Abstract
To explain the evolutionary emergence of uniquely human skills and motivations for cooperation, Tomasello et al. (2012, in Current Anthropology 53(6):673-92) proposed the interdependence hypothesis. The key adaptive context in this account was the obligate collaborative foraging of early human adults. Hawkes (2014, in Human Nature 25(1):28-48), following Hrdy (Mothers and Others, Harvard University Press, 2009), provided an alternative account for the emergence of uniquely human cooperative skills in which the key was early human infants' attempts to solicit care and attention from adults in a cooperative breeding context. Here we attempt to reconcile these two accounts. Our composite account accepts Hrdy's and Hawkes's contention that the extremely early emergence of human infants' cooperative skills suggests an important role for cooperative breeding as adaptive context, perhaps in early Homo. But our account also insists that human cooperation goes well beyond these nascent skills to include such things as the communicative and cultural conventions, norms, and institutions created by later Homo and early modern humans to deal with adult problems of social coordination. As part of this account we hypothesize how each of the main stages of human ontogeny (infancy, childhood, adolescence) was transformed during evolution both by infants' cooperative skills "migrating up" in age and by adults' cooperative skills "migrating down" in age.