High rate of extrapair paternity in a human population demonstrates diversity in human reproductive strategies

• Published in: Science advances Vol. 6; no. 8; p. eaay6195
• Main Authors: Scelza, B A, Prall, S P, Swinford, N, Gopalan, S, Atkinson, E G, McElreath, R, Sheehama, J, Henn, B M
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 01-02-2020
• Subjects: SciAdv r-articles; Social Sciences
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.aay6195

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."