In the majority of human societies, including ours, women have won the argument. Most are monogamous. Some primates are monogamous, some are polygamous. Those species, including homo sapiens , in which males tend to stay with one partner for a lifetime have half the number of circulating white blood cells of species in which males spread their seed far and wide. Messing around exposes individuals to a whole range of venereal infections.
White cells are major weapons in the infection-fighting arsenal of mammals.
The more exposure to venereal disease, the more white blood cells a body needs. Beefed up immune systems are apparently so necessary to the survival of polygamous creatures, that individuals of these species are born with high white blood cell counts and maintain them throughout their adult lives, even if they remain virgins. The same immune system that repels invaders is charged with surveillance of the body for internal interlopers too, including renegade cancer cells. In other words, the price for promiscuity is the need to maintain a supercharged immune system, without which a group risks wholesale death from infection. AIDS, for instance, is a scourge among the segments of human society that are least restrictive in numbers of sex partners, including prostitutes and the gay bath house subculture that used to indulge in, unprotected, indiscriminate sex.