For these animals, there is documented evidence of homosexual behavior of one or more of the following kinds: sex, courtship, affection, pair bonding, or parenting, as noted in researcher and author Bruce Bagemihl's 1999 book Biological Exuberance: Animal Homosexuality and Natural Diversity.
Bagemihl writes that the presence of same-sex sexual behavior was not "officially" observed on a large scale until the 1990s due to observer bias caused by social attitudes towards nonheterosexual people, making the homosexual theme taboo. [2] [3] Bagemihl devotes three chapters, "Two Hundred Years at Looking at Homosexual Wildlife", "Explaining (Away) Animal Homosexuality" and "Not For Breeding Only" in his 1999 book Biological Exuberance to the "documentation of systematic prejudices" where he notes "the present ignorance of biology lies precisely in its single-minded attempt to find reproductive (or other) 'explanations' for homosexuality, transgender, and non-procreative and alternative heterosexualities." [4] Petter Bøckman, academic adviser for the Against Nature? exhibit, stated "[M]any researchers have described homosexuality as something altogether different from sex. They must realize that animals can have sex with who they will, when they will and without consideration to a researcher's ethical principles." Homosexual behavior is found amongst social birds and mammals, particularly the sea mammals and the primates. [3] [5] In 1986, it was even discovered amongst insects when butterfly scientist W.J. Tennent observed four male Mazarine blues competing for the attention of another male in Morocco. [6]
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. Bagemihl's research shows that homosexual behavior, not necessarily sex, has been documented in about five hundred species as of 1999, ranging from primates to gut worms. [2] [7] Homosexuality in animals is seen as controversial by social conservatives because it asserts the naturalness of homosexuality in humans, while others counter that it has no implications and is nonsensical to equate natural animal behaviors to morality. [8] [9] Sexual preference and motivation is always inferred from behavior. Thus homosexual behavior has been given a number of terms over the years. The correct usage of the term homosexual is that an animal exhibits homosexual behavior, however this article conforms to the usage by modern research, [10] [11] [12] [13] applying the term homosexuality to all sexual behavior (copulation, genital stimulation, mating games and sexual display behavior) between animals of the same sex.
In October 2023, biologists reported studies of mammals (over 1,500 different species) that found same-sex behavior (not necessarily related to human orientation) may help improve social stability by reducing conflict within the groups studied. [14] [15]
Homosexual behaviour is demonstrated by 120 known species of birds. [41] While an uptick in research on bird homosexuality – and animal homosexuality in general – has been coming out in recent years, it's common for some authors to labour in articulating the view any root cause or function of bird homosexuality is poorly understood. [42]
Hypotheses contrived in an attempt to explain the behaviour – homosexuality in birds – typically diverge from one another, further exacerbating an apparent perception in the concerned scientific communities knowledge's quest to realise bird homosexuality remains elusive as an objective. Some authors posit the behaviours are a result of any bird demonstrably homosexual being less inclined to rear young, [41] while other authors posit the timing of emergence from the egg is a factor. [43]
In 1977, The New York Times also reported on a colony of lesbian seagulls "off [the] coast of California." [44]
The all-female Whiptail lizard species Aspidoscelis neomexicanus (center), which reproduces via parthenogenesis, is shown flanked by two sexual species having males, A. inornatus (left) and A. tigris (right). Research has shown that simulated mating behavior increases fertility for Aspidoscelis neomexicanus. One female lies on top of another, playing the role of the male, the lizard that was on bottom has larger eggs, in most cases. The lizards switch off this role each mating season. [61]
Male homosexuality has been inferred in several species of dragonflies. A survey of damsel and dragonflies reveals characteristic cloacal pincher mating damage in 20–80 percent of the males, indicating a fairly high occurrence of sexual coupling between males. [71] [Young, L.C., et al. (2008) Successful same-sex pairing in Laysan albatross. Biol. Lett. 4, 323–325. 1]
In his news book, Biological Exuberance: Animal Homosexuality and Natural Diversity ... author Bruce Bagemihl portrays an animal kingdom that embraces a whole spectrum of sexual orientations ... [and] paints a complex mosaic that resembles humanity ... At 751 pages and with photos and documentation of homosexual behaviour in more than 450 species of mammals, birds, repties, and insects, Biological Exuberance brings the dusty facts to light as Bagemihl deconstructs the all-heterosexual Noah's Ark we've been sold.
...frequent sex (including male-to-male and female-to-female) characterize bonobo society.
Sexual dimorphism is the condition where sexes of the same species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most dioecious species, which consist of most animals and some plants. Differences may include secondary sex characteristics, size, weight, color, markings, or behavioral or cognitive traits. Male-male reproductive competition has evolved a diverse array of sexually dimorphic traits. Aggressive utility traits such as "battle" teeth and blunt heads reinforced as battering rams are used as weapons in aggressive interactions between rivals. Passive displays such as ornamental feathering or song-calling have also evolved mainly through sexual selection. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is monomorphism, when both biological sexes are phenotypically indistinguishable from each other.
Dactyloidae are a family of lizards commonly known as anoles and native to warmer parts of the Americas, ranging from southeastern United States to Paraguay. Instead of treating it as a family, some authorities prefer to treat it as a subfamily, Dactyloinae, of the family Iguanidae. In the past they were included in the family Polychrotidae together with Polychrus, but the latter genus is not closely related to the true anoles.
Anolis carolinensis or green anole is a tree-dwelling species of anole lizard native to the southeastern United States and introduced to islands in the Pacific and Caribbean. A small to medium-sized lizard, the green anole is a trunk-crown ecomorph and can change its color to several shades from brown to green.
Various non-human animal species exhibit behavior that can be interpreted as homosexual or bisexual. This may include same-sex sexual activity, courtship, affection, pair bonding, and parenting among same-sex animal pairs. Various forms of this are found in every major geographic region and every major animal group. The sexual behavior of non-human animals takes many different forms, even within the same species, though homosexual behavior is best known from social species.
Frot or frotting is a gay sexual practice that usually involves direct penis-to-penis contact. The term was popularized by gay male activists who disparaged the practice of anal sex, but has since evolved to encompass a variety of preferences for the act, which may or may not imply particular attitudes towards other sexual activities. This can also be used as some type of foreplay.
A gynandromorph is an organism that contains both male and female characteristics. The term comes from the Greek γυνή (gynē) 'female', ἀνήρ (anēr) 'male', and μορφή (morphē) 'form', and is used mainly in the field of entomology. Gynandromorphism is most frequently recognized in organisms that have strong sexual dimorphism such as certain butterflies, spiders, and birds, but has been recognized in numerous other types of organisms.
A dewlap is a longitudinal flap of skin or similar flesh that hangs beneath the lower jaw or neck of many vertebrates. More loosely, it can be various similar structures in the neck area, such as those caused by a double chin or the submandibular vocal sac of a frog. More generally, it can be any hanging mass of skin, such as a fold of loose skin on an elderly person's neck, or the wattle of a bird. Dewlaps can be considered as a caruncle, defined as "a small, fleshy excrescence that is a normal part of an animal's anatomy".
Animal sexual behaviour takes many different forms, including within the same species. Common mating or reproductively motivated systems include monogamy, polygyny, polyandry, polygamy and promiscuity. Other sexual behaviour may be reproductively motivated or non-reproductively motivated.
The pelvic thrust is the thrusting motion of the pelvic region, which is used for a variety of activities, such as dance, exercise, or sexual activity.
The desert grassland whiptail lizard is an all-female species of reptiles in North America. It was formerly placed in the genus Cnemidophorus. A common predator of the whiptail lizard is the leopard lizard that preys on A. uniparens by using ambush and stalk hunting tactics. These reptiles reproduce by parthenogenesis. In this process, eggs undergo a chromosome doubling after meiosis, developing into lizards without being fertilized. However, ovulation is enhanced by female-female courtship and mating (pseudo-copulation) rituals that resemble the behavior of closely related species that reproduce sexually.
Human male sexuality encompasses a wide variety of feelings and behaviors. Men's feelings of attraction may be caused by various physical and social traits of their potential partner. Men's sexual behavior can be affected by many factors, including evolved predispositions, individual personality, upbringing, and culture. While most men are heterosexual, there are minorities of homosexual or varying degrees of bisexual men.
Androphilia and gynephilia are terms used in behavioral science to describe sexual orientation, as an alternative to a gender binary homosexual and heterosexual conceptualization. Androphilia describes sexual attraction to men and/or masculinity; gynephilia describes the sexual attraction to women and/or femininity. Ambiphilia describes the combination of both androphilia and gynephilia in a given individual, or bisexuality.
The Guianan cock-of-the-rock is a species of cotinga, a passerine bird from South America. It is about 30 cm (12 in) in length and weighs about 200 to 220 g. It is found in tropical rainforests, near its preferred habitat of rocky outcrops. The female's plumage is brownish/dark smokey grey in colour, and generally less noticeable than the males because of their nesting work in rocky areas. The male's feathers are a bright orange. Both have a heavy body, broad-based bill and wear a remarkable half-moon crest on the head. It is one of two species of the genus Rupicola, the other being the Andean cock-of-the-rock. The Guianan cock-of-the-rock lives across the forested region of northeastern South America. Its diet consists mostly of fruit, but they sometimes feast on small snakes and lizards.
Penis fencing is a mating behavior engaged in by many species of flatworm, such as Pseudobiceros hancockanus. Species which engage in the practice are hermaphroditic; each individual has both egg-producing ovaries and sperm-producing testes.
Bruce Bagemihl is a Canadian biologist, linguist, and author of the book Biological Exuberance: Animal Homosexuality and Natural Diversity.
Animal non-reproductive sexual behavior encompasses sexual activities that non-human animals participate in which do not lead to the reproduction of the species. Although procreation continues to be the primary explanation for sexual behavior in animals, recent observations on animal behavior have given alternative reasons for the engagement in sexual activities by animals. Animals have been observed to engage in sex for social interaction bonding, exchange for significant materials, affection, mentorship pairings, sexual enjoyment, or as demonstration of social rank. Observed non-procreative sexual activities include non-copulatory mounting, oral sex, genital stimulation, anal stimulation, interspecies mating, and acts of affection, although it is doubted that they have done this since the beginning of their existence. There have also been observations of sex with cub participants, same-sex sexual interaction, as well as sex with dead animals.
In zoology, copulation is animal sexual behavior in which a male introduces sperm into the female's body, especially directly into her reproductive tract. This is an aspect of mating. Many animals that live in water use external fertilization, whereas internal fertilization may have developed from a need to maintain gametes in a liquid medium in the Late Ordovician epoch. Internal fertilization with many vertebrates occurs via cloacal copulation, known as cloacal kiss, while most mammals copulate vaginally, and many basal vertebrates reproduce sexually with external fertilization.
Homosexual behavior in sheep has been well documented and studied. The domestic sheep is the only species of mammal except for humans which exhibits exclusive homosexual behavior. "About 10% of rams (males), refuse to mate with ewes (females) but do readily mate with other rams." Thirty percent of all rams demonstrate at least some homosexual behavior. One report on sheep found that 8% of rams exhibited homosexual preferences—that is, even when given a choice, they chose male over female partners. This documented homosexual preference has garnered much discussion. Such rams prefer to court and mount other rams only, even in the presence of estrous ewes. Moreover, around 18–22% of rams are bisexual.