Institutions and cooperation: The cultural evolutionary roots of prosociality in Oaxaca, Mexico

Abstract

Although humans are capable of remarkable feats of cooperation, failures of cooperation lie at the root of many of humanity’s biggest challenges, from managing common resources to combating the spread of infectious disease. Moreover, there is puzzling variation between groups in when people cooperate, how intensely, and with whom. Why do we see this variation? In this dissertation, I combine cultural evolutionary theory with methods from anthropology, psychology, and economics to examine how institutions– packages of social norms– structure prosocial psychology and cooperation within groups. Chapter 1 begins by establishing a theoretical framework for understanding how culturally evolved institutions harness psychological and social mechanisms to stabilize cooperation. Then, I put this framework to the test at my fieldsite in a Zapotec village of Oaxaca, Mexico. Drawing on qualitative and quantitative data from participant observation, interviews, surveys, and vignettes, I dissect two of the village’s cooperative institutions, uncovering the mechanisms through which they foster mutual aid and collective action. I find that these institutions are governed by social norms that drive domain-specific cooperation; they are not associated with generalized prosociality. Moreover, the institutions rely on overlapping but distinct sets of psychological and social mechanisms to stabilize cooperation. These results suggest that as institutions culturally evolve, they can stitch together different cooperation-sustaining mechanisms– elucidating the rich diversity of culturally evolved institutions. Chapter 2 focuses on usos y costumbres, a set of traditional political institutions by which indigenous Oaxacan communities self-govern. Leveraging secondary and newly coded ethnographic survey data from 418 Oaxacan municipalities, I show that communities with stronger usos y costumbres institutions mobilize more cooperation for the group benefit– consistent with a cultural evolutionary view of cooperation. In Chapter 3, I return to my fieldsite to examine another institution, fiestas– elaborate, multiday festivals that honor patron saints. Positing that fiestas function as cohesion-enhancing collective rituals, I compare prosocial attitudes and cooperation in a behavioral economics game several months before and immediately after the village’s biggest annual fiesta. Results do not support the hypothesis, instead revealing declines in ingroup altruism and cooperation, and no change in cohesion. At the same time, data indicate that the fiesta itself is a massive cooperative undertaking for the community, complicating interpretation of the data. Taken together, these studies provide novel insights into the evolution of human cooperation, elucidating the role of culturally evolved institutions.