Hermaphrodite

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For other uses, see Hermaphrodite (disambiguation).
Mating Helix aspersa (garden snails).

In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.[1]

Many taxonomic groups of animals (mostly invertebrates) do not have separate sexes.[2] In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both partners can act as the "female" or "male". For example, the great majority of pulmonate snails, opisthobranch snails and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites.

Historically, the term hermaphrodite has also been used to describe ambiguous genitalia and gonadal mosaicism in individuals of gonochoristic species, especially human beings. The word intersex has come into preferred usage for humans, since the word hermaphrodite is considered to be misleading and stigmatizing,[3] as well as "scientifically specious and clinically problematic".[4]

Etymology[edit]

The term derives from the Latin: hermaphroditus, from Ancient Greek: ἑρμαφρόδιτος hermaphroditos,[5] which derives from Hermaphroditos ( 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 both sexes;[6] according to the earlier Diodorus Siculus, he was born with a physical body combining both sexes.[7] The word hermaphrodite entered the English lexicon in the late fourteenth century.[8]

Zoology[edit]

Sequential hermaphrodites[edit]

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 is born as one sex, but can later change into the opposite sex.[9] This contrasts simultaneous hermaphrodites, in which an individual may possess fully functional male and female gonads. Sequential hermaphroditism is common in fish (particularly teleost fish) and some jellyfish, many gastropods (such as the common slipper shell), and some flowering plants. While some sequential hermaphrodites can change sex multiple times, most can only change sex once.[citation needed] Sequential hermaphroditism can best be understood in terms of behavioral ecology and evolutionary life history theory, as described in the size-advantage mode[10] first proposed by Michael T. Ghiselin[11] 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:

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[edit]

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.

A simultaneous (or synchronous) hermaphrodite (or homogamous) is an adult organism that has both male and female sexual organs at the same time.[9] Usually, self-fertilization does not occur.

Pseudohermaphroditism[edit]

Main article: Pseudohermaphroditism
A photograph by Nadar of an intersex person displaying genitalia, one of a nine-part series. The series may be the earliest medical photographic documentation of intersexuality.[13]

When spotted hyenas were first discovered by explorers, they were thought to be hermaphrodites. Early observations of spotted hyenas in the wild led researchers to believe that all spotted hyenas, male and female, were born with what appeared to be a penis. The apparent penis in female spotted hyenas is in fact an enlarged clitoris, which contains an external birth canal.[14][15] It can be difficult to determine the sex of wild spotted hyenas until sexual maturity, when they may become pregnant. When a female spotted hyena gives birth, they pass the cub through the cervix internally, but then pass it out through the elongated clitoris.[16]

Humans[edit]

Main article: Intersex

Aside from having an ambiguous-looking external genitalia, true hermaphroditism in humans differs from pseudohermaphroditism in that the person's karyotype has both XX and XY chromosome pairs (47XXY, 46XX/46XY, 46XX/47XXY or 45X/XY mosaic) and having both testicular and ovarian tissue. One possible pathophysiologic explanation of this rare phenomenon is a parthenogenetic division of a haploid ovum into two haploid ova. Upon fertilization of the two ova by two sperm cells (one carrying an X and the other carrying a Y chromosome), the two fertilized ova are then fused together resulting in a person having dual genitalial, gonadal (ovotestes) and genetic sex.

Another common cause of hermaphroditism is the crossing over of the 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 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.[17]

Botany[edit]

Hylocereus undatus, a hermaphrodite plant with both carpels and stamens

Hermaphrodite is used in botany to describe a flower that has both staminate (male, pollen-producing) and carpellate (female, ovule-producing) parts. This condition is seen in many common garden plants. A closer analogy to hermaphroditism in botany is the presence of separate male and female flowers on the same individual—such plants are called monoecious. Monoecy is especially common in conifers, but occurs in only about 7% of angiosperm species.[18]

Other uses of the term[edit]

Main article: Intersex
Hermaphroditus, the son of the Greek god Hermes and the goddess Aphrodite, origin of the word "hermaphrodite".

Hermaphrodite was used to describe any person incompatible with the biological gender binary, but has recently been replaced by intersex in medicine. Humans with typical reproductive organs but atypical clitoris/penis are called pseudohermaphrodites in medical literature. Pseudohermaphroditism also refers to a human possessing both the clitoris and testicles.[19]

People with intersex conditions sometimes choose to live exclusively as one sex or the other, using clothing, social cues, genital surgery, and hormone replacement therapy to blend into the sex they identify with more closely. Some people who are intersex, such as some of those with androgen insensitivity syndrome, outwardly appear completely female or male already, without realizing they are intersex. Other kinds of intersex conditions are identified immediately at birth because those with the condition have a sexual organ larger than a clitoris and smaller than a penis. Intersex is thought by some to be caused by unusual sex hormones; the unusual hormones may be caused by an atypical set of sex chromosomes.

Sigmund Freud (based on work by his associate Wilhelm Fliess) held fetal hermaphroditism to be a fact of the physiological development of humans.[citation needed] He based much of his theory of innate sexuality on that assumption.[citation needed] Similarly, in contemporary times, fetuses before sexual differentiation are sometimes described as female by doctors explaining the process.[20] Neither concept is technically true. Before this stage, humans are simply undifferentiated and possess a Müllerian duct, a Wolffian duct, and a genital tubercle.

See also[edit]

References[edit]

  1. ^ Merriam-Webster Dictionary Retrieved 28 June 2011
  2. ^ "hermaphroditism". Encyclopædia Britannica Online. Retrieved 9 April 2013. 
  3. ^ "Is a person who is intersex a hermaphrodite?". Intersex Society of North America. Retrieved 2 October 2011. 
  4. ^ Herndon, April. "Getting Rid of "Hermaphroditism" Once and For All". Intersex Society of North America. Retrieved 2 October 2011. 
  5. ^ "Definition of hermaphroditus". Numen: The Latin Lexicon. Retrieved 19 July 2013. 
  6. ^ Ovid, Metamorphoses, Book IV: The story of Hermaphroditus and Salmacis.
  7. ^ Diodorus Siculus — Book IV Chapters 1–7
  8. ^ Oxford English Dictionary, 1st edn, s.v. hermaphrodite, n. and adj.; "Online Etymology Dictionary". Retrieved 3 June 2012. 
  9. ^ a b c d e Barrows, Edward M. (2001). Animal behavior desk reference: a dictionary of animal behavior, ecology, and evolution (2nd ed.). Boca Raton, Fla: CRC Press. p. 317. ISBN 0-8493-2005-4. OCLC 299866547. 
  10. ^ Warner, Robert R (June 1988). "Sex change and the size-advantage model". Trends in Ecology and Evolution 3 (6): 133–136. doi:10.1016/0169-5347(88)90176-0. PMID 21227182. 
  11. ^ Ghiselin, Michael T. (1969). "The evolution of hermaphroditism among animals". Quarterly Review of Biology 44 (2): 189–208. doi:10.1086/406066. PMID 4901396. 
  12. ^ Rodgers, E.W.; Early, R.L., abd Grober, M.S. (2007). "Social status determines sexual phenotype in the bi-directional sex changing bluebanded goby Lythrypnus dalli". J Fish Biol 70: 1660–1668. 
  13. ^ Schultheiss, Herrmann & Jonas 2006, p. 358.
  14. ^ The Painful Realities of Hyena Sex
  15. ^ Graphic depiction of female hyena's reproductive system
  16. ^ Hermaphrodite Hyenas? – Animal Life by Mary Ellen Schoeman
  17. ^ Margarit, E.; Coll, M. D.; Oliva, R.; Gómez, D.; Soler, A.; Ballesta, F. (2000). "SRY gene transferred to the long arm of the X chromosome in a Y-positive XX true hermaphrodite". American Journal of Medical Genetics 90 (1): 25–28. doi:10.1002/(SICI)1096-8628(20000103)90:1<25::AID-AJMG5>3.0.CO;2-5. PMID 10602113.  edit
  18. ^ Molnar, Sebastian (17 February 2004). "Plant Reproductive Systems". Evolution and the Origins of Life. Geocities.com. Archived from the original on 2009-10-22. Retrieved 12 September 2009. 
  19. ^ Voss, Heinz-Juergen: Sex In The Making – A Biological Account. Online: http://DasEndeDesSex.blogsport.de/images/voss_2011_sex_in_the_making.pdf
  20. ^ Leyner, Mark; Goldberg M.D., Billy (2005). Why Do Men Have Nipples?: Hundreds of Questions You'd Only Ask a Doctor After Your Third Martini. New York: Three Rivers Press. ISBN 1-4000-8231-5. OCLC 57722472. 

Further reading[edit]

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