Friday, September 25, 2009

Can life evolve backwards?

Science fiction writers have often played with the idea that life, under the right conditions, can evolve backward into an ancestral form. Biologists have been fascinated by this, too, but it's hard to test. Now an American scientific team has found a way to examine it on the molecular level, looking at the proteins and receptors needed to build a life form, and the answer is a qualified "no." Over time, "genetic blockades" develop that appear to forbid any backwards steps.
COMMENT: It's not clear, at least to me, whether this is a hard rule at the organism level - could an organism evolve ways around these blocks? It would no longer be precisely the ancestral organism, of course. Speculation is always fascinating...

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