Ontogeny of prosocial behavior across diverse societies
- aDepartment of Anthropology, University of California, Los Angeles, CA 90024;
- bSchool of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85287;
- cDepartments of Psychology and Economics, University of British Columbia, Vancouver, BC, Canada V6T 1Z4;
- dDepartment of Anthropology, Washington State University, Vancouver, WA 98686;
- eDepartment of Anthropology, University of California, Davis, CA 95616; and
- fDepartment of Philosophy, University of Sheffield, Sheffield S3 7QB, United Kingdom
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Edited by Susan Gelman, University of Michigan, Ann Arbor, MI, and approved July 1, 2013 (received for review December 13, 2012)

Abstract
Humans are an exceptionally cooperative species, but there is substantial variation in the extent of cooperation across societies. Understanding the sources of this variability may provide insights about the forces that sustain cooperation. We examined the ontogeny of prosocial behavior by studying 326 children 3–14 y of age and 120 adults from six societies (age distributions varied across societies). These six societies span a wide range of extant human variation in culture, geography, and subsistence strategies, including foragers, herders, horticulturalists, and urban dwellers across the Americas, Oceania, and Africa. When delivering benefits to others was personally costly, rates of prosocial behavior dropped across all six societies as children approached middle childhood and then rates of prosociality diverged as children tracked toward the behavior of adults in their own societies. When prosocial acts did not require personal sacrifice, prosocial responses increased steadily as children matured with little variation in behavior across societies. Our results are consistent with theories emphasizing the importance of acquired cultural norms in shaping costly forms of cooperation and creating cross-cultural diversity.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: bailey.house{at}gmail.com.
Author contributions: B.R.H., J.B.S., J.H., H.C.B., and S.L. designed research; B.R.H., J.B.S., H.C.B., B.A.S., and A.H.B. performed research; B.R.H. and R.M. analyzed data; and B.R.H., J.B.S., J.H., H.C.B., B.A.S., A.H.B., B.S.H., R.M., and S.L. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
Data deposition: The data described in this paper is available on the website of the Culture and the Mind project, at http://www.philosophy.dept.shef.ac.uk/culture&mind/Data.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1221217110/-/DCSupplemental.