The Bonobo displays the highest rate of homosexual activity in any animal, being a fully bisexual species.^[1][2]

Homosexual (as well as bisexual) behavior is widespread in the animal kingdom.^[3] Animal sexual behavior takes many different forms, even within the same species and the motivations for and implications of their behaviors have yet to be fully understood. A 1999 review by researcher Bruce Bagemihl shows that homosexual behavior, not necessarily sex, has been observed in close to 1500 species, ranging from primates to gut worms, and is well documented for 500 of them.^[4][5] Image File history File links Metadata Size of this preview: 750 × 600 pixelsFull resolution‎ (1,344 × 1,075 pixels, file size: 1. ... Image File history File links Metadata Size of this preview: 750 × 600 pixelsFull resolution‎ (1,344 × 1,075 pixels, file size: 1. ... For other uses, see Bonobo (disambiguation). ... In human sexuality, bisexuality describes a man or woman having a sexual orientation to persons of either or both sexes (a man or woman who sexually likes both sexes; people who are sexually and/or romantically attracted to both males and females). ... Since its coinage, the word homosexuality has acquired multiple meanings. ... In human sexuality, bisexuality describes a man or woman having a sexual orientation to persons of either or both sexes (a man or woman who sexually likes both sexes; people who are sexually and/or romantically attracted to both males and females). ... See Animal. ... Animal sexual behavior takes many different forms, even within the same species. ... For other uses, see Species (disambiguation). ... This article is about the year. ... Bruce Bagemihl, PhD., is the author of the controversial book Biological Exuberance: Animal Homosexuality and Natural Diversity, which first argues that homosexual and bisexual behaviors are rife through the natural world, and then proposes an overarching theory of natural sexuality in which reproduction is only one of its principal biological... This article or section does not cite its references or sources. ... For the ecclesiastical use of this term, see primate (religion) Families 13, See classification A primate is any member of the biological order Primates, the group that contains all lemurs, monkeys, and apes, including humans. ... Classes Archiacanthocephala Palaeacanthocephala Eoacanthocephala The Acanthocephala (gr. ...

Homosexuality in animals is seen as controversial because some assert it points to the naturalness of homosexuality in humans, while others counter that it has no implications and is nonsensical to use animal behavior to justify what is or is not immoral.^[6][7] This article is about human sexual perceptions. ... Morality (from the Latin manner, character, proper behavior) has three principal meanings. ...

Applying the term homosexual to animals

The term homosexual was coined in Prussia in the 1870's to describe same-sex sexual attraction and sexual behaviour in humans. Its use in animal studies has been controversial for two main reasons: animal sexuality and motivating factors have been and remain poorly understood, and the term has strong cultural implication in western society that are irrelevant for other species than humans.^[8] Since its coinage, the word homosexuality has acquired multiple meanings. ... For other uses, see Prussia (disambiguation). ... Events and Trends Technology Invention of the telephone ( 1876) and phonograph ( 1877) Science Ludwig Boltzmanns statistical definition of thermodynamic entropy War, peace and politics Franco-Prussian War ( 1870– 1871) results in the collapse of the Second French Empire and in the formation of both the French Third Republic... This article is about modern humans. ...

Animal preference and motivation is always inferred from behaviour. Thus homosexual behaviour has been given a number of terms over the years. The correct usage of the term homosexual is that an animal exhibit homosexual behaviour, however this article conform to the usage by modern research ^{[9][10][11][12]} applying the term homosexuality to all sexual behaviour (copulation, genital stimulation, mating games and sexual display behaviour) between animals of the same sex. A pair of lions copulating in the Maasai Mara, Kenya. ... A sex organ, or primary sexual characteristic, narrowly defined, is any of those parts of the body (which are not always bodily organs according to the strict definition) which are involved in sexual reproduction and constitute the reproductive system in an complex organism; namely: Male: penis (notably the glans penis... Display is a form of animal behaviour, linked to survival of the species in various ways. ...

Research on homosexual behavior in animals

The presence of same-sex sexual behavior was not 'officially' observed on a large scale until recent times, possibly due to observer bias caused by social attitudes to same-sex sexual behavior. It appears to be widespread amongst social birds and mammals, particularly the sea mammals and the primates. Sexual behavior is a form of physical intimacy that may be directed to reproduction (one possible goal of sexual intercourse) and/or to the enjoyment of activity involving sexual gratification. ... Observer Effect is the name of the 87th episode from the television series Star Trek: Enterprise. ... Sexual behavior is a form of physical intimacy that may be directed to reproduction (one possible goal of sexual intercourse) and/or to the enjoyment of activity involving sexual gratification. ... For other uses, see Bird (disambiguation). ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including those that produce milk, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... For the ecclesiastical use of this term, see primate (religion) Families 13, See classification A primate is any member of the biological order Primates, the group that contains all lemurs, monkeys, and apes, including humans. ...

"No species has been found in which homosexual behaviour has not been shown to exist, with the exception of species that never have sex at all, such as sea urchins and aphis. Moreover, a part of the animal kingdom is hermaphroditic, truly bisexual. For them, homosexuality is not an issue."^[13] Subclasses Subclass Perischoechinoidea Order Cidaroida (pencil urchins) Subclass Euechinoidea Superorder Atelostomata Order Cassiduloida Order Spatangoida (heart urchins) Superorder Diadematacea Order Diadematoida Order Echinothurioida Order Pedinoida Superorder Echinacea Order Arbacioida Order Echinoida Order Phymosomatoida Order Salenioida Order Temnopleuroida Superorder Gnathostomata Order Clypeasteroida (sand dollars) Order Holectypoida Wikispecies has information related to... Look up Aphis in Wiktionary, the free dictionary. ... For other uses, see Hermaphrodite (disambiguation). ...

Some researchers believe it to have its origin in male social organization and social dominance, similar to the dominance traits shown in prison sexuality. Others, particularly Joan Roughgarden, Bruce Bagemihl and Paul Vasey point to that the social function of sex (both homosexual and heterosexual) is not necessarily connected to dominance, but serves to strengthen alliances and social ties within a flock. Others cast doubt on social organization theory, pointing to citing gay penguins that mate for life and refuse to pair with females when given the chance.^[14] While reports on many such mating scenarios are still only anecdotal, a growing body of scientific work confirm that permanent homosexuality occur in species with permanent pair bonds, but also in non-monogamous species like sheep. Prison sexuality deals with sexual relationships between confined individuals. ... Joan E. Roughgarden (b. ... Bruce Bagemihl, PhD., is the author of the controversial book Biological Exuberance: Animal Homosexuality and Natural Diversity, which first argues that homosexual and bisexual behaviors are rife through the natural world, and then proposes an overarching theory of natural sexuality in which reproduction is only one of its principal biological... Modern genera Aptenodytes Eudyptes Eudyptula Megadyptes Pygoscelis Spheniscus For prehistoric genera, see Systematics Some penguins are curious. ...

One report on sheep cited below states:

"Approximately 8% of rams exhibit sexual preferences [that is, even when given a choice] for male partners (male-oriented rams) in contrast to most rams, which prefer female partners (female-oriented rams). We identified a cell group within the medial preoptic area/anterior hypothalamus of age-matched adult sheep that was significantly larger in adult rams than in ewes..."^[15] In fact, apparent homosexual individuals are known from all of the traditional domestic species.

Cross-species sex

Although a commonly held conception is that animals' sexuality is instinctive almost to the point of being mechanistic, research regularly records that many animals are sexual opportunists, and may show an interest in other partners than their own or related species. This is more visible in domesticated species, as domestication commonly selects for increased breeding rate (and so an accelerated breeding cycle has commonly arisen in domesticated species over the centuries), and also because these species are easier to witness by humans. Nevertheless non-domesticated animals have been observed to attempt sexual activity with other species, or indeed inanimate objects. This form of cross-species sex has occasionally been observed in the wild, however most observations are from animals in captivity (such as the zoo).

If the pair are a male and a female, hybrid offspring can result if the two species are related. However, this offspring may not be able to breed itself. The mule, for example (horse/donkey cross) is normally sterile, whilst the liger (lion/tiger cross) is sometimes fertile. Novosibirsk zoo director Rostislav Shilo says on the liger (born in its zoo); “It’s just that the lion and the tiger live in neighboring caves in the Novosibirsk zoo, and got used to each other. It’s practically impossible in the wild.”. Cross species sex in the wild has been observed between several species, among them blue tit and great tit, Chimpanzees and olive baboons and Amazon River Dolphin and the tucuxi dolphin. This article is about a biological term. ... For other uses, see Mule (disambiguation). ... For other uses, see Liger (disambiguation). ... Binomial name Parus caeruleus Linnaeus, 1758 The Blue Tit Parus caeruleus (syn. ... Binomial name Parus major Linnaeus, 1758 The Great Tit, Parus major, is a passerine bird in the tit family Paridae. ... Type species Simia troglodytes Blumenbach, 1775 distribution of Species Pan troglodytes Pan paniscus Chimpanzee, often shortened to chimp, is the common name for the two extant species of apes in the genus Pan. ... Binomial name Papio anubis (Lesson, 1827) The Olive Baboon (Papio anubis), also called the Anubis Baboon, is a member of the family Cercopithecidae (Old World monkeys). ... Binomial name Blainville, 1817 Boto range The Boto, Amazon River Dolphin or Pink River Dolphin[1] (Inia geoffrensis) is a freshwater river dolphin endemic to the Amazon River and Orinoco River systems. ... Binomial name Sotalia fluviatilis (Gervais & Deville, 1853) Tucuxi range The Tucuxi (Sotalia fluviatilis) is a dolphin found both in the rivers of the Amazon Basin and in the coastal waters to the north and east of South America. ...

Some selected species and groups

See also: List of animals displaying homosexual behavior

This list includes animals for which there is documented evidence of homosexual or transgender behavior of one or more of the following kinds: sex, courtship, affection, pair bonding, or parenting, as listed in Bruce Bagemihls 1999 scientific study Biological Exuberance: Animal Homosexuality and Natural Diversity. ...

American Bison

The American Bison is a bovine mammal which commonly displays homosexual behavior.

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 behaviour, to "ensure the return of the buffalo in the coming season."^[16] Also, mounting of one female by another is common among cattle. Inter-sexual bison also occur. The Lakota refer to them as pte winkte —pte meaning bison and winkte designating two-spirit— thereby drawing an explicit parallel between transgender in animals and people.^[16] Image File history File links Download high resolution version (2700x1761, 1348 KB) Summary A bison, taken by the USDA http://www. ... Image File history File links Download high resolution version (2700x1761, 1348 KB) Summary A bison, taken by the USDA http://www. ... Tribes Bovini Boselaphini Strepsicerotini The biological subfamily Bovinae includes a diverse group of about 24 medium-sized to large ungulates, including domestic cattle, bison, the Water Buffalo, the Yak, and the four-horned and spiral-horned antelopes. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including those that produce milk, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... Roman men having anal sex. ... Binomial name (Linnaeus, 1758) Subspecies B. b. ... This article is about the Native American tribe. ... For general information about the genus, including other species of cattle, see Bos. ... Eddie Plenty Holes, a Sioux Indian photographed about 1899. ... Berdache (from French, from Arabic bardajo meaning kept boy) is a generic term used by some for a third gender (woman-living-man) among many, if not most, Native American tribes. ... A transgender woman at New York Citys gay pride parade Transgender (IPA: , from trans (Latin) and gender (English)) is a general term applied to a variety of individuals, behaviors, and groups involving tendencies that diverge from the normative gender role (woman or man) commonly, but not always, assigned at...

Birds

The Black Swan, Cygnus atratus is a large waterbird which breeds mainly in the southeast and southwest regions of Australia.

An estimated one-quarter of all black swans pairings are homosexual and they steal nests, or form temporary threesomes with females to obtain eggs, driving away the female after she lays the eggs.^[17] More of their cygnets survive to adulthood than those of different-sex pairs possibly due to their superior ability to defend large portions of land. Image File history File links Download high-resolution version (800x700, 175 KB) Image of a pair of Black Swans, converted from JPG to PNG format. ... Image File history File links Download high-resolution version (800x700, 175 KB) Image of a pair of Black Swans, converted from JPG to PNG format. ... Binomial name Cygnus atratus Latham, 1790 Subspecies Black Swan New Zealand Swan (extinct) Synonyms Anas atrata Latham, 1790 Chenopis atratus The Black Swan, Cygnus atratus is a large non-migratory waterbird which breeds mainly in the southeast and southwest of Australia. ... Falcated Duck at Slimbridge Wildfowl and Wetlands centre, Gloucestershire, England Wildfowl or waterfowl, also waterbirds, is the collective term for the approximately 147 species of swans, geese and ducks, classified in the order Anseriformes, family Anatidae. ... Binomial name Cygnus atratus (Latham, 1790) The Black Swan (Cygnus atratus) is an Australian waterbird and the official state bird of Western Australia. ...

In early February 2004 the New York Times reported a male pair of chinstrap penguins in the Central Park Zoo in New York City were partnered and even successfully hatched a female chick from an egg.^[18] Other penguins in New York have also been^[19] reported to be forming same-sex pairs. Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... The New York Times is an internationally known daily newspaper published in New York City and distributed in the United States and many other nations worldwide. ... Binomial name Pygoscelis antarctica The Chinstrap Penguin (Pygoscelis antarctica) is a species of [penguin which is found in the South Sandwich Islands, Antarctica, the South Orkneys, South Shetland, South Georgia, Bouvet Island, Balleny and Peter I Island. ... The Central Park Zoo is located in Central Park in New York City and run by the Wildlife Conservation Society. ... New York, New York and NYC redirect here. ...

Zoos in Japan and Germany have also documented gay male penguin couples.^[14] The couples have been shown to build nests together and use a stone to replace an egg in the nest. Researchers at Rikkyo University in Tokyo, found 20 gay pairs at 16 major aquariums and zoos in Japan. Bremerhaven Zoo in Germany attempted to break up the gay male couples by importing female penguins from Sweden and separating the male couples, they were unsuccessful. The zoo director stated the relationships were too strong between the gay couples. Rikkyo University (St. ... For other uses, see Tokyo (disambiguation). ...

Studies have shown that 10 to 15 percent of female western gulls in some populations in the wild are lesbian.^[20] This article is about same-sex desire and sexuality among women. ...

Bonobo and other apes

The bonobo, which has a matriarchal society (unusual amongst apes), is a fully bisexual species -- both males and females engage in heterosexual and homosexual behavior, being noted for lesbianism in particular. About 60% of all sexual activity in this species is between two or more females. While the homosexual bonding system in bonobos represent the highest frequency of homosexuality known in any species, homosexuality has been reported for all great apes, including humans, as well as a number of other primate species.^{[1][21][22][23][24][25][26][27][28]} For other uses, see Bonobo (disambiguation). ... A matriarchy is a tradition (and by extension a form of government) in which community power lies with the eldest mother of a community. ... In human sexuality, bisexuality describes a man or woman having a sexual orientation to persons of either or both sexes (a man or woman who sexually likes both sexes; people who are sexually and/or romantically attracted to both males and females). ... This article is about homosexual women, not inhabitants of the Greek island of Lesbos A lesbian (lowercase L) is a homosexual woman. ... Genera Subfamily Ponginae Pongo - Orangutans Gigantopithecus (extinct) Sivapithecus (extinct) Subfamily Homininae Gorilla - Gorillas Pan - Chimpanzees Homo - Humans Paranthropus (extinct) Australopithecus (extinct) Sahelanthropus (extinct) Ardipithecus (extinct) Kenyanthropus (extinct) Pierolapithecus (extinct) (tentative) The Hominids (Hominidae) are a biological family which includes humans, extinct species of humanlike creatures and the other great apes... This article is about modern humans. ... Families 15, See classification A primate is any member of the biological order Primates, the group that contains all the species commonly related to the lemurs, monkeys, and apes, with the latter category including humans. ...

Bottlenose Dolphins

Bottlenose Dolphin males have been observed working in pairs or larger groups to follow and/or restrict the movement of a female for weeks at a time, waiting for her to become sexually receptive. The same pairs/groups have also been observed engaging in ardent sexual play with each other. Binomial name Montagu, 1821 Bottlenose Dolphin range (in blue) The Bottlenose Dolphin is the most common and well-known dolphin. ...

Janet Mann, Georgetown University professor of biology and psychology, argues that the strong personal behaviour among male dolphin calves is about bond formation and benefits the species in an evolutionary context.^[20] She cites studies showing that these dolphins later in life as adults are in a sense bisexual, and the male bonds forged earlier in life work together for protection as well as locating females to reproduce with. Georgetown University is an elite private research university located in Georgetown, Washington, D.C., United States. ...

Dragonflies

The head of Darner Dragonfly (Basiaeschna janata).

Male homosexuality has been inferred in several species of dragonflies (the order Odonata). The cloacal pinchers of male damselflies and dragonflies inflict characteristic head damage to females during sex. A survey of 11 species of damsel and dragonflies^[29][30] has revealed such mating damages in 20 to 80 % of the males too, indicating a fairly high occurrence of sexual coupling between males. Image File history File links Size of this preview: 600 × 600 pixelsFull resolution‎ (2,500 × 2,500 pixels, file size: 3. ... Image File history File links Size of this preview: 600 × 600 pixelsFull resolution‎ (2,500 × 2,500 pixels, file size: 3. ... Families Aeshnidae Austropetaliidae Cordulegastridae Corduliidae Gomphidae Libellulidae Neopetaliidae Petaluridae The dragonfly is an insect belonging to the Order Odonata, Suborder Anisoptera and characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body. ... In scientific classification used in biology, the order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). ... Suborders Epiprocta (dragonflies), including infraorder Anisoptera (true dragonflies) Zygoptera (damselflies) Reference: ITIS 101593 as of 2002-07-26 Odonata is an order of insects, encompassing dragonflies (Anisoptera) and damselflies (Zygoptera). ...

Elephants

African, as well as Asiatic 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. 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. Unlike heterosexual relations, which are always of a fleeting nature, those between males result in a "companionship", consisting of an older individual and one or two younger, attendant males. Same-sex relations are common and frequent in both sexes, with Asiatic elephants in captivity devoting roughly 45% of sexual encounters to same-sex activity.^[31]

Fruit flies

Male Drosophila melanogaster flies bearing two copies of a mutant allele in the fruitless gene court and attempt to mate exclusively with other males. Binomial name Meigen, 1830[1] Drosophila melanogaster (from the Greek for black-bellied dew-lover) is a two-winged insect that belongs to the Diptera, the order of the flies. ... There are very few or no other articles that link to this one. ...

Giraffes

Two giraffes in Kenya.

Researchers have treated homosexual behavior in animals as a taboo subject perhaps from innocent confusion or even from a fear of "being ridiculed by their colleagues."^[13] A case of overlooking behaviour is noted by Bruce Bagemihl describing mating giraffes where nine out of ten pairings occur between males. Image File history File links Size of this preview: 506 × 599 pixelsFull resolution‎ (1,332 × 1,578 pixels, file size: 5. ... Image File history File links Size of this preview: 506 × 599 pixelsFull resolution‎ (1,332 × 1,578 pixels, file size: 5. ... Binomial name Giraffa camelopardalis Linnaeus, 1758 The Giraffe (Giraffa camelopardalis) is an even-toed ungulate mammal and the tallest of all land living animal species. ... This article is about cultural prohibitions in general, for other uses, see Taboo (disambiguation). ... Bruce Bagemihl, PhD., is the author of the controversial book Biological Exuberance: Animal Homosexuality and Natural Diversity, which first argues that homosexual and bisexual behaviors are rife through the natural world, and then proposes an overarching theory of natural sexuality in which reproduction is only one of its principal biological...

"Every male that sniffed a female was reported as sex, while anal intercourse with orgasm between males was only "revolving around" dominance, competition or greetings.^[13] For the meaning of the word dominance in genetics, please see Dominance relationship Dominance in the context of biology and anthropology is the state of having high social status relative to other individuals, who react submissively to dominant individuals. ... Greeting is a way for human beings (as well as other members of the animal kingdom) to intentionally communicate awareness of each others presence, to show attention to, and/or to affirm or suggest a type of relationship or social status between individuals or groups of people coming in...

Japanese Macaque

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 will form such bonds, which will vary in duration from a few days to a few weeks. Often, strong and lasting friendships will 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.^[32] Binomial name Macaca fuscata Blyth, 1875 The Japanese Macaque (Macaca fuscata), also known as the Snow Monkey, is a terrestrial Old World monkey species native to northern Japan, although an introduced free-ranging population has been living near Laredo, Texas since 1972. ... Approximate worldwide distribution of monkeys. ... Homosexuality refers to sexual interaction and / or romantic attraction between individuals of the same sex. ... A consort is somebodys spouse, usually a royalty. ...

Lions

A group of male lions at the Melbourne zoo.

Both male and female lions have been seen to interact homosexually.^[33][34] Male lions pair-bond for a number of days and initiate homosexual activity with affectionate nuzzling and caressing, leading to mounting and thrusting. About 8% of mountings have been observed to occur with other males, while female pairings are held to be fairly common in captivity but have not been observed in the wild. Image File history File links Size of this preview: 800 × 534 pixelsFull resolution‎ (1,600 × 1,067 pixels, file size: 777 KB, MIME type: image/jpeg) Lion, Melbourne Zoo If you are a (commercial) publisher and you want me to write you an email or paper mail giving you permission... Image File history File links Size of this preview: 800 × 534 pixelsFull resolution‎ (1,600 × 1,067 pixels, file size: 777 KB, MIME type: image/jpeg) Lion, Melbourne Zoo If you are a (commercial) publisher and you want me to write you an email or paper mail giving you permission... For other uses, see Lion (disambiguation). ... This article is about the Australian city; the name may also refer to City of Melbourne or Melbourne city centre. ... Animal sexual behavior takes many different forms, even within the same species. ...

Lizards

Whiptail lizard (Teiidae genus) females have the ability to reproduce through parthenogenesis and as such males are rare and sexual breeding non-standard. Females engage in sexual behavior to stimulate ovulation, with their behavior following their hormonal cycles; during low levels of estrogen, these (female) lizards engage in "masculine" sexual roles. Those animals with currently high estrogen levels assume "feminine" sexual roles. Genera Ameiva Aspidoscelis Callopistes Cnemidophorus Crocodilurus Dicrodon Dracaena Kentropyx Teius Tupinambis Teiidae is a family jgh gljljljof lizards, generally known as whiptails, that includes the parthenogenic genera Cnemidophorus and Aspidoscelis and the non-parthenogenic Tegus. ... For the religious belief, see Virgin Birth of Jesus. ... Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction. ...

Lizards that perform the courtship ritual have greater fertility than those kept in isolation due to an increase in hormones triggered by the sexual behaviors. So, even though asexual whiptail lizards populations lack males, sexual stimuli still increase reproductive success.

From an Evolutionary standpoint, these females are passing their full genetic code to all of their offspring (rather than the 50% of genes that would be passed in sexual reproduction). Certain species of gecko also reproduce by parthenogenesis. This article is about biological evolution. ... For other uses, see Gecko (disambiguation). ...

Sheep

An October 2003 study by Dr. Charles E. Roselli et al. (Oregon Health and Science University) states that homosexuality in male sheep (found in 8% of rams) is associated with a region in the rams' brains which the authors call the "ovine Sexually Dimorphic Nucleus" (oSDN) which is two times smaller than the corresponding region in heterosexual male sheep.^[15] For other uses, see October (disambiguation). ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ...

A pair of St. Croix ewes.

It should be noted that some view this study to be flawed in that the determination of homosexuality within the sheep (sample population of 27 for the study) was to have animals who were unable to mount female ewes placed in a cage with two stanchioned males and two unstanchioned females (i.e. the males could not move or struggle while the females could). Given the aggressive nature of sheep copulation, the uneven treatment of males and females, many see this as simply evidence that the sheep in question were unable to be aggressive enough to mount females. As with most animal homosexuality, the results were situational sexuality, unlike the bonds seen in human homosexuality.^{[citation needed]} St Croix sheep from http://www. ... St Croix sheep from http://www. ... A separate article treats the several rivers known as the St. ... Look up ewe, Ewe in Wiktionary, the free dictionary. ...

The scientists found that, "The oSDN in rams that preferred females was significantly larger and contained more neurons than in male-oriented rams and ewes. In addition, the oSDN of the female-oriented rams expressed higher levels of aromatase, a substance that converts testosterone to estradiol, a form of estrogen which is believed to facilitate typical male sexual behaviors. Aromatase expression was no different between male-oriented rams and ewes." Neurons (also called nerve cells) are the primary cells of the nervous system. ... Aromatase belongs to the group of cytochrome P450 enzymes (EC 1. ... Testosterone is a steroid hormone from the androgen group. ... Estradiol (17β-estradiol) (also oestradiol) is a sex hormone. ... Estriol. ... Aromatase belongs to the group of cytochrome P450 enzymes (EC 1. ...

"The dense cluster of neurons that comprise the oSDN express cytochrome P450 aromatase. Aromatase mRNA levels in the oSDN were significantly greater in female-oriented rams than in ewes, whereas male-oriented rams exhibited intermediate levels of expression." These results suggest that "...naturally occurring variations in sexual partner preferences may be related to differences in brain anatomy and its capacity for estrogen synthesis."^[15] As noted prior, given the potential unagressiveness of the male population in question, the differing aromatase levels may also have been evidence of aggression levels, not sexuality. It should also be noted that the results of this study have not been confirmed by other studies.

Spotted Hyena

The Spotted Hyena is a moderately large, terrestrial carnivore native to Africa.

The female Spotted Hyena has a unique urinary-genital system, closely resembling the penis of the male. The family structure is matriarchal and dominance relationships with strong sexual elements are routinely observed between related females. Image File history File links Spotted_hyena2. ... Image File history File links Spotted_hyena2. ... A world map showing the continent of Africa Africa is the worlds second-largest and second most-populous continent, after Asia. ... Binomial name (Erxleben, 1777) Spotted Hyena range The Spotted Hyena, or Laughing Hyena, (Crocuta crocuta) is a mammal of the order Carnivora. ...

Early naturalists thought hyenas were hermaphrodites or commonly practiced homosexuality, largely due to the female spotted hyena's unique urogenital system which looks more like a penis than a vagina.^[35] According to early writings such as Ovid's Metamorphoses and the Physiologus, the hyena continually changed its sex and nature from male to female and back again. In Paedagogus, Clement of Alexandria noted that the hyena (along with the hare) was "quite obsessed with sexual intercourse." Many Europeans associated the hyena with sexual deformity, prostitution, deviant sexual behavior and even witchcraft. Research has shown that "in contrast to most other female mammals, female Crocuta are male-like in appearance, larger than males, and substantially more aggressive,"^[36] they have "been masculinized without being defeminized.”^[35] For other uses, see Hermaphrodite (disambiguation). ... Homosexuality refers to sexual interaction and / or romantic attraction between individuals of the same sex. ... Binomial name (Erxleben, 1777) Spotted Hyena range The Spotted Hyena, or Laughing Hyena, (Crocuta crocuta) is a mammal of the order Carnivora. ... The urogenital system includes the sex organs and the urinary system of vertebrates. ... For other uses, see Ovid (disambiguation) Publius Ovidius Naso (March 20, 43 BC – 17 AD) was a Roman poet known to the English-speaking world as Ovid who wrote on topics of love, abandoned women and mythological transformations. ... Disambiguation: This article is about the poem Metamorphoses written by the poet Ovid. ... The Physiologus was a predecessor of bestiaries (books of beasts). ... Paedagogus, second in the great trilogy of Clement of Alexandria. ... For other uses, see Hare (disambiguation). ... The word masculine can refer to: the property of being biologically male masculinity, a traditionally male gender role the masculine grammatical gender This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Look up feminine in Wiktionary, the free dictionary. ...

This unique genitalia and aggressive behavior in the female hyena has led to the understanding that more aggressive females are better able to compete for resources including food and mating partners.^[37][35] Research has shown that "elevated levels of testosterone in utero"^[38] contributes to extra aggressiveness from their mother and both males and females mount members of the same sex,^[39][38] who in turn are possibly acting more submissive because of lower levels of testosterone from their mothers.^[36] Testosterone is a steroid hormone from the androgen group. ... In Utero is the third and final studio album by the American grunge band Nirvana, released on September 21, 1993 by DGC Records. ... Submissiveness is the trait of being willing to yield to the will of another person or a superior force. ...

References

Frans B.M. de Waal, PhD (b. ... is the 100th day of the year (101st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... The National Institute of Water and Atmospheric Research, commonly abbreviated to NIWA, and known in the Māori language as Taihoro Nukurangi, is a Crown Research Institute of New Zealand. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 253rd day of the year (254th in leap years) in the Gregorian calendar. ... The Advocate (ISSN 0001-8996) is a US-based LGBT-related biweekly news magazine. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 253rd day of the year (254th in leap years) in the Gregorian calendar. ... is the 264th day of the year (265th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... The National Association for Research and Therapy of Homosexuality (NARTH) is a non-profit organization dedicated to affirming a complementary, male-female model of gender and sexuality. NARTH is a proponent of the idea that it is possible alter ones sexual preferences or sexual orientation, that homosexuality is a... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 253rd day of the year (254th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 253rd day of the year (254th in leap years) in the Gregorian calendar. ... American Scientist (ISSN 0003-0996) is an illustrated bimonthly magazine about science and technology. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 254th day of the year (255th in leap years) in the Gregorian calendar. ... Joan E. Roughgarden (b. ... University of California Press, also known as UC Press, is a publishing house associated with the University of California that engages in academic publishing. ... The headquarters of the Cambridge University Press, in Trumpington Street, Cambridge. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 296th day of the year (297th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 253rd day of the year (254th in leap years) in the Gregorian calendar. ... is the 42nd day of the year in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 253rd day of the year (254th in leap years) in the Gregorian calendar. ... Endocrinology is a branch of medicine dealing with disorders of the endocrine system and its specific secretions called hormones. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 253rd day of the year (254th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 167th day of the year (168th in leap years) in the Gregorian calendar. ... is the 320th day of the year (321st in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... For the news website, see msnbc. ...