You dont have to look far, you look at some of the most species that use intercourse not just for breeding, dolphins and chimps are to name a couple. You can also look at dogs(and other animals in the dog family), the act of dry humping someone is to show dominance. Some people would consider that being a homosexual. You can also look at Roman times when you look at the brothels ( i don't think they were called that but you get the idea), you had a selection of boys and girls.