Pornography produced for men does seem to appeal to their evolved interests in sexual variety and multiple matings by depicting numerous women who are willing to engage in casual sex without investment. However, perhaps the most direct way in which pornography could cater to these aspects of male sexual psychology would be to depict situations in which a man gains sexual access to multiple women. By embodying male "harem fantasies," such material should tend to appeal to male interests in sequestering, and monopolizing sexual access to, numerous women. However, a cursory examination of commercially produced pornographic videos and photographs reveals that depictions of situations in which a man gains exclusive sexual access to multiple women are, in fact, relatively rare. Moreover, depictions of sexual activity involving a woman and several men appear to be much more common. In extreme forms, this type of orgiastic sexual activity can involve one woman and a very large number of men.

The sexual performance of domesticated farm animals can be enhanced by allowing them to view other conspecific males engaged in copulatory behavior. After observing another male copulate with a female, bulls ejaculate more frequently and male goats show reduced latencies to mount and ejaculate. Similar improvements in sexual performance are seen in stallions that display a lack of sexual interest. Crucially, the stimulatory effects associated with viewing a female copulating with another male are greater than are those of watching a restrained cow by herself. Moreover, similar effects are seen in boars that have merely viewed another male mounting and ejaculating over a dummy sow.

Sperm competition is the competition between the sperm of different males to fertilize a female's gamete(s). In a species with internal fertilization, it can occur whenever a female engages in "double mating" such that live sperm from two (or more) males are present within her reproductive tract...
If sperm competition has been an important selection pressure during human evolution, then sexual arousal may be an adaptive response to its occurrence since frequent copulation can be an effective method of paternity assurance. Consequently, although men should generally find mate sharing to be aversive, they may nevertheless find cues of increased sperm competition risk to be sexually arousing.