"As Heine, Norenzayan, and Henrich furthered their search, they began to find research suggesting wide cultural differences almost everywhere they looked: in spatial reasoning, the way we infer the motivations of others, categorization, moral reasoning, the boundaries between the self and others, and other arenas. These differences, they believed, were not genetic. The distinct ways Americans and Machiguengans played the ultimatum game, for instance, wasn’t because they had differently evolved brains. Rather, Americans, without fully realizing it, were manifesting a psychological tendency shared with people in other industrialized countries that had been refined and handed down through thousands of generations in ever more complex market economies. When people are constantly doing business with strangers, it helps when they have the desire to go out of their way (with a lawsuit, a call to the Better Business Bureau, or a bad Yelp review) when they feel cheated. Because Machiguengan culture had a different history, their gut feeling about what was fair was distinctly their own. In the small-scale societies with a strong culture of gift-giving, yet another conception of fairness prevailed. There, generous financial offers were turned down because people’s minds had been shaped by a cultural norm that taught them that the acceptance of generous gifts brought burdensome obligations. Our economies hadn’t been shaped by our sense of fairness; it was the other way around."