The stunning evolutionary success of Homo sapiens over the last 10,000 years has been based on our species’ capacity to sustain widespread cooperation among individuals who are not close genealogical kin. In this chapter, we will argue that the behavioral basis for cooperation is a set of predispositions for prosocial behavior that may be generally termed altruistic: Humans are predisposed to behave in ways that sometimes subordinate personal material gain on behalf of increasing the well-being of other group members, including those who are not close genealogical kin. Moreover, humans have a predisposition to punish selfish group members at a cost to themselves, even where no personal material long-run gain is forthcoming. Finally, humans have a predisposition to follow such moral rules as behaving honestly, truthfully, fairly, and charitably. These behavioral characteristics, unique to our species but with important precursors in other primates, explain the ubiquity and efficacy of cooperation in humans (Gintis, Bowles, Boyd, & Fehr, 2005).