The Ecological Origins of Collectivism and Individualism.

Interdependent subsistence styles, such as rice farming, are thought to underlie the evolution of collectivistic cultures, which emphasize collective welfare over individual gains. Rice farming can produce mutual dependence within communities but also create conflicting interests, as people cooperate to provide valuable public goods. However, current theories of the origins of collectivism fail to address the interplay between mutual dependence and conflict. As a consequence of these limitations, the evolutionary dynamics of collectivism and its association with cooperation are still unclear. We advance a theoretical model to study the evolution of cultural traits that enhance people's valuations of collective welfare, one of the key features of collectivistic cultures. Our model investigates the evolutionary dynamics of cooperation and cultural evolution in ecologies with distinct interdependence structures. We find evidence that higher degrees of mutual dependence facilitate the evolution and persistence of collectivism. However, the degree of conflicting interests also plays a crucial role in driving the diffusion and maintenance of collectivistic norms. In particular, the selective advantage of collectivism is strongest when people experience some degree of conflict of interests, an effect that is magnified by heightened mutual dependence. These results clarify how variation in interdependence could underlie the ecological origins of collectivism, lending support to and expanding the scope of current theories of the cultural evolution of cooperation. More broadly, the framework presented here elucidates how fitness interdependence can be influenced by different ecological factors, and, in turn, influence the evolution of social behaviors. (PsycInfo Database Record (c) 2026 APA, all rights reserved).