Research highlight

Cultural evolution of female genital cutting

Nature Ecology & Evolution

February 7, 2017

The prevalence of female genital cutting (FGC) in certain ethnic groups in Africa can be understood in terms of evolutionary fitness (measured by a mother’s number of surviving offspring, and not an indicator of health or wellbeing), reports a study published this week in Nature Ecology & Evolution. The study suggests that the practice confers a reproductive advantage to women who are part of groups in which FGC occurs at high frequency, but a reproductive disadvantage in groups in which the practice occurs at low frequency. The authors note that understanding the evolutionary reasons why FGC persists could be valuable in the campaign to eliminate the practice.

FGC is a practice that occurs in many ethnic groups, particularly across Africa and the Middle East. It can involve a range of different harmful alterations to the female genital organs for non-medical reasons, which can have severe obstetric, sexual and psychological effects. Therefore, its elimination is a priority for the international community. However, campaigns against the practice have often met with limited success, and a fuller understanding of the behavioural and evolutionary reasons the practice persists may result in better targeted action. Janet Howard and Mhairi Gibson use health and demographic data from over 61,000 women from 47 ethnic groups in five African countries (Nigeria, Senegal, Mali, Burkina Faso, Ivory Coast) to study the evolutionary underpinnings of FGC. They show that an overall high prevalence of FGC within an ethnic group produces a high likelihood that an individual girl will be cut, independent of the effect of whether her mother has been cut. They also show that mothers who are part of the majority within their ethnic group, be that cut or uncut, have a reproductive advantage over the minority, as measured by their number of surviving offspring at the age of 40. The authors suggest that enhanced marriageability and membership of social networks - with access to resources and/or support - may explain this result. As such, for groups in which FGC occurs at a high frequency, they find there is an evolutionary fitness benefit for women who are cut.

It is noteworthy that in groups with a low prevalence of FGC, daughters of cut mothers have a decreased likelihood of being cut, but the opposite is not necessarily true: daughters of uncut mothers in groups with high FGC do not have an increased likelihood of being cut, offering hope that once the practice has been abandoned by a family, there is resistance to its return. The authors also find that there are few groups in which the frequency of cutting is close to 50%, suggesting that if the practice can be reduced below 50% in a group that currently has high prevalence, the reproductive advantage of being in the majority switches to those who are uncut, possibly helping to further eradicate the practice. Such understanding of the relationship between FGC occurrence at the individual and group levels can be used in designing future interventions.

In an accompanying News & Views article, Katherine Wander writes: “… interventions may attempt to foster social connections between cut and uncut women in a community to alleviate the social cost to remaining uncut, shifting the balance between costs and benefits away from cutting.”

doi: 10.1038/s41559-016-0049

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