Marlowe, F., J. C. Berbesque, A. Barr, C. Barrett, A. Bolyanatz, J. C. Cardenas, J. Ensminger, et al.More ‘altruistic’ punishment in larger societies.” Proceedings of the Royal Society B: Biological Sciences 275, no. 1634 (2008): 587-590.Abstract

If individuals will cooperate with cooperators, and punish non-cooperators even at a cost to themselves, then this strong reciprocity could minimize the cheating that undermines cooperation. Based upon numerous economic experiments, some have proposed that human cooperation is explained by strong reciprocity and norm enforcement. Second-party punishment is when you punish someone who defected on you; third-party punishment is when you punish someone who defected on someone else. Third-party punishment is an effective way to enforce the norms of strong reciprocity and promote cooperation. Here we present new results that expand on a previous report from a large cross-cultural project. This project has already shown that there is considerable cross-cultural variation in punishment and cooperation. Here we test the hypothesis that population size (and complexity) predicts the level of third-party punishment. Our results show that people in larger, more complex societies engage in significantly more third-party punishment than people in small-scale societies.

Gintis, H., J. Henrich, S. Bowles, R. Boyd, and E. Fehr. “Strong reciprocity and the roots of human morality.” Social Justice Research 21, no. 2 (2008): 241-253.Abstract

Human morality is a key evolutionary adaptation on which human social behavior has been based since the Pleistocene era. Ethical behavior is constitutive of human nature, we argue, and human morality is as important an adaptation as human cognition and speech. Ethical behavior, we assert, need not be a means toward personal gain. Because of our nature as moral beings, humans take pleasure in acting ethically and are pained when acting unethically. From an evolutionary viewpoint, we argue that ethical behavior was fitness-enhancing in the years marking the emergence of Homo sapiens because human groups with many altruists fared better than groups of selfish individuals, and the fitness losses sustained by altruists were more than compensated by the superior performance of the groups in which they congregated.

Henrich, J., and R. McElreath. “Dual Inheritance Theory: The Evolution of Human Cultural Capacities and Cultural Evolution.” In Oxford Handbook of Evolutionary Psychology, edited by Robin Dunbar and Louise Barrett, 555-570. Oxford: Oxford University Press, 2007. PDF
McElreath, R., and Henrich. J.Modelling cultural evolution.” In The Oxford Handbook of Evolutionary Psychology, edited by R.I.M. Dunbar and Louise Barrett, 571-585. Oxford: Oxford University Press, 2007. PDF
Why Humans Cooperate: A Cultural and Evolutionary Explanation
Henrich, N., and J. Henrich. Why Humans Cooperate: A Cultural and Evolutionary Explanation. New York: Oxford University Press, 2007. Publisher's VersionAbstract

Why Humans Cooperate takes a unique look at the evolution of human cooperation and tries to answer the question: why are people willing to help others at a cost to themselves? The book brings together evolutionary theories, economic experiments, and an anthropological case study that runs throughout the book to explain and illustrate human cooperation.

Using an evolutionary framework, Natalie and Joseph Henrich have expanded upon several diverse theories for explaining cooperative or ‘helpful’ behavior, and integrated them into a unified theory. Established concepts such as kin selection and reciprocity have been linked with theories on social learning and our evolved psychologies to explain the universality of human cooperation—as well as the distinctive ways in which cooperative behavior expresses itself in different cultures.

The theories developed in the book are brought to life by examining the Chaldeans of metropolitan Detroit. By exploring Chaldean cooperation, theoretical concepts are shown to translate into social behavior, and universal psychologies for cooperation lead to culturally-specific norms, beliefs, and practices. The book also introduces a series of economic experiments that help us understand why, when, and to what extent people are willing to help others. These experiments also highlight the variation in behaviors across cultural groups, even when all the groups rely on the same cognitive machinery and evolved psychologies. The merging of theory, experiments, and the Chaldean case study allows for an in-depth exploration of the origins and manifestations of cooperation.

Henrich, J.Cooperation, Punishment, and the Evolution of Human Institutions.” Science 312, no. 5770 (2006): 60-61. PDF
Henrich, J., R. McElreath, J. Ensminger, A. Barr, C. Barrett, A. Bolyanatz, J. C. Cardenas, et al.Costly Punishment Across Human Societies.” Science 312, no. 5781 (2006): 1767-1770. PDF Supplement News & Views in Science
Henrich, J., and N. Henrich. “Culture, evolution and the puzzle of human cooperation.” Cognitive Systems Research 7, no. 2 (2006): 220-245.Abstract

Synthesizing existing work from diverse disciplines, this paper introduces a culture-gene coevolutionary approach to human behavior and psychology, and applies it to the evolution of cooperation. After a general discussion of cooperation in humans, this paper summarizes Dual Inheritance Theory and shows how cultural transmission can be brought under the Darwinian umbrella in order to analyze how culture and genes coevolve and jointly influence human behavior and psychology. We then present a generally applicable mathematical characterization of the problem of cooperation. From a Dual Inheritance perspective, we review and discuss work on kinship, reciprocity, reputation, social norms, and ethnicity, and their application to solving the problem of cooperation. (c) 2006 Published by Elsevier B.V.

Hruschka, D., and J. Henrich. “Friendship, Cliquishness, and the Emergence of Cooperation.” Journal of Theoretical Biology 239, no. 1 (2006): 1-15. PDF
McCauley, R., and J. Henrich. “Susceptibility to the Muller-Lyer Illusion, Theory-Neutral Observation, and the Diachronic Penetrability of the Visual Input System.” Philosophical Psychology 19, no. 1 (2006): 79-101. PDF
Henrich, J.Understanding Cultural Evolutionary Models: A Reply to Read's Critique.” American Antiquity 71, no. 4 (2006). PDF
Silk, Joan B., Sarah F. Brosnan, Jennifer Vonk, Joseph Henrich, Daniel J. Povinelli, Amanda S. Richardson, Susan P. Lambeth, Jenny Mascaro, and Steven J. Shapiro. “Chimpanzees are indifferent to the welfare of unrelated group members.” Nature 437, no. 7063 (2005): 1357-1359. PDF
Henrich, J., R. Boyd, S. Bowles, C. Camerer, E. Fehr, H. Gintis, R. McElreath, et al."Economic man" in cross-cultural perspective: Behavioral experiments in 15 small-scale societies.” Behavioral and Brain Sciences 28, no. 6 (2005): 795-855.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 front around the world. This research, however, cannot determine whether the uniformity results 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 variability 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.

PDF Supplement
Henrich, J., R. Boyd, S. Bowles, C. Camerer, E. Fehr, H. Gintis, R. McElreath, et al.Models of decision-making and the coevolution of social preferences.” Behavioral and Brain Sciences 28, no. 6 (2005): 838-855.Abstract

We would like to thank the commentators for their generous comments, valuable insights and helpful suggestions. We begin this response by discussing the selfishness axiom and the importance of the preferences, beliefs, and constraints framework as away of modeling some of the proximate influences on human behavior. Next, we broaden the discussion to ultimate-level (that is evolutionary) explanations, where we review and clarify gene-culture coevolutionary theory, and then tackle the possibility that evolutionary approaches that exclude culture might be sufficient to explain the data. Finally, we consider various methodological and epistemological concerns expressed by our commentators.

Henrich, J., and N. Smith. “Comparative experimental evidence from Machiguenga, Mapuche, and American Populations.” In Foundations of Human Sociality: Economic experiments and ethnographic evidence from fifteen small-scale societies, edited by Joseph Henrich, Robert Boyd, Samuel Bowles, Herbert Gintis, Ernst Fehr, and Colin Camerer, 125-167. Oxford: Oxford University Press, 2004. PDF
Henrich, Joseph. “Cultural group selection, coevolutionary processes and large-scale cooperation.” Journal of Economic Behavior & Organization 53, no. 1 (2004): 85-88. PDF
Henrich, Joseph. “Demography and cultural evolution: how adaptive cultural processes can produce maladaptive losses: the Tasmanian case.” American Antiquity 69, no. 2 (2004): 197-214. PDF
Foundations of Human Sociality: Economic experiments and ethnographic evidence from fifteen small-scale societies
Henrich, J., R. Boyd, S. Bowles, C. Camerer, E. Fehr, and H. Gintis. Foundations of Human Sociality: Economic experiments and ethnographic evidence from fifteen small-scale societies. New York: Oxford University Press, 2004. Publisher's VersionAbstract

Over the last decade, research in experimental economics has emphatically falsified the textbook representation of Homo economicus. Literally hundreds of experiments suggest that people care not only about their own material payoffs, but they also care about such things as fairness and reciprocity. However, this research left a fundamental question remain unanswered: Are these non-selfish motives a stable aspect of human nature; or, are they substantially modulated economic, social and cultural environments? Prior to this book, the available experimental research could not begin to address this question because virtually all subjects had been university students, and while there are cultural differences among student populations throughout the world, these differences are small compared to the full range of human social and cultural environments. While a vast amount of ethnographic and historical research suggests that people's motives are influenced by the economic, social, and cultural environments, such methods,can only yield circumstantial evidence about human motives. As the longstanding disagreements within the cultural and historical disciplines attest, many different models of human action are consistent with the ethnographic and historical record.

In both testing the universally of previous findings, and in bridging the mythical chasm between ethnographic and experimental approaches, this volume deploys some of the principle experiments (which have been used to show non-selfish motives in university students) in combination with ethnographic data to explore the motives that underlie the diversity of human sociality. Twelve experienced field researchers performed the same experiments in fifteen small-scale societies exhibiting a wide variety of economic and cultural conditions. Our results can be summarized in five points: first, there is no society in which experimental behavior is consistent with the canonical model of rational self-interest; second there is much more variation between groups than has been previously reported; third, differences between societies in market integration and the importance of cooperation explain a substantial portion of the behavioral variation between groups; fourth, individual-level economic and demographic variables do not explain behavior within or across groups; fifth, experimental play often mirrors patterns of interaction found everyday life.

Henrich, J.Inequity Aversion in Capuchins?Nature 428, no. 6979 (2004): 139. PDF
Henrich, J., R. Boyd, Samuel Bowles, C. Camerer, E. Fehr, H. Gintis, and Richard McElreath. “Overview and Synthesis.” In Foundations of Human Sociality: Economic Experiments and Ethnographic Evidence from Fifteen Small-Scale Societies, edited by J. Henrich, R. Boyd, Samuel Bowles, C. Camerer, E. Fehr, and H. Gintis. New York: Oxford University Press, 2004. PDF