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Hermaphrodite

A hermaphrodite is an organism that posses both male and female genitalia.^[1] In many species, hermaphroditism is a common part of the life-cycle, particularly in some asexual animals and some plants. Hermaphroditism is sometimes considered sexual reproduction, not asexual reproduction. Generally, hermaphroditism occurs in the invertebrates, although it occurs in a fair number of fish, and to a lesser degree in other vertebrates.

Historically, the term hermaphrodite has also been used to describe ambiguous genitalia and gonadal mosaicism in individuals of unisexual species, especially human beings.

Recently, intersex has been used and preferred by many such individuals, encouraging medical professionals to use the term.^[2] However, others with the condition do not like the connotations and misunderstanding of the word "intersexed" and thus prefer to use hermaphrodite instead.^{[citation needed]}

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1 In humans
- 1.1 Fetal hermaphroditism in humans
2 In animals
3 In plants
4 Etymology
5 See also
6 Notes
7 References
8 Further reading

In humans

Main article: Intersexuality

Hermaphrodite was used to describe any person incompatible with the biological gender binary, but has recently been replaced by intersexual in medicine. Humans with typical reproductive organs but atypical clitoris/penis are called pseudohermaphrodites in medical literature.

Whether hermaphroditism is a disorder or merely an unusual condition is a matter of opinion. In most societies, the common assumption is that all people are, or at least should be, either male or female.^{[citation needed]} This assumption can make life difficult for hermaphrodites.

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 intersexed, such as some of those with Klinefelter's syndrome and androgen insensitivity syndrome, outwardly appear completely female or male already, without realizing they are intersexed. 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. Intersexuality is caused by unusual sex hormones; the unusual hormones may be caused by an atypical set of sex chromosomes.

Fetal hermaphroditism in humans

Sigmund Freud (based on work by his associate Wilhelm Fliess) held fetal hermaphroditism to be a fact of the physiological development of humans. He was so certain of this, in fact, that he based much of his theory of innate sexuality on that assumption. Similarly, in contemporary times, fetuses before sexual differentiation are sometimes described as female by doctors explaining the process.^[3] Neither concept is technically true. Before this stage, humans are simply undifferentiated and possess a Müllerian duct, a Wolffian duct, and a genital tubercle, although all males among placental and marsupial mammals (except mice, and horses) retain the female structure of nipples.

In animals

Sequential hermaphrodites

Sequential hermaphrodites (dichogamy) are organisms born as one sex and then later change into the other sex, and can only function as one sex at one time. A few species in this group can change gender multiple times, but they can only function as one sex at a time. Unlike humans, these animals' DNA does not determine their gender, allowing full functional gender change without modifying the DNA.

Protandry: When the organism starts as a male, and changes gender to a female later in life.
- Example: The Clownfish (Genus Amphiprion) are colorful reef fish found living in symbiosis with 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 naturally prefer to catch the larger fish. The populations are generally changing sex at a smaller size, due to artificial selection.
Protogyny: When the organism starts as a female, and changes gender to a male later in life.
- Example: Wrasses (Family Labridae) are reef fish that are all Protogynous, but have two different life strategies:
1. For some species, they all start out as females, and when they get large enough they will change their gender to males.
2. Other species start out as females or males (initial phase), and either may shift to become a supermale (terminal phase male). The females and the initial phase males have similar colorations. The supermale is larger and usually brightly colored, and there is only one in a given area of the reef. This supermale dominates the other wrasses of the species, and pair spawns (one male, one female) repeatedly. The initial phase males will group spawn, with many males and females participating. When the supermale dies, the largest wrasse in the area, male or female, changes into the new supermale.

The order of sequential hermaphroditism within a species is often driven by resource demands. In a population where resources are scarce and can support limited bearing of young, it is advantageous to have a larger population of males supporting one female. One would expect that a species that typically faces this scenario (such as many clownfish living in a single anemone) would have organisms that start as male, and perhaps one individual per group would have changed to be female at any given time. Where resources are abundant and can support bearing of many young, on the other hand, it is advantageous to have many females mating with a limited number of males, so that more young are produced. One would expect that a species that typically faces this scenario (such as parrotfish that can forage over large distances) would have individuals that start as female, and perhaps one individual per group would have changed to be male at any given time.

Simultaneous hermaphrodites

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

Hamlets, unlike other fish, 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 the course of several nights.

Earthworms are another example of synchronous hermaphrodite. Although they possess ovaries and testes, they have a protective mechanism against self fertilization and can only function as a single sex at one time. Sexual reproduction occurs when two worms meet and exchange gametes, copulating on damp nights during warm seasons. Fertilized eggs are protected by a cocoon, which is buried on or near the surface of the ground.

Banana Slugs are one more synchronous hermaphrodite example. Mating with a partner is most desirable, as the genetic material of the 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's organ will be bitten off (with the slug's radula). If a banana slug has lost its male sexual organ, it can still self-fertilize, making its hermaphroditic quality an invaluable adaptation.

Other interpretations of hermaphroditism

Some female children are born with an enlarged clitoris, often through their mother's exposure to drugs, chemicals, or hormones during the pregnancy. Since the clitoris is the structure that differentiates into the penis in males, its enlargement may be misinterpreted as a penis if the enlargement is significant.

Hyenas have a clitoris that is greatly enlarged, so much so, that they were described as hermaphrodites -- not only by the ancient Greeks, but as recently as among circus animal handlers in the twentieth century -- until scientific information was provided that clarified the misunderstanding.

In plants

Hermaphrodite is used in botany to describe a flower that has both staminate (male, pollen-producing) and carpelate (female, ovule-producing) parts that are self fertile or self pollenizing. Hermaphrodism in plants is more complex than in animals because plants can have hermaphroditic flowers as described, or bisexual flowers with both male and female types developing on the same individual—a closer analogy to animal hermaphrodism. However, this latter condition constitutes monoecy in plants, and is especially common to the conifers, while occurring in only about 7% of angiosperm species (Molnar, 2004).

Etymology

The term "hermaphrodite" derives from Hermaphroditus, the son of Hermes and Aphrodite in Greek mythology, who was fused with a nymph, Salmacis, resulting in one individual possessing physical traits of both genders. Thus Hermaphroditus could be called, using modern terminology, a simultaneous hermaphrodite. The mythological figure of Tiresias, who figures in the Oedipus cycle as well as the Odyssey, could be called a sequential hermaphrodite, having been changed from a man to a woman and back by the gods.

Notes

^ Merriam-Webster Dictionary
^ http://www.isna.org/
^ Leyner, Mark; Billly Goldberg M.D. (2005). Why Do Men Have Nipples?: Hundreds of Questions You'd Only Ask Your Doctor After Your Third Martini.. Three Rivers Press. ISBN 1400082315.

References

Randall, John E.,(2005) Reef and Shore Fishes of the South Pacific, Univ. of Hawaii Press, p346 and 387. ISBN 0-8248-2698-1
SeaWorld/Busch Gardens Animal Information Database, "Fish Reproduction"
Kyu-Rae Kim M.D., et al. True Hermaphroditism and Mixed Gonadal Dysgenesis in Young Children: A Clinicopathologic Study of 10 Cases, Modern Pathology, 2002;15(10):1013
Discovery Health Channel, (2007) "I Am My Own Twin"