The study analyzed genetic data on 1,706 father-son pairs in a traditional African population—the Dogon people of Mali, West Africa—in which Islam, two types of Christianity, and an indigenous, monotheistic religion are practiced in the same families and villages.The overall rate of 1.8% is close to a reported average of 1.7% (or 1.9%) in a set of different populations. One point of interest is that it may be the case that cuckoldry may often involve patrilineal relatives of a woman's husband (e.g., his brother) or even distant relatives who happen to possess Y chromosomes with shallow common ancestry in a patriarchal society. Such events may not be detectable with a simple Y-STR test, but they may be relatively common in patrilocal societies where brides become part of their husband's communities.
"We found that the indigenous religion allows males to achieve a significantly lower probability of cuckoldry—1.3 percent versus 2.9 percent," said Beverly Strassmann, lead author of the article and a biological anthropologist at the University of Michigan.
In the traditional religion, menstrual taboos are strictly enforced, with women exiled for five nights to uncomfortable menstrual huts. According to Strassmann, the religion uses the ideology of pollution to ensure that women honestly signal their fertility status to men in their husband's family.
"When a woman resumes going to the menstrual hut following her last birth, the husband's patrilineage is informed of the imminency of conception and cuckoldry risk," Strassmann said. "Precautions include postmenstrual copulation initiated by the husband and enhanced vigilance by his family."
Across all four of the religions practiced by the Dogon people, Strassmann and colleagues detected father-son Y DNA mismatches in only 1.8 percent of father-son pairs, a finding that contradicts the prevailing view that traditional populations have high rates of cuckoldry. A similar rate of cuckoldry has been found in several modern populations, but a key difference is that the Dogon do not use contraception.
PNAS doi: 10.1073/pnas.1110442109
Religion as a means to assure paternity
Beverly I. Strassmann et al.
The sacred texts of five world religions (Buddhism, Christianity, Hinduism, Islam, and Judaism) use similar belief systems to set limits on sexual behavior. We propose that this similarity is a shared cultural solution to a biological problem: namely male uncertainty over the paternity of offspring. Furthermore, we propose the hypothesis that religious practices that more strongly regulate female sexuality should be more successful at promoting paternity certainty. Using genetic data on 1,706 father–son pairs, we tested this hypothesis in a traditional African population in which multiple religions (Islam, Christianity, and indigenous) coexist in the same families and villages. We show that the indigenous religion enables males to achieve a significantly (P = 0.019) lower probability of cuckoldry (1.3% versus 2.9%) by enforcing the honest signaling of menstruation, but that all three religions share tenets aimed at the avoidance of extrapair copulation. Our findings provide evidence for high paternity certainty in a traditional African population, and they shed light on the reproductive agendas that underlie religious patriarchy.