How can patriarchal societies be sure that the men who inherit their fathers' goods are actually their fathers' sons? Religions help men to be more confident in their paternity by setting standards for female sexual behaviour.
Beverly Strassmann at the University of Michigan in Ann Arbor and her team studied genetic data from 1,706 father–son pairs among the Dogon of Mali. Although many Dogon are Christian or Muslim, the adherents of their indigenous religion had the lowest rate of male births due to cuckoldry: 1.3% versus 2.9% for the other faiths. The researchers chalk this up to the traditional huts where menstruating women must spend their nights. In a society in which women are often pregnant or unable to conceive owing to intensive breast-feeding, a sojourn in the hut informs a woman's husband and his kin that she has become fertile again. The family can then increase their vigilance towards her.
Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1110442109 (2012)