Horizontal and vertical: The evolution of evolution

New Scientist ^ | Jan 26, 2010 | Mark Buchanan

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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.

At the root of this idea is overwhelming recent evidence for horizontal gene transfer - in which organisms acquire genetic material "horizontally" from other organisms around them, rather than vertically from their parents or ancestors. The donor organisms may not even be the same species. This mechanism is already known to play a huge role in the evolution of microbial genomes, but its consequences have hardly been explored. According to Woese and Goldenfeld, they are profound, and horizontal gene transfer alters the evolutionary process itself. Since micro-organisms represented most of life on Earth for most of the time that life has existed - billions of years, in fact - the most ancient and prevalent form of evolution probably wasn't Darwinian at all, Woese and Goldenfeld say.

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As God is my witness I thought chickens could fly.

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