Van Vugt, M., & Park. J. (2008). The tribal instinct hypothesis: Evolution and the social psychology of intergroup relations. In S. Sturmer & M. Snyder, New Directions in Helping and Intergroup Behavior. London: Blackwell.
The social science literature abounds with examples of people’s tendency to categorize others on the basis of group membership and to preferentially help ingroup members over outgroup members. We argue that this is largely a product of an evolved psychology of intergroup relations, which we refer to as the tribal instinct hypothesis. Furthermore, we argue that tribal tendencies are more powerful among men than among women, which we refer to as the male warrior hypothesis. In this chapter, we outline the evolutionary history of the tribal instinct and male warrior psychology, and we review evidence consistent with these hypotheses. We also discuss implications of these hypotheses for managing real-world intergroup relations.