Not So Selfish a Prescription for How Human Cooperation Evolved Will Provoke Much-Needed Debate About the Origins of Society, Finds Peter Richerson

A. RANTE/BARCROFT MEDIA Showing high levels of cooperation, whale hunters from Lamalera in Indonesia work together to spear a whale.

EVOLUTION Not so selfish A prescription for how human cooperation evolved will provoke much-needed debate about the origins of society, finds Peter Richerson.

umans are capable of remark- on ever larger scales. deters free-riding and sustains cooperation. able feats of cooperation. Warfare Darwin contended Bowles, Gintis and their colleagues have is an extreme example: when under that the primeval used games to probe the moral sentiments of Hattack, hundreds or even millions of people social emotions, more a range of societies in Africa, Indonesia and might join forces to provide a mutual defence. than natural selection, South America. They find that cultures vary In A Cooperative Species, economists Samuel drove the evolution of greatly in their social preferences. Nowhere Bowles and Herbert Gintis update their ideas civilization. do individuals, on average, act with complete on the evolutionary origins of altruism. Con- Around 1900, con- self-interest, but how much they will pay to taining new data and analysis, their book is cern with the Darwin- punish others varies. Moreover, the groups’ a sustained and detailed argument for how ian mechanisms of experimental behaviour correlates with that A Cooperative genes and culture have together shaped our evolution died out in Species: Human in the real world. Societies living in hamlets ability to cooperate. the emerging social Reciprocity and Its within tropical forests who cooperate little in Modern hunting and gathering societies sciences, shortly before Evolution real life also show little regard for the welfare offer clues as to how human cooperation the topic exploded in SAMUEL BOWLES AND of others in the games. By contrast, an Indo- evolved. They are typically organized into biology. Sociobiol- HERBERT GINTIS nesian society of whale hunters rates highest tribes of a few hundred to a few thousand ogist E. O. Wilson and Princeton University on strong reciprocity. Press: 2011. 288 pp. people. Each tribe is composed of smaller others resurrected $35, £24.95 The lack of completely selfish societies and bands of around 75 individuals united interest in the 1970s. the variability in strong reciprocity across dif- by bonds of kinship and friendship. Formal- Around the same time, ferent societies implies that the evolution of ized leadership is often weak, but cooperation geneticists Luigi Luca Cavalli-Sforza and cooperation involves both genes and culture. is buttressed by social norms and institutions, Marcus Feldman introduced the methods of The question is how the two systems inter- such as marriage, kinship and property rights. population genetics to the study of cultural acted during our evolutionary history. The tribal scale of social organization prob- evolution. A Cooperative Species attacks this problem ably evolved by the late Pleistocene (126,000– Bowles and Gintis seek to explain, as did theoretically and empirically. After intro- 11,700 years ago), or perhaps much earlier. Darwin, why humans have moral senti- ducing the mathematical models that have Human societies are diverse and com- ments. Most people care about the welfare been used to explain the evolution of social petitive, often violently so. Charles Darwin of others, even beyond kin and close associ- behaviour in humans and other animals, the conjectured in The Descent of Man (John ates. Economists use experimental games to authors caution that some are implausible. Murray, 1871) that the main evolutionary test the assumption that humans are self- For example, game theorists have discovered motor behind human cooperation was inter- interested actors, and often find it want- that these games have many solutions and dif- tribal competition, and suggested that coop- ing. Many participants show fairness and ferent groups might choose different rules to eration evolved in two stages. In ‘primeval’ cooperation, punishing those who behave govern and reward behaviour by negotiation times, well before the dawn of recorded his- selfishly. The term ‘strong reciprocity’ is among self-interested parties. Bowles and tory, our ancestors came under selection for used to describe the tendency of people to Gintis point out that the solution adopted by cooperative instincts, such as sympathy and sacrifice their own payoffs by rewarding a group emerges as a result of historical pro- group loyalty. In more recent ‘civilized’ times, or punishing others. Even in anonymous cesses and is hard to change by negotiation or laws and customs have fostered cooperation groups in the laboratory, strong reciprocity persuasion.

To illustrate how cooperative behaviour may have arisen, the authors build simple computer simulations of T. HOFFMAN T. Pleistocene human societies. Plausibly, they propose that the crucial step towards human social systems was the evolution of a cooperative unit that was big enough to insure against the risks involved in hunting large game, comprising around 32 adults plus juveniles and the elderly. Such bands, the authors argue, would have a modest amount of genetic variation between them. So, even if violent conflict between bands was common, group selection could not favour costly altruistic acts. Selection among groups for cooperation gains traction only where it exceeds that for selfishness within a group. Social institutions can reduce the advantages of selfish behaviour. For example, modern hunter-gatherers typically share their resources. More successful providers are ‘taxed’ in food to support the collective. This sharing limits variation in reproduc- Biochemist David Deamer poured chemicals into a hot pool in 2005 to see if primitive cells would form. tive success within groups, imposing selection on groups for individually costly acts ASTROBIOLOGY of cooperation. The authors’ modelling shows that other institutions — such as ostracism, coordinating punishment of defectors Life’s beginnings and restricting altruism to the local genetically related group — can have the same Robert Shapiro on a reminder that laboratory effects. They suggest that selection can experiments don’t always translate to nature. favour emotions such as shame or guilt that internalize social norms and benefit the group but cost the individual. n June 2005, an group of international demonstration that we Although A Cooperative Species is scientists clustered around a small, cannot translate lab broadly representative of the gene–culture near-boiling pool in a volcanic region results to natural set- co-evolutionary approach to human Iof Siberia. Biochemist David Deamer took tings is valuable. cooperation, I beg to differ on some a sample of the waters, then added to the Because we can get points. In my view, the critical late-Pleisto- pool a concoction of organic compounds reactions to work in cene groups in which altruism should be that probably existed 4 billion years ago the controlled condi- explained are the larger tribes composed on the early Earth. One was a fatty acid, a tions of a laboratory, of many bands. These have the crucial component of soap, which his laboratory he cautions, it does feature of substantial cooperation between studies suggested had a significant role in not follow that simi- First Life: genetically unrelated individuals, on the origin of life. Discovering the lar ones occurred on which the evolution of complex societies Over several days, Deamer took many Connections prebiotic Earth. We is based. Although bands do sometimes more samples. He wished to see whether between Stars, might overlook some- have violent conflicts, intratribal relations the chemical assembly process that he had Cells, and How Life thing that becomes are usually more peaceful than intertribal observed in his laboratory, which eventu- Began apparent when we try ones. In my opinion, the authors also ally produced complex ‘protocell’ structures, DAVID DEAMER to reproduce the reac- University of California accept too high a value for the genetic could also take place in a natural setting. Press: 2011. 288 pp. tions in a natural set- differences between neighbouring popu- The answer was a resounding no. The clays $28.95, £19.95 ting. This provocative lations in their simulations. However, and metal ions present in the Siberian pool insight explains why such a discussion illustrates the book’s blocked the chemical interactions. the origin-of-life field has been short on strength. By presenting clear models that This experiment was a reality check, progress over the past half century, whereas are tied tightly to empirically derived explains Deamer in First Life. He proposes molecular biology has flourished. parameters, Bowles and Gintis encour- in the book that the complex molecules Today, the simplest living cells depend on age much-needed debate on the origins that led to life developed not in ‘warm lit- molecules that are far more intricate than of human cooperation. ■ tle ponds’, but in tiny droplets bound by those that have been isolated from sources fatty acids. Although unrelated to life (abiotic), such as meteorites. Peter Richerson is professor emeritus in his account lacks the NATURE.COM The most noteworthy chemical substances the Department of Environmental Science tales of personal- For more on the in life are functioning polymers — large and Policy, University of California, ity and conflict that RNA-world molecules made of smaller units called Davis, California 95616, USA. enliven other works in hypothesis, see: monomers, connected in a specific order. e-mail: [email protected] astrobiology, Deamer’s go.nature.com/kuolyb The nucleic acids RNA and DNA, carriers of