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Evolutionary history and socio-ecological functions of genital mutilation

Geographic distribution and evolutionary history of female (left) and male (right) genital mutilation. Nat. Hum Behav. https://doi.org/10.1038/s41562-022-01321-x

The existence of costly rituals that are painful and harmful to human health is an enduring puzzle to evolutionary anthropologists and psychologists. These rituals include traditional forms of male and female genital cutting or genital mutilation (GM). Due to the significant health risks, female GM is now illegal in most countries where it has been practiced, however, the efforts to eradicate it have had only limited success. More than 200 million women alive today have been genitally mutilated. Male genital cutting is even more widespread (about a third of the male population is circumcised) but receives much less attention from researchers and human rights organizations.

Historically, these practices were widespread in Africa and the Middle East, Central and South Asia, Australia and Oceania, but rare in North and South America. The World Health Organization distinguishes several types of female GM, which differ in their severity and the associated health risks. These include clitoridectomy, often called female circumcision (removal of clitoris), excision (removal of clitoris and labia minora) and infibulation (complete removal of the external genitalia). Likewise, there are several types of male GM. The most common are circumcision (ablation of the foreskin) and superincision (split of the foreskin without its removal). In addition, there are other, less common, types, such as subincision (ventral longitudinal slit of the penis) and testicular ablation (extirpation or crushing of one testis). Adverse health effects of these practices require us to understand their origins and function, but we still know relatively little about them. Archaeologists believe that they might have originated in ancient Egypt, or in the region of today’s Sudan or Ethiopia some 3000–5000 years ago. However, the diversity and distribution of these rituals suggest that they might have originated several times independently. However, most previous studies have focused only on female or male GM, usually did not distinguish between the different types of GM, and focused only on some geographic regions, such as sub-Saharan Africa.

Gabriel Šaffa, Jan Zrzavý and Pavel Duda from the Faculty of Science, University of South Bohemia performed a global phylogenetic analysis to uncover the evolutionary history of GM practices. They did so by mapping ethnographic data onto a phylogenetic tree of human societies based on genes and languages. They also attempted to explain why these practices were adopted in the first place, by exploring the socio-ecological correlates of various types of male and female GM. One of the important findings of the study, published in the journal Nature Human Behavior, is that GM did in fact originated several times over the past 5,000–7,000 years, in some cases much earlier, than archeological and written records suggest. Female and male GM co-evolve, with GM arising in the society only after it started practicing male GM. Interestingly, different types of GM have different socio-ecological correlates such as mode of subsistence and social organization. However, most of GM practices seem to have originated in agricultural or pastoral, polygynous societies, where co-wives live in separate dwellings, where marriages are arranged by parents, and where bride price is paid. Separate residence of co-wives causes concerns over marital infidelity, and the bride price incentivize parents to have their daughters cut, because it increases the price they receive. (Female GM increases marriageability, since it is perceived as a signal of chastity.) The most severe forms of female GM were adopted in pastoral societies where husband spends a lot of time away from home. This leads to the efforts to secure paternity through drastic methods such as infibulation. Some researchers believe that the expansion of Islam in the past centuries is partly responsible for the current spread of GM. However, this study suggests that in most cases it was that GM practicing societies adopted Islam, rather than vice versa. In some regions, such as East Africa or Indonesia, Islamic forms of GM have replaced the “traditional” forms that were practiced there long before the advent of Islam.

Many questions remain unanswered. The assumption that separate residence of co-wifes increases the risk of cuckoldry has not been substantiated by paternity tests. It is also not clear whether male circumcision effectively guards against cuckoldry by impairing male fertility and interest in extramarital sex. Some types of male GM, such as subincision and testicular ablation are probably quite effective, while circumcision, which is now widespread, is not. However, anthropological studies suggest that the actual risk of marital infidelity or the usefulness of GM in preventing it might not be all that important. If men are convinced that the risk of infidelity is high, they prefer their future wife or daughter-in-law to be cut.

Today, GM serves not only as signal of virginity and purity, but also of maturity, bravery, respect for authority and traditional institutions, and, importantly, a group or religious identity. The fact that the original socio-ecological factors behind the origins of these practices are likely different from those maintaining them is a challenge for all researchers who seek to understand them. Female GM is linked to social institutions such as polygyny, the payment of bride-price, and the practice of male genital cutting that are highly valued in these societies. The fact that female GM is intrinsically linked to male GM means that it may be more difficult to eliminate it if we treat male GM as a separate and relatively harmless practice.

Šaffa, G., Zrzavý, J., & Duda, P. (2022). Global phylogenetic analysis reveals multiple origins and correlates of genital mutilation/cutting. Nature Human Behaviour6(5), 635-645.

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