Lesbian gorillas having sex in Rwanda filmed by scientist

Lesbian gorillas having sex in Rwanda were filmed for the first time by an Australian scientist. He found that female gorillas are more likely to engage in lesbian sex when they are sexually aroused, especially after being turned down by a male they were attempting to attract – another female is an alternative outlet for their libido. Rather than lesbian (homosexual), the female gorillas appear to be bisexual.

The research formed part of a study facilitated through the Dian Fossey Gorilla Fund International, which was focusing on the feeding ecology of Rwandan mountain gorillas.

Associate Professor Cyril Grueter, who works at the The University of Western Australia’s department of Physiology and Human Biology, and Tara S. Stoinski, from The Dian Fossey Gorilla Fund International in the USA, wrote about their study findings in the scientific journal PLOS ONE (citation below).

Lesbian GorillasTwo female gorillas engaging in ventro-ventral homosexual mounting. The mountee was uttering copulatory vocaluzations. (Image: PLOS ONE).

Bonobos, one of the great apes, are well-known for their rich sexual repertoire, which includes homosexual acts. However, nobody knew much about the homosexual behaviour of other Great Apes, that is, until now.

Lesbian interactions linked to sexual gratification

The authors said their observations were ‘intriguing’, and led them to test three sociosexual hypotheses that might explain the gorilla’s behaviour:

1. The gorilla’s asserting dominance based on social status.

2. A reconciliation after a fight or confrontation.

3. The reinforcing of social bonds.

Relative Dominance RanksRelative dominance ranks of mounter & mountee, i.e. ‘mounting direction’. ‘Down’ = down the hierarchy, while ‘up’ = up the hierarchy. (Image: PLOS ONE)

Prof. Grueter said:

“None of the three hypotheses received any consistent support. So a more prosaic explanation was considered – that homosexual behaviour reflects elevated arousal, as there was evidence that homosexual behaviour was more frequent at times when females also engaged in heterosexual copulations.”

The researchers observed cases where female gorillas directed their sexual attention to other females after a male had shown no interest in their advances. In other words, the females appeared to have served as an alternative outlet for their sex drive.

Regarding homosexual activity among wild gorillas, Prof. Grueter said:

“Given that all these observations come from wild groups, not gorillas held in captivity, it is obvious that homosexual activity is part of the gorillas’ natural behaviour.”

“My impression is that these females derive pleasure from sexual interaction with other females.”

As gorillas are closely related to human beings, their study findings may be of interest to researchers who are studying homosexual interactions among humans, the authors wrote.

Prof. Grueter added:

“One thing female gorillas have in common with human women, that has been well documented, is that they can shift from homosexual to heterosexual sex.”

In an Abstract in the journal, the authors wrote:

“There is also some limited evidence that same-sex behavior reflects an overall state of arousal or is triggered via a ‘pornographic’ effect.”

“An adaptive function of female homosexual behavior is not readily apparent, and we tentatively conclude (until a more rigorous test becomes available) that it may simply be related to sexual gratification or that it is an evolutionary by-product of an adaptation.”

About the Dian Fossey Gorilla Fund

The Dian Fossey Gorilla Fund (Fund) International is dedicated to the protection of wild gorillas in Africa and their habitats.

It says it is committed to promoting continued research on gorillas and their ecosystems, which are threatened. It also aims to provide education about their relevance to the world we live in.

The Fund collaborates with international partners and government agencies to provide assistance to local communities through development initiatives, education, health and training.

Citation: Homosexual Behavior in Female Mountain Gorillas: Reflection of Dominance, Affiliation, Reconciliation or Arousal? Cyril C. Grueter & Tara S. Stoinski. PLOS ONE, 11(5): e0154185. 11 May 2016. DOI: 10.1371/journal.pone.0154185.

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