https://www.queerty.com/excerpt-giraffe ... l-20190323
Precision in these demographics doesn’t really matter when thinking about the broad sweep of evolution. Homosexuality exists, and hundreds of millions of people identify as homosexual. Conception remains an impossibility following homosexual sex, which superficially suggests that it might be maladaptive. That poses a potential problem when searching for an evolutionary exploration of a particular behavior. How can sexual behavior that cannot produce offspring persist at such a high frequency? Could this be an example of something that has delineated a boundary between human animals and non-human animals?
Apparently not. Homosexuality abounds in nature too.
Consider the giraffe. Giraffes are beloved of evolutionary biologists for a number of reasons. They are, of course, the tallest of all living animals, and that elegant neck is the primary reason why. The origin of that beautiful neck has also been attributed to sexual selection. It is extravagant and slightly absurd, like a peacock’s tail, so it might be one of those runaway traits that we see exaggerated in males of so many sexual beasts. This is where the sex lives of giraffes gets interesting. The neck is certainly a major part of sexual and social behavior. Since 1958, the male-to-male wrestling that giraffes are often seen engaging in has been called “necking.” They curl their necks around each other and rut. It’s incredible to watch, the necks twisting and bending at almost right angles, the normal grace of these animals replaced by ungainly aggression and awkward legs, with none of the elegant power of two stags clashing antlers.
Necking, as with its human teenage counterpart, is often foreplay to more serious sex. It looks similar to many male-to-male competitive behaviors that precede copulating with a female. They battle, and one comes out on top. The primary difference in giraffes seems to be that after a bout of heavy necking, the males will often have penetrative sex. As with so many of the interesting behaviors of wild animals that we observe and try to understand, there hasn’t been a great deal of work in this area. Numbers therefore are not huge, and robust conclusions are elusive. But it does appear that the majority of sexual encounters in giraffes involve two males necking, followed by anal sex. Not all necking encounters result in attempted or successful mounting, but in many cases, the necking males spar with erect unsheathed penises.