Societies use punishment as a tool to enforce norms in large populations

A society with a large number of people uses punishment to enforce norms, while the same does not hold true for societies with lower population, where everybody knows each other, claims a study.

The new study co-authored by University of California, Davis, anthropologist Richard McElreath suggests that the cooperative nature of each society is at least partly dependent upon historical forces - such as 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.

"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.

"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 added.

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.

The researchers used behavioural experiments administered across 15 diverse populations, and 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.

The study has been published in Science magazine.