In-group loyalty or out-group avoidance? Isolating the links between pathogens and in-group assortative sociality.

The target article gives two explanations for the correlation between pathogens, family ties, and religiosity: one highlights the benefits of xenophobic attitudes for reducing pathogen exposure, the other highlights the benefits of ethnic loyalty for mitigating the costs when a person falls ill. Preliminary data from traditional societies provide some support for the former explanation but not the latter.