So this is the kind of news that one ought to be careful with now that everyone has had a chance to read the Black Swan.

It has probably more to do with genetic drift. You cannot stumble upon a tribe, take some random property they all share, and then make causal inferences from all the other properties they all share. This holds especially when this property correlates with survival of the tribe; it is actually more informative to investigate a group of people with properties that reduce survival, e.g. bad heart conditions.