Gay men have similar brains to straight women, scientists claim

[Gio Takahashi]

http://www.neowin.net/forum/style_emoticons/default/noexpression.gif

http://image.guim.co.uk/sys-images/Guardian/Pix/pictures/2008/06/16/Brai_Scan_460X276.jpg

"Striking similarities between the brains of gay men and straight women have been discovered by neuroscientists, offering fresh evidence that sexual orientation is hardwired into our neural circuitry.

Scans reveal homosexual men and heterosexual women have symmetrical brains, with the right and left hemispheres almost exactly the same size. Conversely, lesbians and straight men have asymmetrical brains, with the right hemisphere significantly larger than the left.

Scientists at the prestigious Stockholm Brain Institute in Sweden also found certain brain circuits linked to emotional responses were the same in gay men and straight women.

The findings, published tomorrow in the US journal Proceedings of the National Academy of Sciences, suggest the biological factors that influence sexual orientation - such as exposure to testosterone in the womb - may also shape the brain's anatomy.

The study, led by the neurobiologist Ivanka Savic, builds on previous research that has identified differences in spatial and verbal abilities related to sex and sexual orientation. Tests have found gay men and straight women fare better at certain language tasks, while heterosexual men and lesbians tend to have better spatial awareness.

Savic and her colleague Per Linstr?m took MRI brain scans of 90 volunteers who were divided into four groups of similar ages according to whether they were male, female, heterosexual or homosexual. The scans showed the right side of the brain in heterosexual men was typically 2% larger than the left. Lesbians showed a similar asymmetry, with the right hand side of the brain 1% larger than the left.

Scans on homosexual men and heterosexual women revealed both sides of the brain were the same size.

The results could explain a University of London study earlier this year that found gay men and straight women share a poor sense of direction compared with heterosexual men, and were more likely to navigate using landmarks alone.

The right hand side of the brain dominates spatial capabilities, so may be slightly more developed in heterosexual men and lesbians. An earlier study by the same team found gay men and straight women outperformed lesbians and straight men at tasks designed to test verbal fluency.

Savic's team has yet to confirm whether the differences in brain shape are responsible for sexual orientation, or are a consequence of it. To find out, they have begun another study to investigate brain symmetry in newborn babies, to see if it can be used to predict their future sexual orientation.

"These differences might be laid down during brain development in the womb, or they could happen after birth, though it could very likely be a combination of the two," said Savic.

In another series of tests, Savic and Lindstr?m used a technique called positron emission tomography (PET) to look at brain wiring in a smaller group of volunteers. They found heterosexual women and gay men shared brain circuitry linking a region called the amygdala, which plays a key role in emotional responses, to other parts of the brain.

The research is part of a larger effort to identify differences between the male and female brain, in the hope they will shed light on why some mental disorders affect men and women differently. For example, major depressive disorders are far more common and persistent in women, while autism is around four times more common in boys than girls.

"There's a well known uneven sex distribution in the number of psychiatric disorders and trying to understand sex differences, and differences in orientation, may give you a hint of the mechanism underlying these diseases," said Savic."

Linky (http://www.guardian.co.uk/science/2008/jun/16/neuroscience.psychology)

[Jack Gradus]

Wow, human behavior related to biology? WHO KNEW?!?

[tjkitsune]

eh. Rather interesting. However, I'm horrible with directions.. Ask Jasmin.. But that doesn't mean I'm gay. Just ask any female that's talked to me. I'm far from it. Heh.

[RonDo]

Alrighty then.

[Bloodcinder]

I am better at verbal skills than driving places. Thank you, scientists, for giving me an excuse for the latter.

[Killer_Man_]

I'm the opposite, I can find my places and drive well but yet suck at verbal skills. xD

[Detrevni]

So wait.. gay men and straight women think alike? WHO KNEW?

OMG NEXT THING YOU KNOW THEY'LL TELL ME THEY BOTH LIKE PENIS

[Bloodcinder]

KM, that correlates with being straight according to this study, so that's not surprising.

[Killer_Man_]

I know, I was just stating the obvious cause I make Zeit have a headache from my posts. :P

And rofl @ Det.

[SpaceProg]

Hm... would explain a lot of things indeed...

[Z]

By the look of the pictures alone, Straight Men and Gay Women look far more similar than the focus of this article (Gay men and Straight Women). I wonder why they went the other way with it.

Savic's team has yet to confirm whether the differences in brain shape are responsible for sexual orientation, or are a consequence of it. To find out, they have begun another study to investigate brain symmetry in newborn babies, to see if it can be used to predict their future sexual orientation.

"These differences might be laid down during brain development in the womb, or they could happen after birth, though it could very likely be a combination of the two," said Savic.

In any case, it'll be interesting if they decide something "triggers" sexual orientation.

[Bloodcinder]

The popular theory about the trigger currently is uterine immune reaction of some kind, since for every older brother a male has from the same mother that male has a 30% increased chance of being gay, whether or not raised around that mother or those brothers.

[Seegtease]

So wait.. gay men and straight women think alike? WHO KNEW?

OMG NEXT THING YOU KNOW THEY'LL TELL ME THEY BOTH LIKE PENIS

Dude. How did you know? That study wasn't even released yet.

[Killer_Man_]

The popular theory about the trigger currently is uterine immune reaction of some kind, since for every older brother a male has from the same mother that male has a 30% increased chance of being gay, whether or not raised around that mother or those brothers.

Wha? Do you have a source?

[Bloodcinder]

A ton of results on Google. (Link) (http://www.google.com/search?q=fraternal+birth+order+effect) There's also a Wikipedia summary with its own references. (Link) (http://en.wikipedia.org/wiki/Fraternal_birth_order_and_sexual_orientation)

Basically, scientists think that women develop some kind of immunity to male fetuses. After having so many male fetuses, something happens which causes future male fetuses to be more gay-wired. Female fetuses are irrelevant. Who the baby is raised by or whether or not the siblings know each other is irrelevant to the effect.

Of course, that doesn't mean it's the only cause. I'm an only son, so there obviously are other environmental and biological triggers. Sexuality is a complex characteristic, and it's naive to think there is only one cause for a given orientation.

[SpaceProg]

I can see why female babies were considered irrelevant. 1. The mother is female, and 2. All babies start out in the womb as female by default anyway.

I wonder how lesbians can be explained?

[Bloodcinder]

The consensus currently is that there is no real parallelism between male and female sexual orientation. But in general scientists understand much less about lesbians than they do about gay men.

[SpaceProg]

>_< START STUDYING WOMEN MORE! WE ARE NOT CARBON COPIES OF MEN. DUH.

[Gio Takahashi]

10% Men has a genetic mutation where 1% of them are incapable of reproducing. in 125,000 years, Men will be extinct.

And there was an article on that. I need to find it.

[deathofcheese]

Basically, scientists think that women develop some kind of immunity to male fetuses. After having so many male fetuses, something happens which causes future male fetuses to be more gay-wired. Female fetuses are irrelevant. Who the baby is raised by or whether or not the siblings know each other is irrelevant to the effect.

Almost sounds related to how alligator/crocodile baby sexes are determined. Don't quote me, but if some eggs are warmer, they become female crocodiles.

...yeah, reading that back now, even I think that sounds like internet idiocy.

[Bloodcinder]

There are some species whose sex is determined in incubation.

[Z]

in 125,000 years, Men will be extinct.

I'll do my part to mate like a Mexican for the safety of our species.

[Seegtease]

>_< START STUDYING WOMEN MORE! WE ARE NOT CARBON COPIES OF MEN. DUH.

Try explaining this to a feminist.

[SpaceProg]

Women are different, not inferior. I don't see what feminism has to do with it, other than maybe getting scientists to study women more often as far as medical conditions and medicines. Anything to do with medicine or psychology.

THE MORE YOU KNOW! *star flies*

[Bloodcinder]

Women are different, not inferior.
HAH

[SpaceProg]

*Gives BC a tight wedgie* If you were a woman, that wouldn't have hurt so much.

[Bloodcinder]

Oh no, my genitalia! NOW MY PENIS-OBSESSED LIFE IS RUINED.

[Seegtease]

Women are different, not inferior. I don't see what feminism has to do with it, other than maybe getting scientists to study women more often as far as medical conditions and medicines. Anything to do with medicine or psychology.

THE MORE YOU KNOW! *star flies*

It was just a tangent point I was making. I never said they were inferior, and certainly don't believe that. But there are plenty of groups out there who would push that any job a male can do, a woman can do just as well, and they have the same needs, which is simply not true. The converse (male being able to do all the same as a woman can) is also false. IE: We are not carbon copies. Not everybody believes that.

[SpaceProg]

Oh I didn't think you were. I thought we were on the same page pretty much, except I didn't know what feminism had to do with doctors studying women more. I would have thought they'd be more apt to want that, considering women have different chemical balances and all. That can make or break whether a drug works or not.

[Bloodcinder]

Guess we know why such a brain difference persists in the population now.
PADOVA, Italy, June 24 (UPI)

Italian scientists say they’ve found the same genetic factors leading to male homosexuality also lead to increased fertility in the homosexuals’ mothers.

The researchers said male homosexuality is associated with a phenomenon called sexually antagonistic selection, in which a genetic factor confers a reproductive advantage.

University of Padova Professors Andrea Camperio Ciani and Giovanni Zanzotto, along with Paolo Cermelli of the University of Torino, said the persistence of gay men in a population isn’t easily explained by Darwin’s theory of evolution, because men who possess genes predisposing them to homosexual behavior are much less likely to reproduce.

Gay men’s lower rate of reproduction would be expected to lead to their eventual disappearance from a population, the researchers said. Empirical studies, however, have revealed steady rates of gay men in populations.

The researchers screened a large set of explanatory models and eliminated those inconsistent with observed data. They concluded that male homosexuality benefits populations by promoting female fecundity. Gay men, therefore, give rise to an increase of the fecundity of the whole population, they said.

The study is reported in the online journal PLoS One.

? 2008 United Press International, Inc. All Rights Reserved.
This just confirms my own scientific view that being gay confers a heterozygous advantage by proxy.

[SpaceProg]

But what about gay WOMEN?! *Splodes*

[Bloodcinder]

Again, it seems to be unrelated.

[deathofcheese]

So, for every gay man, that means there's a woman out there who will have more children than average to make up for it? Does this happen in the gay person's lineage or does it somehow affect people from different family trees?

[Bloodcinder]

They're saying that any given mother of a gay son is more likely than another mother to reproduce. Thus, although the gay son will most likely not reproduce, the mother will produce more children. This may cause the fraternal birth order effect, too.

[Seegtease]

They're saying that any given mother of a gay son is more likely than another mother to reproduce. Thus, although the gay son will most likely not reproduce, the mother will produce more children. This may cause the fraternal birth order effect, too.

Well, unless the gene causes the mother to have more kids than a non-gay son would make, it's not going to make up for it.

After all, the mother may not want more kids. She would have to have twice as many kids because of this gene to compensate, technically.

[Bloodcinder]

You can argue with the study if you want.

[Seegtease]

Didn't say it was false, but the number would have to be pretty great to compensate.

[Bloodcinder]

I didn't say it was true. I just said you can argue with the study, since nobody here is an authority on the matter.

[Bloodcinder]

LONDON, June 30 (UPI)
A study of 3,826 same-gender twin pairs in Sweden found homosexual behavior is largely shaped by genetics and random environmental factors, researchers say.
Researchers at Queen Mary’s School of Biological and Chemical Sciences and Karolinska Institutet in Stockholm, Sweden, say that overall, genetics accounted for around 35 percent of the differences between men in homosexual behavior and other individual-specific environmental factors accounted for around 64 percent.
Individual-specific environmental factors may include biological processes such as different hormone exposure in the womb — not societal attitudes, family or parenting which are shared by twins, the researchers say.
“This study puts cold water on any concerns that we are looking for a single ‘gay gene’ or a single environmental variable which could be used to ’select out’ homosexuality,” study co-author Dr. Qazi Rahman of Queen Mary’s School of Biological and Chemical Sciences said in a statement
The researchers tracked all adult twins ages 20 to 47 in Sweden — 3,826 same-gender twin pairs, who were asked about opposite sex and same sex partners.
For women, genetics explained roughly 18 percent of the variation in same-sex behavior, non-shared environment roughly 64 percent and shared factors, such as family environment, explained 16 percent, the researchers say.
The study, published in Archives of Sexual Behavior, shows that genetic influences are important but modest, and that non-shared environmental factors, such as different hormone exposure in the womb, dominate.
? 2008 United Press International, Inc. All Rights Reserved.
It would have been nice to know all of this stuff back when my distant father and close mother thought they had ruined me.