Endogamy as a Basis for Ethnic Behavior *

In this article I argue for endogamy as a fundamental cause of human behavior that is often classified as ethnic. Specifically, I show that it would make evolutionary sense for people to help possible co-progenitors of their descendants. This suggests that in many situations people will help preferentially the minimal endogamous set of people to which they belong. Such help mostly will be restricted to providing benefits that are nearly “non-rival”—benefits that group members can “consume” without making others consume less. This (partial) explanation of pro-ethny behavior reconciles key points from various approaches to ethnicity and agrees with many empirical observations, such as the link between endogamy and ethnicity and the variability of criteria for ethnicity. This explanation yields predictions and explanations in a number of problematic areas; for example, it suggests that expansion of the marriage pool, often occurring as a result of urbanization, is a crucial factor in the transformation of local identities into nationalism.