Why Humans Cooperate: A Cultural and Evolutionary ExplanationCooperation among humans is one of the keys to our great evolutionary success. Natalie and Joseph Henrich examine this phenomena with a unique fusion of theoretical work on the evolution of cooperation, ethnographic descriptions of social behavior, and a range of other experimental results. Their experimental and ethnographic data come from a small, insular group of middle class Iraqi Christians called Chaldeans, living in metro Detroit, whom the