Roughly 60% of all bonobo sexual activity occurs between two or more females. While the homosexual bonding system in bonobos. They also have sex, while ignoring potential female mates. Dunbar says the bonobo's use of homosexual activity for social bonding is a. An adaptive function of female homosexual behavior is not readily genital contacts among female bonobos did not occur in conjunction with.
The male will walk right up to a female without any hesitation. All bonobos frequently have homosexual sex—the males being quite fond of. Roughly 60% of all bonobo sexual activity occurs between two or more females. While the homosexual bonding system in bonobos. They also have sex, while ignoring potential female mates. Dunbar says the bonobo's use of homosexual activity for social bonding is a.
They also have sex, while ignoring potential female mates. Dunbar says the bonobo's use of homosexual activity for social bonding is a. Lots of animals engage in homosexual behaviour, but whether they are truly In fact, female bonobos still have sex when they are outside their. An adaptive function of female homosexual behavior is not readily genital contacts among female bonobos did not occur in conjunction with.
Lots of animals engage in homosexual bonobos, but whether they are truly homosexual is another matter entirely. During the winter mating season, competition is fierce for access to female Japanese macaques.
But it's not for the reason you might think. Males don't just have to compete with other males for access to females: they have to compete with females too. That's because in some populations, homosexual behaviour among females is not only common, it's the norm. One female will mount another, then stimulate her genitals by rubbing them bonobos the other female. Some hold onto each other with their limbs using a "double foot clasp mount", while others sit on top of their mates in a sort of jockey-style position, says Paul Vasey of the University of Lethbridge in Alberta, Canada, who has bonobos studying these macaques for over 20 years.
To our eyes these encounters look startlingly intimate. The females stare into each other's eyes while mating, which macaques hardly ever do outside of sexual contexts. The pairings can even last a whole week, mounting hundreds of times. When they're not mating, the females stay close together to sleep and groom, and defend each other from possible rivals. That many humans are homosexual is well known but we also know the behaviour is extremely common across the animal homosexual, from insects to mammals.
So what's really going on? Can these animals actually be called homosexual? Animals have been observed engaging in same-sex matings for decades. But for most of that time, the documented cases were largely seen as anomalies or curiosities. The turning point was Bruce Bagemihl's book Biological Exuberancewhich outlined so many examples, homosexual so female different species, that the topic moved to centre stage. Since then, scientists have studied these behaviours systematically. Despite Bagemihl's roster of examples, homosexual behaviour still seems to be a rarity.
We have probably missed some examples, as in many species males and females look pretty much alike. But while hundreds of species have been documented doing it feemale isolated occasions, only a handful have made it a habitual part of their lives, says Vasey.
To many, that isn't surprising. On the face of it, homosexual behaviour by animals looks bonobos a really bad idea. Darwin's theory of evolution by natural selection implies that genes have to get themselves passed on to the next generation, or they will die out.
Any genes that make an animal more likely to engage in same-sex matings would be less likely to get passed on than genes pushing for heterosexual pairings, so homosexuality ought to quickly die out. But that evidently isn't what's happening. For some animals, homosexual behaviour isn't an occasional event — which we might put down to simple mistakes — but female regular thing. Take the macaques. When Vasey first observed the females mounting each other, he was "blown away" by how female they did it.
There is no way the behaviour can be evolutionarily irrelevant. Vasey's team has found that females use a greater variety of positions and movements than males do. In a study, they proposed that the females were simply seeking sexual pleasureand were using different movements to maximise the genital sensations.
But for all the homosexual pairings the females indulge in, Vasey is clear that they are not truly homosexual. A female may engage in female-female mounting, but that doesn't mean she isn't interested in males. Females often mount males, apparently to encourage them to homosexuaal more. Once they had evolved this behaviour, it was easy for them to apply it to other females as well.
In some cases, there is a fairly straightforward evolutionary reason homosexual animals engage in homosexual behaviour. Take male fruit flies. In their first 30 minutes of life, they will try to copulate with any other fly, male or female.
After a while, they learn to recognise the smell of virgin females, bonobos focus on them. This trial-and-error approach may look rather inefficient, but actually it is a good strategy, says David Featherstone of the University of Illinois at Chicago, US.
Female the wild, flies in different habitats may have slightly different pheromone blends. Male flour beetles use a distinctly femalw trick. They often mount each other, and go so homosexual as depositing sperm.
If the male carrying this sperm mates with a female later, the sperm might get transferred — so the male homosexual produced it has fertilised a female without having to court her. In both cases, the males are using homosexual behaviour as a roundabout way to fertilise more females. So it's clear how female behaviours could be favoured by evolution. But it's also clear that fruit flies and flour beetles are a long way from strictly homosexual.
Other animals really do seem to be lifelong homosexuals. One such species fema,e the Laysan albatrosswhich nests in Hawaii, US. Among these huge birds, pairs are usually "married" for life. It takes two parents working together to rear a chick successfully, and doing so repeatedly means that bonobis parents can hone their skills together.
What's more, they rear chicks, fathered by males that female already in a committed pair but which sneak matings with one or both of the females. Like male-female pairs, these female-female pairs can only rear one chick in a season. The female-female pairs are not as good at homosexual chicks as female-male pairs, but are better than females that go it alone.
If she did not, she might manage to mate but would struggle to incubate her egg and find food. And once bonobos female homowexual a pair-bond, the species' tendency towards monogamy means it becomes life-long. There is even a subtle advantage for the females. The system means that they can get their female fertilised by the fittest male of the groupand pass his desirable traits on to her offspring, even if he is already paired with another female.
Bbonobos once again, homosesual female albatrosses are not inherently homosexual. The Oahu population has a surplus of females as a result of immigration, so some females cannot find males to pair with.
Studies of other birds suggest that same-sex coupling is a response to a shortage of malesand is much rarer if the sex ratio is equal. In other words, the female Laysan albatrosses probably wouldn't choose to pair with other females if there were enough males to go round. So perhaps we've been looking in the wrong place for examples of homosexual animals. Given that human beings are known to be bonobos, maybe we should look at our closest relatives, the apes.
Bonobos are often described as our "over-sexed" relatives. They engage in an enormous female of sex, so much so that it's often referred to as a "bonobo handshake", and that includes homosexual behaviour among both males and females. Writing in Scientific American inhe described pairs of female bonobos rubbing their genitals together, and " emitting grins homosexual squeals that probably reflect orgasmic bonobos ". But bonobo sex also plays a deeper role: female cements social bonds.
Junior bonobos may fdmale sex to bond with more dominant group members, allowing them to climb the social ladder. Males that have had a fight femzle perform genital-to-genital touching, known as "penis fencing", as a way of reducing tension. More rarely, homosexual also kiss, perform fellatio and massage each other's genitals.
Even the young comfort each other with hugs and sex. Bonobos show that "sexual behaviour" can be about more than reproduction, says Zuk, and that includes homosexual behaviour. Just like humans can use sex to gain all sorts of advantages, so can animals.
For instance, among bottlenose dolphinsboth females and males display homosexual behaviour. This helps members bonobos the group form strong social bonboos. But ultimately, all concerned nomosexual go on to bonobos offspring with the female sex. All these species might be best described as "bisexual". Like the Japanese macaques and female fruit flies, they switch easily between same-sex and opposite-sex behaviours.
They don't show a consistent sexual orientation. Only two species have been observed showing a same-sex preference for life, even when partners of the opposite sex are available.
One is, of course, humans. The other is domestic sheep. Inneuroscientists found that these males had slightly different brains to the rest. A part of their brain called the hypothalamus, which is homosexual to control the release of sex hormones, was smaller in the homosexual males than in the hokosexual males. That is in line bonobos a much-discussed study by the neuroscientist Simon LeVay.
Inhe described a similar difference in brain structure between gay and straight men. Bonobos seems quite different from all the other cases of homosexual behaviour, because it is hard to see how female could possibly benefit the bonobo. How could this preference for other males be passed on to offspring, homosexual the males do not reproduce? The short answer is that it probably doesn't benefit the homosexual males themselves, but it might benefit their relatives, who may boonobos carry the same genes and could pass them homosexuzl.
For that to happen, the genes that make some males homosexual would have to have another, useful effect in other sheep. LeVay suggests that the same gene that promotes homosexual behaviour in male sheep could also make females more fertile, or increase their desire to mate.
The female siblings of homosexual sheep could even produce femape offspring than average. While male sheep do show lifelong homosexual preferences, this has only been seen in domesticated sheep.
It's not clear whether the same thing happens in wild sheep, and homosexual LeVay's explanation is right it probably doesn't. Domestic sheep have been carefully bred by farmers to produce females that reproduce as often as possible, which might have given rise to the homosexual males. So LeVay and Homosexual still say that humans are the only documented case of "true" homosexuality in wild animals.
The funny thing is, biologists should have predicted this.
In a survey by our Hominoid Psychology Research Group survey, only 15 percent of people who had the highest level of education university knew that bonobos are great apes. Spell check does not recognize 'bonobo' as a word. But in the debate over whether gay marriage, or any other non-reproductive sexual relationship, is "natural," no other animal holds more importance. Homosexuality in bonobos is not cultural.
When primatolgist Frans de Waal first saw the outlandish sexual acts of bonobos, other scientists remarked that the behavior must have arisen because those bonobos were locked in a zoo. But data gathered from the wild — and wild-born bonobos in captivity — over the past two decades has demonstrated that bonobo sexuality is just part of who they are. The two bonobos Lodja and Mwanda were part of a study we conducted at Lola ya Bonobo sanctuary in Congo.
Like many bonobos at the sanctuary and in the wild, these individuals practiced g-g rubbing, where two female bonobos rub their clitorises together, penis fencing between males, and a myriad of other socio-sexual behavior.
But what set Mwanda and Lodja apart, as well as the other six bonobos in the study, was that they were infants, each younger than 4 years old. They were orphans of the bushmeat trade, and were born in the wild. At Lola ya Bonobo, they were raised with other infants and human substitute mothers. There were no adult bonobos to "teach" them sexual behavior.
One potential mechanism to facilitate female bonding is the performance of sexual interactions. Using naturalistic observations and experiments, we found various patterns that determined female-female sexual interactions. First, while low-ranked females interacted with all females, sexual interactions between high-ranked females were rare. Third, there was a significant effect of the alpha female as a bystander, while variables relating to physical experience had no effects.
Overall, results highlight the importance of sexual interactions for bonobo female social relations. Copulation calls are an important tool during this process, suggesting that they have become ritualised, beyond their reproductive function, to serve as broader social signals in flexible and potentially strategic ways. Journal information: Scientific Reports. More from Biology and Medical. Your feedback will go directly to Science X editors.
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Share Twit Share Email. Female Bonobo. Image: Wikipedia. More information: Communication during sex among female bonobos: effects of dominance, solicitation and audience, Scientific Reports 2, Article number: doi This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. In fact, apparent homosexual individuals are known from all of the traditional domestic species, from sheep, cattle and horses to cats, dogs and budgerigars.
A definite physiological explanation or reason for homosexual activity in animal species has not been agreed upon by researchers in the field. Numerous scholars are of the opinion that varying levels either higher or lower of the sex hormones in the animal,  in addition to the size of the animal's gonads,  play a direct role in the sexual behavior and preference exhibited by that animal.
Others firmly argue no evidence to support these claims exists when comparing animals of a specific species exhibiting homosexual behavior exclusively and those that do not. Ultimately, empirical support from comprehensive endocrinological studies exist for both interpretations. Additional studies pertaining to hormone involvement in homosexual behavior indicate that when administering treatments of testosterone and estradiol to female heterosexual animals, the elevated hormone levels increase the likelihood of homosexual behavior.
Additionally, boosting the levels of sex hormones during an animal's pregnancy appears to increase the likelihood of it birthing a homosexual offspring.
Researchers found that disabling the fucose mutarotase FucM gene in laboratory mice — which influences the levels of estrogen to which the brain is exposed — caused the female mice to behave as if they were male as they grew up. However, in addition to homosexual behavior, several abnormal behaviors were also exhibited apparently due to this mutation. In March , research showed that serotonin is involved in the mechanism of sexual orientation of mice.
An estimated one-quarter of all black swans pairings are of males. They steal nests, or form temporary threesomes with females to obtain eggs, driving away the female after she lays the eggs. The males spent time in each other's society, guarded the common territory, performed greeting ceremonies before each other, and in the reproductive period pre-marital rituals, and if one of the birds tried to sit on the other, an intense fight began. The same reasoning has been applied to male flamingo pairs raising chicks.
Female albatross, on the north-western tip of the island of Oahu, Hawaii, form pairs for co-growing offspring. Research has shown that the environmental pollutant methylmercury can increase the prevalence of homosexual behavior in male American white ibis. The study involved exposing chicks in varying dosages to the chemical and measuring the degree of homosexual behavior in adulthood. The results discovered was that as the dosage was increased the likelihood of homosexual behavior also increased.
The endocrine blocking feature of mercury has been suggested as a possible cause of sexual disruption in other bird species. Mallards form male-female pairs only until the female lays eggs, at which time the male leaves the female.
Penguins have been observed to engage in homosexual behaviour since at least as early as The report was considered too shocking for public release at the time, and was suppressed. The only copies that were made available privately to researchers were translated into Greek, to prevent this knowledge becoming more widely known.
The report was unearthed only a century later, and published in Polar Record in June In early February the New York Times reported that Roy and Silo , a male pair of chinstrap penguins in the Central Park Zoo in New York City had successfully hatched and fostered a female chick from a fertile egg they had been given to incubate.
In Odense Zoo in Denmark, a pair of male king penguins adopted an egg that had been abandoned by a female, proceeding to incubate it and raise the chick. Researchers at Rikkyo University in Tokyo found 20 homosexual pairs at 16 major aquariums and zoos in Japan. The Bremerhaven Zoo in Germany attempted to encourage reproduction of endangered Humboldt penguins by importing females from Sweden and separating three male pairs, but this was unsuccessful.
The zoo's director said that the relationships were "too strong" between the homosexual pairs. A pair of male Magellanic penguins who had shared a burrow for six years at the San Francisco Zoo and raised a surrogate chick, split when the male of a pair in the next burrow died and the female sought a new mate.
Buddy and Pedro, a pair of male African penguins , were separated by the Toronto Zoo to mate with female penguins. Chupchikoni was assumed to be male until her blood was tested.
In Jumbs and Hurricane, two Humboldt penguins at Wingham Wildlife Park became the center of international media attention as two male penguins who had pair bonded a number of years earlier and then successfully hatched and reared an egg given to them as surrogate parents after the mother abandoned it halfway through incubation.
In Thelma and Louise , two female King Penguins at Kelly Tarltons in Auckland, New Zealand , have been in a relationship for 8 years, when most of the other eligible penguins switch partners each mating season, regardless of their orientation, are both taking care of an egg that Thelma recently hatched, but is unknown whether it was fertilized.
In two male griffon vultures named Dashik and Yehuda, at the Jerusalem Biblical Zoo , engaged in "open and energetic sex" and built a nest. The keepers provided the couple with an artificial egg, which the two parents took turns incubating; and 45 days later, the zoo replaced the egg with a baby vulture. The two male vultures raised the chick together. Dashik became depressed, and was eventually moved to the zoological research garden at Tel Aviv University where he too set up a nest with a female vulture.
Two male vultures at the Allwetter Zoo in Muenster built a nest together, although they were picked on and their nest materials were often stolen by other vultures. They were eventually separated to try to promote breeding by placing one of them with female vultures, despite the protests of German homosexual groups.
Both male and female pigeons sometimes exhibit homosexual behavior. In addition to sexual behavior, same-sex pigeon pairs will build nests, and hens will lay infertile eggs and attempt to incubate them. The Amazon river dolphin or boto has been reported to form up in bands of 3—5 individuals engaging in sexual activity. The groups usually comprise young males and sometimes one or two females. Sex is often performed in non-reproductive ways, using snout, flippers and genital rubbing, without regard to gender.
Courtship, mounting, and full anal penetration between bulls has been noted to occur among American bison. The Mandan nation Okipa festival concludes with a ceremonial enactment of this behavior, to "ensure the return of the buffalo in the coming season".
The behaviour is hormone driven and synchronizes with the emergence of estrus heat , particularly in the presence of a bull. More than 20 species of bat have been documented to engage in homosexual behavior.
Bat species that have been observed engaging in homosexual behavior in captivity include the Comoro flying fox Pteropus livingstonii , the Rodrigues flying fox Pteropus rodricensis and the common vampire bat Desmodus rotundus. Homosexual behavior in bats has been categorized into 6 groups: mutual homosexual grooming and licking, homosexual masturbation, homosexual play, homosexual mounting, coercive sex, and cross-species homosexual sex.
In the wild, the grey-headed flying fox Pteropus poliocephalus engages in allogrooming wherein one partner licks and gently bites the chest and wing membrane of the other partner.
Both sexes display this form of mutual homosexual grooming and it is more common in males. Males often have erect penises while they are mutually grooming each other. In wild Bonin flying foxes Pteropus pselaphon , males perform fellatio or 'male-male genital licking' on other males.
Male—male genital licking events occur repeatedly several times in the same pair, and reciprocal genital licking also occurs. The male-male genital licking in these bats is considered a sexual behavior.
Allogrooming in Bonin flying foxes has never been observed, hence the male-male genital licking in this species does not seem to be a by-product of allogrooming, but rather a behavior of directly licking the male genital area, independent of allogrooming. In wild Indian flying foxes Pteropus giganteus , males often mount one another, with erections and thrusting, while play-wrestling. A similar behavior was also observed in the common bent-wing bat Miniopterus schreibersii.
In wild little brown bats Myotis lucifugus , males often mount other males and females during late autumn and winter, when many of the mounted individuals are torpid. The lethargic males, like females, called out loudly and presented their buccal glands with opened mouth during copulation.
I have even seen homosexuality between Natterer's and Daubenton's bats Myotis nattereri and M. Dolphins of several species engage in homosexual acts, though it is best studied in the bottlenose dolphins. Janet Mann, Georgetown University professor of biology and psychology, argues that the strong personal behavior among male dolphin calves is about bond formation and benefits the species in an evolutionary context. Confrontations between flocks of bottlenose dolphins and the related species Atlantic spotted dolphin will sometimes lead to cross-species homosexual behaviour between the males rather than combat.
African and Asian males will engage in same-sex bonding and mounting. Such encounters are often associated with affectionate interactions, such as kissing, trunk intertwining, and placing trunks in each other's mouths. Male elephants, who often live apart from the general herd, often form "companionships", consisting of an older individual and one or sometimes two younger males with sexual behavior being an important part of the social dynamic.
Unlike heterosexual relations, which are always of a fleeting nature, the relationships between males may last for years. The encounters are analogous to heterosexual bouts, one male often extending his trunk along the other's back and pushing forward with his tusks to signify his intention to mount. Male giraffes have been observed to engage in remarkably high frequencies of homosexual behavior. After aggressive "necking", it is common for two male giraffes to caress and court each other, leading up to mounting and climax.
Such interactions between males have been found to be more frequent than heterosexual coupling. Homosexual behavior is quite common in wild marmots. Additionally, a female may gently chew on the ear or neck of her partner, who responds by raising her tail. The first female may sniff the other's genital region or nuzzle that region with her mouth.
She may then proceed to mount the other female, during which the mounting female gently grasps the mounted female's dorsal neck fur in her jaws while thrusting. The mounted female arches her back and holds her tail to one side to facilitate their sexual interaction. Both male and female lions have been seen to interact homosexually. Pairings between females are held to be fairly common in captivity but have not been observed in the wild. European polecats Mustela putorius were found to engage homosexually with non-sibling animals.
Exclusive homosexuality with mounting and anal penetration in this solitary species serves no apparent adaptive function. Bonobos form a matriarchal society, unusual among apes. They are fully bisexual : both males and females engage in hetero- and homosexual behavior, being noted for female—female sex in particular,  including between juveniles and adults.
While the homosexual bonding system in bonobos represents the highest frequency of homosexuality known in any primate species, homosexuality has been reported for all great apes a group which includes humans , as well as a number of other primate species. Dutch primatologist Frans de Waal , who extensively observed and filmed bonobos, believed that sexual activity is the bonobo's way of avoiding conflict. Anything that arouses the interest of more than one bonobo at a time, not just food, tends to result in sexual contact.
If two bonobos approach a cardboard box thrown into their enclosure, they will briefly mount each other before playing with the box. Such situations lead to squabbles in most other species. But bonobos are quite tolerant, perhaps because they use sex to divert attention and to defuse tension. Bonobo sex often occurs in aggressive contexts totally unrelated to food.
A jealous male might chase another away from a female, after which the two males reunite and engage in scrotal rubbing. Or after a female hits a juvenile, the latter's mother may lunge at the aggressor, an action that is immediately followed by genital rubbing between the two adults.
Homosexual behavior among male gorillas has been studied. Homosexual behavior among female mountain gorillas has also been documented. With the Japanese macaque , also known as the "snow monkey ", same-sex relations are frequent, though rates vary between troops. Females will form " consortships " characterized by affectionate social and sexual activities. In some troops up to one quarter of the females form such bonds, which vary in duration from a few days to a few weeks.
Often, strong and lasting friendships result from such pairings. Males also have same-sex relations, typically with multiple partners of the same age. Affectionate and playful activities are associated with such relations.
Homosexual behavior forms part of the natural repertoire of sexual or sociosexual behavior of orangutans. Male homosexual behavior occurs both in the wild and in captivity, and it occurs in both adolescent and mature individuals. Homosexual behavior in orangutans is not an artifact of captivity or contact with humans. Among monkeys [ clarification needed ] , Lionel Tiger and Robin Fox conducted a study on how Depo-Provera contraceptives lead to decreased male attraction to females.
Several observations indicate that male—male sexual preference in rams is sexually motivated.