Sneaky Sex The Norm For Some Monkeys
October 31, 2012

A Little Privacy Please – Monkeys Dont Like Nosey Neighbors When Mating

April Flowers for - Your Universe Online

Ever tried to have sex in a house full of people, especially people you feel in competition with? It's not that easy, and the feeling of being watched is off-putting for most of us. It would be worse if those people could actually see you, and harass you during the act, right?

Apparently, monkeys feel the same way. A new study by Anne Overduin-de Vries and her team from the Biomedical Primate Research Center reveals that monkeys shy away from bystanders during copulation, regardless of the bystanders' rank or gender. The findings, published online in Behavioral Ecology and Sociobiology, also suggest that sneaky sex is opportunistic and not a tactical deception where the monkeys hide the sexual behavior on purpose.

Highly prevalent in multi-male, multi-female primate groups, sexual competition may lead to copulations in the absence of interfering bystanders. It is unclear if this sneaky sex is the result of tactical deception or rather just chance encounters when competitors are absent.

To answer these questions, the sexual dynamics of a group of 27 long-tailed macaques at the Biomedical Primate Research Center in the Netherlands were observed. The team examined which individuals put others off sex and why. For example, was this inhibition linked to the watcher's interfering behavior, sex or rank in the group? They also watched to see if the monkeys adjusted how often they solicited copulation depending on the presence of potentially harassing bystanders. The research team was also interested in whether those engaging in sneaky sex separated themselves from the rest of the group for their trysts intentionally, or if it was happenstance.

Overduin-de Vries and her team found that both males and females can harass copulating partners, and both inhibit the sexual behavior of fellow group members. Both sexes also adjusted how often they solicited copulation depending on the presence of potentially harassing bystanders. Both male-male competition and female-female competition effects are expressed in these bystander interactions. The competitions are important factors in the sexual dynamics of long-tailed macaques.

The team found no evidence that the sneaky sex was tactically motivated. Instead, it appears that the monkeys copulate sneakily because they exploit the peripheral position of non-alpha males — they mate with males positioned on the outside of the group.