I Blame the Parasites

The Economist has an article with a provocative sub-heading: “Religious diversity may be caused by disease.” The article refers to a recent scientific study suggesting that religious groups might form as a way of protecting their followers from exposure to diseases. The Economist summarizes the paper thus:

“[The] hypothesis is that in places where disease is rampant, it behoves groups not to mix with one another more than is strictly necessary, in order to reduce the risk of contagion. [The authors of the study] therefore predict that patterns of behaviour which promote group exclusivity will be stronger in disease-ridden areas. Since religious differences are certainly in that category, they specifically predict that the number of different religions in a place will vary with the disease load. Which is, as they report in the Proceedings of the Royal Society, the case.”

While there are numerous possible criticisms of this study, it could explain in part why I occasionally feel an urge to wash my hands after talking to a Southern Baptist. And as intuitively far-fetched as it sounds to propose that the development of religions might have been driven by parasites, ever since I read about Toxoplasma gondii on science writer Carl Zimmer’s blog, The Loom, I can’t put anything past parasites. (Seriously, if you’ve never heard of Toxoplasma gondii, click on that link and read. It might change the way you look at the world.)

(Via The Rough Guide to Evolution.)