2386 WORDS

The origins of human sexuality and homosexuality in particular have puzzled
philosophers, theologians and ordinary people for thousands of years. In scatter
cultures, homosexuals have been regarded as a normal part of life, however, same
sex attraction to most cultures have been treated as an unforgivable sin or a
terrible crime. Many psychologists and psychiatrist had attempted to "treat
and counsel" the homosexuals. In our social norm, male attracts to female and
female attracts to male. To everyone this is a natural and biological urge.

However, there is a significant minority who attracts to their own sex. It’s
about five percent of the population in the world. There are many opposing
viewpoints of whether it derives from variation in our genes or our physiology,
from the intricacies of our personal history or from convergence of these? Is it
for that matter a choice rather than a compulsion? Chances are no one factor or
study can alone explicate and clarify the human sexual orientation. However,
there are evidences that prove being gay is not a choice. The nature of
homosexuality primarily comes from one’s biological sexual orientation and the
environment is just a source to bring forth or repress the behavior Many
researchers and scientists have long search for the distinguishable brain
structures, the biochemistry in the human brains to differentiate the
differences to classify between the two obvious sexes we now have in our
society, male and female. Such sex differentiation of the brain’s structure is
called sexual dimorphism. . (LeVay/ Hamer 22) The first significant observation
of sexual dimorphism performed in an animal laboratory. Roger A. Gorski, a
professor at University of California, Los Angeles, conducted an experiment on
rats. In 1978, Gorski examined the rat’s hypothalamus, a region at the base of
its brain that is involved in instinctive behaviors and regulation of
metabolism. He discovered there is a group on front of the hypothalamus is
several times larger in millimeter of the male rats compared to the female rats.

The cell group is very small but it could be easily observed on a stained slice
when being viewed under a microscope. More interestingly, Gorski’s finding
applied to the sexual orientation between males and females. That particular
group of cell is known as the medial preoptic are has been involved in the
sexual behaviors typically displayed in males. For instance, if there is a male
rat has a injury medial preoptic area, he apparently couldn’t indifferent to
sex with another female. From the study of Gorski and his co-workers, we now
know the androgen is the typical male hormone and the estrogen is the female
hormone played a major role in bring about dimorphism during the fetus
development. (LeVay/Hamer 23) Another finding also involved with Gorski and his
colleagues at U.C.L.A, especially with his student, Dr. Laura S. Allen. They
also found the dimorphic structure in the human brain. A cell group named INAH3,
shorten for the third interstitial nucleus of the anterior hypothalamus, in the
medial preoptic region of the hypothalamus is about three times larger in men
that in women. (LeVay/Hamer 23) Animal studies make available a good deal of
evidence for biological basis of disease, but in this case, sexual orientation.

Through a careful exploitation of hormone level on rats, Gorski as been able to
produce male rodents that demonstrate feminine behavior and injected into the
female fetus that develop with the male fetus and it appear to be masculine
because of the male testosterone. They also look and act more like males. In
addition, they are less attractive to male mice (Gorman 60) Related to Gorski
and Allen’s study, Simon LeVay, a British biologist and neurologist at San

Diego Salk Institute, who is also gay, performed another study for Biological

Studies, in 1990. LeVay decided to check whether INAH3 or some other cell group
in the medial preoptic area varies in size with sexual orientation as well as
with sex. LeVay conducted an experiment on the hypothalamus in autopsy specimens
from nineteen homosexual men, all of whom died of AIDS and sixteen heterosexual
men, six of whom had also died of complication of AIDS. After encoding the
specimens to eliminate all the bias that could skew the outcome. LeVay carefully
sliced the hypothalamus into serial slices. He measured their cross-sectional
areas and their thickness under a microscope. LeVay has concluded the sexually
dimorphic nucleus INAH3 were significantly larger than of female and smaller in
male homosexuals than in straight men and similar in size to the nucleus of
female. In some gay men, this group

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