Rules, preferences and evolutionfrom the family angle

This paper reviews the literature concerning the evolution ofcultural traits in general and preferences in particular, and theemergence and persistence of rules or norms, from a family per-spective. In models where each person is e§ectively the clone ofan existing one (either a parent or anyone else), there may beevolution only in the demographic sense that the share of thepopulation who hold a certain trait increases or decreases. Evo-lution in the strict sense of new traits making their appearanceoccurs in models where the trait characterizing any given mem-ber of any given generation is a combination of traits drawn atrandom from those represented in the previous generation. Pref-erences may be altruistic or non-altruistic, but individuals maybehave as if they were altruistic even if they are not, because arule or norm may make it in their interest to do so. Evolutionarystability and renegotiation proofness play analogous roles, theformer by selecting altruistic preferences, and the latter by se-lecting cooperation-inducing rules. The existence of populationgroups recognizable by outward characteristics like ethnicity orreligious practice may convey useful information regarding im-perfectly observable traits of direct interest to individuals, but itmay also lead individuals to judge others by their group member-ship rather than by their unobservable individual qualities, andthus to see them as possible foes.