Monday, January 25, 2010

Initial Evolution of Life Non-Darwinian??

Spock: "Well, its life, Jim, but not as we know it." New Scientist has an article on the evolution of early life in which it is posited by several researchers that this progressed in strikingly non-Darwinian fashion. Mark Buchanan writes:
JUST suppose that Darwin's ideas were only a part of the story of evolution. Suppose that a process he never wrote about, and never even imagined, has been controlling the evolution of life throughout most of the Earth's history. It may sound preposterous, but this is exactly what microbiologist Carl Woese and physicist Nigel Goldenfeld, both at the University of Illinois at Urbana-Champaign, believe. Darwin's explanation of evolution, they argue, even in its sophisticated modern form, applies only to a recent phase of life on Earth.
What is not so clear from the initial section of the article is that this applies to the microbiological world almost exclusively. The authors argue that, at an early stage of evolution, horizontal gene transfer was largely responsible for the genetic code being spread among all organisms:
"In some sense," says Woese, "the genetic code is a fossil or perhaps an echo of the origin of life, just as the cosmic microwave background is a sort of echo of the big bang. And its form points to a process very different from today's Darwinian evolution." For the researchers the conclusion is inescapable: the genetic code must have arisen in an earlier evolutionary phase dominated by horizontal gene transfer.
Given the behavior of viruses (H1N1 for example) in which genes are swapped between different viral strains and that of ERVs in which viral RNA is written into the DNA of living organisms, perhaps this is not as surprising as it sounds. The authors are quick to note that the vast majority of evolution is now Darwinian in nature but that we see evidence of how things may have started out. Read the whole thing.

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