Editing Homosexual behavior in animals (section)

{{Short description|Sexual behavior among non-human species that is interpreted as homosexual}}
{{For|homosexuality in humans|Homosexuality}}
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{{Use dmy dates|date=June 2023}}

[[File:Males Anas platyrhynchos 2.jpg|300px|thumb|Two male [[mallard]]s (''Anas platyrhynchos'')]]

Various non-human [[animal]] species exhibit behavior that can be interpreted<!-- NOTE: For why "interpreted" is used, see the second paragraph (Bruce Bagemihl) and points made lower in the article.--> as [[homosexual]] or [[Bisexuality|bisexual]], often referred to as ''same-sex sexual behavior'' (SSSB) by scientists. This may include same-sex [[Animal sexual behaviour|sexual activity]], [[Courtship display|courtship]], [[affection]], [[pair bond]]ing, and [[Homosexual parenting in animals|parenting among same-sex animal pairs]].<ref name="ES">{{cite journal|last=Braithwaite|first=L. W.|title=Ecological studies of the Black Swan III – Behaviour and social organization |journal=Wildlife Research |date=1981 |volume=8 |issue=1 |pages=134–146 |doi=10.1071/WR9810135 |publisher=[[CSIRO]] |location=Canberra, Australia|bibcode=1981WildR...8..135B }}</ref><ref name="Bailey_2009">{{cite journal | last1 = Bailey|first1=N. W.|last2=Zuk|first2=M. | title = Same-sex sexual behavior and evolution | journal = [[Trends in Ecology and Evolution]] | volume = 24 | issue = 8 | pages = 439–46 | date = August 2009 | pmid = 19539396 | doi = 10.1016/j.tree.2009.03.014|bibcode=2009TEcoE..24..439B }}</ref><ref>{{cite press release |date=June 17, 2009 |title=Same-sex Behavior Seen In Nearly All Animals, Review Finds |website=[[ScienceDaily]] |url=https://www.sciencedaily.com/releases/2009/06/090616122106.htm}}</ref> Various forms of this are found among a variety of [[vertebrate]] and [[arthropod]] taxonomic [[class (biology)|classes]]. The sexual behavior of non-human animals takes many different forms, even within the same species, though homosexual behavior is best known from [[Sociality|social species]].

Scientists observe same-sex sexual behavior in animals in different degrees and forms among different species and [[clade]]s. A 2019 paper states that it has been observed in over 1,500 species.<ref>{{Cite journal |last1=Monk |first1=Julia D. |last2=Giglio |first2=Erin |last3=Kamath |first3=Ambika |last4=Lambert |first4=Max R. |last5=McDonough |first5=Caitlin E. |date=December 2019 |title=An alternative hypothesis for the evolution of same-sex sexual behaviour in animals |journal=[[Nature Ecology and Evolution]] |volume=3 |issue=12 |pages=1622–1631 |doi=10.1038/s41559-019-1019-7 |pmid=31740842 |s2cid=256708244 |issn=2397-334X|doi-access=free |bibcode=2019NatEE...3.1622M }}</ref> Although same-sex interactions involving genital contact have been reported in many animal species, they are routinely manifested in only a few, including humans.<ref>{{cite journal | vauthors = Bailey JM, Vasey PL, Diamond LM, Breedlove SM, Vilain E, Epprecht M | title = Sexual Orientation, Controversy, and Science | journal = [[Psychological Science in the Public Interest]] | volume = 17 | issue = 2 | pages = 45–101 | date = September 2016 | pmid = 27113562 | doi = 10.1177/1529100616637616 | s2cid = 42281410 | doi-access = free }}</ref> Other than humans, the only known species to exhibit exclusive homosexual orientation is the domesticated sheep (''[[Ovis aries]]''), involving about 10% of males.<ref name="Poiani2010">{{cite book| first1 = Aldo | last1 = Poiani | first2 = A. F. | last2 = Dixson | name-list-style = vanc |title=Animal Homosexuality: A Biosocial Perspective|url=https://books.google.com/books?id=EftT_1bsPOAC&pg=PA179|date=2010|publisher=[[Cambridge University Press]]|page=179|quote=This makes O. aries (ram) only the second mammal known, apart from humans, capable of displaying exclusive homosexuality.|isbn=9781139490382}}</ref><ref name="levay">{{cite book |title=Gay, Straight, and The Reason Why: The Science of Sexual Orientation|last=Levay| first=Simon | name-list-style = vanc |year=2017| url=https://books.google.com/books?id=-J6kDAAAQBAJ |via=[[Google Books]]|edition=Second |url-access=limited |publisher=[[Oxford University Press]] |location=Cambridge, Massachusetts |pages=38, 119|isbn=978-0-19-029737-4 }}</ref><ref>{{cite journal |last1=Raymond |first1=Michel |last2=Crochet |first2=Pierre-André |title=Carving Non-Proximal Explanations for Same-Sex Sexual Orientation |journal=Archives of Sexual Behavior |date=October 2023 |volume=52 |issue=7 |pages=3007–3012 |doi=10.1007/s10508-022-02497-z |pmid=36469147 |url=https://hal.science/hal-04284860/file/Carving%20non-proximal%20explanations%20for%20same-sex%20sexual%20orientation_pour_HAL.pdf |quote=There are numerous reports of homosexual behavior in many animal species in the wild, but there are no reports of exclusive same-sex sexual orientation (Bagemihl, 2000). It is, however, well-established that some domestic rams exhibit exclusive same-sex sexual orientation.}}</ref> The motivations for and implications of these behaviors are often lensed through anthropocentric thinking; [[Bruce Bagemihl]] states that any hypothesis is "necessarily an account of human interpretations of these phenomena".<ref name=Bagemihl>{{cite book| last1=Bagemihl| first1=Bruce|url=https://archive.org/details/biologicalexuber00bage/page/164/mode/1up|title=Biological Exuberance: Animal Homosexuality and Natural Diversity|date=1999|publisher=[[St. Martin's Press]]|isbn=9780312253776|edition=Stone Wall Inn|location=New York City|name-list-style=vanc|via=[[Internet Archive]]|url-access=registration|author-link=Bruce Bagemihl}}</ref>{{rp|2}}

Proposed causes for same-sex sexual behavior vary across species. Theories include mistaken identity (especially for arthropods<!--arachnids verified below-->), [[sexual conflict|sexually antagonistic selection]], [[balancing selection]], practice of behaviors needed for reproduction, expression of social dominance or submission, and social bonding.<ref>{{cite journal |last1=Balfour |first1=Vicki L. |last2=Shuker |first2=David M. |title=Same-sex sexual behaviour |journal=Current Biology |date=November 2020 |volume=30 |issue=22 |pages=R1345–R1346 |doi=10.1016/j.cub.2020.09.005 |pmid=33202225 |bibcode=2020CBio...30R1345B |url=https://www.cell.com/current-biology/fulltext/S0960-9822(20)31336-1 |access-date=25 June 2024}}</ref> Genetic, hormonal, and neurological variations as a basis for individual behavioral differences within species have been proposed, and same-sex sexual behavior has been induced in laboratory animals by these means.<!--citations in Basis section-->