On the Origin of the Family

Abstract

This paper presents an overlapping generations model to explain why humans live in families rather than in other pair groupings. Since most non-human species are not familial, something special must be behind the family. It is shown that the two necessary features that explain the origin of the family are given by uncertain paternity and overlapping cohorts of dependent children. With such two features built into our model, our analysis indicates that fldelity families dominate promiscuous pair bonding, in the sense that they can achieve greater survivorship and enhanced genetic fltness. The explanation lies in the free riding behavior that characterizes the interactions between competing fathers in the same promiscuous pair grouping. Kin ties could also be related to the emergence of the family. When we consider a kinship system in which an adult male cares both for his ofispring and close relatives, we flnd that kin ties never emerge as an equilibrium outcome in a promiscuous environment. In a fldelity family environment, instead, kinship can occur in equilibrium and, when it does, it is e‐ciency enhancing in terms of greater survivorship and fltness. The model can also be used to shed light on the issue as to why virtually all major world religions are centered around the importance of the family.