2023-07-10 18:19:26
Having sex between males is common. At least in a wild colony of macaques in Puerto Rico that has been observed for three years by researchers from Imperial College London (United Kingdom) in which they have also seen that this practice can be beneficial at a social level, since it reinforces the ties between individuals, who then support each other during conflicts. The results have just been published in the journal ‘Nature Ecology and Evolution‘.
The study challenges the old belief, increasingly disproven by science, that having sexual relations between individuals of the same sex is a rare behavior in non-human animals, or the result of unusual environmental conditions (for example, when females are scarce). . Not, at least, in the case of macaques.
“We found that the majority of men were bisexual in their behavior, and that variation in same-sex activity was heritable. This means that the behavior may have an evolutionary basis; For example, we also found that males that mounted each other were also more likely to support each other in conflict; perhaps this could be one of the many social benefits of same-sex sexual activity,” explains Jackson Clive, of the Georgina Mace Center and first author of the study.
“Therefore, our research shows that same-sex sexual behaviors may be common among animals and may evolve. I hope that our results will encourage further discoveries in this area.”
More gay than straight sex
The team studied 236 males within a colony of 1,700 free-living rhesus macaques on the tropical island of Cayo Santiago, Puerto Rico. In addition to observing their behavior and performing genetic analyses, the team had access to genealogical records, detailing the origin of each individual dating back to 1956.
The researchers recorded all ‘social’ sexual relations between the 236 males, both males with males and males with females. They found that same-sex encounters between men were widespread: 72% of males in the sample engaged in sex with similar individuals, compared with 46% of different-sex encounters.
Homosexual intercourse has been observed in thousands of different animals, from insects to penguins, leading to different theories, including ideas about establishing dominance in groups, the scarcity of different-sex mates, and the reduction of sexual intercourse. tension after the attack. However, little data is available to support any theory.
The team investigated several of these theories with their data and found that, for this macaque colony, encounters between males were strongly correlated with “coalition ties.” This means that male partners who regularly engage in sexual acts are more likely to support each other in conflict, giving them an advantage in the group.
hereditary behaviors
The researchers also investigated whether this type of encounter had some kind of cost in the reproduction of the species, but found the opposite: the males that participated in these practices were more successful in perpetuating the species, “possibly due to the benefits of more ties coalition,” the authors note.
The team also analyzed whether performing this type of sex had any hereditary connotations. Using pedigree data, they found that these practices in males passed from father to son in 6.4% of cases, establishing the first evidence of a genetic link. A figure similar to other hereditary behaviors in primates, such as grooming and sociability.
These findings support arguments against the idea that homosexual relationships ‘defy nature and evolution’ (the so-called ‘Darwinian paradox’).
The team also found some genetic correlation between males who were more often ‘mounters’ or ‘mounted’, suggesting that these sub-behaviours may have a common basis. However, whether individuals were more likely to be mounters or mounted did not correlate with their social position, suggesting that asserting their place in the hierarchy is not an important factor for these sexual practices in this species.
Differences and similarities with humans
Although the researchers caution that direct comparisons between macaques and humans are not possible, they say their study challenges the beliefs of those who think homosexual behavior is rare or circumstantial. Instead, the results suggest that some degree of these practices may evolve adaptively, depending on the context, and thus may be a common feature of primate reproductive ecology. There are many examples of other primate groups participating in different forms of these oractics, so further in-depth genetic studies could strengthen this conclusion.
“Unfortunately, there is still a belief among some people that same-sex behavior is ‘unnatural’ and sadly some countries still apply the death penalty for homosexuality. Our research shows that same-sex behavior is, in fact, widespread among non-human animals,” says Vincent Savolainen, director of the Georgina Mace Center.
“Our mission is to advance the scientific understanding of same-sex behavior, including exploring the benefits it brings to nature and within animal societies. Among the macaques we observed in this study, more than two-thirds displayed same-sex behavior and this practice strengthened bonds within the community,” he concludes.
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