Kin selection and ethnic group selection

Ethnicity looks something like kinship on a larger scale. The same math can be used to measure genetic similarity within ethnic/racial groups and relatedness within families. For example, members of the same continental race are about as related (r = 0.18–0.26) as half-siblings (r = 0.25). However (contrary to some claims) the theory of kin selection does not apply straightforwardly to ethnicity, because inclusive fitness calculations based on Hamilton's rule break down when there are complicated social interactions within groups, and/or groups are large and long-lasting. A more promising approach is a theory of ethnic group selection, a special case of cultural group selection. An elementary model shows that the genetic assimilation of a socially enforced cultural regime can promote group solidarity and lead to the regulation of recruitment to groups, and to altruism between groups, based on genetic similarity – in short, to ethnic nepotism. Several lines of evidence, from historical population genetics and political psychology, are relevant here.     

Compensatory up-regulation of behavioral disease avoidance in immuno-compromised people with rheumatoid arthritis

Disgust and disease-related cues can activate the immune system. Here, we test whether immuno-suppression is associated with an up-regulation of cognitions and behaviors that assist in disease avoidance. People with rheumatoid arthritis (RA), who have a heightened risk of infection-related morbidity and mortality, were compared to age, gender and demographically matched healthy controls on a range of disease avoidance tasks. People with RA scored higher on reports of behavior likely to control infection, were more accurate in spotting individuals who were sick, and showed disease-specific ethnocentrism, ascribing a greater risk of contracting disease to non-Caucasians, although having no overall propensity for greater racism on the Modern Racism Scale. Contrary to predictions, disgust sensitivity (DS) did not differ between groups, however among people with RA, DS was found to be lower in those taking drugs that can increase infection risk. While more explicit disease avoidance behaviors are clearly up-regulated in people with RA, changes in DS may have a different and perhaps more biological casual basis.