Wednesday, June 11, 2008

A Landmark Scientific Finding, and Behe's Denial Hits a New Low

In his book The Edge of Evolution Michael Behe makes the argument that certain kinds of evolutionary change are beyond the ability of evolutionary mechanisms to accomplish. Behe argues that some of evolutionary history involves the development of traits that would require multiple mutations, and thus would be so unlikely to occur as to be dismissible. It is a probabilistic variation on his old argument from irreducible complexity.

Unfortunately, as with so much ID theorizing, it doesn't square with experimental evidence. One of the most important experiments in evolution, undertaken by Richard Lenski, which has been running now for over 20 years, revealed the evolution of a novel ability in bacteria (eating citrates), that required three mutations to occur. This happened in a way that IDers/creationists always dismiss from consideration: variation in genes which did not confer an advantage, and simply drifted through the population until later mutations combined with them to confer the observed advantage. So the next time you hear an evolution denier claim that every mutation in the link must convey an advantage in survival, you can reference this study in response. Another pillar of creationism destroyed by evidence. For detailed analyses of the study, go here, here, and here. This is scientific history.

For the comedy side of the issue, you can read Michael Behe's response. It is typical of IDer/creationist epistemology: do no research, and claim everyone elses' supports your position, even when, as in this case, it flat contradicts it. In evolutionary terms, this experiment involved a minute amount of time. 20 years of experiment is nothing in comparison to the 3+ billion year history of bacteria. Likewise, the population of bacteria in the experiment is, pardon the pun, microscopic compared to the entire world. Yet Behe has the audacity to say this:

"The major point Lenski emphasizes in the paper is the historical contingency of the new ability. It took trillions of cells and 30,000 generations to develop it, and only one of a dozen lines of cells did so. What’s more, Lenski carefully went back to cells from the same line he had frozen away after evolving for fewer generations and showed that, for the most part, only cells that had evolved at least 20,000 generations could give rise to the citrate-using mutation. From this he deduced that a previous, lucky mutation had arisen in the one line, a mutation which was needed before a second mutation could give rise to the new ability. The other lines of cells hadn’t acquired the first, necessary, lucky, “potentiating” (1) mutation, so they couldn’t go on to develop the second mutation that allows citrate use. Lenski argues this supports the view of the late Steven Jay Gould that evolution is quirky and full of contingency. Chance mutations can push the path of evolution one way or another, and if the “tape of life” on earth were re-wound, it’s very likely evolution would take a completely different path than it has. I think the results fit a lot more easily into the viewpoint of The Edge of Evolution."

He then goes on to reassert his now-disproved hypothesis as if this experimental evidence didn't exist. We have now proven two things in the evolution debate:

1) Traits can be created by evolutionary mechanisms, in both relatively short time and small population, even if one or more of those mutations did not confer a survival advantage.

2) Michael Behe will claim any and all experimental results support his hypothesis.

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