Comment: Interesting study on Himba people, pastoralists living in Namibia. “Seventy-seven percent of women and 85% of men had at least one nonmarital partner,” and about half of all children are fathered by someone other than the mother’s husband. Researchers hypothesize that,

men may be choosing to provide care for nonbiological children as part of the duties of social fatherhood in return for greater security for their other children or the benefits of strong male alliances, or because socioecological conditions such as a male-skewed sex ratio make polyandry the best choice for some males.”

Science Advances (full text)

19 Feb 2020: Vol. 6, no. 8, eaay6195 DOI: 10.1126/sciadv.aay6195

B. A. Scelza1, S. P. Prall1,2, N. Swinford3, S. Gopalan4, E. G. Atkinson4,5,6, R. McElreath7, J. Sheehama8 and B. M. Henn3,4


Among nonhuman species, social monogamy is rarely accompanied by complete fidelity. Evolutionary theory predicts that the rate of extrapair paternity (EPP) should vary according to socioecological conditions. In humans, however, geneticists contend that EPP is negligible and relatively invariable. This conclusion is based on a limited set of studies, almost all of which describe European-descent groups. Using a novel, double-blind method designed in collaboration with a community of Himba pastoralists, we find that the rate of EPP in this population is 48%, with 70% of couples having at least one EPP child. Both men and women were very accurate at detecting cases of EPP. These data suggest that the range of variation in EPP across human populations is substantially greater than previously thought. We further show that a high rate of EPP can be accompanied by high paternity confidence, which highlights the importance of disaggregating EPP from the notion of “cuckoldry.”