Culling the cousins: Kingship, kinship, and competition in mid-millennial England

Kin selection, an aspect of evolutionary theory, argues that, all else equal, individuals should give preferential treatment to relatives, based on the degree of relatedness [Hamilton, W. D. (1964). The genetical evolution of social behaviour I, II. Journal of Theoretical Biology, 7, 1-52.]. However, one may observe instances where competition for scarce or unique resources is stronger between family members than between unrelated individuals. Such a situation existed between 1377 and 1603 with intense competition for the throne of England among descendents of Edward III. During this period, monarchs were executed by relatives to gain or maintain the throne for him or herself or descendents. Despite the widespread destruction of kindred, we show that executioners never sacrificed lineal relatives nor executed collateral relatives in excess of their own legitimate nuclear relatedness, and the number of executed relatives was positively correlated to the age and legitimate reproductive success of the executioner. Moreover, when resources are scarce, have an intrinsically high value, and are inherited, it may be in your Darwinian reproductive interest not to maximize but to minimize the number of legitimate children in order to reduce competition among family members.