Theoretical origin of life; horizontal gene transfer (Introduction)

by dhw, Tuesday, September 12, 2017, 12:08 (255 days ago) @ David Turell

DAVID: A suggestion that HGT played a major role:

QUOTE: "The Last Universal Common Ancestor is dated to be about 3.8 billion years ago. The earth is 4.6 billion years old. Life went from zero to essentially the complexity of the modern cell in less than a billion years. In fact, probably a lot less: Since then, relatively little has happened in terms of the evolution of cellular architecture. So evolution was slow for the last 3.5 billion years, but very fast initially. Why did life evolve so fast?
"[The late biophysicist] Carl Woese and I felt that it was because it evolved in a different way. The way life evolves in the present era is through vertical descent: You give your genes to your children, they give their genes to your grandchildren, and so on. Horizontal gene transfer gives genes to an organism that’s not related to you. It happens today in bacteria and other organisms, with genes that aren’t really so essential to the structure of the cell.

I don’t think he’s trying to explain the origin of life at all – just the reason for evolution slowing down. It all makes perfect sense, and fits in with Margulis’s emphasis on cooperation as the key to evolution. Cells cooperated and merged to produce innovations, and initially the potential was enormous. But there has to be a limit somewhere, so the process slows down as the limit approaches. Of course we have no idea what that limit is, and for all we know, life might look very different a thousand million years from now. We are clearly going through a period of stasis. Great article! Thank you.

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