Abstract:
Extrapair paternity is a crucial parameter for evolutionary explanations of reproductive
behavior. Early studies and human testis size suggest that human males secure/suffer
frequent extrapair paternity. If these high rates are indeed true, it brings into question
studies that use genealogies to infer human life history and the history of diseases since the
recorded genealogies do not reflect paths of genetic inheritance. We measure the rate of
nonpaternity in an old Afrikaner family in South Africa by comparing Y-chromosome short
tandem repeats to the genealogy of males. In this population, the nonpaternity rate was
0.73%. This low rate is observed in other studies that matched genealogies to genetic
markers and more recent studies that also find estimates below 1%. It may be that imposed
religious morals have led to reduced extrapair activities in some historic populations. We
also found that the mutation rate is high for this family, but is unrelated to age at
conception.
