Non-reproductive sexual behavior in animals

Animal non-reproductive sexual behavior encompasses sexual activities that 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.

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.

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.