Human large-scale cooperation as a product of competition between cultural groups

This research investigates how humans evolved to cooperate with unrelated strangers in fleeting interactions. The study tests a key prediction of Cultural Group Selection (CGS) theory—that cooperation between groups correlates with cultural similarity. Researchers documented beliefs and cooperative tendencies among 759 individuals from nine clans within four Kenyan pastoral ethnic groups. Findings show that inter-group cooperation is predicted by cultural similarity, suggesting that cooperation norms evolved under the influence of group-level selection on cultural variation. This selection may explain humans' capacity for widespread cooperation, yet also its cultural limitations.

Carla Handley, Sarah Mathew