Societies that contain widespread cooperation can solve problems of public good provision and resource conservation, yet many societies fail to display the cooperation necessary to solve these problems. A puzzle facing the social sciences is understanding the origin of cross-societal variation in cooperation. Strikingly, multiple disciplines propose the same, not yet established, explanation: ecological conditions, such as subsistence, environmental hazards, and relational mobility, determine how people are interdependent (i.e. how actions affect own and others’ outcomes), and interdependence can be the mechanism through which diverse ecologies shape a culture of cooperation. For example, rice versus wheat production plausibly has led to more versus less dependence on others, which then led to different cultures (e.g. values, beliefs, and norms) that affect strategies of when and how people cooperate. I use a multi-discipline, multi-method approach to answer three questions about whether ecologies indeed create different interdependence, and how this leads to variation in culture and cooperation.
Do ecologies create different kinds of interdependence? I measure the interdependence and cooperation people experience across different ecologies in 10 contemporary small-scale societies, among rice and wheat farmers in China, and in over 200 societies documented in the ethnographic record.
Can interdependence cause differences in culture and cooperation? I use agent-based models and experiments to study how variation in interdependence can cause different norms of cooperation.
Does variation in interdependence relate to culture and cooperation? I apply experience sampling to measure interdependence and cooperation in daily life across 35 societies that vary in culture.
