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? To shed light on this question, I will present two studies that examine how institutions– packages of social norms– structure cooperation within communities of Oaxaca, Mexico. I’ll begin by discussing a framework for understanding how culturally evolved institutions harness psychological and social mechanisms to stabilize cooperation. In the first study, I put this framework to the test at my fieldsite, a Zapotec village in Oaxaca. Drawing on 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. In the second study, I examine how cooperation relates to institutional variation. Leveraging secondary and newly-coded ethnographic data from 418 self-governing Oaxacan municipalities, I show that communities with stronger traditional political institutions (such as those that more harshly sanction defectors) mobilize more cooperation for the group benefit. Taken together, these studies provide insights into the evolution of human cooperation, elucidating the role of culturally evolved institutions.

Reference

Cameron Curtin, “Institutions and the cultural evolution of cooperation: Insights from Oaxaca, Mexico”, IAST Lunch Seminar, Toulouse: IAST, April 10, 2026, 12:45–13:45, room Auditorium 4 (first floor -TSE building).