...the strongest predictor of fairness was the community’s level of “market integration,” - measured by the percentage of the diet that was purchased. The people who got all or most of their food by hunting, fishing, foraging or growing it themselves were less inclined to share a prize equally....Markets don’t work very efficiently if everyone acts selfishly and believes everyone else will do the same...You end up with high transaction costs because you have to have all these protections to cover every loophole. But if you develop norms to be fair and trusting with people beyond your social sphere, that provides enormous economic advantages and allows a society to grow.The work he is summarizing is by Henrich et al. Their abstract:
Large-scale societies in which strangers regularly engage in mutually beneficial transactions are puzzling. The evolutionary mechanisms associated with kinship and reciprocity, which underpin much of primate sociality, do not readily extend to large unrelated groups. Theory suggests that the evolution of such societies may have required norms and institutions that sustain fairness in ephemeral exchanges. If that is true, then engagement in larger-scale institutions, such as markets and world religions, should be associated with greater fairness, and larger communities should punish unfairness more. Using three behavioral experiments administered across 15 diverse populations, we show that market integration (measured as the percentage of purchased calories) positively covaries with fairness while community size positively covaries with punishment. Participation in a world religion is associated with fairness, although not across all measures. These results suggest that modern prosociality is not solely the product of an innate psychology, but also reflects norms and institutions that have emerged over the course of human history.