Cooperation in large-scale human societies—What, if anything, makes it unique, and how did it evolve?

Simon Powers (Edinburgh Napier University)

20 mai 2022, 11h30–12h30


Salle Auditorium 4


Understanding how large-scale human societies arose from small-scale ones and still continue to function is a central challenge in science. It raises the question of why individuals would continue to act in a prosocial manner, once they no longer interact mainly with kin or with other individuals that they know personally. This has led to major controversy in evolutionary biology around the extent to which prosocial behaviour in large-scale societies can be explained by (genetic) self-interest. Some researchers have argued that the reciprocity principle allows pro-social behaviour to be self-interested in societies of any size. Others have argued that reciprocity must break down as group size increases, and so pro-social behaviour cannot be self-interested and must be maintained by special mechanisms such as altruistic punishment or conformist social learning. To resolve this controversy, we propose that two questions need to be answered. First, how do social interactions in small-scale and large-scale societies differ? By reviewing the exchange and collective-action dilemmas in both small-scale and large-scale societies, we show they are not different. Second, are individual decision-making mechanisms driven by self-interest? We extract from the literature three types of individual decision-making mechanism, which differ in their social influence and sensitivity to self-interest, and conclude that humans interacting with non-relatives are largely driven by self-interest. We then ask: what was the key mechanism that allowed prosocial behaviors to continue as societies grew? We show the key role played by new institutions—changes in the rules of exchange and collective-action dilemmas. These rule changes are devised by the interacting individuals themselves, and allow for self-interested individuals to remain prosocial as societies grow.


Simon Powers (Edinburgh Napier University), « Cooperation in large-scale human societies—What, if anything, makes it unique, and how did it evolve? », IAST General Seminar, Toulouse : IAST, 20 mai 2022, 11h30–12h30, salle Auditorium 4.