Rape has always been part of the conquering ritual. I don't know why, really - arguments have been made for propagation of the winner's tribe, but that doesn't explain why boys are also raped nor why women are generally raped so brutally they die.
This is from the Annals of Asul Nasir-Pal, an Assyrian king from c.870 BC.
"600 of their fighting men with (my) arms I destroyed; 3,000 of their captives I consigned to the flames; as hostages I left not one of them alive; Hulai the governor of their town I captured by (my) hand alive; their corpses into piles I built; their boys and maidens I dishonored."
The Annals repeat this boast, with precise numbers and rapes, for each of the 39 cities Asul conquered.
There is a lot of rape in the Bible (on God's instruction) - and that's ignoring the mass rapes undertaken as part of the Israelites' serial demolishment of cities, which were tactfully mistranslated as 'taking spoils and livestock'. Joshua was practically identical to Asul Nasir-Pal, except that Joshua publicly murdered more of his captured kings.
There's no doubting that the 'inner crocodile' is alive and well in us today, as throughout history. Although some reptiles pair-bond, I don't know whether a fight between males would entail the winner fucking the loser's mate ...