Zapotec cooperative institutions: Exploring the psychological and social mechanisms

Cross-cultural variation in the scale and intensity of human cooperation poses a challenge to classic evolutionary accounts. Confronting popular evolutionary explanations that deemphasize “culture,” researchers have proposed that social norms and institutions culturally evolve to shape cooperation. Testing these theories, we examine how institutions shape cooperation by conducting a detailed comparative analysis of two cooperative institutions in a Zapotec community of Oaxaca, Mexico. The first, gozona, is a mutual support institution that promotes cooperation in agricultural labor and celebrations. The second, usos y costumbres, represents a set of traditional political institutions that facilitate the provisioning of public goods. Drawing on ethnography, vignettes, and surveys, we dissect the intertwined, cooperation-sustaining psychological and social mechanisms embodied in these institutions. We find that gozona and usos y costumbres are governed by different norms, which drive context-specific cooperation; they are not associated with generalized prosociality. Moreover, gozona and usos y costumbres norms harness distinct but overlapping sets of mechanisms, including reciprocity, interdependence, reputation, and punishment. These results support the view that institutions tap into and recombine diverse cooperation-sustaining mechanisms as they culturally evolve, challenging “culture-free” efforts to explain human cooperation. Indeed, even within a single, small community, different cooperative institutions work in different ways.