Homosexual rape, which is a stress-related pseudosexual dominance activity, is expressed by many primate species, including our own.
Usually it is in male -> male or male -> female form (and in many human cultures forms the backbone of the family unit). But female -> female and even female -> male rape become increasingly more prevalent the greater degree to which a culture moves away from a stable system of child rearing into one which favors only chaos and confusion.
In modern civilization, women tend to be raised who are basically male homosexuals in female skin.
As for the original primate angle, check out Frans de Waal‘s books, such as Chimpanzee Politics.
Bored now.
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