Friday, February 10, 2012

Mooncalf Mooney

Chris Mooney touts himself as pro-science and pro-evolution. But, in an essay in the Huffington Post to promote his new book, he does evolution a disservice. One of the claims commonly leveled at evolutionary biologists by creationists is that they tell 'just-so stories'. That is, they pick a trait and create an often plausible argument about the selection environments that would favour the evolution of the trait. But, critically they do not demonstrate that such selection environments exist, that the trait in question is inherited, or that it does increase fitness.

The title of Mooney's piece is "Want to understand Republicans? First understand evolution", which is ironic because, in writing it, he shows that he does not have a good understanding of evolution. He argues that political preferences may stem from natural selection on the brain that leads to differential responses to aversive stimuli (such as negative, threatening or disgusting images). The speed and strength of these responses is correlated with political ideology. Mooney does provide some evidence that may (emphasis on the 'may') show that the brain differences leading to political preferences are genetically linked. 

Showing that traits can be inherited is necessary, but insufficient to demonstrate that the trait has or is undergoing adaptive evolutionary change. Without evidence that the trait results in differential reproductive success there is no good reason to conclude that evolution by natural selection is responsible for producing the trait. But, Mooney foolishly does. Jerry Coyne, of 'Why Evolution is True' fame, goes into more detail about Mooney's foolishness here.

Adaptationist is the technical term for someone who accepts plausible arguments alone as evidence for adaptation. Gould and Lewontin published an excellent critique of this way of thinking, which is freely available for download from here. By coincidence, there is also a couple of posts about adaptationism on Sandwalk, here and here.

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