Cultural influences may play role in maintaining non-conceptive sexual behaviour in Japanese macaques

The diverse sexual behaviour of the female Japanese macaque is reminiscent of human patterns of sexuality, particularly female sexual fluidity, suggests a new study from University of Lethbridge researchers.

Dr. J.B. Leca is a U of L post-doctoral researcher and the lead author of the study.

The research, conducted at three different field sites in Japan and involving four free-ranging groups of Japanese macaques, compared two non-conceptive sexual behavioural patterns, finding that social and cultural influences within the groups were the likely reason for the existence of different sexual practices.

The study, entitled "Inter-group variation in non-conceptive activity in female Japanese macaques: Could it be cultural?” was published by Drs. Jean-Baptiste Leca, Nöelle Gunst, Lydia Ottenheimer-Carrier and Paul Vasey in a recent issue of the journal Animal Behavior and Cognition.

“We explored the possibility that some of these intergroup differences in non-conceptive sexual behaviours might be cultural practices that arise in groups when certain socio-demographic conditions are met,” says Leca, a U of L post-doctoral researcher and the lead author of the study. “We actually found that female-male and female-female mounting were more frequent and more diverse in groups with few resident males, most of them being old, sexually under-motivated, and ‘mellow’ in the sense that they are less aggressive and less controlling than the average male Japanese macaque.”

Dr. Paul Vasey has been studying the Japanese macaque for years.

While researchers believe that sexual culture accounts for some of the observed patterns of sexual behaviour in Japanese macaques, they point out that evolution plays a role as well.

“Our working hypothesis is that females solicit sexually mellow males by mounting them, which prompt the males to, in turn, perform a male-female mount,” says Vasey, a professor in the U of L’s Department of Psychology and one of the authors of the study. “Much of this activity takes place in the context of high female-female competition for male mates, so we think female-male mounting also functions to control the male’s movement. All of this would result in adaptive outcomes for the mounting female who would have greater control over which male inseminates her.”

The researchers admit there is no direct evidence for the social transmission of female mounting behavior within a group of Japanese macaques, but argue that relatively high levels of social tolerance towards non-conceptive behaviours suggest the existence of a female mounting culture, socially maintained in specific groups.

“To some extent, our results dovetail nicely with research on sexual fluidity in women, which shows that social contexts can influence women’s sexual and romantic inclinations including the propensity of some women to engage in same-sex sexual interactions,” says Leca.

The journal article can be found online.