Abstract

A core feature of human societies is that people often transfer resources to others. Such transfers can be governed by several different mechanisms, such as gift giving, communal sharing, or lottery-type arrangements. We present a simple model of the circumstances under which each of these three forms of transfer would be expected to evolve through direct fitness benefits. We show that in general, individuals should favor transferring some of their resources to others when there is a fitness payoff to having social partners and/or where there are costs to keeping control of resources. Our model thus integrates models of cooperation through interdependence with tolerated theft models of sharing. We also show, by extending the HAWK-DOVE model of animal conflict, that communal sharing can be an adaptive strategy where returns to consumption are diminishing and lottery-type arrangements can be adaptive where returns to consumption are increasing. We relate these findings to the observed diversity in human resource-transfer processes and preferences and discuss limitations of the model.