Why do animals engage in non-reproductive sex?

Non-reproductive sexual behavior in animals encompasses activities that do not lead to species reproduction. Beyond procreation, observations show animals engage in sexual acts for social interaction, bonding, affection, mentorship, or demonstrating social rank. These behaviors can include same-sex interactions, non-copulatory mounting, oral sex, and genital stimulation.

What we know

• Animals engage in sexual activities for reasons other than procreation, such as social interaction, bonding, material exchange, affection, mentorship pairings, sexual enjoyment, and demonstrating social rank. [2]
• Observed non-procreative sexual activities include non-copulatory mounting, oral sex, genital and anal stimulation, interspecies mating, and same-sex sexual interactions. [2]
• Historically, it was believed that animal sexuality was purely instinctive stimulus-response behavior and that only humans and a few other species performed sexual acts outside of reproduction. [3]
• Same-sex sexual behavior has been observed in over 1,500 animal species, taking forms such as courtship, affection, pair bonding, and parenting. [4]

Still open

• It is doubted whether animals have engaged in non-reproductive sexual behaviors since the beginning of their existence.
• Proposed causes for same-sex sexual behavior vary widely across species, and interpretations of these behaviors can be influenced by anthropocentric thinking.

Where to go next

• how we knowHow does same-sex behavior manifest in animals?
• how it workedWhat role does estrus play in animal mating?
• the bigger pictureHow does animal sexual behaviour function more broadly?
• a case in pointDo bonobos engage in sex outside of estrus?
• compared withHow do human and animal sexual behaviors compare regarding pleasure?
• an unexpected connectionWhich animal species exhibits exclusive homosexual orientation besides humans?The domesticated sheep is noted as the only known non-human species to exhibit exclusive homosexual orientation, involving about 10% of males.

Sources

• [1]non-reproductive sexual behavior in animals (Wikidata Q23807917) · CC0 1.0
• [2]Non-reproductive sexual behavior in animals · CC BY-SA 4.0
• [3]Animal sexual behaviour · CC BY-SA 4.0
• [4]Homosexual behavior in animals · CC BY-SA 4.0
• [5]Sexual intercourse · CC BY-SA 4.0