Xenophobia and disease

An interesting post at the Scientific American blog about the relationship between xenophobia and disease.
Do Wild Bats Hold the Key to Understanding Human Tribal Behavior?

(A) new fungus has arrived in North America, most likely via introduction by humans, and it is killing bats. This fungus (Geomyces destructans) causes “white nose syndrome,” which was first seen in the U.S. in New York in 2006. Where it met the bats, the fungus spread quickly among roosts, killing nearly all of the little brown bats and other bat species in each of the caves in which it appeared. 

But not all is lost. Although it looked as though the little brown bats and several other species might soon face extinction, at least in some regions and perhaps even in North America, the little brown bats have begun to rebound in some places, albeit modestly. A new paper out this week takes notice of one of the reasons they appear to be rebounding, the bats are avoiding each other. Little brown bats (at least historically) tend to roost in large, groups, one next to the other, bumping fuzzies as it were. But not anymore. More and more, this new study, led by Kate Langwig, a graduate student at Boston University, suggests, the bats are spreading themselves out in their roosting caves, their hibernacula. Once, they clumped, warming themselves around the tiny fires of their bodies. Now, they go it alone.

Interestingly, this little brown bat behavior is precisely what the literature on human behavior, xenophobia and tribalism would have predicted.