Surnames and a Theory of Social Mobility

Using the information content of surnames to measure social mobility, it is shown that the true intergenerational correlation of social status is in the order of 0.7-0.8, much higher than is estimated by conventional methods. This intergenerational correlation is similar across dramatically different societies: medieval England, modern England, pre-industrial Sweden, modern Sweden, the USA, Quing and Communist China, Meiji and modern Japan, and Chile. Surnames also show mobility to follow a simple law-like process across many generations. One simple Law of Motion seems to capture all social mobility. In this paper I offer a theory as to why these measures differ from conventional mobility estimates. I also argue that the nature of the process suggests biological inheritance of abilities, as opposed to intergenerational capital transfers, is the main determinant of social position.