Female–male mounting in Japanese macaques: Some males may utilize FMM in a quest for their own sexual stimulation, which sometimes culminated in masturbation by the male

When males have females on their backs: Male's tolerance, solicitation, and use of female–male mounting in Japanese macaques. Noëlle Gunst, Jean-Baptiste Leca, Paul L. Vasey. American Journal of Primatology, May 25 2022. https://doi.org/10.1002/ajp.23395

Abstract: Previous research on Japanese macaques has shown that female-to-male mounting (FMM) is performed by some females as an exaggerated form of sexual solicitation that may occur in the context of high female competition for male mates. This supernormal courtship behavior functions to prompt subsequent male-to-female mounting. In this report, we focused on the male consort partners' responses to FMM. We studied a free-ranging population of Japanese macaques at Arashiyama, Japan, in which FMM is frequent and prevalent. We analyzed 240 consortships involving 31 females and 19 males. We tested three hypotheses regarding male's tolerance, solicitation, and use of FMM. First, we found that FMM was tolerated by male mountees who were no more likely to aggress their female partners during a short time window around a FMM than they were during the rest of the consortship period. Second, we showed that FMM could be triggered by male recipients, via explicit male-to-female sexual solicitations. Third, we found that some males may utilize FMM in a quest for their own sexual stimulation, which sometimes culminated in masturbation by the male during FMM. Our findings indicate that male partners facilitate the expression of FMM both passively (via their tolerance) and actively (via their solicitation). In addition, FMM appears to enhance the sexual arousal of male partners during consortships. We argued that, for females to have expanded their repertoire of sexual solicitations by adopting FMM, male mates must have played a role in the evolutionary origins and maintenance of this nonconceptive but intense and powerful female mating tactic.

Research Highlights

Previous research in Japanese macaques has shown that female-to-male mounting (FMM) is a supernormal courtship behavior that functions to prompt subsequent male-to-female mounting.

As mounting is a male-typical behavior, we studied male consort partners' responses towards FMM in a free-ranging population of Japanese macaques in which this behavior is particularly frequent and prevalent.

By tolerating and triggering the performance of FMM in their female mates, males may have passively and actively contributed to the evolution and maintenance of this sexual adaptation, while deriving sexual gratification from this behavior.