Experts underestimate same-sex sexual behavior in animal studies

Two male African elephants display same-sex sexual behavior in Tsavo, Kenya. Photo by Sergio Pitamitz/VWPics/Universal Images Group/Getty Images via CNN Newsource

By Rosa Rahimi, CNN

(CNN) — Same-sex sexual behavior has been observed in more than 1,500 animal species, but a new study finds that it is massively underreported by researchers.

Observations of this same-sex behavior in animals, such as sexual mounting and genital touching, date back to the 18th and 19th centuries, but research on this topic only progressed in the 20th and 21st centuries.

In a study published Thursday in the journal PLOSOne, a team of researchers from the University of Toronto, Northwestern University and the University of Warsaw found that experts who study animal behavior underestimate their observations of same-sex sexual behavior and rarely publish them.

The study surveyed 65 experts and found that 77 percent of them observed same-sex sexual behavior in the species studied. But only 48 percent collected data on this behavior and even fewer – just 18 percent – published papers on these findings.

“Many respondents said they did not record or publish data on same-sex sexual behavior because they perceived it to be very rare,” Karyn Anderson, a doctoral student in evolutionary anthropology at the University of Toronto who led the study, told CNN. “Looking at a broader level, we instead found that it was very commonly observed by our survey participants.”

The idea that this sexual behavior is rare in the animal kingdom has been and continues to be used in debates about the ethics of human homosexuality, the study says.

Anderson says her study, like other studies of same-sex sexual behavior in animals, found that this behavior is indeed “widespread and natural” in the animal kingdom.

Nevertheless, homosexual behavior continues to be discovered in various species. In 2018, sex between male spider monkeys was reported for the first time. In the same year, two male gentoo penguins made headlines for “adopting” an egg that had been abandoned by a male-female penguin pair.

The field appears ripe for future research – of the species in which same-sex behavior was found in the survey, nearly 39% had no previous reports of this behavior, according to the authors.

Josh Davis, a science journalist at the Natural History Museum in London and author of A Little Gay Natural History, was not surprised by the study’s findings but said he found it “pretty exciting” to have data to support these numbers.

“Homosexual behavior has been officially identified in about 1,500 species of animals, but I think most people have long suspected that this is most likely a huge underestimate,” he told CNN. “Because it is found in almost every branch of the evolutionary tree … from beetles and butterflies to lizards and squirrels.”

By uncovering this research gap, Anderson hopes that other mammalogists will be encouraged to publish their studies on same-sex sexual behavior.

Two female penguins stand in front of two cuddling male penguins in February 2005 at Bremerhaven Zoo, where three homosexual male penguins live. (Photo by David Hecker/DDP/AFP/Getty Images via CNN Newsource)

Why is there so little reporting about it?

The authors suspected that discomfort or sociopolitical reasons might contribute to the underreporting of same-sex sexual behavior, but they found no such case among the researchers interviewed.

Instead, respondents said it may be because these sexual behaviors are rare or not a research priority in their lab. Most of their observations are considered “anecdotal” rather than the result of a systematic investigation, which may make scientific journals less inclined to publish their findings.

Davis added that there are other obstacles to documenting same-sex behavior in animals.

“In the past, there was definitely a fear on the part of researchers that if they published about these behaviors, they might be associated with these behaviors,” he said, but the situation has “improved over time.”

Another challenge for researchers is that when observing sexual activity in certain species, the sex of the animal is not always clear. “It is assumed that researchers are observing a male and a female,” Davis said.

“The most important finding from this research is that same-sex sexual behavior is widespread but underreported in mammals,” Anderson explained, adding, “This may also be true for other behaviors that are thought to be rare but turn out to be more common when examined in a larger context.”