A cue of kinship promotes cooperation for the public good

• Published in: Evolution and human behavior 2008, Vol.29 (1), p.49-55
• Main Authors: Krupp, Daniel Brian, Debruine, Lisa M, Barclay, Pat
• Format: Article
• Language: English
• Subjects: Cooperation; Cooperatives; Extended Family; Kinship; Kinship Networks; Lineage; Psychiatry; Public Goods; Social Behavior; Social behaviour; Social Networks; Social philosophy; Social theory; Tragedy of the commons
• ISSN: 1090-5138; 1879-0607
• DOI: 10.1016/j.evolhumbehav.2007.08.002

Abstract Relatedness is a cornerstone of the evolution of social behavior. In the human lineage, the existence of cooperative kin networks was likely a critical stepping stone in the evolution of modern social complexity. Here we report the results of the first experimental manipulation of a putative cue of human kinship (facial self-resemblance) among ostensible players in a variant of the “tragedy of the commons,” the one-shot public goods game, in which group-level cooperation—via contributions made to the public good and the punishment of free riders—is supported at a personal cost. In accordance with theoretical predictions, contributions increased as a function of the “kin density” of the group. Moreover, the distribution of punishment was not contingent on kin density level. Our findings indicate that the presence of a subtle cue of genealogical relatedness facilitates group cooperation, supporting the hypothesis that the mechanisms fostering contemporary sociality took root in extended family networks.