To scrounge or not to scrounge? Towards a unified theory of human food-sharing

Abstract While it is widely believed that human food-sharing behavior can be explained by the concurrent influence of tolerated scrounging, kin selection and reciprocal exchange, no theoretically unified set of predictions has ever been derived from these models. The present work develops such an integrated explanatory framework for the first time and shows that a pure scrounging equilibrium is the only evolutionarily stable outcome when the tolerated scrounging, kin selection and reciprocal exchange mechanisms simultaneously concur to determine food-sharing behavior. In the discussion section, I argue that the formal proof developed here invites extensive revision of theoretical claims put forward by evolutionary anthropologists in their study of human food sharing and cooperation.