A pair of male macaques in Cayo Santiago, Puerto Rico
Chloe Coxshall
Vincent Savolainen of Imperial College London says dads may pass on homosexuality to their sons in wild macaque monkeys. Strong male relationships may benefit evolution from this behaviour. These unions may improve female access and offspring, according to Savolainen.
Same-sex touching is unusual among animals. Savolainen disputes the “Darwinian paradox of homosexuality,” which holds that homosexuality has no value and should be eradicated by natural selection because it does not lead to reproduction.
Savolainen and his crew studied 1700 wild rhesus macaques (Macaca mulatta) in Cayo Santiago, Puerto Rico, to research primate homosexuality. The scientists have observed this colony everyday for 67 years and performed DNA paternity testing since 1992. The researchers monitored 236 boys from two social groups for 72 days, 7 hours every day, from 2017 to 2020.
72% of men mounted other men, while 46% mounted women. To avoid disturbing the animals, the scientists examined them from afar and could not always witness penetration. Some guys had post-ejaculation sperm plugs in their anuses.
After fighting, 16.5% of male monkeys mounted each other. Same-sex mounting reduced with age, suggesting it may “practise” reproductive activity.
Based on the monkeys’ family history, same-sex mounting was 6.4% heritable. Males who mounted same-sex had somewhat more offspring.
As lower-ranking males mounted higher-ranking men, Savolainen claims that males’ mounting action is not a dominance show. According to Savolainen, monkeys occasionally have erections, penetration, and ejaculation, making their behaviour sex rather than dominance.
Jon Richardson from the University of Minnesota, who was not involved in the study, feels this data disproves the idea that same-sex behaviour is unnatural in animals. He thinks this work dispels the concept that animal homosexuality is an evolutionary conundrum or anomaly.
FAQs
Q1: What is the focus of the study on same-sex sexual behavior in wild macaque monkeys?
A1: The study explores the potential heritability of homosexuality and its role in macaque evolution. Researchers observed and analyzed same-sex sexual behaviors in wild macaque monkeys to understand their significance.
Q2: How did the researchers conduct the study on macaque monkeys?
A2: The study was conducted on 1700 wild rhesus macaques in Cayo Santiago, Puerto Rico. Researchers monitored and observed the monkeys’ sexual behaviors and performed DNA paternity testing to study primate homosexuality.
Q3: What percentage of male monkeys exhibited same-sex sexual behavior in the study?
A3: In the study, 72% of male monkeys mounted other males, while 46% mounted females. Same-sex mounting reduced with age, suggesting possible “practice” of reproductive activity.
Q4: Is same-sex behavior heritable in macaque monkeys?
A4: Based on the monkeys’ family history, the study found that same-sex mounting was 6.4% heritable, indicating a potential genetic influence on homosexuality in macaques.
Q5: How does same-sex mounting contribute to macaque evolution, according to Savolainen?
A5: Savolainen suggests that strong male-male relationships and same-sex mounting may benefit evolution by improving female access and offspring in macaque colonies, challenging traditional ideas about the Darwinian paradox of homosexuality.
