Younger men, he says, willingly submit to having their reproductive ability reduced because they benefit socially from the older men, by forming alliances, and by gaining access to weapons or tribal lore.
The older men have also gone through the ritual, and seen their own reproductive effectiveness reduced.
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.
David Barash, an evolutionary biologist at the University of Washington in Seattle, US, says that the paper makes a convincing case. Journal reference: Evolution and Human Behavior (vol 29 p 149) Evolution & Human Behaviour, May 2008, Vol 29, Issue 3, pp 149-164 Male genital mutilation: an adaptation to sexual conflict Christopher G.
Genital mutilation, in this view, is just another way to win the sperm war.