Sexually frustrated monkeys expand horizons: they fell in love with deer

In Japan, some monkeys are trying to have sex with deer sika. No one knows why, but scientists have some guesses.

The first time scientists began to talk about the monkeys’ sexual desire in relation to Sika deer was in 2015.

On Yakushima’s Japanese forest island, a male monkey jumped to the back of a Cerdo Sika deer female and started trying to mate with her, says.

At the time, it was thought to have been treating an unusual case isolated, but it was not: in 2018, it happened again, this time with monkey females trying to mate with male deer, also in Japan, but far away, near Osaka , at Minoh Quasi National Park.

It happened again. Again, and again, in 2020, in 2021, in 2023…

Some incidents, however, involved, yet I cannot confirm with certainty, the same monkey of the first episode. “It’s difficult, but when you are a primatologist, you need to recognize each individual in the group,” says the scientist Cédric Sueur.

“What is interesting is that perhaps the first time the male did it was due to sexual frustration, that is, with a specific objective ”, explains the investigator, author of published in December in Cultural Science.

The monkey may have started this bizarre behavior and then transmitted to others by a phenomenon called social transmission.

However, it is not as if the deer and monkeys were complete unknown. They already have a long history as friends, and this friendship may now be becoming a colorful friendship.

“My guess is that the deer are extremely socially tolerant With the monkeys, because they are catching the parasites, ”says ecologist Jusith Bronstein.

There are, therefore, who believes that the fact that some deer accept the behavior of monkeys (although some reject) may have benefits. This is because it is a win-win: Primates relieve their sexual tension, while deer receive nutrients from monkeys.

“I mean, there is clearly a Protection and Nutrition Exchangejust because the deer don’t run away when the monkeys are around, ”says Bronstein.

In addition, monkeys do not always have second intentions with their larger friends: often, according to another published in the magazine Primatesmoments have already been documented when monkeys go up on the back of the deer and stay there – without any sexual advance. It looks like an affectionate act.

Deep down, they are friends, and can even like each other’s heat-monkeys often get together when they are cold, why not do it with new companions?