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{{Short description|Sexually reproducing organism that produces both male and female gametes}}
]]
{{Other uses}}
A '''hermaphrodite''' is an individual or ] that contains both ] and ] ] at some point during their lives. Generally, hermaphroditism occurs in the ], although it occurs in a fair number of ], and to a lesser degree in the higher organisms. This term includes:
{{Distinguish|Intersex{{!}}Intersex people|Intersex (biology)}}
{{cs1 config|name-list-style=vanc|display-authors=6}}
] mating]]
A '''hermaphrodite''' ({{IPAc-en|h|ər|ˈ|m|æ|f|r|ə|ˌ|d|aɪ|t}}) is a ] ] that produces both ] and ] ]s.<ref name="Avise-2011">{{Cite book| vauthors = Avise JC |url=https://books.google.com/books?id=jqiR8C0lEckC&q=Sex+is+defined+by+gametes&pg=PA1|title=Hermaphroditism: A Primer on the Biology, Ecology, and Evolution of Dual Sexuality|date=2011-03-18|publisher=Columbia University Press|isbn=978-0-231-52715-6|pages=1–7|language=en}}</ref> Animal species in which individuals are either male or female are ], which is the opposite of hermaphroditic.<ref name="Holub-2020">{{cite book|url=https://www.toddkshackelford.com/downloads/Holub-Shackelford-Gonochorism-EACB-2021.pdf|title=Encyclopedia of Animal Cognition and Behavior|vauthors=Holub AM, Shackelford TK|date=2020|publisher=Springer International Publishing|isbn=978-3-319-47829-6|veditors=Vonk J, Shackelford TK|place=Cham|pages=1–3|language=en|chapter=Gonochorism|doi=10.1007/978-3-319-47829-6_305-1|s2cid=240938739|author-link2=Todd K. Shackelford}}</ref>


The individuals of many ] groups of ]s, primarily invertebrates, are hermaphrodites, capable of producing viable gametes of both ]es. In the great majority of ]s, ]s, and ]s, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. Hermaphroditism is ], but is rare in other ] groups. Most hermaphroditic species exhibit some degree of self-fertilization. The distribution of self-fertilization rates among animals is similar to that of plants, suggesting that similar pressures are operating to direct the evolution of ] in animals and plants.<ref name="Jarne-2006">{{cite journal | vauthors = Jarne P, Auld JR | title = Animals mix it up too: the distribution of self-fertilization among hermaphroditic animals | journal = Evolution; International Journal of Organic Evolution | volume = 60 | issue = 9 | pages = 1816–24 | date = September 2006 | pmid = 17089966 | doi = 10.1554/06-246.1 | s2cid = 23849389 }}</ref>
*''']''': The organism is born as one sex and later changes into the other sex.
**''']''': When the organism starts as a male, and changes sex to a female later in life. ''Example: The seabasses (Family ]). These are a highly sought food fish complex made up of primarily groupers. Since even a small male can produce more than enough ] to fertilize a huge number of ], while a female's egg output increases greatly with an increase in size, this strategy makes sense for an organism (fishes in general) where over 99% of the eggs laid will not result in a fish that reaches sexual maturity. It has been shown that fishing pressure actually is causing a change in when the switch from male to female occurs, since fishermen naturally prefer to catch the larger fishes. The populations are generally changing sex at a smaller size, due to ].''
**''']''': When the organism starts as a female, and changes sex to a male later in life. ''Example: Wrasses (Family ]) are reef fishes that tend to have three distinct sexual types. Small females, immature males and supermales. The small females and the immature males have identical colorations. The supermale is usually brightly colored, and there is only one in a given area of the reef. This supermale dominates the other wrasses of the species, having the choice of females to mate with. When the supermale dies, the largest wrasse in the area, male ''or'' female, becomes the new supermale.
*''']''': The organism has both male and female sexual organs at the same time as an adult. Usually, self-fertilization does not occur. Also called '''synchronous hermaphrodites.''' ''Examples: Earthworms. ] (Family Haemulidae) are a type of fish that are curious for many reasons, including that they seem to be evolving into different species quite rapidly. Unlike other fishes, hamlets seem quite at ease mating in front of divers, allowing observations in the wild to occur readily. They do not practice self fertilization, but when they find a mate, the pair takes turns between which one acts as the male, and which acts as the female, through multiple matings, usually over several nights.''


A rough estimate of the number of hermaphroditic animal species is 65,000, about 5% of all animal species, or 33% excluding insects. Insects are almost exclusively gonochoric, and no definitive cases of hermaphroditism have been demonstrated in this group.<ref name="Royer-1975">{{cite book| vauthors = Royer M |chapter=Hermaphroditism in Insects. Studies on Icerya purchasi |date=1975 | veditors = Reinboth R | title=Intersexuality in the Animal Kingdom |pages=135–145 |publisher=Springer |location=Berlin, Heidelberg |doi=10.1007/978-3-642-66069-6_14 |isbn=978-3-642-66071-9 }}</ref> There are no known hermaphroditic species among ]s<ref name="Gorshkov-2012">{{Cite book| vauthors = Gorshkov V |url=https://books.google.com/books?id=xaO1BwAAQBAJ&q=No+cases+of+hermaphroditism+or+parthenogenesis+are+found+among+birds+and+mammals.&pg=PT165|title=Physical and Biological Bases of Life Stability: Man, Biota, Environment|date=2012-12-06|publisher=Springer Science & Business Media|isbn=978-3-642-85001-1|language=en}}</ref> or ]s.<ref name="Schärer-2017a">{{cite journal|vauthors=Schärer L|date=February 2017|title=The varied ways of being male and female|journal=Molecular Reproduction and Development|volume=84|issue=2|pages=94–104|doi=10.1002/mrd.22775|pmid=28032683|quote=Of note, the otherwise well-studied insects, birds, and mammals are strikingly absent here—with not a single species among these groups showing hermaphroditism (for details on a supposedly hermaphroditic scale insect, however, see Gardner and Ross, 2011).|doi-access=free}}</ref>
Hermaphroditism occurs in about one percent of ]s (including ]s), and it is extremely rare for both sets of sexual organs to be functional. In most cases neither set is functional. In many cases, these manifestations can be "corrected", sometimes only cosmetically, shortly after birth.


About 94% of ] species are either hermaphroditic (all flowers produce both male and female gametes) or ], where both male and female flowers occur on the same plant. There are also ], in both plants and animals, where hermaphrodite individuals coexist with males (called ]) or with females (called ]), or all three exist in the same species (called ]). Sometimes, both male and hermaphrodite flowers occur on the same plant (]) or both female and hermaphrodite flowers occur on the same plant (]).
== Etymology ==
The term "hermaphrodite" derives from ], the son of ] and ] in ], who was fused with a ], resulting in one being possessing physical traits of both sexes.


Hermaphrodism is not to be confused with ] in mammals, which is a separate and unrelated phenomenon. While people with the condition were previously called "''true hermaphrodites''" in medical literature, this usage is now considered to be outdated as of 2006 and misleading,<ref name="Herndon-2011">{{cite web| vauthors = Herndon A |title=Getting Rid of "Hermaphroditism" Once and For All|url=http://www.isna.org/node/979|url-status=live|archive-url=https://web.archive.org/web/20110927013509/http://www.isna.org/node/979|archive-date=27 September 2011|access-date=2 October 2011|publisher=]}}</ref><ref name="IntersexSoc">{{Cite web |title=Is a person who is intersex a hermaphrodite? |url=https://isna.org/faq/hermaphrodite/ |access-date=2024-01-20 |website=Intersex Society of North America |quote=The mythological term “hermaphrodite” implies that a person is both fully male and fully female. This is a physiologic impossibility. The words “hermaphrodite” and “pseudo-hermaphrodite” are stigmatizing and misleading words.}}</ref> as people with ovotesticular syndrome do not have functional sets of both male and female organs.<ref name="Rosenfield-2018">{{Citation| vauthors = Rosenfield KA |title=Hermaphrodite |date=2018 |encyclopedia=Encyclopedia of Animal Cognition and Behavior|pages=1–2| veditors = Vonk J, Shackelford T |place=Cham |publisher=Springer International Publishing|language=en|doi=10.1007/978-3-319-47829-6_329-1|isbn=978-3-319-47829-6 }}</ref><ref name="Mills-2018">{{Cite book |url=https://books.google.com/books?id=bLhcDwAAQBAJ&q=term+hermaphrodite+misleading+biology+of+sex&pg=PA309 |title=Biology of Sex |vauthors=Mills A |date=2018-01-01 |publisher=University of Toronto Press |isbn=978-1-4875-9337-7 |pages=309 |language=en |quote=In the past, the term ''hermaphrodite'' was widely applied in such cases, but humans are not hermaphroditic. In a truly hermaphroditic species, individuals have functional sets of male and female organs.}}</ref>
''See also:'' ] (human versions)

==Etymology==
The term hermaphrodite derives from the {{langx|la|hermaphroditus}}, from {{langx|grc|ἑρμαφρόδιτος|hermaphroditos}},<ref name=LatinLexicon>{{cite web|title=Definition of hermaphroditus|publisher=Numen: The Latin Lexicon|url=http://latinlexicon.org/definition.php?p1=2025388|access-date=19 July 2013|url-status=live|archive-url=https://web.archive.org/web/20141106082854/http://latinlexicon.org/definition.php?p1=2025388|archive-date=6 November 2014}}</ref> which derives from ] (Ἑρμαφρόδιτος), the son of ] and ] in ]. According to ], he fused with the ] ] resulting in one individual possessing physical traits of male and female sexes.<ref name="Ovid">]</ref> According to the earlier ], he was born with a physical body combining male and female sexes.<ref name="Diodorus">{{cite book | url=https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Diodorus_Siculus/4A*.html#6.5|title= The Library of History of Diodorus Siculus | volume = IV | chapter = Chapters 1–7 | page = 361 | via = penelope.uchicago.edu}}</ref> The word ''hermaphrodite'' entered the ] as early as the late fourteenth century.<ref name="OnlineEtymologyDictionary">{{cite web|title= Hermaphrodite | work = Online Etymology Dictionary|url=http://www.etymonline.com/index.php?term=hermaphrodite|access-date=3 June 2012|url-status=live|archive-url=https://web.archive.org/web/20131105230942/http://www.etymonline.com/index.php?term=hermaphrodite|archive-date=5 November 2013}}</ref>

==Animals==

===Sequential hermaphrodites===
{{main|Sequential hermaphroditism}}
]'' (common slipper shell)]]
] are initially male; the largest fish in a group becomes a female.]]] start life as females and later change into males.]]

Sequential hermaphrodites (]) occur in ] in which the individual first develops as one sex, but can later change into the opposite sex.<ref name="Barrows-2001">{{cite book |title=Animal behavior desk reference: a dictionary of animal behavior, ecology, and evolution |url=https://archive.org/details/animalbehaviorde00barr_955 |url-access=limited | vauthors = Barrows EM |edition=2nd |year=2001 |publisher=CRC Press |location= Boca Raton, Fla|isbn=978-0-8493-2005-7|oclc=299866547 |page= }}</ref> (Definitions differ on whether sequential hermaphroditism encompasses serial hermaphroditism; for authors who exclude serial hermaphroditism, a sequential hermaphrodite is also stipulated to only change sex once.<ref name="Pandian-2011">{{cite book|url=https://books.google.com/books?id=eAjSBQAAQBAJ&pg=PA164|title=Sex Determination in Fish | vauthors = Pandian TJ |date=2 September 2011|publisher=CRC Press|via=Google Books|url-status=live|archive-url=https://web.archive.org/web/20171107033127/https://books.google.co.uk/books?id=eAjSBQAAQBAJ&pg=PA164|archive-date=7 November 2017|isbn=978-1-4398-7919-1}}</ref>) This contrasts with simultaneous hermaphrodites, in which an individual possesses fully functional male and female genitalia. Sequential hermaphroditism is common in fish (particularly ]s) and many ] (such as the ]). Sequential hermaphroditism can best be understood in terms of ] and evolutionary ], as described in the size-advantage mode<ref name="Warner-1988">{{cite journal | vauthors = Warner RR | title = Sex change and the size-advantage model | journal = Trends in Ecology & Evolution | volume = 3 | issue = 6 | pages = 133–6 | date = June 1988 | pmid = 21227182 | doi = 10.1016/0169-5347(88)90176-0 | bibcode = 1988TEcoE...3..133W }}</ref> first proposed by ]<ref name="Ghiselin-1969">{{cite journal | vauthors = Ghiselin MT | title = The evolution of hermaphroditism among animals | journal = The Quarterly Review of Biology | volume = 44 | issue = 2 | pages = 189–208 | date = June 1969 | pmid = 4901396 | doi = 10.1086/406066 | s2cid = 38139187 }}</ref> which states that if an individual of a certain sex could significantly increase its reproductive success after reaching a certain size, it would be to their advantage to switch to that sex.

Sequential hermaphrodites can be divided into three broad categories:
* '''Protandry''': Where an organism develops as a male, and then changes sex to a female.<ref name="Barrows-2001"/>
** Example: The ] (genus '']'') are colorful reef fish found living in ] with ]s. Generally, one anemone contains a 'harem', consisting of a large female, a smaller reproductive male, and even smaller non-reproductive males. If the female is removed, the reproductive male will change sex and the largest of the non-reproductive males will mature and become reproductive. It has been shown that fishing pressure can change when the switch from male to female occurs, since fishermen usually prefer to catch the larger fish. The populations are generally changing sex at a smaller size, due to ].
* '''Protogyny''': Where the organism develops as a female, and then changes sex to a male.<ref name="Barrows-2001"/>
** Example: ]s (family ]) are a group of reef fish in which protogyny is common. Wrasses also have an uncommon life history strategy, which is termed diandry (literally, two males). In these species, two male morphs exists: an initial phase male and a terminal phase male. Initial phase males do not look like males and spawn in groups with females. They are not territorial. They are, perhaps, female mimics (which is why they are found swimming in group with females). Terminal phase males are territorial and have a distinctively bright coloration.<ref>{{Cite book | vauthors = Bagemihl B |title=Biological exuberance : animal homosexuality and natural diversity |publisher=St. Martin's Press |year=1999 |isbn=978-0-312-25377-6 |edition=2nd |location=New York}}</ref> Individuals are born as males or females, but if they are born males, they are not born as terminal phase males. Females and initial phase males can become terminal phase males. Usually, the most dominant female or initial phase male replaces any terminal phase male when those males die or abandon the group.
*'''Bidirectional sex changers''': Where an organism has female and male reproductive organs, but may act either as a female or as a male during different stages in life.<ref name="Barrows-2001"/>
**Example: '']'' (family ]) are a group of ] in which bidirectional sex change occurs. Once a social hierarchy is established, a fish changes sex according to its social status, regardless of the initial sex, based on a simple principle: if the fish expresses subordinate behavior then it changes its sex to female, and if the fish expresses dominant or non-dominant superior behavior then it changes its sex to male.<ref name="Rodgers-2007">{{cite journal| vauthors = Rodgers EW, Early RL, Grober MA |title=Social status determines sexual phenotype in the bi-directional sex changing bluebanded goby Lythrypnus dalli|journal=J Fish Biol|year=2007|volume=70|issue=6|pages=1660–1668|doi=10.1111/j.1095-8649.2007.01427.x|bibcode=2007JFBio..70.1660R }}</ref>
Dichogamy can have both conservation-related implications for humans, as mentioned above, as well as economic implications. For instance, ]s are favoured fish for eating in many Asian countries and are often ]. Since the adults take several years to change from female to male, the ] are extremely valuable individuals.

===Simultaneous hermaphrodites===
]ns mating by ]. Each has two penises on the undersides of their heads which they use to inject sperm.]]]s are simultaneous hermaphrodites, having both male and female reproductive organs.]]
] (or homogamous hermaphrodites) are individuals in which both male and female sexual organs are present and functional at the same time.<ref name="Barrows-2001"/> ] often occurs.<ref name="Rosenfield-2018" />
* ] ]s and land ]s are perhaps the best-known kinds of simultaneous hermaphrodites, and are the most widespread of terrestrial animals possessing this sexual polymorphism. Sexual material is exchanged between both animals via ]s, and is then stored in the ]. After exchange of ], both animals will lay fertilized eggs after a period of gestation. The eggs will proceed to hatch after a development period. Snails typically reproduce from early spring through late autumn.<ref name="Janssen-2015">{{cite journal | vauthors = Janssen R, Baur B | title = Seasonal effects on egg production and level of paternity in a natural population of a simultaneous hermaphrodite snail | journal = Ecology and Evolution | volume = 5 | issue = 14 | pages = 2916–28 | date = July 2015 | pmid = 26306176 | pmc = 4541995 | doi = 10.1002/ece3.1560 | bibcode = 2015EcoEv...5.2916J }}</ref>
* ]s are an example of a hermaphroditic gastropod. Mating with a partner is more desirable biologically than self-fertilization, as the genetic material of the resultant offspring is varied, but if mating with a partner is not possible, self-fertilization is practiced. The male sexual organ of an adult banana slug is quite large in proportion to its size, as well as compared to the female organ. It is possible for banana slugs, while mating, to become stuck together. If a substantial amount of wiggling fails to separate them, the male organ will be bitten off (using the slug's ]), see ]. If a banana slug has lost its male sexual organ, it can still mate as a female, making hermaphroditism a valuable adaptation.<ref name="Leonard-2002">{{cite journal| vauthors = Leonard JL, Pearse JS, Harper AB |title=Comparative reproductive biology of ''Ariolimax californicus'' and ''A. dolichophallus'' (Gastropoda; Stylommiatophora)|journal=Invertebrate Reproduction & Development|date=2002|volume=41|issue=1–3|pages=83–93|doi=10.1080/07924259.2002.9652738|bibcode=2002InvRD..41...83L |s2cid=83829239}}</ref>
* The species of colourful ] '']'' is hermaphroditic, with both male and female organs active at the same time during copulation. After mating, the external portion of the penis detaches, but is able to regrow within 24 hours.<ref name="Morelle R-2013">{{cite news | url = https://www.bbc.co.uk/news/science-environment-21431678 | title = Sea slug's 'disposable penis' surprises | author = Morelle R | author-link=Rebecca Morelle |date = 12 February 2013 | work=BBC News}}</ref><ref>{{cite journal | vauthors = Sekizawa A, Seki S, Tokuzato M, Shiga S, Nakashima Y | title = Disposable penis and its replenishment in a simultaneous hermaphrodite | journal = Biology Letters | volume = 9 | issue = 2 | pages = 20121150 | date = April 2013 | pmid = 23407499 | pmc = 3639767 | doi = 10.1098/rsbl.2012.1150 }}</ref>
*]s are another example of a simultaneous hermaphrodite. Although they possess ovaries and testes, they have a protective mechanism against self-fertilization. Sexual reproduction occurs when two worms meet and exchange ]s, copulating on damp nights during warm seasons.
* The free-living hermaphroditic nematode '']'' reproduces primarily by self-fertilization, but infrequent out-crossing events occur at a rate of approximately 1%.<ref name="Barrière-2005">{{cite journal | vauthors = Barrière A, Félix MA | title = High local genetic diversity and low outcrossing rate in Caenorhabditis elegans natural populations | journal = Current Biology | volume = 15 | issue = 13 | pages = 1176–84 | date = July 2005 | pmid = 16005289 | doi = 10.1016/j.cub.2005.06.022 | arxiv = q-bio/0508003 | s2cid = 2229622 | bibcode = 2005CBio...15.1176B }}</ref>
* ] do not practice self-fertilization, but a pair will mate multiple times over several nights, taking turns between which one acts as the male and which acts as the female.<ref name="Russell-2016">{{Cite book| vauthors = Russell PJ, Hertz PE, McMillan B |chapter-url=https://books.google.com/books?id=bLgaCgAAQBAJ&q=simultaneous+hermaphroditism+mammals&pg=PT1192|title=Biology: The Dynamic Science|date=2016-01-01|publisher=Cengage Learning|isbn=978-1-305-85610-3|pages=1151|language=en|chapter=Animal Reproduction}}</ref>{{Failed verification|date=June 2021}}
* The mangrove killifish ('']'') are simultaneous hermaphrodites, producing both eggs and sperm and routinely reproducing by self-fertilization. Each individual normally fertilizes itself when an egg and sperm produced by an internal organ unite inside the fish's body.<ref name="Sakakura-2006">{{cite journal | vauthors = Sakakura Y, Soyano K, Noakes D, Hagiwara A |date=2006 |title=Gonadal morphology in the self-fertilizing mangrove killifish, Kryptolebias marmoratus |journal=Ichthyological Research |volume=53 |issue=4 |pages=427–430 |doi=10.1007/s10228-006-0362-2 |bibcode=2006IchtR..53..427S |hdl=10069/35713 |s2cid=9474211 |hdl-access=free }}</ref> This species is also regarded as the only known vertebrate species that can reproduce by ].<ref name="Kanamori-2006">{{cite journal | vauthors = Kanamori A, Yamamura A, Koshiba S, Lee JS, Orlando EF, Hori H | title = Methyltestosterone efficiently induces male development in the self-fertilizing hermaphrodite fish, Kryptolebias marmoratus | journal = Genesis | volume = 44 | issue = 10 | pages = 495–503 | date = October 2006 | pmid = 17029221 | doi = 10.1002/dvg.20240 | s2cid = 13639701 }}</ref>

===Pseudohermaphroditism===
{{main|Pseudohermaphroditism}}

When ]s were first scientifically observed by explorers, they were thought to be hermaphrodites. Early observations of wild spotted hyenas led researchers to believe that all spotted hyenas, male or female, were born with what looked to be a penis. A ] is in fact an enlarged clitoris, which contains an external birth canal.<ref name="LiveScience-2006">{{cite web|url=http://www.livescience.com/699-painful-realities-hyena-sex.html|title=The Painful Realities of Hyena Sex|website=]|date=26 April 2006|url-status=live|archive-url=https://web.archive.org/web/20121119124756/http://www.livescience.com/699-painful-realities-hyena-sex.html|archive-date=2012-11-19}}</ref><ref name="EurekAlert!">{{cite web|url=http://www.eurekalert.org/multimedia/pub/716.php|title=Hyena Graphic|website=EurekAlert!|url-status=dead|archive-url=https://web.archive.org/web/20110310230213/http://www.eurekalert.org/multimedia/pub/716.php|archive-date=2011-03-10|access-date=2011-03-20}}</ref> It can be difficult to determine the sex of spotted hyenas until ], when they may become pregnant. When a female spotted hyena gives birth, she passes the cub through the cervix internally, but then passes it out through the elongated clitoris.<ref name=bella>{{cite web|url=http://www.bellaonline.com/articles/art27509.asp|title=Hermaphrodite Hyenas?|url-status=dead|archive-url=https://web.archive.org/web/20101123173312/http://www.bellaonline.com/articles/art27509.asp|archive-date=2010-11-23|access-date=2011-03-19}}</ref>

==Plants==
{{Main|Sexual reproduction in plants|Plant reproductive morphology#Bisexual|Monoicy}}
]'', a hermaphrodite plant with perfect flowers that have both functional ]s and ]s.]]

The term '''hermaphrodite''' is used in ] to describe, for example, a ] ] that has both ] (male, pollen-producing) and ]late (female, ovule-producing) parts. The overwhelming majority of flowering plant species are hermaphroditic.<ref name="Soni-2010">{{Cite book| vauthors = Soni NK |url=https://books.google.com/books?id=RvBe_bCQAukC&q=hermaphrodite+or+bisexual+flower&pg=PA87|title=Fundamentals of Botany|date=2010-04-01|publisher=Tata McGraw-Hill Education|isbn=978-0-07-068177-4|pages=87|language=en}}</ref>

=== Monoecy ===
Flowering plant species with separate, imperfect, male and female flowers on the same individual are called ]. Monoecy only occurs in about 7% of flowering plant species.<ref name="Molnar-2004">{{cite web | vauthors = Molnar S |title= Plant Reproductive Systems|url= http://www.geocities.com/we_evolve/Plants/breeding_sys.html|date= 17 February 2004|work= Evolution and the Origins of Life|publisher= Geocities.com |access-date=12 September 2009 |archive-url=https://web.archive.org/web/20091022174814/http://geocities.com/we_evolve/Plants/breeding_sys.html |archive-date=2009-10-22}}</ref> Monoecious plants are often referred to as hermaphroditic because they produce both male and female gametes. However, the individual flowers are not hermaphroditic if they only produce gametes of one sex.<ref name="Glover-2014">{{Cite book| vauthors = Glover B |url=https://books.google.com/books?id=uXMVDAAAQBAJ&q=Monoecy&pg=PA139|title=Understanding Flowers and Flowering | edition = Second|date=February 2014|publisher=Oxford University Press|isbn=978-0-19-966159-6|pages=138–139|language=en}}</ref> 65% of ] species are dioecious, but ] are almost all monoecious.<ref name="Walas-2018">{{cite journal| vauthors = Walas Ł, Mandryk W, Thomas PA, Tyrała-Wierucka Ż, Iszkuło G |date=2018|title=Sexual systems in gymnosperms: A review|journal=Basic and Applied Ecology|volume=31|pages=1–9|doi=10.1016/j.baae.2018.05.009|bibcode=2018BApEc..31....1W |s2cid=90740232|url=http://keele-repository.worktribe.com/previewfile/457433/29052018_1-s2.0-S1439179117304498-main.pdf}}</ref> Some plants can change their sex throughout their lifetime, a phenomenon called ].{{citation needed|date=July 2021}}

=== Andromonoecy ===
In ] species, the plants produce ] (hermaphrodite) flowers and separate fertile male flowers that are sterile as female.<ref name="Fusco-2019">{{Cite book|url=https://books.google.com/books?id=AKGsDwAAQBAJ&q=The+Biology+of+Reproduction+PAGE+112|title=The Biology of Reproduction|vauthors=Fusco G, Minelli A|date=2019-10-10|publisher=Cambridge University Press|isbn=978-1-108-49985-9|pages=111–113|language=en|author-link2=Alessandro Minelli (biologist)|access-date=29 March 2021|archive-url=https://web.archive.org/web/20210401100101/https://books.google.com/books?id=AKGsDwAAQBAJ&newbks=0&printsec=frontcover&dq=The+Biology+of+Reproduction+PAGE+112&hl=en|archive-date=1 April 2021|url-status=live}}</ref><ref name="Kouonon-2009">{{cite journal | vauthors = Kouonon LC, Jacquemart AL, Bi AI, Bertin P, Baudoin JP, Dje Y | title = Reproductive biology of the andromonoecious Cucumis melo subsp. agrestis (Cucurbitaceae) | journal = Annals of Botany | volume = 104 | issue = 6 | pages = 1129–39 | date = November 2009 | pmid = 19671577 | pmc = 2766191 | doi = 10.1093/aob/mcp196 }}</ref> Andromonoecy occurs in about 4000 species of flowering plants (2% of flowering plants).<ref name="Vallejo-Marín-2007">{{cite journal | vauthors = Vallejo-Marín M, Rausher MD | title = The role of male flowers in andromonoecious species: energetic costs and siring success in Solanum carolinense L | journal = Evolution; International Journal of Organic Evolution | volume = 61 | issue = 2 | pages = 404–12 | date = February 2007 | pmid = 17348949 | doi = 10.1111/j.1558-5646.2007.00031.x | s2cid = 781464 }}</ref>

=== Gynomonoecy ===
In ] species, the plants produce hermaphrodite flowers and separate male-sterile pistillate flowers.<ref name="Fusco-2019"/> One example is the meadow saxifrage, '']''.<ref name="Stevens-1985">{{cite journal | vauthors = Stevens D, Richards A |date=1985 |title=Gynodioecy in ''Saxifraga granulata'' L. |journal=Plant Systematics and Evolution |volume=151 |pages=43–54 |doi=10.1007/BF02418018 |s2cid=21632274 }}</ref> Charles Darwin gave several other examples in his 1877 book "The Different Forms of Flowers on Plants of the Same Species".<ref name="Darwin-1877">{{cite book | vauthors = Charles D |date=1877 |title=The different forms of flowers on plants of the same species |publisher=John Murray |location =London }}</ref>

About 57% of moss species and 68% of liverworts are ], meaning that their gametophytes produce either male or female gametes, but not both.<ref name="Shaw-2000">{{cite book | veditors = Shaw AJ, Goffinet B | title = Bryophyte biology | vauthors = Shaw AJ, Goffinet B |date=2000 |chapter= Chapter 12: Population ecology, population genetics, and microevolution |pages=369–402 |publisher=Cambridge University Press |location=Cambridge, UK |isbn=978-0-521-66794-4 }}</ref>{{rp|377}}

Sequential hermaphroditism is common in ]s and some vascular plants.{{citation needed|date=April 2023}}

==Use regarding humans==
{{Intersex sidebar|rights}}
{{Main|Disorders of sex development|Intersex}}
], the "son" of the Greek god ] and the goddess ], origin of the word "hermaphrodite"]]
] in the ], before becoming a Catholic festival, was initially an ] dedicated to the hermaphrodite deity, Lakapati, who presided over fertility.<ref>{{Cite web|url=https://www.aswangproject.com/lakapati-the-transgender-tagalog-deity/|title=LAKAPATI: The "Transgender" Tagalog Deity? Not so fast…|website=THE ASWANG PROJECT|date=29 November 2018|language=en-US|access-date=2019-07-03}}</ref>]]
] of a person displaying ambiguous genitalia, one of a ]. The series may be the earliest medical photographic documentation of an intersex person.<ref>{{cite journal | vauthors = Schultheiss D, Herrmann TR, Jonas U | title = Early photo-illustration of a hermaphrodite by the French photographer and artist Nadar in 1860 | journal = The Journal of Sexual Medicine | volume = 3 | issue = 2 | pages = 355–60 | date = March 2006 | pmid = 16490032 | doi = 10.1111/j.1743-6109.2005.00157.x }} {{subscription required}}
</ref>{{rp|358}}]]

Historically, the term hermaphrodite was used in law to refer to people whose sex was in doubt. The 12th-century {{lang|la|]}} states that "Whether an hermaphrodite may witness a testament, depends on which sex prevails" ("Hermafroditus an ad testamentum adhiberi possit, qualitas sexus incalescentis ostendit.").<ref>Decretum Gratiani, C. 4, q. 2 et 3, c. 3</ref><ref>{{cite web | url = http://geschichte.digitale-sammlungen.de/decretum-gratiani/kapitel/dc_chapter_1_1585 | title = Decretum Gratiani (Kirchenrechtssammlung) | work = Bayerische StaatsBibliothek (]) | date = February 5, 2009 | url-status=live | archive-url = https://web.archive.org/web/20161220084841/http://geschichte.digitale-sammlungen.de/decretum-gratiani/kapitel/dc_chapter_1_1585 | archive-date = December 20, 2016 }}</ref>

] (1461–1523) stated, using the term ''hermaphrodite,'' that the people who bore the sexes of both man and woman were regarded by the Athenians and the Romans as monsters, and thrown into the sea at Athens and into the Tiber at Rome.<ref name="de Jaucourt-1765">{{Cite journal| vauthors = chevalier de Jaucourt L |title=Hermaphrodite |journal = Encyclopedia of Diderot & d'Alembert |volume=8 |pages=165–167 |date=1765 |url=http://quod.lib.umich.edu/d/did/did2222.0000.208/--hermaphrodite?rgn=main;view=fulltext;q1=hair|access-date=13 April 2023 }}</ref> Similarly, the 17th-century English jurist and judge ] (Lord Coke), wrote in his '']'' on laws of succession stating, "Every heire is either a male, a female, or an hermaphrodite, that is both male and female. And an hermaphrodite (which is also called ''Androgynus'') shall be heire, either as male or female, according to that kind of sexe which doth prevaile."<ref>{{cite book | vauthors = ] | title = The First Part of the Institutes of the Laws of England, Institutes 8.a. | edition = 1st Am. | date = 1812 }}</ref><ref>{{Cite journal| volume = 41| vauthors = Greenberg J | title = Defining Male and Female: Intersexuality and the Collision Between Law and Biology| journal = Arizona Law Review| date = 1999| ssrn = 896307|pages = 277–278}}</ref>

During the ], medical authors attempted to ascertain whether or not humans could be hermaphrodites, adopting a precise biological definition to the term.<ref>{{Cite book| publisher = Johns Hopkins University Press| isbn = 978-0-8018-9155-7| vauthors = Reis E | title = Bodies in Doubt: an American History of Intersex| location = Baltimore| pages = 55–81| date = 2009}}</ref> From that period until the early 21st century, individuals with ] were termed ] if their ]al tissue contained both testicular and ovarian tissue, and ] if their external appearance (]) differed from sex expected from internal gonads. This language has fallen out of favor due to misconceptions and stigma associated with the terms,<ref>{{cite journal | vauthors = Dreger AD, Chase C, Sousa A, Gruppuso PA, Frader J | title = Changing the nomenclature/taxonomy for intersex: a scientific and clinical rationale | journal = Journal of Pediatric Endocrinology & Metabolism | volume = 18 | issue = 8 | pages = 729–733 | date = August 2005 | pmid = 16200837 | doi = 10.1515/JPEM.2005.18.8.729 | url = http://www.aissg.org/PDFs/Dreger-Nomenclature-2005.PDF | access-date = 27 July 2016 | url-status = dead | s2cid = 39459050 | archive-url = https://web.archive.org/web/20161220154642/http://www.aissg.org/PDFs/Dreger-Nomenclature-2005.PDF | archive-date = 20 December 2016 }}</ref><ref>{{cite journal | vauthors = Vilain E, Achermann JC, Eugster EA, Harley VR, Morel Y, Wilson JD, Hiort O | title = We used to call them hermaphrodites | journal = Genetics in Medicine | volume = 9 | issue = 2 | pages = 65–66 | date = February 2007 | pmid = 17304046 | doi = 10.1097/GIM.0b013e31802cffcf | quote = use of the words “hermaphrodite,” “pseudohermaphrodite,” and “intersex” should be abandoned, as they either are confusing or have a negative social connotation that may be perceived as harmful by some patients and parents. | doi-access = free }}</ref><ref name="IntersexSoc" /><ref name="Mills-2018" /> and also a shift to nomenclature based on genetics.

The term "intersex" described a wide variety of combinations of what are ambiguous biological characteristics. Intersex biology may include, for example, ambiguous-looking external genitalia, ]s that include mixed XX and XY chromosome pairs (46XX/46XY, 46XX/47XXY or 45X/XY ]). Clinically, medicine currently uses the terminology "]" <ref name="Georgiann-2011">{{Cite journal|url=http://www.emeraldinsight.com/books.htm?chapterid=1943090 | vauthors = Georgiann D |author-link=Georgiann Davis| date =2011|title =DSD is a Perfectly Fine Term": Reasserting Medical Authority through a Shift in Intersex Terminology | veditors = McGann PJ, Hutson DJ |journal=Sociology of Diagnosis (Advances in Medical Sociology)|series=Advances in Medical Sociology |volume =12|pages=155–182|doi=10.1108/S1057-6290(2011)0000012012 |isbn=978-0-85724-575-5 }}</ref> (also known as ].)<ref>{{Cite web |title=Information about the standard for gender, sex, and variations of sex characteristics {{!}} Stats NZ |url=https://www.stats.govt.nz/methods/information-about-the-standard-for-gender-sex-and-variations-of-sex-characteristics |access-date=2024-03-12 |website=www.stats.govt.nz}}</ref> This is particularly significant because of the relationship between medical terminology and medical intervention.<ref name="Black-2017">{{Citation|title=Darlington Statement|date=March 2017|url=https://oii.org.au/darlington-statement/|archive-url=https://web.archive.org/web/20170322204013/https://oii.org.au/darlington-statement/|access-date=March 21, 2017|archive-date=2017-03-22|author1-link=Androgen Insensitivity Syndrome Support Group Australia|author2-link=Intersex Trust Aotearoa New Zealand|author3-link=Organisation Intersex International Australia|author6-link=Tony Briffa (politician)|author7-link=Morgan Carpenter|vauthors=((Androgen Insensitivity Support Syndrome Support Group Australia)), ((Intersex Trust Aotearoa New Zealand)), ((Organisation Intersex International Australia)), Black E, Bond K, Briffa T, Carpenter M, Morgan, Cody C, David A, Driver B, Hannaford C, Harlow E, Hart B, Hart P, Leckey D, Lum S, Mitchell MB, Nyhuis E, O'Callaghan B, Perrin S, Smith C, Williams T, Yang I, Yovanovic|author17-link=Mani Mitchell|first24=Georgie|author14-link=Phoebe Hart|author13-link=Bonnie Hart|url-status=dead}}</ref>

], and many human rights institutions,<ref name="IACHR-2016">{{Citation | author1 = UN Committee against Torture | author1-link = United Nations Convention against Torture#Committee against Torture | author2 = UN Committee on the Rights of the Child | author2-link = Committee on the Rights of the Child | author3 = UN Committee on the Rights of People with Disabilities | author3-link = Committee on the Rights of Persons with Disabilities | author4 = UN Subcommittee on Prevention of Torture and other Cruel, Inhuman or Degrading Treatment or Punishment | author5 = Méndez J | author5-link = Juan E. Méndez | author6 = Pῡras D | author7 = Šimonoviæ D | author8 = Santos Pais M | author9 = African Commission on Human and Peoples' Rights | author9-link = African Commission on Human and Peoples' Rights | author10 = Council of Europe Commissioner for Human Rights | author10-link = Commissioner for Human Rights | author11 = Inter-American Commission on Human Rights | author11-link = Inter-American Commission on Human Rights | work = ] | title = Intersex Awareness Day – Wednesday 26 October. End violence and harmful medical practices on intersex children and adults, UN and regional experts urge | date = October 24, 2016 | url = http://www.ohchr.org/EN/NewsEvents/Pages/DisplayNews.aspx?NewsID=20739&LangID=E | url-status = live | archive-url = https://web.archive.org/web/20161121185256/http://ohchr.org/EN/NewsEvents/Pages/DisplayNews.aspx?NewsID=20739&LangID=E | archive-date = November 21, 2016 }}</ref><ref name="Commissioner for Human Rights-2015">{{Citation| author1 = Council of Europe| author2 = Commissioner for Human Rights| author1-link = Council of Europe| author2-link = Commissioner for Human Rights| title = Human rights and intersex people, Issue Paper| date = April 2015| url = https://wcd.coe.int/ViewDoc.jsp?Ref=CommDH/IssuePaper(2015)1&Language=lanEnglish&Ver=original| url-status = dead| archive-url = https://web.archive.org/web/20160106203349/https://wcd.coe.int/ViewDoc.jsp?Ref=CommDH%2FIssuePaper%282015%291&Language=lanEnglish&Ver=original| archive-date = 2016-01-06| access-date = 2018-06-10}}</ref> have criticized ] designed to make bodies more typically male or female.

In some cases, variations in sex characteristics are caused by unusual levels of sex hormones, which may be the result of an atypical set of sex chromosomes.{{medical citation needed|date=July 2023}} One common cause of variations in sex characteristics traits is the crossing over of the ] (SRY) from the Y chromosome to the X chromosome during ]. The SRY is then activated in only certain areas, causing development of ] in some areas by beginning a series of events starting with the upregulation of the ] (SOX9), and in other areas not being active (causing the growth of ] ]). Thus, ] and ovarian tissues will both be present in the same individual.<ref>{{cite journal | vauthors = Margarit E, Coll MD, Oliva R, Gómez D, Soler A, Ballesta F | title = SRY gene transferred to the long arm of the X chromosome in a Y-positive XX true hermaphrodite | journal = American Journal of Medical Genetics | volume = 90 | issue = 1 | pages = 25–8 | date = January 2000 | pmid = 10602113 | doi = 10.1002/(SICI)1096-8628(20000103)90:1<25::AID-AJMG5>3.0.CO;2-5 }}</ref> Of all total recorded cases of ovotesticular DSD, in only 8% percent of all cases was SRY present, leaving the rest of cases that could be explained to other or less common causes, with the vast majority simply being currently unexplainable.

Fetuses were previously thought to be phenotypically female before the ] stage;<ref>{{cite book| vauthors = Leyner M, Goldberg B |author-link1=Mark Leyner |title=Why Do Men Have Nipples?: Hundreds of Questions You'd Only Ask a Doctor After Your Third Martini|year=2005|publisher=Three Rivers Press|location=New York|isbn=978-1-4000-8231-5|oclc=57722472|url=https://archive.org/details/whydomenhavenipp00leyn}}</ref> however, this is now known to be incorrect, as humans are simply undifferentiated before this stage and possess ]s, ]s, and a ].<ref name="Rey-2020">{{cite book | vauthors = Rey R, Josso N, Racine C |title=Endotext |date=2020-05-27 |publisher=MDText.com, Inc. |location=South Dartmouth, Mass. |chapter=Sexual Differentiation |pmid=25905232 |access-date=28 Mar 2023 | veditors = Feingold KR, Anawalt B, Blackman MR, Boyce A, Chrousos G, Corpas E, de Herder WW, Dhatariya K, Dungan K, Hofland J, Kalra S, Kaltsas G, Kapoor N, Koch C, Kopp P, Korbonits M, Kovacs CS, Kuohung W, Laferrère B, Levy M, McGee EA, McLachlan R, New M, Purnell J, Sahay R, Shah AS, Singer F, Sperling MA, Stratakis CA, Trence DL, Wilson DP | display-editors = 6 |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK279001/ |via=] |orig-year=first published 2000 }}</ref><ref name="Hughes-2001">{{cite journal | vauthors = Hughes IA | title = Minireview: sex differentiation | journal = Endocrinology | volume = 142 | issue = 8 | pages = 3281–3287 | date = August 2001 | pmid = 11459768 | doi = 10.1210/endo.142.8.8406 | doi-access = free }}</ref>

== Evolution ==
{{Main|Evolution of sexual reproduction}}
{{For|evolution of sexual systems with hermaphodites|Trioecy#Evolution of trioecy|Androdioecy#Evolution of androdioecy|Gynodioecy#Evolution}}The evolution of ] may have contributed to the evolution of simultaneous hermaphroditism and sequential hermaphroditism,<ref name="Schärer-2017b">{{cite journal |vauthors=Schärer L |date=February 2017 |title=The varied ways of being male and female |journal=Molecular Reproduction and Development |volume=84 |issue=2 |pages=94–104 |doi=10.1002/mrd.22775 |pmid=28032683 |quote= |doi-access=free}}</ref> it remains unclear if the evolution of anisogamy first led to hermaphroditism or ].<ref name="Kliman-2016">{{cite book | vauthors = Kliman R |url=https://books.google.com/books?id=_r4OCAAAQBAJ |title=Encyclopedia of Evolutionary Biology |date=2016 |publisher=Academic Press |isbn=978-0-12-800426-5 |volume=2 |location= |pages=212–224 |access-date=2021-09-29 |archive-url=https://web.archive.org/web/20210506205920/https://www.google.com/books/edition/Encyclopedia_of_Evolutionary_Biology/_r4OCAAAQBAJ?hl=en&gbpv=0&kptab=overview |archive-date=2021-05-06 | url-status = live }}</ref>{{rp|213}}

A 2023 study argued that hermaphroditism can evolve directly from ] under certain circumstances, such as if the fertilization is well organized and the average size of groups is small.<ref name="Henshaw-2023">{{cite journal | vauthors = Henshaw JM, Bittlingmaier M, Schärer L | title = Hermaphroditic origins of anisogamy | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 378 | issue = 1876 | pages = 20220283 | date = May 2023 | pmid = 36934747 | pmc = 10024982 | doi = 10.1098/rstb.2022.0283 }}</ref> Simultaneous hermaphroditism that exclusively reproduces through self-fertilization has evolved many times in plants and animals, but it might not last long evolutionarily.<ref name="Leonard-2019">{{Cite book |url=https://books.google.com/books?id=0rWZDwAAQBAJ&q=sexual+system |title=Transitions Between Sexual Systems: Understanding the Mechanisms of, and Pathways Between, Dioecy, Hermaphroditism and Other Sexual Systems |vauthors=Leonard JL |date=2019-05-21 |publisher=Springer |isbn=978-3-319-94139-4 |pages= |language=en}}</ref>{{Rp|page=14}}

=== In animals ===
] and Priya Iyer argued that the last ] for animals was hermaphroditic and that transitions from hermaphroditism to gonochorism were more numerous than the reverse. Other scientists have criticized this argument; saying it’s based on ] ], assignments of sexual modes for the ] level than the species level, and methods exclusively based on ].<ref name="Sasson-2017">{{cite journal |vauthors=Sasson DA, Ryan JF |date=December 2017 |title=A reconstruction of sexual modes throughout animal evolution |journal=BMC Evolutionary Biology |volume=17 |issue=1 |pages=242 |bibcode=2017BMCEE..17..242S |doi=10.1186/s12862-017-1071-3 |pmc=5717846 |pmid=29207942 |doi-access=free}}</ref>

Hermaphroditism is ] in ]s where it ]<ref name="Avise-2011"/>{{Rp|page=97}} and gonochorism is also ancestral to hermaphroditic fishes.<ref name="Erisman-2013">{{cite journal |vauthors=Erisman BE, Petersen CW, Hastings PA, Warner RR |date=October 2013 |title=Phylogenetic perspectives on the evolution of functional hermaphroditism in teleost fishes |journal=Integrative and Comparative Biology |volume=53 |issue=4 |pages=736–54 |doi=10.1093/icb/ict077 |pmid=23817661 |doi-access=free}}</ref> According to ] simultaneous hermaphroditism in animals most likely evolved due to a limited number of mating partners.<ref name="Cabej-2013">{{Cite book | vauthors = Cabej NR |url=https://books.google.com/books?id=THz_-R8BSs0C&q=The+most+plausible+hypothesis+on+the+evolution+of+simultaneous+hermaphroditism+is+the+limited+availability+of+mating+partners.&pg=PA101 |title=Building the Most Complex Structure on Earth: An Epigenetic Narrative of Development and Evolution of Animals |date=2013-04-01 |publisher=Newnes |isbn=978-0-12-401729-0 |pages=101 |language=en}}</ref>

=== In plants ===
{{See also|Monoecy#Evolution|Andromonoecy#Evolution|Gynomonoecy#Evolution}}
It is widely accepted that the first ]s were outcrossing hermaphrodites.<ref name="Orton-2019">{{Cite book| vauthors = Orton TJ |url=https://books.google.com/books?id=rte_DwAAQBAJ&q=Horticultural+Plant+Breeding|title=Horticultural Plant Breeding|date=2019-11-21|publisher=Academic Press|isbn=978-0-12-815570-7|pages=176|language=en}}</ref> In flowering plants, hermaphroditism is ancestral to dioecy.<ref name="Núñez-Farfán-2020">{{Cite book| vauthors = Núñez-Farfán J, Valverde PL |url=https://books.google.com/books?id=iF70DwAAQBAJ&q=consensus+dioecy&pg=PA177|title=Evolutionary Ecology of Plant-Herbivore Interaction |date=2020-07-30|publisher=Springer Nature|isbn=978-3-030-46012-9|pages=177|language=en}}</ref>

Hermaphroditism in plants may promote self fertilization in pioneer populations.<ref name="Burns-2019">{{Cite book| vauthors = Burns KC |url=https://books.google.com/books?id=wbOQDwAAQBAJ&q=evolution+of+hermaphroditism+in+plants|title=Evolution in Isolation: The Search for an Island Syndrome in Plants|date=2019-05-16|publisher=Cambridge University Press|isbn=978-1-108-42201-7|pages=21–22|language=en}}</ref> However, plants have evolved multiple different mechanisms to avoid self-fertilization in hermaphrodites, including ], molecular recognition systems and mechanical or morphological mechanisms such as ].<ref name="Judd-2002">{{cite book | vauthors = Judd WS, Campbell CS, Kellogg EA, Stevens PF, Donoghue MJ |title=Plant systematics, a phylogenetic approach |edition=2 |date=2002 |publisher=Sinauer Associates Inc. |location=Sunderland MA, US |isbn=0-87893-403-0 }}</ref>{{rp|73,74}}

==See also ==
<!-- DO NOT add any person, living or dead, to this article as an example of a hermaphrodite as hermaphroditism does not exist in humans (the phenomenon you are probably thinking of is intersexuality, which is not the same as hermaphroditism). It will be deleted. -->
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== References ==
{{Reflist|30em}}

== Further reading ==
{{refbegin|30em}}
* {{cite web|title= Bony Fishes: Reproduction|url= http://www.buschgardens.org/animal-info/info-books/bony-fish/reproduction.htm|year= 2009|work= SeaWorld/Busch Gardens Animal Infobooks|publisher= Busch Entertainment Corporation|access-date= 12 September 2009|archive-url= https://web.archive.org/web/20110725112536/http://www.buschgardens.org/animal-info/info-books/bony-fish/reproduction.htm|archive-date= 25 July 2011|url-status= dead}}
* Discovery Health Channel, (2007) "I Am My Own Twin"
* {{cite journal | vauthors = Kim KR, Kwon Y, Joung JY, Kim KS, Ayala AG, Ro JY | title = True hermaphroditism and mixed gonadal dysgenesis in young children: a clinicopathologic study of 10 cases | journal = Modern Pathology | volume = 15 | issue = 10 | pages = 1013–9 | date = October 2002 | pmid = 12379746 | doi = 10.1097/01.MP.0000027623.23885.0D | doi-access = free | oclc = 357415945 }}
* {{Cite book | vauthors = Randall JE | title =Reef and Shore Fishes of the South Pacific: New Caledonia to Tahiti and the Pitcairn Islands| year = 2005 | publisher = University of Hawaii Press | location = Honolulu, Hawaii | isbn = 978-0-8248-2698-7 | pages = 346, 387|oclc=52152732}}
* {{Cite book | vauthors = Chase C | veditors = Atkins D |title = Looking Queer: Body Image and Identity in Lesbian, Bisexual, Gay, and Transgender Communities |chapter= Affronting Reason| year = 1998 | publisher = Haworth Press | location = New York | isbn = 978-1-56023-931-4 | pages = 205–219|oclc=38519315}}
* {{cite news | vauthors = Fausto-Sterling A |author-link= Anne Fausto-Sterling|title= How Many Sexes Are There?|newspaper= The New York Times|location= New York|page= Op–Ed|date= 12 March 1993}}, reprinted in: {{cite book | veditors = Harwood S |title= Business As Ethical and Business As Usual: Text, Readings, and Cases|year= 1996|publisher= Wadsworth Pub|location= Belmont, CA|isbn= 978-0-534-54251-1|oclc= 141382073|pages= 168–170}}
* {{Cite book| vauthors = Grumbach MM, Conte FA |author-link1=Melvin M. Grumbach| veditors = Williams RH, Wilson JD |title=Williams Textbook of Endocrinology|year=1998|chapter=Disorders of sex differentiation|publisher=Saunders|location=Philadelphia|isbn=978-0-7216-6152-0|pages=|oclc=35364729|chapter-url=https://archive.org/details/williamstextbook00wils|url=https://archive.org/details/williamstextbook00wils/page/1303}}
{{refend}}

== External links ==
{{wiktionary|hermaphrodite}}
{{commons}}
<!-- DO NOT add any person, living or dead, to this article as an example of a hermaphrodite as hermaphroditism does not exist in humans (the phenomenon you are probably thinking of is intersexuality, which is not the same as hermaphroditism). It will be deleted. -->

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{{Sex (biology)}}
{{Human sexuality and sexology}}
{{Intersex}}

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Latest revision as of 21:43, 26 December 2024

Sexually reproducing organism that produces both male and female gametes For other uses, see Hermaphrodite (disambiguation). Not to be confused with Intersex people or Intersex (biology).

Garden snails mating

A hermaphrodite (/hərˈmæfrəˌdaɪt/) is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic.

The individuals of many taxonomic groups of animals, primarily invertebrates, are hermaphrodites, capable of producing viable gametes of both sexes. In the great majority of tunicates, mollusks, and earthworms, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. Hermaphroditism is also found in some fish species, but is rare in other vertebrate groups. Most hermaphroditic species exhibit some degree of self-fertilization. The distribution of self-fertilization rates among animals is similar to that of plants, suggesting that similar pressures are operating to direct the evolution of selfing in animals and plants.

A rough estimate of the number of hermaphroditic animal species is 65,000, about 5% of all animal species, or 33% excluding insects. Insects are almost exclusively gonochoric, and no definitive cases of hermaphroditism have been demonstrated in this group. There are no known hermaphroditic species among mammals or birds.

About 94% of flowering plant species are either hermaphroditic (all flowers produce both male and female gametes) or monoecious, where both male and female flowers occur on the same plant. There are also mixed breeding systems, in both plants and animals, where hermaphrodite individuals coexist with males (called androdioecy) or with females (called gynodioecy), or all three exist in the same species (called trioecy). Sometimes, both male and hermaphrodite flowers occur on the same plant (andromonoecy) or both female and hermaphrodite flowers occur on the same plant (gynomonoecy).

Hermaphrodism is not to be confused with ovotesticular syndrome in mammals, which is a separate and unrelated phenomenon. While people with the condition were previously called "true hermaphrodites" in medical literature, this usage is now considered to be outdated as of 2006 and misleading, as people with ovotesticular syndrome do not have functional sets of both male and female organs.

Etymology

The term hermaphrodite derives from the Latin: hermaphroditus, from Ancient Greek: ἑρμαφρόδιτος, romanizedhermaphroditos, which derives from Hermaphroditus (Ἑρμαφρόδιτος), the son of Hermes and Aphrodite in Greek mythology. According to Ovid, he fused with the nymph Salmacis resulting in one individual possessing physical traits of male and female sexes. According to the earlier Diodorus Siculus, he was born with a physical body combining male and female sexes. The word hermaphrodite entered the English lexicon as early as the late fourteenth century.

Animals

Sequential hermaphrodites

Main article: Sequential hermaphroditism
Shells of Crepidula fornicata (common slipper shell)
Clownfish are initially male; the largest fish in a group becomes a female.
Most species of parrotfish start life as females and later change into males.

Sequential hermaphrodites (dichogamy) occur in species in which the individual first develops as one sex, but can later change into the opposite sex. (Definitions differ on whether sequential hermaphroditism encompasses serial hermaphroditism; for authors who exclude serial hermaphroditism, a sequential hermaphrodite is also stipulated to only change sex once.) This contrasts with simultaneous hermaphrodites, in which an individual possesses fully functional male and female genitalia. Sequential hermaphroditism is common in fish (particularly teleosts) and many gastropods (such as the common slipper shell). Sequential hermaphroditism can best be understood in terms of behavioral ecology and evolutionary life history theory, as described in the size-advantage mode first proposed by Michael T. Ghiselin which states that if an individual of a certain sex could significantly increase its reproductive success after reaching a certain size, it would be to their advantage to switch to that sex.

Sequential hermaphrodites can be divided into three broad categories:

  • Protandry: Where an organism develops as a male, and then changes sex to a female.
    • Example: The clownfish (genus Amphiprion) are colorful reef fish found living in symbiosis with sea anemones. Generally, one anemone contains a 'harem', consisting of a large female, a smaller reproductive male, and even smaller non-reproductive males. If the female is removed, the reproductive male will change sex and the largest of the non-reproductive males will mature and become reproductive. It has been shown that fishing pressure can change when the switch from male to female occurs, since fishermen usually prefer to catch the larger fish. The populations are generally changing sex at a smaller size, due to natural selection.
  • Protogyny: Where the organism develops as a female, and then changes sex to a male.
    • Example: Wrasses (family Labridae) are a group of reef fish in which protogyny is common. Wrasses also have an uncommon life history strategy, which is termed diandry (literally, two males). In these species, two male morphs exists: an initial phase male and a terminal phase male. Initial phase males do not look like males and spawn in groups with females. They are not territorial. They are, perhaps, female mimics (which is why they are found swimming in group with females). Terminal phase males are territorial and have a distinctively bright coloration. Individuals are born as males or females, but if they are born males, they are not born as terminal phase males. Females and initial phase males can become terminal phase males. Usually, the most dominant female or initial phase male replaces any terminal phase male when those males die or abandon the group.
  • Bidirectional sex changers: Where an organism has female and male reproductive organs, but may act either as a female or as a male during different stages in life.
    • Example: Lythrypnus dalli (family Gobiidae) are a group of coral reef fish in which bidirectional sex change occurs. Once a social hierarchy is established, a fish changes sex according to its social status, regardless of the initial sex, based on a simple principle: if the fish expresses subordinate behavior then it changes its sex to female, and if the fish expresses dominant or non-dominant superior behavior then it changes its sex to male.

Dichogamy can have both conservation-related implications for humans, as mentioned above, as well as economic implications. For instance, groupers are favoured fish for eating in many Asian countries and are often aquacultured. Since the adults take several years to change from female to male, the broodstock are extremely valuable individuals.

Simultaneous hermaphrodites

Turbellarians mating by penis fencing. Each has two penises on the undersides of their heads which they use to inject sperm.
Earthworms are simultaneous hermaphrodites, having both male and female reproductive organs.

Simultaneous hermaphrodites (or homogamous hermaphrodites) are individuals in which both male and female sexual organs are present and functional at the same time. Self-fertilization often occurs.

  • Pulmonate land snails and land slugs are perhaps the best-known kinds of simultaneous hermaphrodites, and are the most widespread of terrestrial animals possessing this sexual polymorphism. Sexual material is exchanged between both animals via spermatophores, and is then stored in the spermatheca. After exchange of spermatozoa, both animals will lay fertilized eggs after a period of gestation. The eggs will proceed to hatch after a development period. Snails typically reproduce from early spring through late autumn.
  • Banana slugs are an example of a hermaphroditic gastropod. Mating with a partner is more desirable biologically than self-fertilization, as the genetic material of the resultant offspring is varied, but if mating with a partner is not possible, self-fertilization is practiced. The male sexual organ of an adult banana slug is quite large in proportion to its size, as well as compared to the female organ. It is possible for banana slugs, while mating, to become stuck together. If a substantial amount of wiggling fails to separate them, the male organ will be bitten off (using the slug's radula), see apophallation. If a banana slug has lost its male sexual organ, it can still mate as a female, making hermaphroditism a valuable adaptation.
  • The species of colourful sea slugs Goniobranchus reticulatus is hermaphroditic, with both male and female organs active at the same time during copulation. After mating, the external portion of the penis detaches, but is able to regrow within 24 hours.
  • Earthworms are another example of a simultaneous hermaphrodite. Although they possess ovaries and testes, they have a protective mechanism against self-fertilization. Sexual reproduction occurs when two worms meet and exchange gametes, copulating on damp nights during warm seasons.
  • The free-living hermaphroditic nematode Caenorhabditis elegans reproduces primarily by self-fertilization, but infrequent out-crossing events occur at a rate of approximately 1%.
  • Hamlets do not practice self-fertilization, but a pair will mate multiple times over several nights, taking turns between which one acts as the male and which acts as the female.
  • The mangrove killifish (Kryptolebias marmoratus) are simultaneous hermaphrodites, producing both eggs and sperm and routinely reproducing by self-fertilization. Each individual normally fertilizes itself when an egg and sperm produced by an internal organ unite inside the fish's body. This species is also regarded as the only known vertebrate species that can reproduce by self fertilization.

Pseudohermaphroditism

Main article: Pseudohermaphroditism

When spotted hyenas were first scientifically observed by explorers, they were thought to be hermaphrodites. Early observations of wild spotted hyenas led researchers to believe that all spotted hyenas, male or female, were born with what looked to be a penis. A female spotted hyena's apparent penis is in fact an enlarged clitoris, which contains an external birth canal. It can be difficult to determine the sex of spotted hyenas until sexual maturity, when they may become pregnant. When a female spotted hyena gives birth, she passes the cub through the cervix internally, but then passes it out through the elongated clitoris.

Plants

Main articles: Sexual reproduction in plants, Plant reproductive morphology § Bisexual, and Monoicy
Photo of a flower with a large orange centre and delicate yellow stigma protruding. The centre is surrounded by white petals and a halo of green and yellow spikes.
Hylocereus undatus, a hermaphrodite plant with perfect flowers that have both functional carpels and stamens.

The term hermaphrodite is used in botany to describe, for example, a perfect flower that has both staminate (male, pollen-producing) and carpellate (female, ovule-producing) parts. The overwhelming majority of flowering plant species are hermaphroditic.

Monoecy

Flowering plant species with separate, imperfect, male and female flowers on the same individual are called monoecious. Monoecy only occurs in about 7% of flowering plant species. Monoecious plants are often referred to as hermaphroditic because they produce both male and female gametes. However, the individual flowers are not hermaphroditic if they only produce gametes of one sex. 65% of gymnosperm species are dioecious, but conifers are almost all monoecious. Some plants can change their sex throughout their lifetime, a phenomenon called sequential hermaphroditism.

Andromonoecy

In andromonoecious species, the plants produce perfect (hermaphrodite) flowers and separate fertile male flowers that are sterile as female. Andromonoecy occurs in about 4000 species of flowering plants (2% of flowering plants).

Gynomonoecy

In gynomonoecious species, the plants produce hermaphrodite flowers and separate male-sterile pistillate flowers. One example is the meadow saxifrage, Saxifraga granulata. Charles Darwin gave several other examples in his 1877 book "The Different Forms of Flowers on Plants of the Same Species".

About 57% of moss species and 68% of liverworts are unisexual, meaning that their gametophytes produce either male or female gametes, but not both.

Sequential hermaphroditism is common in bryophytes and some vascular plants.

Use regarding humans

Intersex topics
Intersex flag
Human rights and legal issues
Healthcare and biology
Society and culture
History and events
Rights by country
See also
Main articles: Disorders of sex development and Intersex
Hermaphroditus, the "son" of the Greek god Hermes and the goddess Aphrodite, origin of the word "hermaphrodite"
The Obando Fertility Rites in the Philippines, before becoming a Catholic festival, was initially an Anitist ritual dedicated to the hermaphrodite deity, Lakapati, who presided over fertility.
1860 photograph by Nadar of a person displaying ambiguous genitalia, one of a nine-part series. The series may be the earliest medical photographic documentation of an intersex person.

Historically, the term hermaphrodite was used in law to refer to people whose sex was in doubt. The 12th-century Decretum Gratiani states that "Whether an hermaphrodite may witness a testament, depends on which sex prevails" ("Hermafroditus an ad testamentum adhiberi possit, qualitas sexus incalescentis ostendit.").

Alexander ab Alexandro (1461–1523) stated, using the term hermaphrodite, that the people who bore the sexes of both man and woman were regarded by the Athenians and the Romans as monsters, and thrown into the sea at Athens and into the Tiber at Rome. Similarly, the 17th-century English jurist and judge Edward Coke (Lord Coke), wrote in his Institutes of the Lawes of England on laws of succession stating, "Every heire is either a male, a female, or an hermaphrodite, that is both male and female. And an hermaphrodite (which is also called Androgynus) shall be heire, either as male or female, according to that kind of sexe which doth prevaile."

During the Victorian era, medical authors attempted to ascertain whether or not humans could be hermaphrodites, adopting a precise biological definition to the term. From that period until the early 21st century, individuals with ovotesticular syndrome were termed true hermaphrodites if their gonadal tissue contained both testicular and ovarian tissue, and pseudohermaphrodites if their external appearance (phenotype) differed from sex expected from internal gonads. This language has fallen out of favor due to misconceptions and stigma associated with the terms, and also a shift to nomenclature based on genetics.

The term "intersex" described a wide variety of combinations of what are ambiguous biological characteristics. Intersex biology may include, for example, ambiguous-looking external genitalia, karyotypes that include mixed XX and XY chromosome pairs (46XX/46XY, 46XX/47XXY or 45X/XY mosaic). Clinically, medicine currently uses the terminology "disorders of sex development" (also known as variations in sex characteristics.) This is particularly significant because of the relationship between medical terminology and medical intervention.

Intersex civil society organizations, and many human rights institutions, have criticized medical interventions designed to make bodies more typically male or female.

In some cases, variations in sex characteristics are caused by unusual levels of sex hormones, which may be the result of an atypical set of sex chromosomes. One common cause of variations in sex characteristics traits is the crossing over of the testis-determining factor (SRY) from the Y chromosome to the X chromosome during meiosis. The SRY is then activated in only certain areas, causing development of testes in some areas by beginning a series of events starting with the upregulation of the transcription factor (SOX9), and in other areas not being active (causing the growth of ovarian tissues). Thus, testicular and ovarian tissues will both be present in the same individual. Of all total recorded cases of ovotesticular DSD, in only 8% percent of all cases was SRY present, leaving the rest of cases that could be explained to other or less common causes, with the vast majority simply being currently unexplainable.

Fetuses were previously thought to be phenotypically female before the sexual differentiation stage; however, this is now known to be incorrect, as humans are simply undifferentiated before this stage and possess paramesonephric ducts, mesonephric ducts, and a genital tubercle.

Evolution

Main article: Evolution of sexual reproduction For evolution of sexual systems with hermaphodites, see Trioecy § Evolution of trioecy, Androdioecy § Evolution of androdioecy, and Gynodioecy § Evolution.

The evolution of anisogamy may have contributed to the evolution of simultaneous hermaphroditism and sequential hermaphroditism, it remains unclear if the evolution of anisogamy first led to hermaphroditism or gonochorism.

A 2023 study argued that hermaphroditism can evolve directly from mating types under certain circumstances, such as if the fertilization is well organized and the average size of groups is small. Simultaneous hermaphroditism that exclusively reproduces through self-fertilization has evolved many times in plants and animals, but it might not last long evolutionarily.

In animals

Joan Roughgarden and Priya Iyer argued that the last common ancestor for animals was hermaphroditic and that transitions from hermaphroditism to gonochorism were more numerous than the reverse. Other scientists have criticized this argument; saying it’s based on paraphyletic Spiralia, assignments of sexual modes for the phylum level than the species level, and methods exclusively based on maximum parsimony.

Hermaphroditism is polyphyletic in invertebrates where it evolved from gonochorism and gonochorism is also ancestral to hermaphroditic fishes. According to Nelson Çabej simultaneous hermaphroditism in animals most likely evolved due to a limited number of mating partners.

In plants

See also: Monoecy § Evolution, Andromonoecy § Evolution, and Gynomonoecy § Evolution

It is widely accepted that the first vascular plants were outcrossing hermaphrodites. In flowering plants, hermaphroditism is ancestral to dioecy.

Hermaphroditism in plants may promote self fertilization in pioneer populations. However, plants have evolved multiple different mechanisms to avoid self-fertilization in hermaphrodites, including sequential hermaphroditism, molecular recognition systems and mechanical or morphological mechanisms such as heterostyly.

See also

References

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