Cross-cultural patterns of marriage and inheritance: A phylogenetic approach

There is a strong correlation between marriage system and wealth inheritance pattern across societies (Hartung 1982); as the degree of polygyny increases, so too does the degree of male bias in inheritance. In this paper, we reevaluate this pattern using a new technique in cross-cultural analyses that effectively controls for the nonindependence of cultures (Galton's problem) through the identification of independent instances of cultural change (Mace and Pagel 1994). First, we produce cultural phylogenetic trees for the societies under study, from phylogenies previously constructed on the basis of linguistic similarity (Ruhlen 1987). Then, following standard methods for the analysis of discrete characters on phylogenetic trees, we use parsimony to determine the ancestral condition of both marriage and inheritance, and subsequently tally the number of independent instances of cultural change in each trait. The results show that transitions to polygyny are much more commonly associated with male-biased inheritance than are transitions to monogamy across human societies in our sample. They illustrate how the degree of change in the evolution of these traits differs considerably between divergent cultural groups. The advantages of this technique are discussed.