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<blockquote>It seems reasonable that in order to discuss, much less discover, the '''Origin of life''' one must first answer the question, "What is [[Life]]?"  Yet, as discussed in the article, [[Life]], we should pose that question more coherently by asking, "What processes give rise to the activity of living?"  In searching for the origin of life, we need to search for the beginnings of the physico-chemical processes that we know underpin the activity of living and how those led to the first cells, the basic building blocks and working units of all living things. Indeed we must search for the characteristics of the cell &mdash; the last universal common ancestor cell &mdash; from which all current living things descended, remembering that that cell may have descended with modification from an earlier cell of different characteristics. Because we must work backward to a time nearly four billion years ago, we will find little in the way of remains to examine. We can hypothesize, and submit those hypotheses to existing knowledge of earth's early conditions and to experiments attempting to reproduce those conditions. We can narrow our hypotheses and search-paths by dissecting out the most basic and essential physico-chemical process common to all known living things &mdash; the universal biophysics<ref name=schneider05> Schneider ED, Sagan D (2005) ''Into the Cool: Energy Flow, Thermodynamics, and Life.'' Chicago: The University of Chicago Press. ISBN 0-226-73937-6 [http://www.intothecool.com/ Chapter Excerpts and Reviews]</ref> and biochemistry<ref name=pacepnas>[http://www.pnas.org/cgi/content/full/98/3/805 The universal nature of biochemistry, by Norman R. Pace]</ref> of living things &mdash; because as conserved core processes they have the greatest probability of embryonic status. We search for the origin of a system we recognize as living in virtue that it has the informational content and information-processing ability to remain in a near steady-state as a self-organized system of hierarchical robust modular biochemical networks, where the networks work autonomously in their own behalf, to offset responses to perturbations, and facilitate the system's reproducing itself.  We search for the origin of a system enabled by influx of energy and matter and by a more than compensatory efflux of waste (disorder), thereby sustaining and exploiting a state far from the equilibrium state of randomness. Finally, we search for the origin of a system capable, through its self-reproductive ability, of participating in the evolutionary processes<ref name=jablonkalamb>Jablonka E, Lamb MJ (2005) ''Evolution in Four Dimension: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life.'' Cambridge: The MIT Press</ref> that enable transgenerational evolution of the species to which it belongs in adapting to changing environments.</blockquote>.
It seems reasonable that in order to discuss, much less discover, the '''Origin of life''' one must first answer the question, "What is [[Life]]?"  Yet, as discussed in the article, [[Life]], we should pose that question more coherently by asking, "What processes give rise to the activity of living?"  In searching for the origin of life, we need to search for the beginnings of the physico-chemical processes that we know underpin the activity of living and how those led to the first cells, the basic building blocks and working units of all living things. Indeed we must search for the characteristics of the cell &mdash; the last universal common ancestor cell &mdash; from which all current living things descended, remembering that that cell may have descended with modification from an earlier cell of different characteristics. Because we must work backward to a time nearly four billion years ago, we will find little in the way of remains to examine. We can hypothesize, and submit those hypotheses to existing knowledge of earth's early conditions and to experiments attempting to reproduce those conditions. We can narrow our hypotheses and search-paths by dissecting out the most basic and essential physico-chemical process common to all known living things &mdash; the universal biophysics<ref name=schneider05> Schneider ED, Sagan D (2005) ''Into the Cool: Energy Flow, Thermodynamics, and Life.'' Chicago: The University of Chicago Press. ISBN 0-226-73937-6 [http://www.intothecool.com/ Chapter Excerpts and Reviews]</ref> and biochemistry<ref name=pacepnas>[http://www.pnas.org/cgi/content/full/98/3/805 The universal nature of biochemistry, by Norman R. Pace]</ref> of living things &mdash; because as conserved core processes they have the greatest probability of embryonic status. We search for the origin of a system we recognize as living in virtue that it has the informational content and information-processing ability to remain in a near steady-state as a self-organized system of hierarchical robust modular biochemical networks, where the networks work autonomously in their own behalf, to offset responses to perturbations, and facilitate the system's reproducing itself.  We search for the origin of a system enabled by influx of energy and matter and by a more than compensatory efflux of waste (disorder), thereby sustaining and exploiting a state far from the equilibrium state of randomness. Finally, we search for the origin of a system capable, through its self-reproductive ability, of participating in the evolutionary processes<ref name=jablonkalamb>Jablonka E, Lamb MJ (2005) ''Evolution in Four Dimension: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life.'' Cambridge: The MIT Press</ref> that enable transgenerational evolution of the species to which it belongs in adapting to changing environments.
 
==Origin of planet earth and its pre-biotic characteristics==
==Origin of planet earth and its pre-biotic characteristics==


Revision as of 05:02, 29 April 2007

It seems reasonable that in order to discuss, much less discover, the Origin of life one must first answer the question, "What is Life?" Yet, as discussed in the article, Life, we should pose that question more coherently by asking, "What processes give rise to the activity of living?" In searching for the origin of life, we need to search for the beginnings of the physico-chemical processes that we know underpin the activity of living and how those led to the first cells, the basic building blocks and working units of all living things. Indeed we must search for the characteristics of the cell — the last universal common ancestor cell — from which all current living things descended, remembering that that cell may have descended with modification from an earlier cell of different characteristics. Because we must work backward to a time nearly four billion years ago, we will find little in the way of remains to examine. We can hypothesize, and submit those hypotheses to existing knowledge of earth's early conditions and to experiments attempting to reproduce those conditions. We can narrow our hypotheses and search-paths by dissecting out the most basic and essential physico-chemical process common to all known living things — the universal biophysics[1] and biochemistry[2] of living things — because as conserved core processes they have the greatest probability of embryonic status. We search for the origin of a system we recognize as living in virtue that it has the informational content and information-processing ability to remain in a near steady-state as a self-organized system of hierarchical robust modular biochemical networks, where the networks work autonomously in their own behalf, to offset responses to perturbations, and facilitate the system's reproducing itself. We search for the origin of a system enabled by influx of energy and matter and by a more than compensatory efflux of waste (disorder), thereby sustaining and exploiting a state far from the equilibrium state of randomness. Finally, we search for the origin of a system capable, through its self-reproductive ability, of participating in the evolutionary processes[3] that enable transgenerational evolution of the species to which it belongs in adapting to changing environments.

Origin of planet earth and its pre-biotic characteristics

Pre-replicator chemical evolution

Pre-biotic pre-replicator chemical evolution as prelude to origin of living systems. See, for example:

Also:

  • Danchin 2007[7]

The first replicators

Sources of energy

Community metabolism

Coding for amino acids

The RNA World

Rampant horizontal gene transfer hypothesis

RNA to DNA transition

Emergence of Darwinian struggle

Emergence of cells

Oldest fossils

References

Citations

  1. ↑ Schneider ED, Sagan D (2005) Into the Cool: Energy Flow, Thermodynamics, and Life. Chicago: The University of Chicago Press. ISBN 0-226-73937-6 Chapter Excerpts and Reviews
  2. ↑ The universal nature of biochemistry, by Norman R. Pace
  3. ↑ Jablonka E, Lamb MJ (2005) Evolution in Four Dimension: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life. Cambridge: The MIT Press
  4. ↑ Dyson F (1982) A model for the origin of life. See Dyson (1982) J Mol Evol 18:344-350
  5. ↑ Post RL. (1990) The origin of homeostasis in the early earth. Journal of Molecular Evolution 31:257-64 Summary and Link to Full-Text.
  6. ↑ Galimov EM. (2004) Phenomenon of life: between equilibrium and non-linearity. Orig.Life Evol Biosph. 34:599-613.
  7. ↑ Danchin A, Fang G, Noria S. (2007) The extant core bacterial proteome is an archive of the origin of life. Proteomics 7:875-889 PMID 17370266
  8. ↑ Sayer RM. (2006) Self-organizing proto-replicators and the origin of life. Biosystems PMID 17014952
  9. ↑ Deamer D, Singaram S, Rajamani S, Kompanichenko V, Guggenheim S. (2006) Self-assembly processes in the prebiotic environment. Philos Trans R Soc Lond B Biol Sci 361:1809-1818 PMID 17008220
  10. ↑ Szathmary E. (2006) The origin of replicators and reproducers. Philos Trans R Soc Lond B Biol Sci 361:1761-1776 PMID 17008217
  11. ↑ Davies P. The FIFTH MIRACLE: The Search for the Origin and Meaning of Life (Paperback) Simon & Schuster ISBN-10: 068486309X ISBN-13: 978-0684863092

External links

Further reading

  • Forterre P (2006) Three RNA cells for ribosomal lineages and three DNA viruses to replicate their genomes: A hypothesis for the origin of cellular domain PNAS 103:3669-3674
  • Davies P. (2000) The Fifth Miracle: Search for the Origin and Meaning of Life. Simon & Schuster ISBN 978-0684863092
  • From The New York Times Book Review, by Lee Smolin: "If you are going to read only one book on the origin of life, seriously consider this one. From Scientific American: "His thesis is that 'the first terrestrial organisms lived deep underground, entombed within geothermally heated rocks in pressure-cooker conditions.' Davies also looks at the theories that life began by chemical assembly in a watery medium and that it came to the earth from space in the form of already viable microbes--the panspermia hypothesis.

See also

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