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第821行： − + − In his "Thermodynamic Dissipation Theory of the Origin and Evolution of Life", 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.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 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，<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>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. − − 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。 − − − ===Protein amyloid=== − 淀粉样蛋白 − A new origin-of-life theory based on self-replicating beta-sheet structures has been put forward by Maury in 2009.<ref>{{cite journal | last1 = Maury | first1 = CP | year = 2009 | title = Self-proagating beta-sheet polypeptide structures as prebiotic informational entities:The amyloid world | journal = Origins of Life and Evolution of Biospheres | volume = 39 | issue = 2| pages = 141–150 | doi = 10.1007/s11084-009-9165-6 | pmid = 19301141 | s2cid = 20073536 }}</ref><ref>{{cite journal | last1 = Maury | first1 = CP | year = 2015 | title = Origin of Life.Primordial genetics: Information transfer in a pre-RNA world based on self-replicating beta-sheet amyloid conformers | journal = Journal of Theoretical Biology | volume = 382 | pages = 292–297 | doi = 10.1016/j.jtbi.2015.07.008 | pmid = 26196585 | doi-access = free }}</ref> The theory suggest that self-replicating and self-assembling catalytic [[amyloid]]s were the first informational polymers in a primitive pre-RNA world. The main arguments for the ''amyloid hypothesis'' is based on the structural stability, autocatalytic and catalytic properties, and evolvability of beta-sheet based informational systems. Such systems are also error correcting<ref>{{cite journal | last1 = Nanda | first1 = J | last2 = Rubinov | first2 = B | last3 = Ivnitski | first3 = D | last4 = Mukherjee | first4 = R | last5 = Shtelman | first5 = E | last6 = Motro | first6 = Y | last7 = Miller | first7 = Y | last8 = Wagner | first8 = N | last9 = Cohen-Luria | first9 = R | last10 = Ashkenasy | first10 = G | year = 2017 | title = Emergence of native peptide seuqences in prebiotic replication networks | journal = Nature Communications | volume = 8 | issue = 1| page = 343 | doi = 10.1038/s41467-017-00463-1 | pmid = 28874657 | pmc = 5585222 | bibcode = 2017NatCo...8..434N }}</ref> and [[chiroselective]].<ref>{{cite journal | last1 = Rout | first1 = SK | last2 = Friedmann | first2 = MP | last3 = Riek | first3 = R | last4 = Greenwald | first4 = J | year = 2018 | title = A prebiotic templated-directed synthesis based on amyloids | journal = Nature Communications | volume = 9 | issue = 1| pages = 234–242 | doi = 10.1038/s41467-017-02742-3 | pmid = 29339755 | pmc = 5770463 }}</ref> − − <!--Possible subsections to split off after enough content is added: evidence relating to the RNA world and the evolution of protein synthesis--> − − 2009年莫里 Maury提出了一种基于自复制β-片层结构的新的生命起源理论。该理论认为，自复制和自组装催化的淀粉样蛋白是原始的前RNA世界中的第一个信息聚合物。“淀粉样蛋白假说”的主要论据是基于β-片层为基础的信息系统的结构稳定性、自催化和催化性以及可进化性。这种系统还具有纠错性*英文缺失***和手性选择性。*** − − − === Fluctuating salinity: dilute and dry-down === − 变化的盐度：稀释和干涸。 + − 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 > − 非生物起源理论很少涉及哈罗德·布卢姆Harold Blum提出的警告：如果生命的关键信息元素——原核酸链——自发形成双螺旋结构，那么就没有办法将它们解离。+ + − 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>+ − 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.+ − + − + − 第一个在热循环过程中凝结底物的蛋白质：热合成作用 − − − − − − '''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. − + + − 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> − − 热合成假说则用不同的方法，认为在细胞呼吸和光合作用中起着必要作用的化学渗透的生物能量过程比发酵更基础：提出维持化学渗透的ATP合成酶是目前现存的与第一个代谢过程关系最密切的酶。 − − − 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 F<sub>1</sub> moiety in the F<sub>o</sub>F<sub>1</sub> [[ATP synthase]]. Note however that today's enzymes function during isothermal conditions, whereas the hypothetical first protein worked on and during thermal cycling. − − 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.+ − 通过对细胞膜脂质的磷酸化，这“第一种蛋白质”给含有该蛋白质的脂质原细胞带来了选择性优势。这种蛋白质还合成了一个由许多种蛋白质组成的库，其中只有一小部分具有热合成能力。正如Dyson提出的那样，它在功能上进行了传播：它制造了具有类似能力的子代，但它没有复制自己。有功能的子代由不同的氨基酸序列组成。 − 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.+ − 然而铁-硫世界确定的循环通路是最简单的，热合成假说甚至没有调用通路。ATP合成酶的结合变化机制类似于产生自由能的物理吸附过程，而不是减少自由能的普通的酶的机制，。 − 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>+ + − 在只需要一条保守的氨基酸残基的短序列的意义上，所述的第一种蛋白质可能是简单的，这条序列足以满足适当的催化裂隙。相反，有人声称，由于许多所需序列的长度，出现诸如发酵所需的蛋白质催化剂的循环系统是不可信的。+ − 讨论***可见，其实不同假说只是从不同角度考虑“生命的本质是xxx”这一问题*** − + − 前RNA世界:核糖问题和及其旁路+ + − 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，+ + + − + − 普遍接受的生物前核糖的合成，即甲醛聚糖反应，产生了许多没有任何选择性的糖类。+ − 他们得出结论，他们的+ − − 结果表明，第一种遗传物质的主干不可能含有核糖或其他糖类，因为它们不稳定。 − 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.+ − 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. − 虽然自组织和自复制的特征经常被认为是生命系统的标志，但有许多无生命分子在适当条件下表现出这种特征的实例。斯坦·帕拉塞克 Stan Palasek根据理论模型提出，核糖核酸分子（RNA）的自组装可以由于热液喷口的物理因素而自发地发生。病毒在宿主细胞内的自组装对生命起源的研究有启示，因为它进一步证实了生命可能是从自组装有机分子开始的假说。 − + − 病毒的起源 + − 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. − + + + − 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世界 − {{Main|RNA world}} − [[File:Jack-szostak.jpg|thumb|upright|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]].+ + − 已经提出了RNA的形成的许多假说。截至1994年，在解释核苷酸胞嘧啶和尿嘧啶的非生物合成方面还存在困难。随后的研究表明了可能的合成途径；例如，甲酰胺在各种陆地矿物质存在的情况下加热时可产生所有四种核糖核苷酸和其他生物分子。早期的细胞膜可能是由类蛋白自发形成的，类蛋白是氨基酸溶液在正确浓度的水溶液中加热时产生的蛋白质类分子。这些被视为形成微球体，观察到其行为类似于膜封闭的隔室。其他可能产生更复杂的有机分子的方法包括发生在粘土基质或矿物黄铁矿表面的化学反应。+ − 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> − 已经合成了相对较短的RNA分子，能够进行复制。这种复制酶RNA，既起密码，又起催化剂的作用，提供了自己的模板，可以在其上进行复制。Szostak已经证明，某些起催化作用的RNA可以将较小的RNA序列连接在一起，从而产生自复制的潜力。如果具备这些条件，Darwin的自然选择就会有利于这种自催化集的增殖，可以在其上添加进一步的功能。这种能够自我维持复制的RNA自催化系统已经被发现。RNA复制系统包括两个催化彼此的合成的核酶，产物的翻倍时间约为1小时，并且在实验中存在的条件下，受到自然选择的影响。在进化竞争实验中，这导致了新系统的出现，它们的复制效率更高。这是在分子遗传系统中发生进化适应的第一次证明。+ − 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。+ + + + + + + + +
→其他非生物起源的情景
===耗散结构中的有机颜料===
===耗散结构中的有机颜料===
在他的 "生命起源和进化的热力学耗散理论 Thermodynamic Dissipation Theory of the Origin and Evolution of Life "中，<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>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。<ref name="Michaelian, K. 2011"/><ref name="HESS Opinions 'Biological catalysis"/> 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。<ref>Sagan, C. (1973) Ultraviolet Selection Pressure on the Earliest Organisms, J. Theor. Biol., 39, 195–200.</ref> 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。<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> 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。<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> 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。<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>
***讨论：应该做一张图，标注这些理论试图解释的生命起源的时间段，以及瞄准的方面，看看理论之间是否自洽，如何互相联系，以及各自缺乏哪些方面的思考***
***讨论：应该做一张图，标注这些理论试图解释的生命起源的时间段，以及瞄准的方面，看看理论之间是否自洽，如何互相联系，以及各自缺乏哪些方面的思考***
关于生命起源的一些最困难的问题，如RNA和DNA的无酶复制，<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>基本分子的同手型，以及RNA和DNA中信息编码的起源，<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>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。
===淀粉样蛋白===
2009年莫里 Maury提出了一种基于自复制β-片层结构的新的生命起源理论。<ref>{{cite journal | last1 = Maury | first1 = CP | year = 2009 | title = Self-proagating beta-sheet polypeptide structures as prebiotic informational entities:The amyloid world | journal = Origins of Life and Evolution of Biospheres | volume = 39 | issue = 2| pages = 141–150 | doi = 10.1007/s11084-009-9165-6 | pmid = 19301141 | s2cid = 20073536 }}</ref><ref>{{cite journal | last1 = Maury | first1 = CP | year = 2015 | title = Origin of Life.Primordial genetics: Information transfer in a pre-RNA world based on self-replicating beta-sheet amyloid conformers | journal = Journal of Theoretical Biology | volume = 382 | pages = 292–297 | doi = 10.1016/j.jtbi.2015.07.008 | pmid = 26196585 | doi-access = free }}</ref>该理论认为，自复制和自组装催化的淀粉样蛋白是原始的前RNA世界中的第一个信息聚合物。“淀粉样蛋白假说”的主要论据是基于β-片层为基础的信息系统的结构稳定性、自催化和催化性以及可进化性。这种系统还具有纠错性<ref>{{cite journal | last1 = Nanda | first1 = J | last2 = Rubinov | first2 = B | last3 = Ivnitski | first3 = D | last4 = Mukherjee | first4 = R | last5 = Shtelman | first5 = E | last6 = Motro | first6 = Y | last7 = Miller | first7 = Y | last8 = Wagner | first8 = N | last9 = Cohen-Luria | first9 = R | last10 = Ashkenasy | first10 = G | year = 2017 | title = Emergence of native peptide seuqences in prebiotic replication networks | journal = Nature Communications | volume = 8 | issue = 1| page = 343 | doi = 10.1038/s41467-017-00463-1 | pmid = 28874657 | pmc = 5585222 | bibcode = 2017NatCo...8..434N }}</ref> 和手性选择性。<ref>{{cite journal | last1 = Rout | first1 = SK | last2 = Friedmann | first2 = MP | last3 = Riek | first3 = R | last4 = Greenwald | first4 = J | year = 2018 | title = A prebiotic templated-directed synthesis based on amyloids | journal = Nature Communications | volume = 9 | issue = 1| pages = 234–242 | doi = 10.1038/s41467-017-02742-3 | pmid = 29339755 | pmc = 5770463 }}</ref>
===变化的盐度：稀释和干涸 ===
非生物起源理论很少涉及哈罗德·布卢姆Harold Blum提出的警告：<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>如果生命的关键信息元素——原核酸链——自发形成双螺旋结构，那么就没有办法将它们解离。
<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.
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。
</blockquote>
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。<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>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，<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专门促进核酸<ref name="ReferenceB"/>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，<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>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。<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> 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。<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>
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。
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。
=== A first protein that condenses substrates during thermal cycling: thermosynthesis===
===第一个在热循环过程中凝结底物的蛋白质：热合成作用===
[[File:ConvectionCells.svg|thumb|upright=1.25|放置在重力场中的流体中的对流小室是自组织的，能够使流体中的悬浮物进行热循环，例如含有在热循环中起作用的原酶的原始细胞。]]
[[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.]]
放置在重力场中的流体中的对流小室是自组织的，能够使流体中的悬浮物进行热循环，例如含有在热循环中起作用的原酶的原始细胞。
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-辅酶A通路进行的，这两种通路都与原始的铁-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。
热合成假说则用不同的方法，认为在细胞呼吸和光合作用中起着必要作用的化学渗透的生物能量过程比发酵更基础：提出维持化学渗透的ATP合成酶是目前现存的与第一个代谢过程关系最密切的酶。<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>
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<sub>o</sub>F<sub>1</sub> ATP合成酶中的F<sub>1</sub>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。
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<sub>o</sub>F<sub>1</sub> ATP合成酶中的F<sub>1</sub>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。
热合成假说下的能量来源是热循环，是原细胞悬浮在对流中的结果，就像在火山热泉中一样是似可信的；对流说明了任何生命起源模型中所需要的自组织和耗散结构。热循环在发芽和细胞分裂中仍然无处不在的作用被认为是原始热合成的遗迹。
热合成假说下的能量来源是热循环，是原细胞悬浮在对流中的结果，就像在火山热泉中一样是似可信的；对流说明了任何生命起源模型中所需要的自组织和耗散结构。热循环在发芽和细胞分裂中仍然无处不在的作用被认为是原始热合成的遗迹。
通过对细胞膜脂质的磷酸化，这“第一种蛋白质”给含有该蛋白质的脂质原细胞带来了选择性优势。这种蛋白质还合成了一个由许多种蛋白质组成的库，其中只有一小部分具有热合成能力。正如Dyson提出的那样，<ref name="Dyson 1999" />它在功能上进行了传播：它制造了具有类似能力的子代，但它没有复制自己。有功能的子代由不同的氨基酸序列组成。
然而铁-硫世界确定的循环通路是最简单的，热合成假说甚至没有调用通路。ATP合成酶的结合变化机制类似于产生自由能的物理吸附过程，,<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> 而不是减少自由能的普通的酶的机制，。
在只需要一条保守的氨基酸残基的短序列的意义上，所述的第一种蛋白质可能是简单的，这条序列足以满足适当的催化裂隙。相反，有人声称，由于许多所需序列的长度，出现诸如发酵所需的蛋白质催化剂的循环系统是不可信的。<ref>{{harvnb|Orgel|1987|pp=9–16}}</ref>
讨论***可见，其实不同假说只是从不同角度考虑“生命的本质是xxx”这一问题***
=== 前RNA世界:核糖问题和及其旁路 ===
=== Pre-RNA world: The ribose issue and its bypass ===
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。<ref>{{cite journal |last=Orgel |first=Leslie E. |date=17 November 2000 |title=A Simpler Nucleic Acid |journal=Science |volume=290 |issue=5495 |pages=1306–1307 |doi=10.1126/science.290.5495.1306 |pmid=11185405|s2cid=83662769 }}</ref><ref>{{cite journal |last1=Nelson |first1=Kevin E. |last2=Levy |first2=Matthew |last3=Miller |first3=Stanley L. |date=11 April 2000 |title=Peptide nucleic acids rather than RNA may have been the first genetic molecule |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=97 |issue=8 |pages=3868–3871 |bibcode=2000PNAS...97.3868N |doi=10.1073/pnas.97.8.3868|pmc=18108 |pmid=10760258}}</ref>拉腊尔德 Larralde等人说，
<blockquote>
the generally accepted prebiotic synthesis of ribose, the formose reaction, yields numerous sugars without any selectivity.
普遍接受的生物前核糖的合成，即甲醛聚糖反应，产生了许多没有任何选择性的糖类。<ref>{{cite journal |last1=Larralde |first1=Rosa |last2=Robertson |first2=Michael P. |last3=Miller |first3=Stanley L. |date=29 August 1995 |title=Rates of Decomposition of Ribose and Other Sugars: Implications for Chemical Evolution |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=92 |issue=18 |pages=8158–8160 |bibcode=1995PNAS...92.8158L |doi=10.1073/pnas.92.18.8158 |pmc=41115 |pmid=7667262}}</ref>
</blockquote>
他们得出结论，他们的结果表明，
<blockquote>
the backbone of the first genetic material could not have contained ribose or other sugars because of their instability.
< blockquote >
第一种遗传物质的主干不可能含有核糖或其他糖类，因为它们不稳定。
</blockquote>
已知RNA中核糖和磷酸的酯连接容易发生水解。<ref>{{cite journal |last=Lindahl |first=Tomas |author-link=Tomas Lindahl |date=22 April 1993 |title=Instability and decay of the primary structure of DNA |journal=Nature |volume=362 |issue=6422 |pages=709–715 |bibcode=1993Natur.362..709L |doi=10.1038/362709a0|pmid=8469282|s2cid=4283694 }}</ref>
< blockquote >
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％。<ref>{{cite journal |last1=Anastasi |first1=Carole |last2=Crowe |first2=Michael A. |last3=Powner |first3=Matthew W. |last4=Sutherland |first4=John D. |date=18 September 2006 |title=Direct Assembly of Nucleoside Precursors from Two- and Three-Carbon Units |journal=Angewandte Chemie International Edition |volume=45 |issue=37 |pages=6176–6179 |doi=10.1002/anie.200601267|pmid=16917794}}</ref> 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。<ref>{{cite journal |last1=Powner |first1=Matthew W. |last2=Sutherland |first2=John D. |date=13 October 2008 |title=Potentially Prebiotic Synthesis of Pyrimidine β-D-Ribonucleotides by Photoanomerization/Hydrolysis of α-D-Cytidine-2'-Phosphate |journal=[[ChemBioChem]] |volume=9 |issue=15 |pages=2386–2387 |doi=10.1002/cbic.200800391 |pmid=18798212|s2cid=5704391 }}</ref>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。<ref name="pmid19444213">{{cite journal |last1=Powner |first1=Matthew W. |last2=Gerland |first2=Béatrice |last3=Sutherland |first3=John D. |date=14 May 2009 |title=Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions |journal=Nature |volume=459 |issue=7244 |pages=239–242 |bibcode=2009Natur.459..239P |doi=10.1038/nature08013 |pmid=19444213|s2cid=4412117 }}</ref>
***评论：不依赖模板链的RNA合成***
***评论：不依赖模板链的RNA合成***
===Viral origin===
===RNA结构===
虽然自组织和自复制的特征经常被认为是生命系统的标志，但有许多无生命分子在适当条件下表现出这种特征的实例。斯坦·帕拉塞克 Stan Palasek根据理论模型提出，核糖核酸分子（RNA）的自组装可以由于热液喷口的物理因素而自发地发生。<ref>{{cite arXiv |last=Palasek |first=Stan |eprint=1305.5581v1 |title=Primordial RNA Replication and Applications in PCR Technology |class=q-bio.BM |date=23 May 2013}}</ref>病毒在宿主细胞内的自组装对生命起源的研究有启示，<ref name="pmid16984643">{{cite journal |last1=Koonin |first1=Eugene V. |author-link=Eugene Koonin |last2=Senkevich |first2=Tatiana G. |last3=Dolja |first3=Valerian V. |date=19 September 2006 |title=The ancient Virus World and evolution of cells |journal=[[Biology Direct]] |volume=1 |page=29 |doi=10.1186/1745-6150-1-29 |pmc=1594570 |pmid=16984643}}</ref>因为它进一步证实了生命可能是从自组装有机分子开始的假说。<ref name="pmid16044244">{{cite journal |last1=Vlassov |first1=Alexander V. |last2=Kazakov |first2=Sergei A. |last3=Johnston |first3=Brian H. |last4=Landweber |first4=Laura F. |display-authors=3 |date=August 2005 |title=The RNA World on Ice: A New Scenario for the Emergence of RNA Information |journal=[[Journal of Molecular Evolution]] |volume=61 |issue=2 |pages=264–273 |doi=10.1007/s00239-004-0362-7 |pmid=16044244|bibcode=2005JMolE..61..264V |s2cid=21096886 }}</ref><ref>{{cite journal |last1=Nussinov |first1=Mark D. |last2=Otroshchenko |first2=Vladimir A. |last3=Santoli |first3=Salvatore |year=1997 |title=The emergence of the non-cellular phase of life on the fine-grained clayish particles of the early Earth's regolith |journal=[[BioSystems]] |volume=42 |issue=2–3 |pages=111–118 |doi=10.1016/S0303-2647(96)01699-1 |pmid=9184757}}</ref>
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。
===病毒的起源===
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。<ref name="Urbana–Champaign_pr">{{cite press release |last=Yates |first=Diana |date=25 September 2015 |title=Study adds to evidence that viruses are alive |url=https://news.illinois.edu/blog/view/6367/250879 |location=Champaign, IL |publisher=[[University of Illinois at Urbana–Champaign]] |access-date=2015-10-20 |url-status=live |archive-url=https://web.archive.org/web/20151119153226/https://news.illinois.edu/blog/view/6367/250879 |archive-date=19 November 2015}}</ref><ref name="ReferenceA">{{cite journal |doi=10.1089/ast.2018.1851 |title=The Need for Including Virus Detection Methods in Future Mars Missions |journal=Astrobiology |volume=18 |issue=12 |pages=1611–1614 |year=2018 |last1=Janjic |first1=Aleksandar |bibcode=2018AsBio..18.1611J }}</ref>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。<ref>{{cite journal |doi=10.1098/rstb.2012.0493 |pmid=23938747 |pmc=3758182 |title=Paleovirology: Inferring viral evolution from host genome sequence data |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |volume=368 |issue=1626 |page=20120493 |year=2013 |last1=Katzourakis |first1=A }}</ref>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。<ref name="Urbana–Champaign_pr" />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。"<ref>{{cite journal |last1=Arshan |first1=Nasir |last2=Caetano-Anollés |first2=Gustavo |date=25 September 2015 |title=A phylogenomic data-driven exploration of viral origins and evolution |journal=[[Science Advances]] |volume=1 |number=8 |page=e1500527 |doi=10.1126/sciadv.1500527 |pmid=26601271 |pmc=4643759 |bibcode=2015SciA....1E0527N }}</ref> 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。<ref name="Urbana–Champaign_pr" /><ref>{{cite journal |last1=Nasir |first1=Arshan |last2=Naeem |first2=Aisha |last3=Jawad Khan |first3=Muhammad |last4=Lopez-Nicora |first4=Horacio D. |last5=Caetano-Anollés |first5=Gustavo |display-authors=3 |date=December 2011 |title=Annotation of Protein Domains Reveals Remarkable Conservation in the Functional Make up of Proteomes Across Superkingdoms |journal=[[Genes (journal)|Genes]] |volume=2 |issue=4 |pages=869–911 |doi=10.3390/genes2040869 |pmc=3927607 |pmid=24710297}}</ref>
***讨论：那么和病毒最近源的细胞谱系是哪一支呢***
***讨论：那么和病毒最近源的细胞谱系是哪一支呢***
一个计算模型（2015）表明，病毒的衣壳可能起源于RNA世界，它们作为复制因子群体之间水平转移的工具，因为如果基因寄生虫的数量增加，这些群体就无法生存，某些基因负责这些结构的形成，而那些基因有利于自复制群体的生存。 这些祖先基因在细胞生物之间的位移可能有利于进化中新病毒的出现。病毒保留了从前生物阶段继承的复制模块，因为它在细胞中是不存在的。所以这是病毒可能起源于RNA世界的证据，也可能在进化中通过细胞中的遗传逃逸而多次出现。
一个计算模型（2015）表明，病毒的衣壳可能起源于RNA世界，它们作为复制因子群体之间水平转移的工具，因为如果基因寄生虫的数量增加，这些群体就无法生存，某些基因负责这些结构的形成，而那些基因有利于自复制群体的生存。<ref>{{cite journal | vauthors = Jalasvuori M, Mattila S, Hoikkala V | title = Chasing the Origin of Viruses: Capsid-Forming Genes as a Life-Saving Preadaptation within a Community of Early Replicators | journal = PLOS ONE | volume = 10 | issue = 5 | page = e0126094 | date = 2015 | pmid = 25955384 | pmc = 4425637 | doi = 10.1371/journal.pone.0126094 | bibcode = 2015PLoSO..1026094J }}</ref> 这些祖先基因在细胞生物之间的位移可能有利于进化中新病毒的出现。<ref name=Krupovic2019 >{{cite journal | vauthors = Krupovic M, Dolja VV, Koonin EV | s2cid = 169035711 | title = Origin of viruses: primordial replicators recruiting capsids from hosts | journal = Nature Reviews. Microbiology | volume = 17 | issue = 7 | pages = 449–458 | date = July 2019 | pmid = 31142823 | doi = 10.1038/s41579-019-0205-6 | url = https://hal-pasteur.archives-ouvertes.fr/pasteur-02557191/file/Krupovic_NRMICRO-19-022_MS_v3_clean.pdf }}</ref>病毒保留了从前生物阶段继承的复制模块，因为它在细胞中是不存在的。<ref name=Krupovic2019/>所以这是病毒可能起源于RNA世界的证据，也可能在进化中通过细胞中的遗传逃逸而多次出现。<ref name=Krupovic2019/>
***讨论：阮病毒的出现和某种“位移”或“逃逸”有关吗？这里所谓“从前生物阶段继承的复制模块”是什么呢？***
***讨论：阮病毒的出现和某种“位移”或“逃逸”有关吗？这里所谓“从前生物阶段继承的复制模块”是什么呢？***
=== RNA世界===
[[File:Jack-szostak.jpg|thumb|upright|杰克·绍斯塔克 Jack Szostak]]
已经提出了RNA的形成的许多假说。截至1994年，在解释核苷酸胞嘧啶和尿嘧啶的非生物合成方面还存在困难。<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>随后的研究表明了可能的合成途径；例如，甲酰胺在各种陆地矿物质存在的情况下加热时可产生所有四种核糖核苷酸和其他生物分子。<ref name="Saladino2012" /><ref name="Saladino2012b" />早期的细胞膜可能是由类蛋白自发形成的，类蛋白是氨基酸溶液在正确浓度的水溶液中加热时产生的蛋白质类分子。这些被视为形成微球体，观察到其行为类似于膜封闭的隔室。其他可能产生更复杂的有机分子的方法包括发生在粘土基质或矿物黄铁矿表面的化学反应。
支持RNA在早期生命中发挥重要作用的因素包括：它既能储存信息，又能催化化学反应（作为核酶）；它作为现代生物体内遗传信息（以DNA形式）表达和维持的中间体，发挥着许多重要作用；在近似于早期地球的条件下，至少RNA分子的成分容易化学合成。
支持RNA在早期生命中发挥重要作用的因素包括：它既能储存信息，又能催化化学反应（作为核酶）；它作为现代生物体内遗传信息（以DNA形式）表达和维持的中间体，发挥着许多重要作用；在近似于早期地球的条件下，至少RNA分子的成分容易化学合成。<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>
已经合成了相对较短的RNA分子，能够进行复制。<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>这种复制酶RNA，既起密码，又起催化剂的作用，提供了自己的模板，可以在其上进行复制。Szostak已经证明，某些起催化作用的RNA可以将较小的RNA序列连接在一起，从而产生自复制的潜力。如果具备这些条件，Darwin的自然选择就会有利于这种自催化集的增殖，可以在其上添加进一步的功能。<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> 这种能够自我维持复制的RNA自催化系统已经被发现。<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>RNA复制系统包括两个催化彼此的合成的核酶，产物的翻倍时间约为1小时，并且在实验中存在的条件下，受到自然选择的影响。<ref name="Joyce2009" />在进化竞争实验中，这导致了新系统的出现，它们的复制效率更高。<ref name="Robertson2012" /> 这是在分子遗传系统中发生进化适应的第一次证明。<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>
***讨论：就算我们最后提出了一种成功的生命起源机制，我们也很难证实地球生命真的是那样起源的***
***讨论：就算我们最后提出了一种成功的生命起源机制，我们也很难证实地球生命真的是那样起源的***
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。<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>三种主要的适应能力可能是：
# 中等保真度的复制，在允许类型变异的同时增加遗传性；
# 抗衰减能力；
# 加工资源的获取。<ref name="Bernstein" /><ref name="Michod 1999" />
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。
<br>
==Experiments on the origin of life==
==Experiments on the origin of life==