I also examined an alternative hypothesis suggesting that MGM signals group commitment for collective action, particularly inter-societal warfare.Although other forms of male scarification fit this model, the distribution of MGM is not predicted by frequency of inter-societal warfare. put forward a theory that the shape of the glans has evolved with the function of pumping a rival's sperm out of the vagina, tending to ensure that a child born after that intercourse is that of the man concerned and not an earlier one.
The ritual mutilations can leave the man vulnerable to infection and even death.
So why do some societies insist on such a risky ritual for their men?
There may be an evolutionary explanation, according to Christopher Wilson, of Cornell University in New York, US.
Wilson Abstract Male genital mutilation (MGM) takes several forms and occurs in about 25% of societies.
This behavior has puzzled anthropologists, doctors and theologians for centuries, and presents an evolutionary challenge since it involves dangerous and costly surgery.
Especially in societies where paternity uncertainty and reproductive conflict are high, the social benefits of MGM as a signal may outweigh its costs.