U.K. Study: Sexuality is Set Before Birth
U.K. Study: Sexuality is Set Before Birth
A new U.K.-based study claims to prove that sexual orientation is decided before birth, being "hard-wired" into the human brain along with other key traits.
The report, a combination of work between the University of East London (UEL) and the Institute of Psychiatry, investigates sex differences in the startle response -- the eye-blink reaction to sudden loud noises.
The researchers announced on Friday in a press release that there may be a notable difference between homosexual and heterosexual subjects in terms of their brain circuitry. Since being startled is an involuntary reaction, rather than a product of environmental conditioning, researchers claim it is a strong indication that sexual orientation is determined before birth.
The research involved a technique known as prepulse inhibition (PPI), which measures the strength of response to loud noises.
Results showed clear differences between the groups, with lesbians showing a markedly stronger inhibition (a PPI of 33 percent) compared to straight women (just 13 percent).
Although the difference between heterosexual men and gay men is less extreme, 40 percent vs. 32 percent. respectively, researchers claim the difference is still significant.
"The startle response is pre-conscious and cannot be learned, " UEL's Dr. Qazi Rahman explained. "It is mediated by an ancient region of the brain called the limbic system which also controls sexual behavior."
Dr. Rahman added that the findings could have a large impact on the way sexuality is treated, both culturally and during health programs.
Lesbians' Brains May Act Like Straight Men's
Lesbians' Brains May Act Like Straight Men's
WASHINGTON -- Lesbians' brains react differently to sex hormones than those of heterosexual women. An earlier study of gay men also showed their brain response was different from straight men -- an even stronger difference than has now been found in lesbians.
Lesbians' brains reacted somewhat, though not completely, like those of heterosexual men, a team of Swedish researchers said in Tuesday's edition of Proceedings of the National Academy of Sciences.
A year ago, the same group reported findings for gay men that showed their brain response to hormones was similar to that of heterosexual women. In both cases the findings add weight to the idea that homosexuality has a physical basis and is not learned behavior.
"It shows sexual orientation may very well have a different basis between men and women ... this is not just a mirror image situation," said Sandra Witelson, an expert on brain anatomy and sexual orientation at the Michael G. DeGroote School of Medicine at McMaster University in Hamilton, Ontario.
"The important thing is to be open to the likely situation that there are biological factors that contribute to sexual orientation," added Witelson, who was not part of the research team.
The research team led by Ivanka Savic at the Stockholm Brain Institute had volunteers sniff chemicals derived from male and female sex hormones. These chemicals are thought to be pheromones -- molecules known to trigger responses such as defense and sex in many animals.
Whether humans respond to pheromones has been debated, although in 2000 American researchers reported finding a gene that they believe directs a human pheromone receptor in the nose. The same team reported last year on a comparison of the response of male homosexuals to heterosexual men and women. They found that the brains of gay men reacted more like those of women than of straight men.
The new study shows a similar, but weaker, relationship between the response of lesbians and straight men. Hetero-sexual women found the male and female pheromones about equally pleasant, while straight men and lesbians liked the female pheromone more than the male one. Men and lesbians also found the male hormone more irritating than the female one, while straight women were more likely to be irritated by the female hormone than the male one.
All three groups rated the male hormone more familiar than the female one. Straight women found both hormones about equal in intensity, while lesbians and straight men found the male hormone more intense than the female one. The brains of all three groups were scanned when sniffing male and female hormones and a set of four ordinary odors. Ordinary odors were processed in the brain circuits associated with smell in all the volunteers.
In heterosexual males, the male hormone was processed in the scent area but the female hormone was processed in the hypothalamus, which is related to sexual stimulation. In straight women, the sexual area of the brain responded to the male hormone while the female hormone was perceived by the scent area.
In lesbians, both male and female hormones were processed the same, in the basic odor processing circuits, Savic and her team reported.
Each of the three groups of subjects included 12 healthy, unmedicated, right-handed, and HIV-negative individuals. The research was funded by the Swedish Medical Research Council, Karolinska Institute, and the Wallenberg Foundation.
Birds of a Feather
BIRDS OF A FEATHER
by Christina Cardoze
NOTE: A friend sent me the following e-mail: I can still fondly remember growing up on our farm in Canada and how one day my parents were noticing our two male horses, Cedar and Scout, fondly kissing each other as they were grazing in the pasture outside the front of our home. Mum and Dad called me to the window to share this with me, a young teenager, and there we were watching a very "gay" experience. Both Mum and Dad found it endearing--while I not only found it funny, but, even more so, was fascinated to think that my two male riding companions were "family!" Needless to say, it was very curious, yet beautiful, although I never really saw this in terms of "right or wrong." It was portrayed to me as very pragmatic and normal; it was love at a deeper level than the physical aspect of our three-dimensional persons. Was it Ellen White who said nature is God's second book?
Wendell and Cass, two penguins at New York Aquarium, Coney Island, Brooklyn, NY, live in a soap opera world of seduction and intrigue. Among the 22 male and 10 female African black penguins in the aquarium's exhibit, tales of love, lust and betrayal are the norm. These birds mate for life. But given the disproportionate male-female ratio at the aquarium, some of the females flirt profusely and dump their partners for single males with better nests. Wendell and Cass, however, take no part in these cunning schemes. They have been completely devoted to each other for the last 8 years. In fact, neither one of them has ever been with anyone else, says their keeper, Stephanie Mitchell.
But the partnership of Wendell and Cass adds drama in another way. They're both male. That is to say, they're gay penguins.
This is not unusual. "There are a lot of animals that have same-sex relations; it's just that people don't know about it," Mitchell said. " I mean, Joe Schmoe on the street is not someone who's read all sorts of biology books."
One particular book is helpful in this case. Bruce Bagemihl's Biological Exuberance, published in 1999, documents homosexual behavior in more than 450 animal species. The list includes grizzly bears, gorillas, flamingos, owls, and even several species of salmon.
"The world is, indeed, teeming with homosexual, bisexual and transgender creatures of every stripe and feather." Bagemihl writes in the first page of his book. "From the Southeastern Blueberry Bee of the United States to more than 130 different bird species, world- wide, the birds and the bees, literally, are gay."
In New York, it's the penguins. At the Central Park Zoo, Silo and Roy, two male Chinstrap penguins, have been in an exclusive relationship for four years. Last mating season, they even fostered an egg together.
"They got all excited when we gave them the egg." said Rob Gramzay, senior keeper for the polar birds at the zoo. He took the egg from a young, inexperienced couple that hatched an extra and gave it to Silo and Roy. And they did a really great job of taking care of the chick and feeding it."
Of the 53 penguins in the Central Park Zoo, Silo and Roy are not the only ones that are gay. In 1997, the park had four pairs of homosexual penguins.
In an effort to increase breeding, zookeepers tried to separate them by force. They failed, said Gramzay. Only one of the eight bonded with a female. The rest went back to same-sex relationships, not necessarily with the same partner. Silo and Roy, longtime homosexuals, got together (or pair-bonded, in official penguin lingo) after that failed experiment.
At the New York Aquarium, no one suspected Wendell and Cass were gay when they first bonded. Penguins don't have external sex organs, so visually there's no sure-fire way to tell whether they are male or female. But after time, people began to wonder.
In all the years they had been together, neither Wendell nor Cass had laid an egg. This was unusual because the keepers knew they copulated regularly. They had often seen Wendell submit to Cass, the more dominating of the two, but one day, a keeper saw Wendell on top.
When penguins have sex, the female lies on her belly and the male climbs on top with his feet and puts his rump around her rump. Then their cloacas (sexual organs) meet, and the sperm is transferred into the female. It's called the cloacal kiss.
Wendell and Cass were clearly kissing both ways. So in 1999, the aquarium did a blood test to determine their gender. It proved they were both male.
Today, they are one of the best couples at the aquarium. "Sometimes they lie on the rocks together, " Mitchell said. "They're one of the few couples that like to hang out together outside their nest."
Wendell and Cass have a highly coveted nest. During mating season, several other penguins have tried to steal it. Cass, a fierce fighter, keeps them at bay. (Wendell, on the other hand is "afraid of his own shadow." said Mitchell.)
The appeal of the nest is the location, high up close to the water and the feeding station. Rumors that they keep the neatest nest at the aquarium because they're gay are not true. "These are penguins." said Mitchell. "They poop in their nest. Nobody's got a clean nest."
The statement is often made that homosexuality is "against nature." Though all nature in our world is fallen, the well-documented and scientifically sound data in Biological Exuberance: Animal Homosexuality and Natural Diversity (Bruce Bagemihl, Ph. D., St. Martin’s Press, 1999) gives abundant evidence that homosexual behavior and affection is not uncommon among all created beings.
"The world is, indeed, teeming with homosexual, bisexual, and transgendered creatures of every stripe and feather. . .On every continent, animals of the same sex seek each other out. . .They court each other, using intricate and beautiful mating dances. . .Males caress and kiss each other, showing tenderness and affection toward one another rather than just hostility and aggression. Females form long-lasting pair-bonds—or maybe just meet briefly for sex. . .Animals of the same sex build nests and homes together, and many homosexual pairs raise young without members of the opposite sex. Other animals regularly have partners of both sexes, and some even live in communal groups where sexual activity is common among all members, male and female. Many creatures are "trans-gendered," crossing or combining characteristics of both males and females in their appearance or behavior. Amid this incredible variety of different patterns, one thing is certain: the animal kingdom [as well as birds and fish] is most definitely not just heterosexual.
"Homosexual behavior [has been documented] in more than 450 different kinds of animals worldwide, and is found in every major geographic region and every major animal group. It should come as no surprise, then, that animal homosexuality is not a single, uniform phenomenon. Whether one is discussing the forms it takes, its frequency, or its relationship to heterosexual activity, same-sex behavior in animals exhibits every conceivable variation." pp. 9, 12
What can we deduce from this? For one thing, if we believe that animals act from instinct, it appears obvious that such behavior and attraction is not a conscious choice; can we then extrapolate that same-sex attraction in humans is not a conscious choice either?
Born to be Gay
Born to be Gay
By: Rick Nauert, Ph.D., Senior News Editor
Reviewed by: John M. Grohol, Psy.D. on November 8, 2007
Thursday, Nov. 8 (Psych Central) -- For years scientists have debated if sexual orientation is determined by nature or nurture. New evidence suggests genetics is a significant factor for whether an individual is homosexual or heterosexual.
The findings emanate from a Canadian study of the brains of healthy, right-handed, 18- to 35-year-old homosexual and heterosexual men using structural Magnetic Resonance Imaging (MRI).
The research, conducted by Dr. Sandra Witelson, a neuroscientist at McMaster University was a follow-up of a ten-year-old study that demonstrated there is a higher proportion of left-handers in the homosexual population than in the general population – a result replicated in subsequent studies which is now accepted as fact.
Handedness is a sign of how the brain is organized to represent different aspects of intelligence. Language, for example, is usually on the left - music on the right.
In other research, Witelson and research associate Debra Kigar had found that left-handers have a larger region of the posterior corpus callosum – the thick band of nerve fibres connecting the two hemispheres of the brain – than right-handers.
This raised the hypothesis for the current study – whether the anatomy of the brain of the sub-group of right-handed homosexual men is similar to that of left-handers.
They found that the posterior part of the corpus callosum is larger in homosexual than heterosexual men.
The size of the corpus callosum is largely inherited suggesting a genetic factor in sexual orientation, said Witelson “Our results do not mean that heredity is destiny but they do indicate that environment is not the only player in the field,” she said.
While this is not a litmus test for sexual orientation, Witelson said this finding could prove to be one additional valuable piece of information for physicians and individuals who are trying to determine their sexual orientation. “Sometimes people aren’t sure of their sexual orientation.”
The researchers also undertook a correlational analysis which included size of the corpus callosum, and test scores on language, visual-spatial, and finger dexterity tests. “By using all these variables, we were able to predict sexual orientation in 95 percent of the cases,” she said.
Source: McMaster University
Gay Brains Are Different, Study Says
Gay Brains Are Different, Study Says
by Peter Moore
Gays think like women and lesbians' brains work like heterosexual men's according to a new study by English psychiatrists. In tests, scientists from the Institute of Psychiatry in London found that gay men excelled at mental tasks women generally perform better than men, but were not so good at tasks traditionally seen as "male". Similarly, lesbians did as badly as heterosexual men in a test geared to women.
The researchers conducted a series of neurocognitive tests of spatial skill – the ability to mentally reposition shapes and objects and judge the orientation of lines. They found that gay men performed less well than heterosexual men, but matched the ability of women. But gay men performed better than heterosexuals and as well as women at remembering the locations of objects in an array.
In several language tests, traditionally a female strong point, gay men did as well as heterosexual women. Lesbians, on the other hand, performed the tests as poorly as "straight" men. The findings by Doctors Qazi Rahman and Glenn Wilson are published in the journal Neuropsychology.
The researchers theorize that the results indicate that varying levels of exposure to the male hormone testosterone before birth plays a role in "hard-wiring" the brain.
Rahman said: "The fact that gay men and lesbians show cross-sex shifts in their brain functioning might also be related, partly, to the cross-sex shifts in their presentation of certain mental health problems in gay men, such as higher levels of anxiety disorders, depression and eating disorders usually found in women.
"Unraveling variations among groups of people in brain function is becoming an important area for research in human mental health, and a thorough scientific understanding of the biological and social factors which shape human sexual orientation is necessary so we can begin to tackle the mental health problems that gay men and lesbians may suffer from."
Rahman said that the findings show that homosexuality is a normal biological phenomenon and not the result of biological fault.
Mystery Solved? Why Some Men Are Gay
Mystery Solved? Why Some Men Are Gay
Men may be homosexual because of their mother's genes. Scientists from the University of California at Los Angeles have found that the genetics of mothers who have multiple gay sons act differently than those of other women, reports HealthDay News.
Basically, it works like this: Every woman carries two X chromosomes, even though they only require one of them. So the human body routinely inactivates one of those X chromosomes at random. Normally, what happens is half of the X chromosomes go one way, while the second half go the other way. "It's like flipping a coin," study co-author Sven Bocklandt told HealthDay News. "If you look at a woman in any given (bodily) tissue, you'd expect about half of the cells to inactivate one X, and half would inactivate the other."
In this study of 97 mothers of gay sons and 103 mothers who did not have gay sons, 25 percent of the 44 women who had more than one gay son also processed their X chromosomes differently than normal. "When we looked at women who have gay kids, in those with more than one gay son, we saw a quarter of them inactivate the same X in virtually every cell we checked," Bocklandt explained to HealthDay News. "That's extremely unusual." Only 4 percent of the moms whose sons were not gay inactivated the chromosome in this way, as did 13 percent of the mothers who had just one gay son. Bocklandt said this phenomenon is typically seen only in families with major genetic irregularities. He said the research "confirms that there is a strong genetic basis for sexual orientation, and that for some gay men, genes on the X chromosome are involved."
This isn't the final answer. As Dr. Ionel Sandovici, a genetics researcher at The Babraham Institute in Cambridge, England, pointed out to HealthDay News, most of the mothers of multiple gay sons didn't share the unusual X-chromosome trait. In addition, the study is small. The study findings were published in the journal Human Sexuality.