Both female and male macaques engage in same-sex activity. But while males usually only do so for a night, females form intense bonds with each other and are usually monogamous. In some macaque populations, homosexual behavior among females is not only common, but the norm. When not mating, these females stay close together to sleep and groom, and defend each other from outside enemies. The Layson albatross, which nests in Hawaii, is known for its large number of homosexual partnerships.
Around 30 percent of pairings on the island of Oahu are made up of two females. They are monogamous, and usually stay together for life - as it takes two parents to successfully rear a chick together. The chicks are often fathered by males that are already in another committed relationship. Bonobos are considered the closest living relative to us humans, and are known for seeking sexual pleasure. They copulate frequently, including with the same sex. They do so for pleasure - but also to bond with each other, climb the social ladder and reduce tension.
About two-thirds of homosexual activities happen among females, but also males enjoy a roll in the grass with each other. Like many birds, swans are monogamous and stick with one partner for years. Many of them choose a same-sex partner. In fact, around 20 percent of swan couples are homosexuals - and they often start families together.
The Laysan albatross, which nests in Hawaii, is also known for its large number of homosexual partnerships. Around 30 percent of the pairings on the island of Oahu, for instance, are made up of two females. Bonobos are known for seeking sexual pleasure; they copulate extremely frequently, including with the same sex.
Other animals engage in homosexual activity too — but not as exclusively and long-term as some birds do. Take bonobos for instance. Almost all of these apes are entirely bisexual, as sex to them is about more than reproduction.
Just like us humans, they have sex for fun, and they do so with both sexes. Same-sex bonobo pairs have been seen performing fellatio, massaging each other's genitals and kissing each other.
And they use sex to cement social bonds and settle disputes. Male bonobos that have had a fight often perform "penis fencing" - genital-to genital touching - to reduce tension. It's a similar story with male lions, which often band together with their brothers to lead the pride.
To ensure loyalty, they strengthen their bonds by having sex with each other. And even bottlenose dolphins display homosexual behavior, which helps members of the group form strong social bonds. So how do we know if an animal is actually gay? It's very difficult for researchers to determine whether an animal is purely homosexual because unlike with humans, you can't really ask animals what they feel, you can only interpret their behavior. They really have a strong bond," van Tol said. But it's their choice to come back to each other and that really says something.
One researcher in the US gave male domesticated sheep the choice between a female and a male partner and found that between six and 12 percent of the rams always picked another ram to mate with. Further research found that the rams that preferred mating with other males had slightly different brains. The hypothalamus, the part of their brain responsible for releasing sex hormones, was in fact smaller in the homosexual rams, which supports the theory that purely homosexual animals do exist.
Interpreting homosexual behavior in animals remains tricky territory for researchers. The topic needs more research, according to Buikx, as there is not enough data to draw concrete conclusions from.
However, homosexuality is still a taboo in the scientific world. We need to spread the message that homosexuality shouldn't be a taboo. That's one of the reasons why Buikx has been organizing special tours through the ARTIS Zoo for Amsterdam's Gay Pride event for the past 5 years, where he introduces visitors to all the homosexual animals living there. There is room for homosexuals, bisexuals, heterosexuals — everything is natural.
What's very unnatural are homophobia and all those kinds of taboos that are still present in a lot of societies on our planet. A new study has revealed the extent to which male apes use sexual intimidation to control their mates. This could extend to our most familiar primate - humans.
Whales, chimps, dogs - animals seem to suffer when they lose a beloved companion or offspring. Do animals understand death, and do they grieve like humans? He believes bonobos use sex to resolve conflicts between individuals.
Other animals appear to go through a homosexual phase before they become fully mature. For instance, male dolphin calves often form temporary sexual partnerships, which scientists believe help to establish lifelong bonds. Such sexual behavior has been documented only relatively recently. Zoologists have been accused of skirting round the subject for fear of stepping into a political minefield. Whether it's a good idea or not, it's hard not make comparisons between humans and other animals, especially primates.
The fact that homosexuality does, after all, exist in the natural world is bound to be used against people who insist such behavior is unnatural. In the U. Many on the religious right regard homosexuality as a sin. And only this month, President Bush vowed to continue his bid to ban gay marriages after the Senate blocked the proposal.
Already, cases of animal homosexuality have been cited in successful court cases brought against states like Texas, where gay sex was, until recently, illegal. Yet scientists say we should be wary of referring to animals when considering what's acceptable in human society.
For instance, infanticide, as practiced by lions and many other animals, isn't something people, gay or straight, generally approve of in humans. So how far can we go in using animals to help us understand human homosexuality?
Robin Dunbar is a professor of evolutionary psychology at the University of Liverpool, England. Dunbar says the bonobo's use of homosexual activity for social bonding is a possible example, adding, "One of the main arguments for human homosexual behavior is that it helps bond male groups together, particularly where a group of individuals are dependent on each other, as they might be in hunting or warfare.
For instance, the Spartans, in ancient Greece, encouraged homosexuality among their elite troops. Another suggestion is that homosexuality is a developmental phase people go through. He said, "This is similar to the argument of play in young animals to get their brain and muscles to work effectively and together. Off the back of this, there's the possibility you can get individuals locked into this phase for the rest of their lives as a result of the social environment they grow up in.
But he adds that homosexuality doesn't necessarily have to have a function. More than years later, research has moved past some of the taboos those early researchers faced and shown that homosexuality is much more common than previously thought. Same-sex behaviour ranging from co-parenting to sex has been observed in over 1, species with likely many more as researchers begin to look for the behaviour explicitly.
Homosexuality is widespread, with bisexuality even more prevalent across species. Researchers are now going beyond just observing it though, with researchers at Imperial leading the way in unravelling how, and why, homosexuality is found across nature. With this behaviour seen across species from birds and insects to reptiles and mammals - including humans - researchers are trying to understand why. In the past, homosexual behaviour was often ignored because it supposedly contradicted Darwin's theory of evolution.
Scientists argued homosexuality was a sort of 'Darwinian paradox' because it involved sexual behaviour that was non-reproductive. Recent evidence however suggests homosexual behaviour could play important roles in reproduction and evolution. Savolainen is a world-renowned evolutionary biologist who approaches many of the same questions Darwin did, but from a contemporary perspective.
Savolainen's contributions range from solving Darwin's 'abominable mystery' of flowering plants to elucidating how great white sharks evolved to be super-predatory fast-swimmers. Savolainen explains: 'I tackle big evolutionary biology questions. It doesn't really matter what organism, at the end of the day it's all about how genes have evolved either to produce a species or a new behaviour.
The overarching aim of his lab can be summed up with the saying: 'Nothing in biology makes sense except in the light of evolution.
Savolainen has turned this philosophy to 'Darwin's paradox'. In , Savolainen started some work on animal homosexuality, beginning with a chapter on the Evolution of Homosexuality.
Since then, he has assembled a collaborative team of researchers to examine the question through field work, genomic sequencing and new theoretical models. On Imperial's Silwood Park campus, Savolainen's PhD student Jackson Clive is spending some of his final days in the lab before he heads out for field work. It will be his second of many months-long trips to observe rhesus macaques in the wild. Female homosexuality has been well studied in Japanese macaques, but Clive's research would examine how homosexual behaviour differs in males and across environments.
Clive explains: "Behavioural studies take a long time especially for these unpredictable and infrequent behaviours, which includes almost all sexual behaviours.
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