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 behaviors 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 (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, same-sex sexual interaction, 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 as well as sex with dead animals.
Social interaction and bonding
Lions are known to engage in sex to create bonds and interact with each other. Lions live in a social group known as a pride which 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 other 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 will be kicked out and left to find another pride. While in search of 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 bonobos. 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 sex 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 bonds 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 sex 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)."
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. This action was considered as a demonstration of affection and reconciliation.
Reward system 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 including humans.
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. Neurophysiologists have not found any fundamental difference between the structure and function of neurons and synapse between humans and other animals.
Case study In a case study, female Japanese macaques 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 thrusts, the longer copulation lasted. There was an orgasmic response in 80 of the 240 Japanese macaques studied.
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 of 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. Felids 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. Non-human primates also engage in kissing that is incredibly similar to human display of kissing. Chimpanzees 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 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 gorillas, orangutans, and some members of the Macaca genus (namely, stumptail, rhesus, and Japanese macaques). It has also been recorded in at least two New World primate species, the squirrel monkey and the spider monkey. Morris (1970) also described one heterosexual orangutan dyad for whom all penetration was performed anally. However, the practice might have been a consequence of homosexual rearing, as the male orangutan in this dyad had extensive same–sex experience. Anal insertion has also been observed among bonobo, with the observation described as 'anal intromission'.
A case of male homosexual anal insertion with the finger has also been reported among orangutans, and Bruce Bagemihl mentions it as one of the homosexual practices recorded at least once among male chimpanzees.
Autoeroticism or masturbation
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 squirrels, male deer, rhinoceroses, boars, male monkeys, cetaceans, and otters.
A review from the University of Pennsylvania School of Veterinary Medicine says:
[The] behavior 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. 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 geldings. Masturbation is common in both mares and stallions, before and after puberty.
Sexologist Havelock Ellis 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 autofellatio. As regards ferrets ... "if the bitch, when in heat, cannot obtain a dog [ie, male ferret] she 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 documents that:
and that:
Apes and Monkeys use a variety of objects to masturbate with and even deliberately create implements for sexual stimulation ... often in highly creative ways.
David Linden, professor of neuroscience at Johns Hopkins University, remarks that: