Unpublished Manuscript

We here review the evolutionary theory relevant to the question of human cooperation and compare the results to other theoretical perspectives. Then, we will summarize 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-scale cooperation and purely selfish motives. We propose that innate aspects of our social psychology coevolved with group selected cultural institutions to produce just the kinds of social and moral faculties originally proposed by Darwin. We call this the “tribal social instincts” hypothesis. The account is systemic in the sense that human social systems are functionally differentiated, conflicted, and diverse. A successful explanation of human cooperation has to account for these complexities. For example, a tribal scale cultural group selection process alone cannot account for human patterns of cooperation because, on the one hand, much conflict exists within tribes and, on the other, people have proven able to organize cooperation on a much larger scale than tribes. We include multi-level selection and gene-culture coevolution effects to account for some of these complexities. We allude to some empirical tests of the resulting hypotheses. In particular, we argue that strong support for the tribal social instincts hypothesis comes from the structure of modern social institutions. These institutions have conspicuous “work-arounds” that shed light on the underlying instincts.