Study: evangelical Christians have smaller brains

No, this is not a report from The Onion. This is a real study, funded by the N.I.H. and the Templeton Foundation, and it found that mainline Protestants have larger brains than evangelicals, Roman Catholics and the “religiously unaffiliated.”

But why?

RNS reports:

Researchers speculate it may have something to do with the stress of belonging to a minority group. Chronic stress floods the brain with hormones that, over time, may damage the hippocampus.

Sociologists of religion, meanwhile, aren’t buying it. They say the researchers’ theory flies in the face of U.S. religious demographics. While it’s true that evangelicals are a minority, they’re a sizable one—40% of the U.S. population, according to Gallup Polls—and not exactly a stressed-out minority, especially in the South.

I’m not really buying that explanation, and sociologists aren’t either. I’m just waiting for one of them to suggest that it’s a self-selecting thing: dumb people are more likely to believe in the inerrancy of the Bible.

I, of course, would also disagree with that explanation (maybe out of self-defense). It’s not clear from the RNS article whether the researchers controlled for other demographics, but I would anticipate they did. That being said, what is the most accurate explanation for the disparity in the size of the hippocampus?