3 Societal threat and cultural variation in the strength of social norms: An

The strengths of social norms vary considerably across cultures, yet little research has shown whether 30 such differences have an evolutionary basis. Integrating research in cross-cultural psychology with evo31 lutionary game theory, we show that groups that face a high degree of threat develop stronger norms for 32 organizing social interaction, with a higher degree of norm–adherence and higher punishment for devi33 ant behavior. Conversely, groups that have little threat can afford to have weaker norms with less pun34 ishment for deviance. Our results apply to two kinds of norms: norms of cooperation, in which 35 individuals must choose whether to cooperate (thereby benefitting everyone) or enrich themselves at 36 the expense of others; and norms of coordination, in which there are several equally good ways for indi37 viduals to coordinate their actions, but individuals need to agree on which way to coordinate. This is the