title: Collaboration encourages equal sharing in children but not in chimpanzees.
abstract: Humans actively share resources with one another to a much greater degree than do other great apes, and much human sharing is governed by social norms of fairness and equity. When in receipt of a windfall of resources, human children begin showing tendencies towards equitable distribution with others at five to seven years of age. Arguably, however, the primordial situation for human sharing of resources is that which follows cooperative activities such as collaborative foraging, when several individuals must share the spoils of their joint efforts. Here we show that children of around three years of age share with others much more equitably in collaborative activities than they do in either windfall or parallel-work situations. By contrast, one of humans' two nearest primate relatives, chimpanzees (Pan troglodytes), 'share' (make food available to another individual) just as often whether they have collaborated with them or not. This species difference raises the possibility that humans' tendency to distribute resources equitably may have its evolutionary roots in the sharing of spoils after collaborative efforts.
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, Department of Developmental and Comparative Psychology, Deutscher Platz 6, 04103 Leipzig, Germany. khamann@eva.mpg.de
authors.forename: Katharina
authors.initials: K
authors.lastname: Hamann
authors.forename: Felix
authors.initials: F
authors.lastname: Warneken
authors.forename: Julia R
authors.initials: JR
authors.lastname: Greenberg
authors.forename: Michael
authors.initials: M
authors.lastname: Tomasello
mesh_terms: D000367:Age Factors; D000818:Animals; D001522:Behavior, Animal; D005075:Biological Evolution; D002648:Child; D002675:Child, Preschool; D003299:Cooperative Behavior; D005502:Food; D006126:Group Processes; D006801:Humans; D008960:Models, Psychological; D002679:Pan troglodytes / Q000523:psychology*; D010988:Play and Playthings; D012201:Reward; D012935:Social Justice