Tuesday, September 25, 2007

Here we go again...   posted by p-ter @ 9/25/2007 05:24:00 AM

I'm not going to spend too much time on this, but Larry Moran has responded to my post. He, of course, makes it sound as if he's being perfectly reasonable. But consider what he wrote in July:
[E]volutionary biologists like Dawkins and the other adaptationists should have known about random genetic drift. Isn't it amazing that they don't?
And compare with his new line:
There are many adaptationists who recognize that random genetic drift exists. They will, when pressed, admit that neutral alleles can be fixed in a population.
He goes on to dispute that his quotation from Dawkins was misleading. I obviously disagree, because I was misled! When Dawkins writes "If a whole-organism biologist sees a genetically determined difference among phenotypes, he already knows he cannot be dealing with neutrality in the sense of the modern controversy among biochemical geneticists", I assumed (as most readers likely did) that Dawkins was dogmatically asserting that absolutely no phenotypic change can be neutral. He wasn't, of course.

In any case, if Moran wants to define an "adaptationist" as someone who hypothesizes an adaptative force driving most phenotypic changes, then sure, Dawkins is probably an adaptationist, as am I and many reasonable biologists. Hypotheses have to be confirmed, of course, and "adaptationism" (tempered with knowledge of demographic forces) is a powerful hypothesis-generating machine. Keep in mind that one of Moran's "textbook examples" of neutral phenotypes is eye color. OCA2 (the major locus controlling eye color in humans) of course shows one of the strongest signals for selection in the human genome. I have hypotheses about why this is (could be an example of pleiotropy), but if you can just assert that eye color is a neutral character, why even bother?

UPDATE: Larry Moran claims the first of his quotes above was both ironic and sarcastic. Judge for yourself (in his favor, the claim is obviously wrong. in his disfavor, if you weren't familiar with Dawkins's writing, it wouldn't seem obviously wrong). Maybe he means ironic in the Canadian sense.