Female Japanese macaque (Fuscata macaque) desire to be ridden by different females. They reject the continual approaches of males all through virtually the complete yr, besides through the mating season, which is after they permit themselves to be courted. At the opposite finish of the planet, rhesus macaques (Mulatto macaque) males from the island of Cayo Santiago (Puerto Rico) copulate extra with their gender than with them. In each circumstances, gay habits doesn’t compromise the viability of the populations. Now, a scientific overview has confirmed that homosexuality is current in all 5 main teams of primates. These behaviors are extra doubtless in species with larger sexual dimorphism (the feminine or the male is bigger), those who type advanced societies, or those who face extra hostile environments.
Some time in the past, gay acts between animals of the identical intercourse had been, even for scientists, aberrations, deviations or the results of inexperience and confusion. They didn’t match right into a fundamentalist studying of the theories of pure choice or evolution: a reproductive try with specimens of the identical intercourse can be a waste. But the reality of nature prevailed. Starting from occasional circumstances that generated shock or embarrassment, the buildup of research dismantled prejudices. Sex, additionally the animal, has different capabilities than mere copy. For instance, a big research with dozens of mammal species, printed in 2023, confirmed that homosexuality has evolutionary utility.
Within mammals, the group most intently associated to people is that of primates, of which we’re half. There are simply over 500 species they usually vary from tiny marmosets to lemurs, together with cercopithecuses and nice apes. A overview of what science is aware of about homosexuality within the order of primates, simply printed within the scientific journal Nature Ecology & Evolutionreveals that gay habits has been documented in 59 of them. The authors of the research spotlight that the absence of information doesn’t indicate the absence of gay habits; it could be that nobody has documented it.
Among practitioners, there may be all kinds of frequencies. Some macaque species prime the report. “Both the number of cases and the sampling effort were extracted from the existing literature with records of sexual behavior between individuals of the same sex (SSB),” says researcher at Imperial College London (United Kingdom) and first creator of this analysis, Chloë Coxshall, in an e mail. By combining the noticed occasions with the time spent observing them, they sought to keep away from bias and higher measure the relevance of the habits. “For example, in common marmosets, 5 cases of SSB were recorded, with methods indicating 1,729 hours of sampling (0.003 cases per hour of observation). In Japanese macaques, 16,354 cases of SSB were recorded in the literature, with 5,900 hours of sampling (2.77 cases per hour of observation),” particulars Coxshall.
The comparability between marmosets and Japanese macaques is related. The first type {couples} that stay remoted from one another. The latter make up massive teams with a fancy social construction. This scientific overview has detected that homosexuality is non-existent (not noticed) or low frequency amongst species during which dyad formation predominates. And it’s extra frequent in those that stay in communities of quite a few people. But there are different components that favor gay relationships.
“Social structure emerges as the main determining factor,” says Vincent Savolainen, director of the Georgina Mace Center for a Living Planet at Imperial College and senior creator of this analysis. “In particular, group structure has a significant direct effect on sexual behavior between individuals of the same sex: species that live in more complex social groups are more likely to exhibit [conductas] SSB.” This includes everything from most species of macaques to baboons and baboons, including bonobos. The differences in size between males and females, as is the case with mountain gorillas, or the longer life expectancy of primates such as chimpanzees, are also good predictors that they have homosexual behavior.
By comparing species where homosexuality does not occur with those that have more or less frequent homosexual behavior, the researchers found a factor that can encompass almost all the others: the environment. “SSBs appear to be influenced by both genetic and environmental factors. For example, our previous research with Cayo Santiago macaques showed a heritability greater than 6% for SSB among males,” says Savolainen. But it recognizes the specific weight of exogenous, environmental factors. Thus, SSBs are more likely in species and populations that face greater pressure from predators, live in environments with an adverse climate or food scarcity, as occurs with Gibraltar monkeys or Barbary macaques.
The authors of the research highlight that both groups with complex social structures and those that face adverse environments can cause situations of stress and conflict. In this context, sex, of any orientation, would serve as an escape valve. But homosexual behavior would not stop there. In the case of macaques on the Puerto Rican island, for example, everything indicates that males that mount each other are more likely to help each other in a future conflict. Something similar happens with sex among bonobas, which helps them keep the males at bay.
José María Gómez is a researcher at the Experimental Station for Arid Zones (EEZA), a CSIC institute. He is also the first author of that work on homosexuality in mammals. Unrelated to the research, he appreciates that it not only tracks the prevalence of homosexual behavior in the different lineages of primates, “but also tries to go further and evaluate what factors may have helped this behavior to be expressed,” he feedback. It highlights, for instance, that the presence and frequency of SSB is dependent upon social and ecological components, similar to social complexity, being context-dependent. “That is, we should not think that there are exclusively homosexual individuals, as occurs in humans, but rather that they can express homosexual and heterosexual behavior at different times,” he particulars.
Gómez agrees with the authors that the origin of homosexuality within the animal kingdom dates again to the start of time. The undeniable fact that it occurred in separate species tens of millions of years in the past would verify this. Either it’s a frequent ancestor or a number of however unbiased emergence between completely different taxa. “If we extend it to all mammals, SSB is distributed among very disparate and phylogenetically distant groups,” recollects the EEZA researcher. “Inferring the origin of the behavior is difficult, but it seems that it is a behavior that emerged a long time ago,” he provides. And he concludes: “I personally think that it is a very evolutionarily labile behavior, which appears and disappears easily throughout the evolutionary history of the lineages, and which is also expressed only under specific conditions.”
https://elpais.com/ciencia/2026-01-12/la-homosexualidad-esta-presente-en-todos-los-grupos-de-primates.html