Cultural Traditions and Fitness Interdependence

The importance of the social learning and cultural transmission of prosocial (altruistic and cooperative) behaviors has been investigated by many researchers, leading to a wealth of theoretical and mathematical models. The descendant-leaving strategy theory stands apart by emphasizing the vertical transmission of cultural behaviors, while other theories tend to focus on horizontal or oblique transmission. The primary concern of this article is to discern how prosocial behaviors are culturally transmitted in an Iban longhouse community using semistructured, ethnographic interviews. The results reveal that the four cooperative behaviors are largely vertically transmitted, and are therefore traditional, lending support to the descendant-leaving strategy theory. I elaborate on how models of human cooperation, especially fitness interdependence, will benefit from incorporating traditions. Public Significance Statement Behaviors that promote fitness interdependence are revealed to have been vertically transmitted from ancestors to descendants, and are therefore traditional. Other models of human social behavior, especially models of fitness interdependence, will benefit from incorporating traditions.