@2021henrichOrigins name five key facts about human cooperation that must be accounted for by empirical theories—ultrasociality, scale and intensity differences, domain differences, rapid expansion, non-cooperative and maladaptive behavior—and propose explanations based on cultural evolutionary psychology.
| Name of explanatory challenge | Proposed explanations |
|---|---|
| Ultrasociality: “Both the scale and intensity of human cooperation are substantially greater than those found in other mammals” (209).” | Culture provides a second system of inheritance unique to humans, which has additional effects on psychology (e.g., suppression of reactive aggression, enhanced capacity for internalizing norms). |
| Differences in the domains of cooperation | Domains of cooperation across populations vary because social norms vary; people likely will not engage in certain costly cooperative behaviors if there are no norms for doing so. |
| Differences in the scale and intensity of cooperation across populations | Ecological, climatic, geographic, historical factors → intensity of intergroup competition for a given society → selection for different levels of prosociality in norms and institutions. |
| Rapid rise in the scale of cooperation | Beginning of intensive food production and stabilization of global climates (~12,000 years ago) → increased intensity of intergroup competition, driving evolution of culture that scales up cooperation |
| Mechanisms that sustain cooperation can also sustain noncooperative and even maladaptive behaviors | Cultural evolutionary mechanisms related to punishment, signaling, and reputation stabilizes norms costly → noncooperative and maladaptive |
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