Cross-species Sex
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Non-reproductive sexual behavior consists of
sexual activities Human sexual activity, human sexual practice or human sexual behaviour is the manner in which humans experience and express their sexuality. People engage in a variety of sexual acts, ranging from activities done alone (e.g., masturbation) t ...
animals participate in that do not lead to the
reproduction Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual or ...
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 A social relation or also described as a social interaction or social experience is the fundamental unit of analysis within the social sciences, and describes any voluntary or involuntary interpersonal relationship between two or more individuals ...
bonding, exchange for significant materials, affection, mentorship pairings, sexual enjoyment, or as demonstration of
social rank A social class is a grouping of people into a set of hierarchical social categories, the most common being the upper, middle and lower classes. Membership in a social class can for example be dependent on education, wealth, occupation, incom ...
. Observed non-procreative sexual activities include non-copulatory mounting (without insertion, or by a female, or by a younger male who does not yet produce semen), 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.


Social interaction and bonding

Lion The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphi ...
s are known to engage in sex to create bonds and interact with each other. Lions live in a social group known as a pride that consists of 2–18 females and 1–7 males. The females found in these prides were born into the pride. The males enter the pride from other prides. The success of reproduction for each individual lion is dependent on the number of male lions found in their social group. Male lions create coalitions and search for prides to take over. Successful coalitions have usually created a strong bond with each other and will take over prides. Once winning in a competition, all current males in the pride will be kicked out and left to find another pride. While in search for another pride these males will often engage in sexual behavior with each other; creating a strong bond in this new coalition created. Sex plays a fundamental role in the social lives of
bonobo The bonobo (; ''Pan paniscus''), also historically called the pygmy chimpanzee and less often the dwarf chimpanzee or gracile chimpanzee, is an endangered great ape and one of the two species making up the genus '' Pan,'' the other being the comm ...
s. Female bonobos have been observed to engage in sexual activities to create bonds with dominant bonobos. Having created this bond with the male, they will share food with each other and not compete with each other. All members of a bonobo group are potential sex partners, regardless of age combination or gender combination. In "Biological Exuberance," Bagemihl writes: "when new females (usually adolescents) join a troop, they often pair up with an older female with whom they have most of their sexual and affectionate interactions." In addition, bonobos need not limit themselves to a single partner: "These bond need not be exclusive – either party may have sex with other females or males – but such mentorlike pairings can last for a year or more until the newcomer is fully integrated into the troop." Pairings between younger and older male bonobos are also common: "typically an adolescent male spreads his legs and presents his erect penis to an adult male, who takes the shaft in his hand and caresses it with up-and-down movements." Social pairings between youth and adult bonobos happen across gender combinations: "Both adult males and females interact sexually with adolescents and juveniles (three-to-nine-year-olds). In fact, young females go through a five-to-six-year period sometimes referred to as adolescent sterility (although no pathology is involved) during which they actively participate in heterosexual mating (often with adults) but never get pregnant. Sexual behavior between adults and infants of both sexes is common - about a third of the time it is initiated by the infant and may involve genital rubbing and full copulatory postures (including penetration of an adult female by a male infant)."


Social conflict remediation

Several species utilize sexual activity as a way to resolve disagreement. Bonobos are one species famously known for using sexual behavior as a means of resolution of social conflict. In a study concentrated on primate conflict resolution, researchers wanted to observe primates in conflict. How primates coped and resolved conflicts was a main concern in this study. Researchers stated that after primates participated in a heated, physical fight; both primates involved in the fight would hug and have a mouth-to-mouth
kiss A kiss is the touch or pressing of one's lips against another person or an object. Cultural connotations of kissing vary widely. Depending on the culture and context, a kiss can express sentiments of love, passion, romance, sexual attraction, ...
. This action was considered as a demonstration of affection and reconciliation.


Proximate causes

Awareness in species is difficult to determine. Learned behaviors that have been demonstrated in laboratories have provided good evidence that animals have instinct and a reward system. The behavior of laboratory animals demonstrates a mental experience wherein the animal's instincts tell it if it carries out a certain action, it will then receive what it needs. For example, the lab
rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' ( pack rats), ''Bandicota'' (bandicoot ...
will push the lever because it knows food will fall out of the hole in the wall. It does not need awareness, but it does seem to work on a reward system. The lab rat learned the action needed to be fed. Studies of the brain have proven that pleasure and displeasure are an important component in the lives of animals. It has been established that the limbic neural mechanism that generates reactions are very similar across all mammals. Many studies have concentrated on the brain reward system and how similar it is across mammals. Through extensive research, scientists have been able to conclude that the brain reward system in animals is extremely similar to that of humans. The mechanism of core pleasure reaction is significantly important for animals and humans.


Case study

In a case study, female
Japanese macaque The Japanese macaque (''Macaca fuscata''), also known as the snow monkey, is a terrestrial Old World monkey species that is native to Japan. Colloquially, they are referred to as "snow monkeys" because some live in areas where snow covers the gr ...
s were studied to find evidence of possible female copulatory orgasms. The frequency of orgasms did not correlate with the age or rank of the Japanese macaques. Researchers observed that the longer and higher number of
pelvic thrust The pelvic thrust is the thrusting motion of the pelvic region, which is used for a variety of activities, such as dance or sexual activity. Sexual activity The pelvic thrust is used during copulation by many species of mammals, including human ...
s, the longer copulation lasted. There was an orgasmic response in 80 of the 240 Japanese macaques studied.


Reward system

Evolutionary principles have predicted that the reward system is part of the proximate mechanism underlying the behavior. Because animals possess a brain reward system they are motivated to perform in different ways by desire and reinforced by pleasure. Animals establish security of food, shelter, social contact, and mating because proximate mechanism, if they do not seek these necessities they will not survive. All vertebrates share similarities in body structure; they all have a skeleton, a nervous system, a circulatory system, a digestive system and excretory system. Similar to humans, non-human animals also have a sensory system. The sensory system is responsible for the basic five senses from touch to tasting. Most of the physiological and biochemical responses found in animals are found in humans. Neurophysiologists have not found any fundamental difference between the structure and function of neurons and synapse between humans and other animals.


Case study

Recent studies using
positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in Metabolism, metabolic processes, and in other physiological activities including bl ...
(PET) and
magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...
(MRI) has provided evidence proving that chemical changes that occur with emotions are similar between humans and non-human animals. In a study comparing guinea pigs and humans, it was determined that the distress experienced by offspring separation in a guinea pig and a human going through depression activates the same region of the brain. The opiate receptor was also examined, allowing observation of the pleasure stimuli. In the procedure both a human and a rat had their receptors blocked with a certain drug. Once receptors were blocked, both the rat and the human were exposed to pleasurable food, but both were disinclined to eat the food.


Types of behavior

Engagements of sexual activities during non-breeding seasons have been observed in the animal kingdom. Dolphins and Japanese macaques are two of the many species that engage in sexual activities that do not lead to fertilization. Great varieties of non-copulatory mounting are expressed in several species. Male lions engage in mounting with other male lions, especially when in search for another pride. The varieties of mounting include mounting without erections, mounting with erection but no insertion, and mounting from the side. Expressions of affection are displayed in the animal kingdom as well. Affectionate behaviors do not include insertion or genital rubbing, but are still seen as a manner of sexual behavior. An affectionate activity can be as simple as licking. Male lions are known for head rubbing, bats engage in licking, and mountain sheep rub horns and faces with each other. Kissing, touching of noses, mouths and muzzles have been witnessed in African elephants, walruses, and mountain zebras. Primates also engage in kissing that is incredibly similar to
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
display of kissing.
Chimpanzee The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative th ...
s have full mouth-to-mouth contact, and bonobos kiss with their mouth open and mutual tongue stimulation. There are a variety of acts to show affection such as African elephants intertwining their trunks, giraffes engaging in “necking”, and Hanuman langurs cuddling with each other in a front to back sitting position. Non-penetrative genital stimulation is very common throughout the animal kingdom. Different forms of self and partner genital stimulation have been observed in the animal kingdom. Oral sex has been observed throughout the animal kingdom, from dolphins to primates. Bonobos have been observed to transition from a simple demonstration of affection to non-penetrative genital stimulation. Animals perform oral sex by licking, sucking or nuzzling the genitals of their partner. Another form of genital stimulation is masturbation. Masturbation is widespread throughout mammals for both males and females. It is less common in birds. There are several techniques, in which animals engage in masturbation from using paws, feet, flippers, tails, and sometimes using objects like sticks, pebbles, and leaves. Masturbation occurs more often in primate species with large
testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...
relative to their body size.


Anal insertion

Anal insertion with the penis (both in heterosexual and male homosexual dyads, i.e. pairs of animals) has been observed among some primate species. Male homosexual anal insertion has been recorded in Old World primate species, including
gorilla Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or fi ...
s,
orangutan Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus ...
s, and some members of the Macaca genus (namely, stumptail, rhesus, and
Japanese macaques The Japanese macaque (''Macaca fuscata''), also known as the snow monkey, is a terrestrial Old World monkey species that is native to Japan. Colloquially, they are referred to as "snow monkeys" because some live in areas where snow covers the gr ...
). It has also been recorded in at least two
New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 3 ...
primate species, the
squirrel monkey Squirrel monkeys are New World monkeys of the genus ''Saimiri''. ''Saimiri'' is the only genus in the subfamily Saimirinae. The name of the genus is of Tupi origin (''sai-mirím'' or ''çai-mbirín'', with ''sai'' meaning 'monkey' and ''mirím'' ...
and the
spider monkey Spider monkeys are New World monkeys belonging to the genus ''Ateles'', part of the subfamily Atelinae, family Atelidae. Like other atelines, they are found in tropical forests of Central and South America, from southern Mexico to Brazil. The g ...
. Morris (1970) also described one heterosexual orangutan dyad where all insertion was anal. However, the practice might have been a consequence of homosexual rearing, as the male orangutan in this dyad had had extensive same–sex experience. A case of male homosexual anal insertion with the finger has also been reported among orangutans, and
Bruce Bagemihl Bruce Bagemihl is a Canadian biologist, linguist, and author of the book ''Biological Exuberance: Animal Homosexuality and Natural Diversity''. Life and career He completed his BA at the University of Wisconsin–Milwaukee in 1981, and served on th ...
mentions it as one of the homosexual practices recorded at least once among male chimpanzees.


Autoeroticism or masturbation

It appears that many animals, both male and female, masturbate, both when partners are available and otherwise. For example, it has been observed in cats, dogs, male
Cape ground squirrel The Cape ground squirrel or South African ground squirrel (''Geosciurus inauris'') is found in most of the drier parts of southern Africa from South Africa, through to Botswana, and into Namibia, including Etosha National Park. The name ' ...
s, male deer, rhinoceroses, boars, male monkeys and otters. A review from the
University of Pennsylvania School of Veterinary Medicine The University of Pennsylvania School of Veterinary Medicine, commonly referred to as Penn Vet was founded in 1884. It has two campuses; the main campus is located in Philadelphia, and a second campus is located in Kennett Square, Pennsylvania. A ...
says:
hebehavior known within the horse breeding industry as ''masturbation'' ... involves normal periodic erections and penile movements. This behavior, both from the descriptive field studies cited above and in extensive study of domestic horses, is now understood as normal, frequent behavior of male
equids Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus'', w ...
. Attempting to inhibit or punish masturbation, for example by tying a brush to the area of the flank underside where the penis rubs into contact with the underside, which is still a common practice of horse managers regionally around the world, often leads to increased masturbation and disturbances of normal breeding behaviour.
Castration does not prevent masturbation, as it is observed in
gelding A gelding is a castrated male horse or other equine, such as a pony, donkey or a mule. Castration, as well as the elimination of hormonally driven behavior associated with a stallion, allows a male equine to be calmer and better-behaved, makin ...
s. Masturbation is common in both mares and stallions, before and after puberty. Sexologist
Havelock Ellis Henry Havelock Ellis (2 February 1859 – 8 July 1939) was an English physician, eugenicist, writer, progressive intellectual and social reformer who studied human sexuality. He co-wrote the first medical textbook in English on homosexuality in ...
in his 1927 ''Studies in the Psychology of Sex'' identified bulls, goats, sheep, camels and elephants as species known to practice autoeroticism, adding of some other species:
I am informed by a gentleman who is a recognized authority on goats, that they sometimes take the penis into the mouth and produce actual orgasm, thus practicing auto-fellatio. As regards ferrets ... "if the bitch, when in heat, cannot obtain a dog e, male ferretshe pines and becomes ill. If a smooth pebble is introduced into the hutch, she will masturbate upon it, thus preserving her normal health for one season. But if this artificial substitute is given to her a second season, she will not, as formerly, be content with it." ... Blumenbach observed a bear act somewhat similarly on seeing other bears coupling, and hyenas, according to Ploss and Bartels, have been seen practicing mutual masturbation by licking each other's genitals.
In his 1999 book, ''Biological exuberance'',
Bruce Bagemihl Bruce Bagemihl is a Canadian biologist, linguist, and author of the book ''Biological Exuberance: Animal Homosexuality and Natural Diversity''. Life and career He completed his BA at the University of Wisconsin–Milwaukee in 1981, and served on th ...
documents that: and that:
Ape Apes (collectively Hominoidea ) are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and as well as Europe in prehistory), which together with its siste ...
s and Monkeys use a variety of objects to masturbate with and even deliberately create implements for
sexual stimulation Sexual stimulation is any stimulation, stimulus (including bodily contact) that leads to, enhances and maintains sexual arousal, and may lead to orgasm. Although sexual arousal may arise without physical stimulation, achieving orgasm usually requ ...
... often in highly creative ways.
David Linden David J. Linden (born November 3, 1961) is an American professor of neuroscience at Johns Hopkins University in Baltimore, Maryland, and the author of ''The Accidental Mind: How Brain Evolution Has Given Us Love, Memory, Dreams, and God''. The ...
, professor of neuroscience at
Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hem ...
, remarks that:
... perhaps the most creative form of animal masturbation is that of the male bottlenose dolphin, which has been observed to wrap a live, wriggling eel around its penis.
Among elephants, female same-sex behaviours have been documented only in captivity where they are known to masturbate one another with their trunks.


Oral sex

Animals of several species are documented as engaging in both
autofellatio Autofellatio is the act of oral stimulation of one's own penis as a form of masturbation. Only a limited number of males are physically capable of performing autofellatio.Savage, Dan. Savage Love', page 242 (Plume 1998). History Egyptologist ...
and
oral sex Oral sex, sometimes referred to as oral intercourse, is sexual activity involving the stimulation of the genitalia of a person by another person using the mouth (including the lips, tongue, or teeth) and the throat. Cunnilingus is oral sex per ...
. Although easily confused by laypeople, autofellatio and oral sex are separate, sexually oriented behaviors, distinct from non-sexual grooming or the investigation of scents. Auto-fellatio or oral sex in animals is documented in
spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s ( Darwin's bark and
widow A widow (female) or widower (male) is a person whose spouse has Death, died. Terminology The state of having lost one's spouse to death is termed ''widowhood''. An archaic term for a widow is "relict," literally "someone left over". This word ...
),
brown bear The brown bear (''Ursus arctos'') is a large bear species found across Eurasia and North America. In North America, the populations of brown bears are called grizzly bears, while the subspecies that inhabits the Kodiak Islands of Alaska is kno ...
s, stump-tailed macaques,
Tibetan macaques The Tibetan macaque (''Macaca thibetana''), also known as the Chinese stump-tailed macaque or Milne-Edwards' macaque, is a macaque species found from eastern Tibet east to Guangdong and north to Shaanxi in China. It has also been reported from no ...
,
wolves The wolf (''Canis lupus''; plural, : wolves), also known as the gray wolf or grey wolf, is a large Canis, canine native to Eurasia and North America. More than thirty subspecies of Canis lupus, subspecies of ''Canis lupus'' have been reco ...
,
goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...
s,
primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...
s,
bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...
s,
cape ground squirrel The Cape ground squirrel or South African ground squirrel (''Geosciurus inauris'') is found in most of the drier parts of southern Africa from South Africa, through to Botswana, and into Namibia, including Etosha National Park. The name ' ...
s and
sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...
(see section
Masturbation Masturbation is the sexual stimulation of one's own genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. The stimulation may involve hands, fingers, everyday objects, sex toys such as vibrators, or combinatio ...
for details). In the
greater short-nosed fruit bat The greater short-nosed fruit bat (''Cynopterus sphinx''), or short-nosed Indian fruit bat, is a species of megabat in the family Pteropodidae found in South and Southeast Asia. Description These bats have a relatively long snout. Their upper pa ...
, copulation by males is dorsoventral and the females lick the shaft or the base of the male's penis, but not the glans, which has already penetrated the vagina. While the females do this, the penis is not withdrawn and research has shown a positive relationship between length of the time that the penis is licked and the duration of copulation. Post copulation genital grooming has also been observed.


Homosexual behaviour

The presence of same-sex sexual behaviour was not scientifically reported on a large scale until recent times. Homosexual behaviour does occur in the
animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
kingdom outside humans, especially in social species, particularly in marine birds and mammals, monkeys, and the
great apes The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); ''Gorilla'' (the east ...
. As of 1999, the scientific literature contained reports of homosexual behavior in at least 471 wild species. Homosexual behavior exists on a spectrum, and may or may not involve insertion. Apart from sexual activity, it can refer to homosexual pair-bonding, homosexual parenting and homosexual acts of affection. Engaging in homosexual behavior may allow species to obtain benefits such as gaining practice, relieving tension, and experiencing pleasure.
Georgetown University Georgetown University is a private university, private research university in the Georgetown (Washington, D.C.), Georgetown neighborhood of Washington, D.C. Founded by Bishop John Carroll (archbishop of Baltimore), John Carroll in 1789 as Georg ...
professor
Janet Mann Janet Mann (Jessie) (20 January 1805 – 21 April 1867) was the studio assistant of the pioneering Scottish photographers David Octavius Hill and Robert Adamson. She is "a strong candidate as the first Scottish woman photographer" and one of t ...
has specifically theorised that homosexual behaviour, at least in
dolphin A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...
s, is an evolutionary advantage that minimizes intraspecies aggression, especially among males. After studying bonobos for his book ''Bonobo: The Forgotten Ape'', primatologist
Frans de Waal Franciscus Bernardus Maria "Frans" de Waal (born October 29, 1948) is a Dutch primatologist and ethologist. He is the Charles Howard Candler Professor of Primate Behavior in the Department of Psychology at Emory University in Atlanta, Georgia, ...
, a professor of psychology at Emory University in Atlanta, says that such expressions of intimacy are consistent with the homosexual behaviour of what he terms "the erotic champions of the world". "Same-sex, opposite-sex — bonobos just love sex play," de Waal said in an interview. "They have so much sex, it gets boring." Homosexual behaviour is found in 6–10% of rams (sheep) and associated with variations in cerebral mass distribution and chemical activity.
Approximately eight percent of
ale Ale is a Type of beer, type of beer brewed using a Warm fermentation, warm fermentation method, resulting in a sweet, full-bodied and fruity taste. Historically, the term referred to a drink brewed without hops. As with most beers, ale typicall ...
rams exhibit sexual preferences
hat is, even when given a choice A hat is a head covering which is worn for various reasons, including protection against weather conditions, ceremonial reasons such as university graduation, religious reasons, safety, or as a fashion accessory. Hats which incorporate mecha ...
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 ...
Male
bighorn sheep The bighorn sheep (''Ovis canadensis'') is a species of sheep native to North America. It is named for its large horns. A pair of horns might weigh up to ; the sheep typically weigh up to . Recent genetic testing indicates three distinct subspec ...
are divisible into two kinds: the typical males among whom homosexual behaviour, including intercourse, is common and "effeminate sheep", or "behavioural transvestites", which are not known to engage in homosexual behaviour. Male-male copulation has been observed in captive
penguin Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...
s and homosexual behaviour has been observed among bats, in particular, the
fruit bat Megabats constitute the family Pteropodidae of the order Chiroptera (bats). They are also called fruit bats, Old World fruit bats, or—especially the genera ''Acerodon'' and ''Pteropus''—flying foxes. They are the only member of the sup ...
.


Homosexual pair-bonding and parenting

Homosexual pair-bonding can be established several ways; two of the main ways are pair bonding as partners or as companions. As partners, both animals will engage in sexual activities with each other. In companion bonding, sexual engagement is not necessary in the relationship. This form of homosexuality is more of a partnership and friendship; they spend all their time together. More than 70 species of birds engage in one of these two bonding. Homosexual parenting (sometimes referred to as
cooperative breeding Cooperative breeding is a social system characterized by alloparental care: offspring receive care not only from their parents, but also from additional group members, often called helpers. Cooperative breeding encompasses a wide variety of group ...
) occurs in a wide variety of species in the animal kingdom. Homosexual parenting can occur in different ways, one of the most common being two females (typically related) coming together to help one another raise their offspring. An example of this is in
meadow vole The eastern meadow vole (''Microtus pennsylvanicus''), sometimes called the field mouse or meadow mouse, is a North American vole found in eastern Canada and the United States. Its range extends farther south along the Atlantic coast. The weste ...
populations. Summer is peak breeding season for meadow voles; however, going into winter and spring there is a division between the male and female meadow vole populations. They prefer communal nesting (because of the
thermoregulatory Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
benefits), and therefore, in the winter and spring female meadow voles will commonly not only nest with another female, but nurse their offspring together as well. This kind of communal nursing, and same-sex social bonds, among meadow voles is actually thought to benefit the young — increasing growth and survival rates. Homosexual parenting is especially present among certain species of birds, one of the most famous examples being
Laysan albatross The Laysan albatross (''Phoebastria immutabilis'') is a large seabird that ranges across the North Pacific. The Northwestern Hawaiian Islands are home to 99.7% of the population. This small (for its family) gull-like albatross is the second-most ...
. It is fairly uncommon among different species for unrelated individuals of the same sex to raise offspring together, but female-female pairings in Laysan albatross populations are one of the exceptions. This same-sex pairing and mutual cooperation in chick-rearing often occurs in the Laysan albatross populations which have uneven sex ratios (and an overall greater surplus of females). Also, Laysan albatross are known for being monogamous, and this tendency actually allows same-sex parenting to persist.


Genital-genital rubbing

Genital-genital rubbing A sex position is a position of the body that people use for sexual intercourse or other sexual activities. Sexual acts are generally described by the positions the participants adopt in order to perform those acts. Though sexual intercourse ...
, or GG rubbing, among non-human animals is sexual activity in which one animal rubs his or her genitals against the genitals of another animal. The term ''GG rubbing'' is frequently used by
primatologists Primatology is the scientific study of primates. It is a diverse discipline at the boundary between mammalogy and anthropology, and researchers can be found in academic departments of anatomy, anthropology, biology, medicine, psychology, vete ...
to describe this type of sexual intimacy among female bonobos, and is stated to be the "bonobo's most typical sexual pattern, undocumented in any other primate". The term is sometimes used in reference to GG rubbing among male bonobos, under the term "
penis fencing __NOTOC__ 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-produci ...
", which is the non-human form of
frot Frot or frotting (slang for frottage; ) is a non-penetrative form of male-to-male sexual activity that usually involves direct penis-to-penis contact. The term was popularized by gay men activists who disparaged the practice of anal sex, but ...
that human males engage in. Such rubbing between males is thought, according to varying evolutionary theorists, to have existed before the development of hominids into humans and bonobos, and may or may not have occurred in the homosexual activity of both of these genetically related species. Genital rubbing has been observed once among male orangutans and several times in a small group of
lar gibbon The lar gibbon (''Hylobates lar''), also known as the white-handed gibbon, is an endangered primate in the gibbon family, Hylobatidae. It is one of the better-known gibbons and is often kept in captivity. Taxonomy There are five subspecies of ...
s, where two males thrust their genitals together, sometimes resulting in ejaculation in one of the partners. It has been observed among bull
manatee Manatees (family Trichechidae, genus ''Trichechus'') are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species ...
s, in conjunction with "kissing", and is also common among homosexually active mammals.


Inter-species sex

Some animals opportunistically mate with individuals of another species. This is more commonly observed in domesticated species and animals in captivity, possibly because captivity is associated with a decrease in aggression and an increase in sexual receptivity. Nevertheless, animals in the wild have been observed to attempt sexual activity with other species. It is mostly documented among species that belong to the same
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
, but sometimes occurs between species of distant taxa.
Alfred Kinsey Alfred Charles Kinsey (; June 23, 1894 – August 25, 1956) was an American sexologist, biologist, and professor of entomology and zoology who, in 1947, founded the Institute for Sex Research at Indiana University, now known as the Kinsey Instit ...
cites reports of sexual activity involving a female eland with an
ostrich Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There are ...
, a male
dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
with a
chicken The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adult m ...
, a male
monkey Monkey is a common name that may refer to most mammals of the infraorder Simiiformes, also known as the simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the apes, which constitutes an incomple ...
with a
snake Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...
, and a female chimpanzee with a
cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...
. A 2008 review of the literature found 44 species pairs that had been observed attempting interspecies mating, and 46 species pairs that had completed interspecies matings, not counting cases that had resulted in
hybridization Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...
. Most were known from laboratory experiments, but field observations had also been made. It may result in fitness loss because of the waste of time, energy, and nutrients. Male
sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the weasel family, but among the small ...
s have been observed forcibly copulating with
seals Seals may refer to: * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to impress an emblem, used as a means of a ...
, and male seals have been observed forcibly copulating with penguins. Inter-species sexual behavior has also been observed in
sea lion Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. ...
s. Male grasshoppers of the species '' Tetrix ceperoi'' often mount other species of either sex and even flies, but are normally repelled by the larger females. Males of the
spider mite Spider mites are members of the Tetranychidae family, which includes about 1,200 species. They are part of the subclass Acari (mites). Spider mites generally live on the undersides of leaves of plants, where they may spin protective silk webs, a ...
species ''Panonychus citri'' copulate with female ''Panonychus mori'' mites almost as often as with their own species, even though it does not result in reproduction. The Japanese macaque has been observed attempting to mate with the
sika deer The sika deer (''Cervus nippon''), also known as the Northern spotted deer or the Japanese deer, is a species of deer native to much of East Asia and introduced to other parts of the world. Previously found from northern Vietnam in the south to ...
.


Sex involving juveniles

Male
stoat The stoat (''Mustela erminea''), also known as the Eurasian ermine, Beringian ermine and ermine, is a mustelid native to Eurasia and the northern portions of North America. Because of its wide circumpolar distribution, it is listed as Least Conc ...
s (''Mustela erminea'') will sometimes mate with infant females of their species. This is a natural part of their reproductive biology – they have a delayed gestation period, so these females give birth the following year when they are fully grown. In one reported observation, a male spotted hyena attempted to mate with a female hyena, but she succeeded in driving him off. He eventually turned to her ten-month-old cub, repeatedly mounting and ejaculating on it. The cub sometimes ignored this and sometimes struggled "slightly as if in play". The mother did not intervene. It appears to be common in the
Adélie penguin The Adélie penguin (''Pygoscelis adeliae'') is a species of penguin common along the entire coast of the Antarctic continent, which is the only place where it is found. It is the most widespread penguin species, and, along with the emperor p ...
. Among
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s, there have been reports of immature females being forcibly copulated with. Juvenile male chimpanzees have been recorded mounting and copulating with immature chimps. Infants in bonobo societies are often involved in sexual behaviour. Immature male bonobos have been recorded initiating genital play with both adolescent and mature female bonobos. Copulation-like contact between immature bonobo males and mature female bonobos increases with age and continues until the male bonobo has reached juvenile age. In contrast, adult gorillas do not show any sexual interest in juvenile or infant members of their species. Primates regularly have sex in full view of infants, juveniles and younger members of their species.


Necrophilia

Necrophilia describes when an animal engages in a sexual act with a dead animal. It has been observed in mammals, birds, reptiles and frogs. It sometimes occurs in the
Adélie penguin The Adélie penguin (''Pygoscelis adeliae'') is a species of penguin common along the entire coast of the Antarctic continent, which is the only place where it is found. It is the most widespread penguin species, and, along with the emperor p ...
. Homosexual necrophilia has been reported between two male mallard ducks. One duck was believed to be pursuing another duck with the goal of rape (a common aspect of duck sexual behaviour) when the second duck collided with a window and died immediately. The observer,
Kees Moeliker Cornelis W. "Kees" Moeliker (born 9 October 1960) is a Dutch biologist and director of the Natural History Museum Rotterdam. He is also European Bureau Chief of the ''Annals of Improbable Research''. Early years Moeliker's father worked for ...
, suggested that "when one died the other one just went for it and didn't get any negative feedback—well, didn't get any feedback." The case study earned Moeliker an
Ig Nobel Prize The Ig Nobel Prize ( ) is a satiric prize awarded annually since 1991 to celebrate ten unusual or trivial achievements in scientific research. Its aim is to "honor achievements that first make people laugh, and then make them think." The name of ...
in biology, awarded for research that cannot or should not be reproduced.


References

{{Animal sexual behavior Animal sexuality