If crimes of sexuality were confined to the human species, we should not have an opportunity to study the biological beginnings of crime as observed in curious instances of criminality in animals, which raises doubts as to whether these inversions of the genesic instinct are with them unnatural phenomena, or rather an outward manifestation of an imperious functional want. Without exposing the details of the analogy upon which is founded the presumption, we are warranted in saying that as many of the lower beings in the zoölogical scale show virtues having analogy to those of man, we must expect to find parallel vices. It is an error to suppose that aberration of the genesic instinct is confined to our species, time, or race. Evidence shows that unnatural crime exists under all latitudes. It extends from the prehistoric time of the troglodytes up to Hippocrates, who stigmatizes it in his oath, and from his time to the present. I have observed common instances of sexual perversion in dogs and turkeys. A short time since, at the Washington races, a celebrated stallion was the favorite on whom the largest bets were made. A friend of mine, having ascertained from the groom the day before the race that the horse had procured an ejaculation by flapping his penis against the abdomen, accordingly risked his pile on another horse, who, by the way, came in ahead. Only a few days ago, to escape a shower, I took refuge in the elephant house in the Washington Zoölogical gardens, where are confined two male elephants, “Dunk” and “Gold Dust.” To my astonishment they entwined their probosces together in a caressing way; each had simultaneous erection of the penis, and the act was finished by one animal opening and allowing the other to tickle the roof of his mouth with his proboscis after the manner of the oscula more Columbino, mentioned, by the way, in some of the old theological writings, and prohibited by the rules of at least one Christian denomination.
—Irving C. Rosse, “Sexual Hypochrondriasis and Perversion of the Genesis Instinct”, Journal of Nervous and Mental Disease, whole series volume 19, new series, volume 17, number 11, November 1892, pp. 798-799