oped parallel theories of cooperation—rational choice theory takes an individualistic approach while functionalism analyzes the prosocial aspects of institutions.

In this chapter we review the evolutionary theory relevant to the question of human cooperation and compare the results to other theoretical perspectives. Then we review some of our own work distilling a compound explanation that we believe gives a plausible account of human cooperation and selfishness. This account leans heavily on group selection on cultural variation but also includes lower level forces driven by both micro-prosocial and purely selfish motives. Next, we review the empirical literature in commons management. Although much work remains to be done on the problem, we conclude that the existing evidence is consistent with our account. Then, we use our hypothesis to derive lessons for applied research in institution building for commons management. On the one hand, the theory of cultural group selection suggests that humans have cooperative sentiments usually assumed to be absent in rational choice theories. On the other hand, the slow rate at which cooperative institutions evolve suggests that considerable friction will afflict our ability to grow up commons management institutions if they do not already exist and to readapt existing institutions to rapid technological and economic change. A better understanding of the way cooperative institutions arise in the long run promises better tools to foster their more rapid evolution when needed and to regulate their performance as necessary.

Our ideas about cooperation are drawn from many sources. Folk sources include diverse religious doctrines, norms and customs, and folk psychology. Anthropologists and historians document an immense diversity of human social organizations and most of these are accompanied by moral justifications, if often contested ones. Johnson and Earle (1987) provide a good introduction to the vast body of data collected by sociocultural anthropologists. The cross-cultural study of commons management is already a well-advanced field drawing on the disciplines of anthropology, political science, and economics (Agrawal, this volume:Chapter 2; Baland and Platteau, 1996; Bardhan and Dayton-Johnson, this volume:Chapter 3; Berkes, this volume:Chapter 9; McCay, this volume:Chapter 11; (Ostrom, 1998).

Human cooperation has a number of features begging explanation:

• Humans are prone to cooperate, even with strangers. Thus many people cooperate in anonymous one-shot prisoners’ dilemma (PD) games (Marwell and Ames, 1981), and often vote altruistically (Sears and Funk, 1990). People begin