BEHAVIORAL AND BRAIN SCIENCES (2005) 28, 795–855 Printed in the United States of America “Economic man” in cross-cultural perspective: Behavioral experiments in 15 small-scale societies Joseph Henrich Jean Ensminger Department of Anthropology, Emory University, Atlanta, GA 30322. Division of Humanities and Social Sciences, Caltech, Pasadena, CA [email protected] 91125-7700. [email protected] Robert Boyd Natalie Smith Henrich Department of Anthropology, University of California, Los Angeles, Los ORC Macro, Atlanta, GA 30329. [email protected] Angeles, CA 90095. [email protected] Kim Hill Samuel Bowles Department of Anthropology, University of New Mexico, Albuquerque, NM Santa Fe Institute, Santa Fe, NM 87501, and Faculty of Economics, 87131-1086. [email protected] University of Siena, 53100 Siena, Italy. [email protected] Francisco Gil-White Colin Camerer Department of Psychology, University of Pennsylvania, Philadelphia, PA Division of Humanities and Social Sciences, Caltech, Pasadena, CA 91125. 19104-6196. [email protected] [email protected] Michael Gurven Ernst Fehr Department of Anthropology, University of California at Santa Barbara, Santa University of Zurich, CH-8006, Zurich, Switzerland. [email protected] Barbara, CA 93106. [email protected] Herbert Gintis Frank W. Marlowe Santa Fe Institute, Santa Fe, NM 87501, and Faculty of Economics, Central Department of Anthropology, Peabody Museum, Harvard University, European University, H-1051 Budapest, Hungary. [email protected] Cambridge, Massachusetts 02138. [email protected] Richard McElreath John Q. Patton Department of Anthropology, University of California, Davis, Davis, CA 95616. Department of Anthropology, California State University, Fullerton, Fullerton, [email protected] CA 92834-6846. [email protected] Michael Alvard David Tracer Department of Anthropology, Texas A&M University, College Station, TX Department of Anthropology and Health and Behavioral Sciences, University 77843-4352. [email protected] of Colorado at Denver, Denver, CO 80217. [email protected] Abigail Barr Centre for the Study of African Economies, University of Oxford, Oxford OX1 3UL, United Kingdom. [email protected] Abstract: Researchers from across the social sciences have found consistent deviations from the predictions of the canonical model of self-interest in hundreds of experiments from around the world. This research, however, cannot determine whether the uniformity re- sults from universal patterns of human behavior or from the limited cultural variation available among the university students used in virtually all prior experimental work. To address this, we undertook a cross-cultural study of behavior in ultimatum, public goods, and dictator games in a range of small-scale societies exhibiting a wide variety of economic and cultural conditions. We found, first, that the canonical model – based on self-interest – fails in all of the societies studied. Second, our data reveal substantially more behavioral vari- ability across social groups than has been found in previous research. Third, group-level differences in economic organization and the structure of social interactions explain a substantial portion of the behavioral variation across societies: the higher the degree of market integration and the higher the payoffs to cooperation in everyday life, the greater the level of prosociality expressed in experimental games. Fourth, the available individual-level economic and demographic variables do not consistently explain game behavior, either within or across groups. Fifth, in many cases experimental play appears to reflect the common interactional patterns of everyday life. Keywords: altruism; cooperation; cross-cultural research; experimental economics; game theory; ultimatum game; public goods game; self-interest © 2005 Cambridge University Press 0140-525X/05 $12.50 795 Henrich et al.: Economic behavior in cross-cultural perspective 1. Joseph Henrich is an Assistant Professor of An- the research analyzed in this target article. Gintis pub- thropology at Emory University. His work integrates the lished Game Theory Evolving (Princeton University construction of formal models of cultural evolution with Press, 2000) and is coeditor of Moral Sentiments and field methods that synthesize ethnographic and experi- Material Interests (MIT Press, 2005). He has published mental approaches, which have been deployed in the in the following journals, among others: Economic Jour- Peruvian Amazon, rural Chile, and Fiji. He has pub- nal, Quarterly Journal of Economics, Journal of Eco- lished in Nature, American Anthropologist, Current nomic Perspectives, American Economic Review, Jour- Anthropology, American Economic Review, American nal of Economic Literature, Journal of Theoretical Antiquity, and the Journal of Theoretical Biology. Hen- Biology, Theoretical Population Biology, Evolution & rich recently received the Presidential Early Career Human Behavior, Rationality & Society, Analyse & Kri- Award, the highest award bestowed by United States for tik, Theoretical Primatology, Journal of Economic Be- early career contributions. havior and Organization, and Nature. 2. Robert Boyd is Professor of Anthropology at 7. Richard McElreath is Assistant Professor of An- UCLA. Much of his research has been done in collab- thropology at University of California at Davis. His main oration P. J. Richerson and focuses on models of cul- interest is in the nature of social learning as an adapta- tural evolution. This work has been published in a wide tion. He has conducted fieldwork in East Africa, as well range of scientific journals; including Nature, PNAS, as developed analytical models of cultural evolution. His Current Anthropology, and the American Economic graduate textbook written with Robert Boyd, Modeling Review; in the Staley Prize winning book, Culture and the Evolution of Social Behavior: A Primer, is due out the Evolutionary Process; and in their recently pub- from University of Chicago Press in 2006. lished Not by Genes Alone: How Culture Transformed Human Evolution. Boyd has also co-authored an in- 8. Michael Alvard is an Associate Professor of An- troductory textbook in biological anthropology, How thropology at Texas A&M University, where he has Humans Evolved, with his wife, Joan Silk, now in its been on the faculty since 2000. He received his Ph.D. third edition. from the University of New Mexico in 1993. Alvard uses evolutionary theory to understand human social 3. Samuel Bowles (Ph.D., Economics, Harvard Uni- behavior. His recent work in Lamalera, Indonesia fo- versity) is Research Professor at the Santa Fe Institute cused on the problems associated with cooperation in where he heads the Behavioral Sciences Program and the context of big game hunting. His current interests Professor of Economics at the University of Siena. His include understanding the role of culture in evolu- research concerns the nature and evolution of social tionary context. preferences, the dynamics in society-level institutions, the evolution of economic inequality and political hier- 9. Abigail Barr is a researcher at the Centre for the archy, and policies to enhance equality of opportunity. Study of African Economies, University of Oxford (UK), His Microeconomics: Behavior, Institutions, and Evolu- a position she has held since 1997. She received her tion was published by Princeton University Press in D.Phil. in Economics from the University of Oxford. As 2004. a currently funded member of ESRC’s Global Poverty Research Group, she is researching the interaction be- 4. Colin Camerer has been Axline Professor of Busi- tween social factors – such as behavioral norms and so- ness Economics at Caltech (USA) since 1994. He re- cial networks, elements of formal institutional design, ceived his Ph.D. in decision theory from the University and economic outcomes in developing countries. of Chicago in 1981. He was elected a fellow of the Econometric Society and the American Academy of 10. Jean Ensminger is Professor of Anthropology and Arts and Sciences. In his research, Camerer employs ex- Division Chair for the Humanities and Social Sciences perimental and field data to inform behavioral econom- at California Institute of Technology, where she has ics, the creation of psychological foundations for eco- been since 2000. She received her Ph.D. in Anthropol- nomic theory. His most recent research concerns the ogy from Northwestern University. Her research is con- neural foundation of economic decisions, using fMRI, cerned with the political economy of Africa. Currently tracking eye movements and psychophysiological re- she is working on corruption and employing experi- sponses, and studies with brain-damaged patients and mental methods and social network analysis. other special populations. 11. Natalie Smith Henrich is an Adjunct Professor 5. Since 1994, Ernst Fehr has been professor of eco- in the Department of Anthropology at Emory Univer- nomics at the University of Zurich (Switzerland), where sity. Her research focuses on both the evolution of co- he is also the director of both the Institute for Empiri- operation and on the relationship between culture and cal Research in Economics and the Research Priority health outcomes. She has done ethnographic research Program on the “Foundations of Human Social Behav- in the Peruvian Amazon, among the Chaldeans in ior.” He has done research on the behavioral founda- metro-Detroit, and in Fiji. She