Researchers have long been puzzled by large societies in which
strangers routinely engage in voluntary acts of kindness and respect even though there is often an individual cost involved.
Evolutionary forces associated with kinship and reciprocity can explain such cooperative behavior among other primates, but the same isn't true for large societies of strangers.
A new study published today in Science suggests that the cooperative nature of each society may be explained in part by religious beliefs and the growth of market transactions. The study also found the extent to which a society uses punishment to enforce norms increases and decreases with the number of people in the society.
The researchers probed why communities often cooperate in diverse ways, from mutual defense to conservation. People engage in such mutually beneficial acts even though they may be individually costly.
Using behavioral experiments administered across 15 diverse populations, the study sought to measure the influence of three different mechanisms - punishment, market integration and religious beliefs - that might maintain cooperation within societies. Market integration is the extent to which individuals use anonymous, rule-governed transactions to buy and sell goods.
The researchers found that overt punishment, religious beliefs that can act as a form of psychological punishment and market integration each were correlated with fairness in the experiments.
"It is likely that small and large communities regulate cooperation - mutual defense, conservation, etc. - in different ways, because different mechanisms of monitoring and enforcement of norms work better at different scales of society," explained McElreath, an associate professor of anthropology at UC Davis.
"A small town in Kansas, for example, can likely rely upon reputation and the fact that everyone knows everyone else, while the residents of New York City need some mechanism, like punishment, that can work in the absence of reliable reputations," he said.
Citation: Henrich, et al., 'Markets, Religion, Community Size, and the Evolution of Fairness and Punishment', Science March 2010, 327(5972), 1480 - 1484; doi: 10.1126/science.1182238
