Today is Darwin’s birthday, so I thought I’d make one more evolutionary point related to The Believing Brain before I move on.

In that post I worried about facile evolutionary explanations of psychological traits.  At the site Why Evolution is True, Jerry Coyne takes on just such an explanation, based on an article about a forthcoming book, The Republican Brain by Chris Mooney.  The book’s thesis is that Republicans and Democrats have observable differences in brain structure, and these differences have a genetic component.  The author then pushes the theory into the world of evolution, and Coyne (who is a professor of evolutionary biology at the University of Chicago) will have none of it:

Mooney concludes, then, that liberals are a bunch of soft-nosed tree-huggers and bunny lovers, while conservatives are alert and wary, easy to perceive threat.  Where does the evolution come in? Because Mooney suggests that those differences, to the extent that they’re genetic, arose by natural selection.  Not only that, but “liberal” genes are less adaptive than “conservative ones”!:

The big question lying behind all this, of course, is why some people would have stronger and quicker responses than others to that which is perceived as negative and threatening (and disgusting). Or alternatively, why some people — liberals — would be less threat aversive than others. For as the University of Nebraska-Lincoln researchers note: “given the compelling evolutionary logic for organisms to be overly sensitive to aversive stimuli, it may be that those on the political left are more out of step with adaptive behaviors.”

“Compelling evolutionary logic,” of course, is not data: it’s just the perceived ability to make a convincing story. I could easily make a story about why it’s more adaptive for people to smile at bunnies than to frown at Bill Clinton: perhaps that is a byproduct of devotion to one’s children and family, which is also adaptive.  The point, though, is that we have no idea a priori which sort of behavior is or was adaptive in the evolutionary sense of conferring reproductive advantage, and absolutely no data on the reproductive output of liberals versus conservatives.

Science is more powerful than superstition, but you need to think clearly about it, and that often requires experts.  Of course, those alert and wary conservatives don’t have anything good to say nowadays about experts.