The Evolution of Reciprocity in Sizable Groups

Abstract Several lines of evidence suggest that sizable groups of people sometimes behave cooperatively, even in the absence of external sanctions against noncooperative behavior. For example, in many food foraging groups, game is shared among all members of the group regardless of who makes the kill (e.g., Kaplan and Hill, 1984; Lee, 1979; Damas, 1971). In many other stateless societies, men risk their lives in warfare with other groups (e.g., Meggit, 1977). There is also evidence that a great deal of cooperation takes place in contemporary state-level societies without external sanctions. For example, people contribute to charity, give blood, and vote—even though the effect of their own contributions on the welfare of the group is negligible. The groups benefiting are often very large and composed of very distantly related individuals. Perhaps the most dramatic examples of cooperation in contemporary societies are underground movements such as Poland’s Solidarity in which people cooperate to achieve a common goal in opposition to all of the power of the modern state (see Olson, 1971, 1982, and Hardin, 1982, for further examples.) Because of the anecdotal nature of these data, it is possible to doubt any particular example. However, psychologists and sociologists have also shown that people cooperate under carefully controlled laboratory conditions, albeit for smaller stakes.