Rice, Risk, Cooperation, and Gene x Culture Co-evolution

To investigate how culture induced by the irrigation-intensive rice cultivation influences people’s risk taking and cooperative behavior, we make use of several individual choice tasks and behavioral games together with 1,104 university students recruited in Beijing. We find that cooperativeness proxied by the level of contribution in the public goods game varies positively with the proportion of rice cultivation in subjects’ birth province. This finding is mutually replicated in an independent study by Zhou, et al (2018). It is further corroborated by examining survey data relating to cooperativeness from the 26,000 strong China Family Panel Studies. At the same time, we find a positive relation between the proportion of rice cultivation in the birth province and risk taking. This latter finding renders a novel perspective to the reported East-West differentiation in risk attitude and cooperativeness in the extant literature. In conjunction with a collectivist culture, these findings point to an underlying social efficiency orientation in the East. We next report a genetic basis for both cooperativeness and risk taking. Specifically, the dopamine receptor D4 (DRD4) exon III coding region polymorphisms 2R genotypes are associated with increased cooperativeness as well as risk taking. Finally, we find evidence of a gene-culture coevolution across 11,000 years in favor of the 2R genotypes of DRD4 using province-level history on the introduction of rice farming in China.