何组装的，以及这些前生物分子如何过渡到自我复制的RNA分子。

2018年10月，麦克马斯特大学的研究人员宣布开发出一种名为"行星模拟器"的新技术，以帮助研究地球及其他星球上生命的起源。它由一个复杂的气候室组成，以研究生命的构件是如何组装的，以及这些前生物分子如何过渡到自我复制的RNA分子。

== See also ==

== See also ==

人类学原理--哲学前提，即所有的科学观察都预设了一个宇宙，与使这些观察得以实现的有意识生物的出现相适应。

人类学原理--哲学前提，即所有的科学观察都预设了一个宇宙，与使这些观察得以实现的有意识生物的出现相适应。

* {{annotated link|Artificial cell}} 人工细胞

* {{annotated link|Artificial cell}} 人工细胞

* {{annotated link|Artificial life}} Artificial life – A field of study wherein researchers examine systems related to natural life, its processes, and its evolution, through the use of simulations 人工生命--研究人员通过使用模拟技术，对与自然生命相关的系统、其过程和进化进行研究的一个研究领域。

* {{annotated link|Artificial life}} Artificial life – A field of study wherein researchers examine systems related to natural life, its processes, and its evolution, through the use of simulations 人工生命——研究人员通过使用模拟技术，对与自然生命相关的系统、其过程和进化进行研究的一个研究领域。

* {{annotated link|Bathybius haeckelii}}巴氏比目鱼

* {{annotated link|Bathybius haeckelii}}海克尔深水虫

* {{annotated link|Entropy and life}} 熵与生命

* {{annotated link|Entropy and life}} 熵与生命

* {{annotated link|Formamide-based prebiotic chemistry}} 基于甲酰胺的生命起源以前的化学

* {{annotated link|Formamide-based prebiotic chemistry}} 基于甲酰胺的生命起源以前的化学

* {{annotated link|GADV-protein world hypothesis}} GADV-蛋白世界假说

* {{annotated link|GADV-protein world hypothesis}} GADV-蛋白世界假说

* {{annotated link|Hemolithin}} Hemolithin – Protein claimed to be of extraterrestrial origin 卵磷脂 -- -- 据称来自外星的蛋白质。

* {{annotated link|Hemolithin}} Hemolithin – Protein claimed to be of extraterrestrial origin 血石蛋白——据称来自外星的蛋白质。

* {{annotated link|Hypothetical types of biochemistry}} Hypothetical types of biochemistry – Possible alternative biochemicals used by life forms 假设的生物化学类型----生命形式可能使用的替代性生物化学物。

* {{annotated link|Hypothetical types of biochemistry}} Hypothetical types of biochemistry – Possible alternative biochemicals used by life forms 假设的生物化学类型----生命形式可能使用的替代性生物化学物。

* {{annotated link|Mediocrity principle}} 平庸原则

* {{annotated link|Mediocrity principle}} 平庸原则

* {{annotated link|Nexus for Exoplanet System Science}} Nexus for Exoplanet System Science – Dedicated to the search for life on exoplanets 外行星系统科学联盟--致力于寻找外行星上的生命。

* {{annotated link|Nexus for Exoplanet System Science}} Nexus for Exoplanet System Science – Dedicated to the search for life on exoplanets 外行星系统科学联盟--致力于寻找外行星上的生命。

* {{annotated link|Noogenesis}} Noogenesis – Emergence and evolution of intelligence 新生代--智慧的出现和进化

* {{annotated link|Noogenesis}} Noogenesis – Emergence and evolution of intelligence 心理演化——智慧的出现和进化

* {{annotated link|Planetary habitability}} Planetary habitability – Extent to which a planet is suitable for life as we know it 行星宜居性--行星适合我们所知的生命的程度。

* {{annotated link|Planetary habitability}} Planetary habitability – Extent to which a planet is suitable for life as we know it 行星宜居性--行星适合我们所知的生命的程度。

* {{annotated link|Protocell}} Protocell – Lipid globule proposed as a precursor of living cells 原细胞--被认为是活细胞的前体的脂质球。

* {{annotated link|Protocell}} Protocell – Lipid globule proposed as a precursor of living cells 原细胞--被认为是活细胞的前体的脂质球。

* {{annotated link|Rare Earth hypothesis}} Rare Earth hypothesis – Hypothesis that complex extraterrestrial life is improbable and extremely rare 稀土假说--认为复杂的地外生命是不可能的，而且极其罕见的假说。

* {{annotated link|Rare Earth hypothesis}} Rare Earth hypothesis – Hypothesis that complex extraterrestrial life is improbable and extremely rare 地球罕见假说--认为复杂的地外生命是不大可能的，而且极其罕见的假说。

* {{annotated link|Shadow biosphere}} Shadow biosphere – A hypothetical microbial biosphere of Earth that would use radically different biochemical and molecular processes from that of currently known life 影子生物圈 -- -- 假设的地球微生物生物圈，将使用与目前已知生命完全不同的生化和分子过程。

* {{annotated link|Shadow biosphere}} Shadow biosphere – A hypothetical microbial biosphere of Earth that would use radically different biochemical and molecular processes from that of currently known life 影子生物圈 -- -- 假设的地球微生物生物圈，将使用与目前已知生命完全不同的生化和分子过程。

* {{annotated link|Tholin}} Tholin – Class of molecules formed by ultraviolet irradiation of organic compounds 噻唑啉--有机化合物经紫外线照射形成的一类分子。

* {{annotated link|Tholin}} Tholin – Class of molecules formed by ultraviolet irradiation of organic compounds 托林--有机化合物经紫外线照射形成的一类分子。

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