Saturday, April 08, 2006

Ken Willard, creationism, and the flow of sience

A source reports that when Ken Willard, of the Kansas Board of Ed., and Bob Corkins, the still under fire Commissioner of Ed., were visiting Pratt, Willard was asked about transitional species. WIllard was asked about his claim that there was no evidence for macroevolution, and whether feathered dinosaurs and fossil tetrapods didn't count.

My source reports that Willard explained that "he wasn't a biologist." WIllard is being challenged by Donna Viola (R), Jack Wempe (D), and as of yesterday, Republican folk artist M.T. Liggett.

Meanwhile, science moves forward.

In addition to Tikaalik, the newly described tetrapod transitional, scientists in Oregon have reconstructed an ancient protein, one shared by the ancestor of many animals. They showed how a complex interaction between two molecules in all modern bony animals could have evolved. Carl ZImmer explains more.

Is this a test of irreducible complexity? The authors put out a press release and other authors put out an accompanying commentary, both claiming it is. l I don't really know, because I'm not sure that the concept of irreducible complexity was ever coherent or well-defined.

Reading Michael Behe's testimony in Dover and his response to the paper just reinforces that view. In Dover, Behe acknowledged that IC isn't well enough defined to be used as an actual test of evolution. The famous Dover decision explains that

Professor Behe admitted in "Reply to My Critics" that there was a defect in his view of irreducible complexity because, while it purports to be a challenge to natural selection, it does not actually address "the task facing natural selection." Professor Behe specifically explained that "[t]he current definition puts the focus on removing a part from an already- functioning system," but "[t]he difficult task facing Darwinian evolution, however, would not be to remove parts from sophisticated pre-existing systems; it would be to bring together components to make a new system in the first place." In that article, Professor Behe wrote that he hoped to "repair this defect in future work;" however, he has failed to do so even four years after elucidating his defect.
The paper this week shows how a system in which a particular hormone binds to a particular receptor, and a different hormone binds to a different receptor, and each produces different responses, could have evolved.

Clearly, if you remove the receptor or the hormone from a modern human, the person would die. This meets the outlines of Behe's admittedly flawed definition. This doesn't stop Behe from claiming that "The authors (including Christoph Adami in his commentary) are conveniently defining 'irreducible complexity' way, way down. I certainly would not classify their system as IC." To defend this claim, he introduces new criteria without justifying the addition.

Let's, for the sake of argument, grant that something or other meets Behe's internal understanding of IC, even if he can't yet define that thing. He's trying to define what it would mean for something not to be evolvable, to meet Darwin's standard for a condition under which "my theory would absolutely break down": "any complex organ existed which could not possibly have formed by numerous, successive, slight modifications."

It's relatively easy to envision things which would meet that criterion but which don't exist (e.g., a four-legged horse with wings) but it's hard to find anything that even seems like a plausible candidate among existing phenomena. That says a lot right away.

It's hardly these authors fault that Behe's definition doesn't match what he intended. And even if we grant that this system isn't IC, it nicely demonstrates the ways that systems he claims are IC could have evolved.

In this case, the receptor evolved first as a generalized receptor for several similar hormones. The hormone they were studying wasn't even produced in those ancestors of modern bony species. A gene duplication allowed different copies of the gene to evolve higher specificities to different hormones, and when the new hormone came into use, the raw material was there to increase its specificity, too. It's easy to see how a blood clotting cascade (driven by a series of nearly identical genes) could have followed a similar path. The flagellum, which Behe holds out as another example, uses genes duplicated from other well-known pathways.

Of course, when those systems are better explained, Behe will simply whine that the definition of IC is inadequate, and the cycle will repeat itself.

It's worth pointing out that the research is interesting for non-creationist reasons. That it has some bearing on political arguments is nice, and perhaps got it into a more prominent journal. But the ability to reconstruct ancient proteins and the ability to evaluate how they would have evolved are both new opportunities and natural results of new technologies and analyses.