title: Young children, but not chimpanzees, are averse to disadvantageous and advantageous inequities.
abstract: The age at which young children show an aversion to inequitable resource distributions, especially those favoring themselves, is unclear. It is also unclear whether great apes, as humans' nearest evolutionary relatives, have an aversion to inequitable resource distributions at all. Using a common methodology across species and child ages, the current two studies found that 3- and 4-year-old children (N=64) not only objected when they received less than a collaborative partner but also sacrificed to equalize when they received more. They did neither of these things in a nonsocial situation, demonstrating the fundamental role of social comparison. In contrast, chimpanzees (N=9) showed no aversion to inequitable distributions, only a concern for maximizing their own resources, with no differences between social and nonsocial conditions. These results underscore the unique importance for humans, even early in ontogeny, for treating others fairly, presumably as a way of becoming a cooperative member of one's cultural group.
authors.affiliation: Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany. Electronic address: ulber@eva.mpg.de.
authors.forename: Julia
authors.initials: J
authors.lastname: Ulber
authors.affiliation: Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Hamann
authors.affiliation: Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany; Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Tomasello
mesh_terms: D000339:Affect; D000818:Animals; D005075:Biological Evolution; D002648:Child; D002652:Child Behavior / Q000523:psychology*; D002675:Child, Preschool; D003299:Cooperative Behavior; D005260:Female; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D002679:Pan troglodytes / Q000523:psychology*; D040841:Resource Allocation; D012201:Reward; D012919:Social Behavior
keywords: Cooperation; Fairness; Inequity aversion; Pan troglodytes; Resource allocation; Social context