Robert Boyd, Peter J Richerson

We present evidence that people in small-scale, mobile hunter-gatherer societies cooperated in large numbers to produce collective goods. Foragers engaged in large-scale communal hunts, constructed shared capital facilities; they made shared investments in improving the local environment; and they participated in warfare, alliance, and trade. Large-scale collective action often played a crucial role in subsistence. The provision of public goods involved the cooperation of many individuals, so each person made only a small contribution. This evidence suggests that large-scale cooperation occurred in the Pleistocene societies that encompass most of human evolutionary history, and therefore it is unlikely that large-scale cooperation in Holocene food producing societies results from an evolved psychology shaped only in small group interactions. Instead, large scale human cooperation needs to be explained as an adaptation, likely rooted in the distinctive features of human biology, grammatical language, increased cognitive ability, and cumulative cultural adaptation.