Today’s blog post is going to cover some provocative subject
matter, specifically addressing masturbatory behavior among nonhuman
primates. Masturbation is defined as autosexual
behavior wherein an individual stimulates their genitalia with or without the
aid of a tool (or, in colloquial terms, what is more commonly referred to as a “sex
toy”). Various primate species (from
human to nonhuman) have been observed masturbating, and these acts occur among
both captive and wild nonhuman primate species.
Unfortunately, not much is known about these behaviors, which is most
likely due to the taboo nature of the subject.
Today’s blog post is going to address some specific examples of observed
masturbatory behavior among wild nonhuman primate species, as well as address
some of the explanations for this behavior.
Masturbatory behaviors have been observed among captive and
wild nonhuman primate species for decades.
These behaviors among captive nonhuman primate species have not received
the same level of attention because they were believed to be artificial
behaviors induced by captivity (much to the ire of lay individuals who just so
happen to observe these activities). The
presence of these behaviors among wild nonhuman primate species has, however,
intrigued researchers. Various nonhuman
primate species have participated in masturbatory behaviors, including apes and
Old and New World monkey species. It is
important to note, however, that these behaviors are most common among apes and
Old World monkey species, as well as among species that exist in multimale/multifemale
groupings. Both male and female nonhuman
primates participate in masturbation, but it occurs far more frequently among
males.
Masturbatory behaviors among wild nonhuman primate species most
often occur without the use of a tool (aka, “sex toy”), meaning the primate
uses their hands, feet, or other body parts to stimulate their genitalia. These behaviors occur when the primate is
either alone or surrounded by others, be it males or females. It was hypothesized that males who masturbated
in front of females did so to encourage sexual intercourse, but this very
rarely occurs, suggesting that it is not an efficient means of encouraging sex
between the masturbating male and the observant female. There are no explanations for why a male will
masturbate in front of other males as no sexual intercourse occurs afterwards. The adjacent males typically pay no attention
to the masturbating males. There are
very few reports on masturbatory trends among females, so no further comments
can be provided.
At the time of composition of this post there was only one
published report of a nonhuman primate using a tool when masturbating. The researchers reported that an adolescent
male chimpanzee used a discarded bottle to aid in masturbation. The reason for the use of the tool is
unclear, although it was noted that the chimpanzees of this troupe have very
little fear of humans since they regularly indirectly interact with them. This could be why the chimpanzee’s behavior
evolved to use the tool.
As nonhuman primates have been observed masturbating both
with and without ejaculating there are several hypotheses for why they
participate in this behavior. Because
masturbation occurs among lower ranking males who have less access to receptive
and reproductive females it is believed that males may masturbate to remove old
sperm, thereby increasing their chances of conceiving offspring when they are
able to have sexual intercourse with a female.
Masturbation could also be a means of relieving sexual tension or
stress, particularly among lower ranking males who are unable to participate in
frequent or regular sexual activities.
For females, acts of masturbation may occur for very different reasons,
including reducing the likelihood of acquiring a sexually transmitted disease
or increasing the release of pheromones to alert males that she is sexually
available.
Ultimately, it is unclear why masturbation occurs among nonhuman
primates. It is clearly identified as a
pattern of behavior among various species, suggesting that there is probably a
biological and evolutionary need for the behavior, despite its negative effects
on population growth. This refers to the
fact that loss of sperm through ejaculation during masturbation means that the
male has less sperm to provide during sexual intercourse, thereby reducing the
likelihood of conception during sexual intercourse. This idea, however, has not been widely tested
and may not be a legitimate concern. As
additional studies continue on these behavior patterns a clearer understanding
of these behaviors may be realized.
References
Gamalo, L. E. D., Cabrera, S. M. E., delos Reyes, N. C. L.,
de Cadiz, A. E., & Chavez Jr, J. B. (2022). Masturbation in a Free-ranging
Male Long-tailed Macaque Macaca fascicularis (Raffles, 1821) on Mindanao
Island, Philippines. Philippine Journal of Science, 151(6A),
2271-2274.
Hasan, S., Nath, S., Ahmed, M. T., Tasnim, M., Biswas, S.,
Hossain, M. S., & Ahmed, T. (2021). Masturbation in male capped langurs
(Trachypithecus pileatus) at Lawachara National Park, Bangladesh. Bangladesh
Journal of Zoology, 49(3), 441-445.
McLennan, M. R., & van Dijk, K. (2021). Use of a novel
human object as a masturbatory tool by a wild male chimpanzee at Bulindi,
Uganda. Pan Africa News, 28(1), 8-11.
Shalauddin, M., Islam, M. J., & Ahmed, T. (2021).
Masturbation in a male Phayre's langur, Trachypithecus phayrei. Primate
Biology, 8(2), 43-45.
Thomsen, R., & Soltis, J. (2004). Male masturbation in
free-ranging Japanese macaques. International Journal of Primatology, 25(5),
1033-1041.
