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''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>

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>

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The phenomenon we call life defies a simple, one-sentence definition.<ref “Campbell”>{{cite book| last1 = Campbell | first1 = Neil A. |  last2 = Reece | first2 = Jane B.| year = 2005| edition = 7 | title = Biology | location= Sn Feancisco | publisher = Benjamin }}</ref>

''The phenomenon we call life defies a simple, one-sentence definition.<ref “Campbell”>{{cite book| last1 = Campbell | first1 = Neil A. |  last2 = Reece | first2 = Jane B.| year = 2005| edition = 7 | title = Biology | location= Sn Feancisco | publisher = Benjamin }}</ref>''

我们称之为生命的现象，不能用简单的一句话去定义。

''我们称之为生命的现象，不能用简单的一句话去定义。''

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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.''

现在越来越多的人或普遍认为，如果一个实体有能力进行三种基本的功能活动：新陈代谢、自我修复，和复制，那么它就被认为是“有生命的”。<ref “Casti”>{{cite book| last1 = Casti | first1 = John L. | year = 1989| title = Paradigms lost. Images of man in the mirror of science | location= New York | publisher = Morrow | bibcode = 1989plim.book.....C }}</ref>

''现在越来越多的人或普遍认为，如果一个实体有能力进行三种基本的功能活动：新陈代谢、自我修复，和复制，那么它就被认为是“有生命的”。<ref “Casti”>{{cite book| last1 = Casti | first1 = John L. | year = 1989| title = Paradigms lost. Images of man in the mirror of science | location= New York | publisher = Morrow | bibcode = 1989plim.book.....C }}</ref>''

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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. ''

由于生物体可能首先是在缺氧的环境中产生的，因此无氧发酵是从营养分子中获取能量的一种最简单、最原始的生物机制。  

''由于生物体可能首先是在缺氧的环境中产生的，因此无氧发酵是从营养分子中获取能量的一种最简单、最原始的生物机制。 ''

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发酵过程包括糖酵解，它非常低效地将糖的化学能转化为ATP的化学能。

发酵过程包括糖酵解，它非常低效地将糖的化学能转化为ATP的化学能。

====化学渗透====

====化学渗透====

[[File:ATP-Synthase.svg.png|thumb|upright|left|用化学渗透质子梯度描述ATP合成酶，通过氧化磷酸化为ATP合成供能。]]

[[File:ATP-Synthase.svg.png|thumb|upright|left|用化学渗透质子梯度描述ATP合成酶，通过氧化磷酸化为ATP合成供能。]]

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

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

尤金·库宁 Eugene Koonin 说，

尤金·库宁 Eugene Koonin 说，

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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.

''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.''

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。<ref name="pmc1892545">{{cite journal |last=Koonin |first=Eugene V. |date=31 May 2007 |title=The cosmological model of eternal inflation and the transition from chance to biological evolution in the history of life |journal=Biology Direct |volume=2 |page=15 |doi=10.1186/1745-6150-2-15 |pmc=1892545 |pmid=17540027}}</ref>

''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。<ref name="pmc1892545">{{cite journal |last=Koonin |first=Eugene V. |date=31 May 2007 |title=The cosmological model of eternal inflation and the transition from chance to biological evolution in the history of life |journal=Biology Direct |volume=2 |page=15 |doi=10.1186/1745-6150-2-15 |pmc=1892545 |pmid=17540027}}</ref>''

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霍夫曼 Hoffmann已经证明，早期容易出错的翻译机制可以稳定地抵御曾被设想为对生命起源有问题的那种错误灾难，被称为 "奥格尔悖论 Orgel's paradox"。<ref>{{cite journal |last=Hoffmann |first=Geoffrey W. |date=25 June 1974 |title=On the origin of the genetic code and the stability of the translation apparatus |journal=Journal of Molecular Biology |volume=86 |issue=2 |pages=349–362 |doi=10.1016/0022-2836(74)90024-2 |pmid=4414916}}</ref><ref>{{cite journal |last=Orgel |first=Leslie E. |date=April 1963 |title=The Maintenance of the Accuracy of Protein Synthesis and its Relevance to Ageing |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=49 |issue=4 |pages=517–521 |bibcode=1963PNAS...49..517O |doi=10.1073/pnas.49.4.517  |pmc=299893 |pmid=13940312}}</ref><ref>{{cite journal |last=Hoffmann |first=Geoffrey W. |title=The Stochastic Theory of the Origin of the Genetic Code |date=October 1975 |journal=Annual Review of Physical Chemistry|volume=26 |pages=123–144 |bibcode=1975ARPC...26..123H |doi=10.1146/annurev.pc.26.100175.001011 }}</ref>

霍夫曼 Hoffmann已经证明，早期容易出错的翻译机制可以稳定地抵御曾被设想为对生命起源有问题的那种错误灾难，被称为 "奥格尔悖论 Orgel's paradox"。<ref>{{cite journal |last=Hoffmann |first=Geoffrey W. |date=25 June 1974 |title=On the origin of the genetic code and the stability of the translation apparatus |journal=Journal of Molecular Biology |volume=86 |issue=2 |pages=349–362 |doi=10.1016/0022-2836(74)90024-2 |pmid=4414916}}</ref><ref>{{cite journal |last=Orgel |first=Leslie E. |date=April 1963 |title=The Maintenance of the Accuracy of Protein Synthesis and its Relevance to Ageing |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=49 |issue=4 |pages=517–521 |bibcode=1963PNAS...49..517O |doi=10.1073/pnas.49.4.517  |pmc=299893 |pmid=13940312}}</ref><ref>{{cite journal |last=Hoffmann |first=Geoffrey W. |title=The Stochastic Theory of the Origin of the Genetic Code |date=October 1975 |journal=Annual Review of Physical Chemistry|volume=26 |pages=123–144 |bibcode=1975ARPC...26..123H |doi=10.1146/annurev.pc.26.100175.001011 }}</ref>

====同手性====

====同手性====

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。<ref>Hazen, Robert M. (2005). Genesis: The Scientific Quest for Life's Origin. Washington, DC: Joseph Henry Press. ISBN 978-0-309-09432-0. LCCN 2005012839. OCLC 60321860.</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>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。<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>

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。<ref>Hazen, Robert M. (2005). Genesis: The Scientific Quest for Life's Origin. Washington, DC: Joseph Henry Press. ISBN 978-0-309-09432-0. LCCN 2005012839. OCLC 60321860.</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>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。<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>

===有第一颗恒星的早期宇宙===

===有第一颗恒星的早期宇宙===

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。<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}}</ref>

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。<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}}</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。"<ref>Davies, Paul (1999). The Fifth Miracle: The Search for the Origin of Life. London: Penguin Books. ISBN 978-0-14-028226-9.,p155</ref>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。<ref>Bock, Gregory R.; Goode, Jamie A., eds. (1996). Evolution of Hydrothermal Ecosystems on Earth (and Mars?). Ciba Foundation Symposium. 202. Chichester, UK; New York: John Wiley & Sons. ISBN 978-0-471-96509-1. LCCN 96031351.</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。"<ref>Davies, Paul (1999). The Fifth Miracle: The Search for the Origin of Life. London: Penguin Books. ISBN 978-0-14-028226-9.,p155</ref>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。<ref>Bock, Gregory R.; Goode, Jamie A., eds. (1996). Evolution of Hydrothermal Ecosystems on Earth (and Mars?). Ciba Foundation Symposium. 202. Chichester, UK; New York: John Wiley & Sons. ISBN 978-0-471-96509-1. LCCN 96031351.</ref>

== 生命的最早证据：古生物学==

== 生命的最早证据：古生物学==