People quasi-randomly assigned to farm rice are more collectivistic than people assigned to farm wheat.

The rice theory of culture argues that the high labor demands and interdependent irrigation networks of paddy rice farming makes cultures more collectivistic than wheat-farming cultures. Despite prior evidence, proving causality is difficult because people are not randomly assigned to farm rice. In this study, we take advantage of a unique time when the Chinese government quasi-randomly assigned people to farm rice or wheat in two state farms that are otherwise nearly identical. The rice farmers show less individualism, more loyalty/nepotism toward a friend over a stranger, and more relational thought style. These results rule out confounds in tests of the rice theory, such as temperature, latitude, and historical events. The differences suggest rice-wheat cultural differences can form in a single generation.