Bold Origin of Life Theory

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Bold Origin of Life Theory

Postby Timothy Chase » Fri Nov 03, 2006 12:37 am

Biology Direct has a genuine treat: an article by Koonin et al which argues for the view that viruses, prokaryotic and eukaryotic life evolved closely together, with life having originated in a strongly interconnected community of selfish genetic elements which existed prior to organic cells. The theory presented by the authors is quite detailed and incorporates a large body of recent observations. Moreover, it seems to complement the stepwise metabolic theory of House and Ferry.

Afterwards there is the give and take of discussion between several reviewers - including W. Ford Doolittle - and the primary author, where the discussion at several points touches upon the general nature of the scientific enterprise.

Let me strongly recommend:

The ancient Virus World and evolution of cells
Eugene V Koonin, Tatiana G Senkevich, and Valerian V Dolja
Biol Direct. 2006; 1: 29.
http://www.pubmedcentral.nih.gov/articl ... id=1594570

It is open access.
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Postby Secretary » Fri Nov 03, 2006 4:00 pm

Look up into the night sky and tell me what you see. Thousands of suns doing their thing. Look at them with a teleascope and the world opens up for you. The Hummble open the night sky like nothing ever seen by man.
Religion would have stopped with the teleascope by banning it, science does not.

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Postby Timothy Chase » Fri Nov 03, 2006 7:56 pm

Secretary wrote:Look up into the night sky and tell me what you see. Thousands of suns doing their thing. Look at them with a teleascope and the world opens up for you. The Hummble open the night sky like nothing ever seen by man.
Religion would have stopped with the teleascope by banning it, science does not.

Secretary
Afterlife2.org

[wiki]Non_sequitur_(absurdism)[/wiki].

Secretary wrote:Look up into the night sky...
http://bcseweb.org.uk/forum/viewtopic.php?p=1610#1610

Repetition.
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Re: Bold Origin of Life Theory

Postby Monad » Thu Nov 09, 2006 11:22 pm

Timothy Chase wrote:Biology Direct has a genuine treat: an article by Koonin et al which argues for the view that viruses, prokaryotic and eukaryotic life evolved closely together, with life having originated in a strongly interconnected community of selfish genetic elements which existed prior to organic cells. The theory presented by the authors is quite detailed and incorporates a large body of recent observations. Moreover, it seems to complement the stepwise metabolic theory of House and Ferry.

Afterwards there is the give and take of discussion between several reviewers - including W. Ford Doolittle - and the primary author, where the discussion at several points touches upon the general nature of the scientific enterprise.

Let me strongly recommend:

The ancient Virus World and evolution of cells
Eugene V Koonin, Tatiana G Senkevich, and Valerian V Dolja
Biol Direct. 2006; 1: 29.
http://www.pubmedcentral.nih.gov/articl ... id=1594570

It is open access.


Wow! I've long thought the old idea that viruses couldn't precede cellular life might be wrong:

http://www.iidb.org/vbb/showthread.php?t=152356

I must read this :)
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Re: Bold Origin of Life Theory

Postby Timothy Chase » Fri Nov 10, 2006 12:52 am

Monad wrote:Wow! I've long thought the old idea that viruses couldn't precede cellular life might be wrong:

http://www.iidb.org/vbb/showthread.php?t=152356

I must read this :)


I understand the feeling: I have read it several times, will undoubtedly read it several times more - and have already begun looking up the references and related work.

However, it wouldn't be entirely accurate to say that Koonin is suggesting that viruses preceeded cellular life. Rather, his view is that cellular life and viruses coevolved. It is quite possible that either metabolic life or replicators came first. This much is still a matter of considerable debate, but the "viral world" theory brings us much closer as does the stepwise metabolic theory of House and Ferry and numerous other developments, which we have dealt with or will be dealing with in the future. However, according to Koonin's views as expressed in the article, the original cells themselves may have been inorganic mineral formations - similar to the bubbled structure of pumace, I presume.

Thus an inorganic structure would have provided the compartmentalisation needed in order to concentrate chemical reactions which would have preceded modern cellular life. House and Ferry go into somewhat more depth along similar lines. Some minerals have structures which are the appropriate size. Then if one has the appropriate nutrients, this would provide the right sort of substrate for the replicators which would have been the ancestors for today's prokaryotic viruses (i.e., "bacteriophages," or simply "phages"). But at that point it is quite possible that there would have been little or no distinction between the genomes of prokaryotes and the viruses which infect them. Lateral gene transfer would have been rampant - at levels far greater than what we see today - giving rise to the often-symbiotic relationship which we see between viruses and bacteria which we see today, where various kinds of genomic islands (fitness, metabolic, etc.) would have driven the evolution of early bacteria.

Now one of the big questions of recent has been whether the RNA-world directly gave rise to the three branches of cellular life - archaea, prokaryotes and eukaryotes - or whether the RNA-world gave rise to a DNA-world prior to this branching. Koonin gives his reasons for believing that DNA preceded the branching. However, there is one other recent discovery which is presumably quite telling: the initiators for transcription which each of the three kingdoms makes use of share a fairly high degree of homology. Therefore this provides fairly strong, independent support for this conclusion.

Incidentally, I would strongly recommend looking into the work of House and Ferry. The simplest early metabolism proposed prior to their work involved 30 steps and fairly complex chemicals. Their work involves three steps, two enzymes, and three other chemicals: acetate, carbon monoxide and iron sulfide - if I remember correctly. Moreover, they suggest that the two enzymes may not have been necessary at the beginning - but could have simply increased the efficiency of a process which would have existed without them. The metabolism itself is one of several closed metabolic paths employed by an archaea today: the Methanosarcina acetivorans.
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