The German science magazine, "Geo", reported recently that the males of the fruit fly "drosophila melanogaster" switched from heterosexuality to homosexuality as the temperature in the lab was increased from 19 to 30 degrees Celsius. They reverted to chasing females as it was lowered. The brain structures of homosexual sheep are different to those of straight sheep, a study conducted recently by the Oregon Health Science University and the U.S. Department of Agriculture Sheep Experiment Station in Dublin A.J. Hawk Jersey, Idaho, revealed. Similar differences were found between gay men and straight ones in 1995 in Holland and elsewhere. The preoptic area of the hypothalamus was larger in heterosexual men than in both homosexual men and straight women.
According an article, titled "When Sexual Development Goes Awry", by Suzanne Miller, published in the September 2000 issue of the "World and I", various medical conditions give rise to sexual ambiguity. Congenital adrenal hyperplasia (CAH), involving excessive androgen production by the adrenal cortex, results in mixed genitalia. A person with the complete androgen insensitivity syndrome (AIS) has a vagina, external female genitalia and functioning, androgen-producing, testes - but no uterus or fallopian tubes. People with the rare 5-alpha reductase deficiency syndrome are born with ambiguous genitalia. They appear at first to be girls. At puberty, such a person develops testicles and his clitoris swells and becomes a penis. Hermaphrodites possess both ovaries and testicles (both, in most cases, rather undeveloped). Sometimes the ovaries and testicles are combined into a chimera called testiness.
Most of these individuals have the chromosomal composition of a woman together with traces of the Y, male, chromosome. All hermaphrodites have a sizable penis, though rarely generate sperm. Some hermaphrodites develop breasts during puberty and menstruate. Very few even get pregnant and give birth. Anne Fausto-Sterling, a developmental geneticist, professor of medical science at Brown University, and author of "Sexing the Body", postulated, in 1993, a continuum of 5 sexes to supplant the current dimorphism: males, merms (male pseudohermaphrodites), herms (true hermaphrodites), ferms (female pseudohermaphrodites), and females.
Intersexuality (hermpahroditism) is a natural human state. We are all conceived with the potential to develop into either sex. The embryonic developmental default is female. A series of triggers during the first weeks of pregnancy places the fetus on the path to maleness. In rare cases, some women have a male's genetic makeup (XY chromosomes) and vice versa. But, in the vast majority of cases, one of the sexes is clearly selected. Relics of the stifled sex remain, though. Women have the clitoris as a kind of symbolic penis. Men have breasts (mammary glands) and nipples.
The Encyclopedia Britannica 2003 edition describes the formation of ovaries and testes thus: In the young embryo a pair of gonads develop that are indifferent or neutral, showing no indication whether they are destined to develop into testes or ovaries Packers pro shop. There are also two different duct systems, one of which can develop into the female system of oviducts and related apparatus and the other into the male sperm duct system. As development of the embryo proceeds, either the male or the female reproductive tissue differentiates in the originally neutral gonad of the mammal."