The Science of Sexual Orientation Book author: Simon LeVay Reviewed by: His article in Science led the way for numerous studies of sexual orientation as it relates to the biology of humans and nonhuman animals.
Are People Born Gay? There is a popular belief that people are born either gay or straight. Conservatives tend to believe that sexual orientation is actually sexual preference, which is chosen by the individual.
This page represents a review of the scientific literature on the basis for homosexual orientation. Rich Deem Sexual orientation is an abstruse topic with regard to human sexuality. Biologically, human beings, like most mammals, produce two sexes males and females that are encoded genetically by the sex chromosomes X and Y.
From a biological standpoint, males and females are expected to be attracted to each other, ensuring reproduction and subsequent perpetuation of the species. Therefore, same sex attraction SSA is biologically aberrant, since it fails to produce offspring. Since the brain is the seat of emotion and sexual attraction, studies examining SSA and sexual orientation have focused on biological differences in the brains of those who exhibit homosexual behavior vs.
Studies have focused on brain structure, possible hormonal influences, heritability, and genetics. Brain structure Since sexual attraction commences in the brain, scientists initially examined the question of sexual orientation by comparing the anatomy of brains from males and females.
Hypothalamus Studies of the brain indicated that male and female brains were sexually dimorphic in the pre-optic area of the hypothalamus, where males demonstrated a greater than two-fold difference in cell number and size compared to females Swaab and Fliers Since the INAH was involved in sexual dimorphism, Simon LeVay hypothesized that there might be differences in this region in heterosexual vs.
Postmortem examination of the brains of AIDS patients vs. The study has been criticized for its uncertainty of sexual orientation of the subjects, and potential complications caused by the AIDS virus HIV infects the human brainand also by lowered testosterone levels found in AIDS patients.
There was no statistically significant difference between IHAH3 sizes of male heterosexuals vs.
Anterior commissure A study by Allen and Gorski examined the anterior commissure of the brain, finding that females and homosexual males exhibited a larger size than heterosexual males Allen and Gorski However, later studies using more subjects found no such differences Bishop and Wahlsten Sex affects brain structure Scientists originally hypothesized that brain structure affected sexual behavior.
However, studies have shown that sexual experiences themselves can affect brain structure Breedlove So, regardless of the brain differences found between those who practice homosexual vs.
Brain structure conclusions Although early studies found some differences in the brain structure of homosexuals, later, better controlled studies found no such differences. Hormonal influences Sexual differentiation of the fetus occurs within the womb, as a result of hormonal influences on the development process.
These hormones not only affect differentiation of the sex organs, but also affect brain development.
Scientists hypothesized that variation in fetal hormones might affect brain development in such a way as to influence subsequent sexual preferences. However, since it would be unethical to obtain fetal hormone levels too dangerous to the fetusproxies have been used in place of actual hormone levels.
These proxies include differences in skeletal size and shape, including the ratio of the long bones of the arms and legs relative to arm span or stature and the hand bones of adults the ratio of the lengths of various fingers.
However, there are no differences in circulating sex hormones between heterosexual and homosexual men Meyer-Bahlburg Finger length Studies have shown that ratios of digit length are predictors of several hormones, including testosterone an androgenluteinizing hormone and estrogen Manning, et al.
In women, the index finger 2D, second digit is almost the same length as the fourth digit 4D. However, in men, the index finger is usually shorter than the fourth and that this 2D: It was hypothesized that the sex difference in the 2D: A subsequent study showed that the 2D: However, homosexual women displayed significantly smaller 2D:A young male patient developed chronic, severe, and disabling right sided groin pain following resection of his left testicular cancer.
Since there is considerable overlap, ultrasound guided, selective diagnostic nerve blocks were done for ilioinguinal, iliohypogastric, and genitofemoral nerves, to determine the involved nerve territory.
It was revealed that genitofemoral neuralgia was the. 1: Sexual identity is: used to describe sexual orientation. being attracted to both sexes: an inner sense of oneself as a sexual being. one's erotic, romantic, and . The internet has influenced sexual orientation in two ways: it is a common mode of discourse on the subject of sexual orientation and sexual identity, and therefore shapes popular conceptions; and it allows anonymous attainment of sexual partners, as well as facilitates communication and connection between greater numbers of people.
Sexual orientation has been a debated risk factor for adolescent suicidality over the past 20 years. This study examined the link between sexual orientation and suicidality, using data that are nationally representative and that include other critical youth suicide risk factors.
Methods. Schizophrenia is defined as a mental or brain disorder that causes one to suffer symptoms such as delusions, hallucinations, and disorganized speech and behavior. Read about treatment of schizophrenics, types, and testing. Oct 22, · Regardless of sexual orientation or the vows of priestly celibacy or even marital vows, only a small percentage of people seek sexual activity with children and teens, and the vast majority of.