Their widely-quoted study does not mention the foreskin.
One of the popularisers of that theory, Jesse Bering, put readers' questions to Gallup for Scientific American (May 30, 2009) about that issue.
It might also be the case that selection works at a group level, so that societies that enforce mutilation are more stable because of less conflict over paternity, Wilson says.
There is subincision, for example, where cuts are made to the base of the penis.
This causes sperm to be ejaculated from the base rather than the end, and is performed in several Aboriginal Australian societies, says Wilson.
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.
I suggest that MGM is likely to reduce insemination efficiency, reducing a man's capacity for extra-pair fertilizations by impairing sperm competition.
MGM may therefore represent a hard-to-fake signal of a man's reduced ability to challenge the paternity of older men who are already married.
By Kurt Kleiner Circumcision and other forms of male genital mutilation have always been a puzzle.
The ritual mutilations can leave the man vulnerable to infection and even death.
Men who display this signal of sexual obedience may gain social benefits if married men are selected to offer social trust and investment preferentially to peers who are less threatening to their paternity.