A video showing a snow monkey humping a sika deer went viral, prompting a scientific inquiry into the unusual animal behavior.
Researchers found that monkeys’ inclination towards mounting deer, while rather surprising, is not an abnormal thing, Newsweek reports. Rather, it is the result of a cultural action, either a fad or an ingrained tradition among primates such as these monkeys.
In the study, scientists documented Japanese macaques, or snow monkeys, repeatedly climbing onto the backs of deer and making thrusting motions with their pelvises. Since there is a big anatomical difference between the species, any videos don’t show actual sexual penetration. In addition, deer and monkeys are too genetically diverse to produce any sort of hybrid.
It was found that adolescent females were more likely to hump deer, and both species have mating seasons at the same time.
The scientists are sure that the snow monkey’s attitudes are sexual in nature, because the actions they perform resemble what female monkeys do towards male monkeys before they actually have sexual activity.
The videos showed female monkeys mounting primarily male deer. The scientists are unable to tell if this is because female deer and young deer would fling them off, or because the monkeys actually do prefer bucks or stags.
Furthermore, the study documented interactions between snow monkeys and their mating partners of the same species, and found that snow monkeys have no specific preference between having sex with other monkeys or with other kinds of animals. There was also no difference in how long the monkeys spent humping either other monkeys or other species, but they did prefer doggy-style with the deer.
The deer, for their part, did not seem at all bothered by the snow monkeys using them to get their rocks off.
The study was published in Archives of Sexual Behavior.