In a paper published today in Science, a team of biologists shows how a highly-complex molecular system can evolve. The lead author believes the data refutes the notion of “irreducible complexity,” one of the bulwarks of the “intelligent design” view; a leading proponent of intelligent design thinks otherwise (but he may have problems down the road). An article in today’s New York Times reports the story:
By reconstructing ancient genes from long-extinct animals, scientists have for the first time demonstrated the step-by-step progression of how evolution created a new piece of molecular machinery by reusing and modifying existing parts.
The researchers say the findings, published today in the journal Science, offer a counterargument to doubters of evolution who question how a progression of small changes could produce the intricate mechanisms found in living cells. * * *
Dr. Thornton said the experiment refutes the notion of “irreducible complexity” put forward by Michael J. Behe, a professor of biochemistry at Lehigh University.
Dr. Behe, a main advocate of intelligent design, the theory that life is so complicated that the best explanation is that it was designed by an intelligent being, has compared an irreducibly complex system to a mousetrap. Take away any piece, and the mousetrap fails to catch mice. Such all-or-none systems could not have arisen with incremental changes, Dr. Behe has argued.
Dr. Thornton said the key-and-lock mechanism of a hormone-receptor pair was “an elegant exemplar of a system that has been called irreducibly complex.”
“Of course,” he added, “our findings show that it is not irreducibly complex.”
Naturally, Michael Behe has a different view of the significance of the experimental results:
Dr. Behe described the results as “piddling.” . . .
What Dr. Thornton has shown, Dr. Behe said, falls within with incremental changes that he allows evolutionary processes can cause.
“Even if this works, and they haven’t shown that it does,” Dr. Behe said, “I wouldn’t have a problem with that. It doesn’t really show that much.”
Kenneth Chang, Study, in a First, Explains Evolution’s Molecular Advance, NY Times, Apr. 7, 2006.
The intelligent-design crowd has a bit of a problem. They’ve claimed that Systems X and Y and Z are irreducibly complex — that is, allegedly the systems could not have evolved by incremental changes. Typical examples cited by the IDers include the eye, the “molecular motor” found in the cilium, and the cellular protein transfer system.
But the IDers’ claims just give scientists all the more incentive to show how System X or Y or Z could indeed have evolved by incremental changes. Some scientists have taken it upon themselves to do just that; see the (excellent) Wikipedia article on Irreducible Complexity for a good summary.
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