Jun 3, 2008

two decades in the evolving

Ed Brayton points us to a fascinating--and very, very patient--experiment:
If Stephen Jay Gould were alive today, he would be smiling. Maybe even gloating.

New research suggests that the famous evolutionary biologist was right when he argued that, if the evolution of life were “wound back” and played again from the start, it could have turned out very differently.

In experiments on bacteria grown in the lab, scientists found that evolving a new trait sometimes depended on previous, happenstance mutations. Without those earlier random mutations, the window of opportunity for the novel trait would never have opened. History might have been different....

Lenski's team watched 12 colonies of identical E. coli bacteria evolve under carefully controlled lab conditions for 20 years, which equates to more than 40,000 generations of bacteria. After every 500 generations, the researchers froze samples of bacteria. Those bacteria could later be thawed out to "replay" the evolutionary clock from that point in time.

After about 31,500 generations, one colony of bacteria evolved the novel ability to use a nutrient that E. coli normally can't absorb from its environment. Thawed-out samples from after the 20,000-generation mark were much more likely to re-evolve this trait than earlier samples, which suggests that an unnoticed mutation that occurred around the 20,000th generation enabled the microbes to later evolve the nutrient-absorption ability through a second mutation, the researchers report in the Proceedings of the National Academy of Sciences.
Remarkably, in roughly the same amount of time, creationism evolved into Intelligent Design by a similarly subtle mutation--though without much in the way of labwork.

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