Scholarly article about "cuckolding" in Africa-- it turns out that keeping women in "menstrual huts" is a good way to signal their state of fertility to husbands. And when husband and nosy tribal elders keep an eye on fertile wife, they can ensure she won't step out on her husband.
Found in http://dienekes.blogspot.com/2012/06/religion-vs-cuckoldry.html
PNAS doi: 10.1073/pnas.1110442109 Religion as a means to assure paternity Beverly I. Strassmann et al.
STRASSMANN "sheds light on the reproductive agendas that underlie religious patriarchy. Religious practices that more strongly regulate female sexuality should be more successful at promoting paternity certainty...
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."