Inheritance of wealth as human kin investment

Abstract

Like many other animals, humans appear to have evolved to invest time and energy in their relatives in order to maximize inclusive fitness. Inheritance of material wealth may be a uniquely human form of kin investment. If fitness-maximizing dispositions do influence will-makers, beneficiaries may be favored according to their relatedness and reproductive value. An analysis of 1000 probated wills showed that this was the case. Close relatives were favored over distant kin, as were kin of higher reproductive value. Wealthier decedents favored male kin, while poorer decedents favored females. This pattern might reflect a facultative shifting of resources toward males when the family's resources are sufficient to ensure reproductive competitiveness, and toward the safer option of females when resources are less abundant. The results support the possibility that fitness-maximizing dispositions do influence will-makers. It is likely that such dispositions are flexible and responsive to the physical and social environment.