Homosexual behavior in animals

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.^[1]^[2]^[3] 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.

Scientists perceive homosexual behavior in animals to different degrees. A 2019 paper states that same-sex sexual behavior has been observed in over 1,500 species.^[4] A previous 1999 book by Canadian biologist Bruce Bagemihl states same-sex behavior (comprising courtship, sexual, pair-bonding, and parental activities) has been documented in over 450 species of animals worldwide.^[5]^: 12 Although same-sex interactions involving genital contact have been reported in hundreds of animal species, they are routinely manifested in only a few, including humans.^[6] Simon LeVay stated that "[a]lthough homosexual behavior is very common in the animal world, it seems to be very uncommon that individual animals have a long-lasting predisposition to engage in such behavior to the exclusion of heterosexual activities. Thus, a homosexual orientation, if one can speak of such thing in animals, seems to be a rarity."^[7] The motivations for and implications of these behaviors are lensed through anthropocentric thinking; Bagemihl notes that any hypothesis is "necessarily an account of human interpretations of these phenomena".^[5]^: 2

One species in which exclusive homosexual orientation occurs is the domesticated sheep (Ovis aries).^[8]^[9] "About 10% of rams (males), refuse to mate with ewes (females) but do readily mate with other rams."^[9]

In October 2023, biologists reported studies of animals (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.^[10]^[11]

^ Braithwaite, L. W. (1981). "Ecological studies of the Black Swan III – Behaviour and social organization". Wildlife Research. 8. Canberra, Australia: CSIRO: 134–146. doi:10.1071/WR9810135.
^ Bailey, N. W.; Zuk, M. (August 2009). "Same-sex sexual behavior and evolution". Trends in Ecology and Evolution. 24 (8): 439–46. doi:10.1016/j.tree.2009.03.014. PMID 19539396.
^ "Same-sex Behavior Seen In Nearly All Animals, Review Finds". ScienceDaily (Press release). 17 June 2009.
^ Monk, Julia D.; Giglio, Erin; Kamath, Ambika; Lambert, Max R.; McDonough, Caitlin E. (December 2019). "An alternative hypothesis for the evolution of same-sex sexual behaviour in animals". Nature Ecology and Evolution. 3 (12): 1622–1631. Bibcode:2019NatEE...3.1622M. doi:10.1038/s41559-019-1019-7. ISSN 2397-334X. PMID 31740842. S2CID 256708244.
^ ^a ^b Bagemihl B (1999). Biological Exuberance: Animal Homosexuality and Natural Diversity (Stone Wall Inn ed.). New York City: St. Martin's Press. ISBN 9780312253776 – via Internet Archive.
^ Bailey JM, Vasey PL, Diamond LM, Breedlove SM, Vilain E, Epprecht M (September 2016). "Sexual Orientation, Controversy, and Science". Psychological Science in the Public Interest. 17 (2): 45–101. doi:10.1177/1529100616637616. PMID 27113562. S2CID 42281410.
^ Levay S (1996). Queer Science: The Use and Abuse of Research into Homosexuality. Cambridge, Massachusetts: MIT Press. p. 207. ISBN 9780262121996.
^ Poiani A, Dixson AF (2010). Animal Homosexuality: A Biosocial Perspective. Cambridge University Press. p. 179. ISBN 9781139490382. This makes O. aries (ram) only the second mammal known, apart from humans, capable of displaying exclusive homosexuality.
^ ^a ^b Levay S (2017). Gay, Straight, and The Reason Why: The Science of Sexual Orientation (Second ed.). Cambridge, Massachusetts: Oxford University Press. pp. 38, 119. ISBN 978-0-19-029737-4 – via Google Books.
^ Zimmer, Carl (3 October 2023). "Same-Sex Behavior Evolved in Many Mammals to Reduce Conflict, Study Suggests". The New York Times. Archived from the original on 20 October 2023 – via Internet Archive.
^ Gómez, José M.; et al. (3 October 2023). "The evolution of same-sex sexual behaviour in mammals". Nature. 14 (5719): 5719. Bibcode:2023NatCo..14.5719G. doi:10.1038/s41467-023-41290-x. PMC 10547684. PMID 37788987.

[ReferenceA-1] Braithwaite, L. W. (1981). "Ecological studies of the Black Swan III – Behaviour and social organization". Wildlife Research. 8. Canberra, Australia: CSIRO: 134–146. doi:10.1071/WR9810135.

[Bailey_2009-2] Bailey, N. W.; Zuk, M. (August 2009). "Same-sex sexual behavior and evolution". Trends in Ecology and Evolution. 24 (8): 439–46. doi:10.1016/j.tree.2009.03.014. PMID 19539396.

[3] "Same-sex Behavior Seen In Nearly All Animals, Review Finds". ScienceDaily (Press release). 17 June 2009.

[4] Monk, Julia D.; Giglio, Erin; Kamath, Ambika; Lambert, Max R.; McDonough, Caitlin E. (December 2019). "An alternative hypothesis for the evolution of same-sex sexual behaviour in animals". Nature Ecology and Evolution. 3 (12): 1622–1631. Bibcode:2019NatEE...3.1622M. doi:10.1038/s41559-019-1019-7. ISSN 2397-334X. PMID 31740842. S2CID 256708244.

[Bagemihl-5] Bagemihl B (1999). Biological Exuberance: Animal Homosexuality and Natural Diversity (Stone Wall Inn ed.). New York City: St. Martin's Press. ISBN 9780312253776 – via Internet Archive.

[6] Bailey JM, Vasey PL, Diamond LM, Breedlove SM, Vilain E, Epprecht M (September 2016). "Sexual Orientation, Controversy, and Science". Psychological Science in the Public Interest. 17 (2): 45–101. doi:10.1177/1529100616637616. PMID 27113562. S2CID 42281410.

[7] Levay S (1996). Queer Science: The Use and Abuse of Research into Homosexuality. Cambridge, Massachusetts: MIT Press. p. 207. ISBN 9780262121996.

[Poiani2010-8] Poiani A, Dixson AF (2010). Animal Homosexuality: A Biosocial Perspective. Cambridge University Press. p. 179. ISBN 9781139490382. This makes O. aries (ram) only the second mammal known, apart from humans, capable of displaying exclusive homosexuality.

[levay-9] Levay S (2017). Gay, Straight, and The Reason Why: The Science of Sexual Orientation (Second ed.). Cambridge, Massachusetts: Oxford University Press. pp. 38, 119. ISBN 978-0-19-029737-4 – via Google Books.

[NYT-20231003cz-10] Zimmer, Carl (3 October 2023). "Same-Sex Behavior Evolved in Many Mammals to Reduce Conflict, Study Suggests". The New York Times. Archived from the original on 20 October 2023 – via Internet Archive.

[NAT-20231003-11] Gómez, José M.; et al. (3 October 2023). "The evolution of same-sex sexual behaviour in mammals". Nature. 14 (5719): 5719. Bibcode:2023NatCo..14.5719G. doi:10.1038/s41467-023-41290-x. PMC 10547684. PMID 37788987.

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