A monkey has been filmed ‘having sex’ with a female deer in what scientists believe is a world first.
The unlikely pairing was revealed in a research paper about ‘reproductive interference’ between different species, something which is rarely observed in the wild.
Although the Japanese macaque does not penetrate the deer in the footage, he leaps onto her and begins to pleasure himself, eventually ejaculating on her back.
Academics who observed it said that the deer ‘accepted being ridden’, whereas another one the primate tried it on with objected immediately and shook him off.
They argued that their findings could help explain why some human beings feel sexual attraction to animals (although that seems like quite a jump from our non-scientist perspective).
Published today, the paper is called ‘Interspecies sexual behaviour between a male Japanese macaque and female sika deer’ (and you can read the whole thing here.)
The authors said that it was possible the monkey made a mistake or was ‘copulation learning’, i.e. getting in some practice.
However, they said this was unlikely and that the most probable explanation was that the male monkey had a low social status among its own species, and therefore had ‘limited access to females’.
They speculated this could help explain why some humans engage in bestiality.
The study from Yakushima Island in Japan says that although there have been examples of mating between different species, they are normally closely related (for example, a horse and a donkey).
This was the first time ‘sex’ between a macaque and a sika deer was documented, and apparently only the second time that scientists have recorded two unrelated species engaging in sexual activity.
The previous time, a fur seal was filmed ‘sexually harassing’ king penguins in 2014.
In a rather graphic explanation, the paper states:
No penetration occurred (the penis of the macaque was not directed at the genital area, but at the back of the sika deer), probably due to differences in morphology/size.
However, ejaculation seemed to occur as the deer was seen licking the seminal liquid after the mount.
The male then attempted to mount another female deer that did not accept the sexual behaviour as she attempted to escape/remove the macaque by moving, increasing her speed, turning around and displaying threats.
The animals were monitored for an hour before they disappeared in the forest.
They said after the monkey mated with the first deer, it stayed close to her and chased away other macaques in ‘a behaviour similar to male guarding’.
Study authors added that it did not seem to be a case of sexual harassment, and claimed: ‘Moreover, the licking behaviour shown by the deer seems to indicate that the sperm could be a good source of protein.’