Chimpanzees play the ultimatum game

• Type of Material: Article
• Authors: Darby Proctor, Emory University; Rebecca A. Williamson, Emory University; Frans B M De Waal, Emory University; Sarah F. Brosnan, Georgia State University
• Language: English
• Date: 2013-02-05
• Publisher: National Academy of Sciences
• Publication Version: Final Published Version
• Copyright Statement: Copyright © 2019 National Academy of Sciences.
• Final Published Version (URL): http://dx.doi.org/10.1073/pnas.1220806110
• Title of Journal or Parent Work: Proceedings of the National Academy of Sciences
• ISSN: 0027-8424
• Volume: 110
• Issue: 6
• Start Page: 2070
• End Page: 2075
• Grant/Funding Information: At Yerkes, this work was supported by the Living Links Center; Emory’s College of Arts and Sciences; and the Base Grant of the National Center for Research Resources P51RR165 to the YNPRC, currently supported by Office of Research Infrastructure Programs OD P51OD11132.; Funding (to S.F.B.) was provided by National Science Foundation (NSF) Human and Social Dynamics Grants SES 0729244, NSF SES 1123897, and NSF CAREER Award SES 0847351.
• Keywords: Child; Game Theory; Play and Playthings; Biological Evolution; Humans; Animals; Social Behavior; Cooperative Behavior; Pan troglodytes; Reward; Choice Behavior
• Research Categories: Biology, Zoology; Psychology, Behavioral; Biology, Neuroscience

Abstract

Is the sense of fairness uniquely human? Human reactions to reward division are often studied by means of the ultimatum game, in which both partners need to agree on a distribution for both to receive rewards. Humans typically offer generous portions of the reward to their partner, a tendency our close primate relatives have thus far failed to show in experiments. Here we tested chimpanzees (Pan troglodytes) and human children on a modified ultimatum game. One individual chose between two tokens that, with their partner's cooperation, could be exchanged for rewards. One token offered equal rewards to both players, whereas the other token favored the chooser. Both apes and children responded like humans typically do. If their partner's cooperation was required, they split the rewards equally. However, with passive partners-a situation akin to the so-called dictator game-they preferred the selfish option. Thus, humans and chimpanzees show similar preferences regarding reward division, suggesting a long evolutionary history to the human sense of fairness.