Sex Differences in the Brain

[stephaniec]

Sex Differences in the Brain

http://www.the-scientist.com/?articles.view/articleNo/44096/title/Sex-Differences-in-the-Brain/

The Scientist/By Margaret M. McCarthy | October 1, 2015

""We have raised our children in a gender-neutral household since the day they were born, and we never allowed any sort of weapons, not even a water pistol," a young mother told me emphatically from the microphone in the lecture hall where I'd just given a talk on the differences between male and female brains. "But the other day my seven-year-old son bit his peanut butter and jelly sandwich into the shape of a gun and started shooting his little sister with it!" The audience laughed appreciatively; everyone had a similar story. "What did we do wrong?" she pleaded."

[Dee Marshall]

Sweetie's cousin tried that "no toy guns" policy, so her boys became Lego gunsmiths. Unfortunately, I'm not sure you can attribute that particular behavior to brain differences so much as to outside influences and gender roles.

The article differentiates between assigned sex, brain sex which seems to be more what we as transgender people see as gender and gender which as described by the article seems more like gender roles. I guess it just goes to show that even experts can be confused when their research impinges on another discipline. It does point out well that sometimes "separate but equal" really can be equal and not even gender is black and white.

But we knew that.

[HughE]

You have to be quite wary of extrapolating research into brain masculinization in mice and other rodents to human beings, because brain masculinization in rodents is mainly driven through estrogen receptors, whereas in primates it's driven through androgen receptors, and estrogen receptors don't appear to play any significant role. Hence the stuff about PGE2 might not apply to human beings. Otherwise, it's quite a good article though.

[Samantha-Marie]

Firearms are not gender role signifiers. It's absurd to make that inference. Most of the cis Females locally own firearms, hunt, wear cammo, drive trucks, ride ATVs. Redneck hillbilly working-class has no particular gender boundary when it comes to guns.

[DarkEmber]

Without reading the article, but to add an interesting fact to the idea of brain gender, did you know that not too long ago, scientists, through the careful application of hormones, were able to completely switch the cellular gender of neurons in a rat's brain, which led to instant behaviour as the opposite gender? What's even more amazing is they were also able to revert the cellular gender back to the original one. Pretty scary stuff

[Laura_7]

Without reading the article, but to add an interesting fact to the idea of brain gender, did you know that not too long ago, scientists, through the careful application of hormones, were able to completely switch the cellular gender of neurons in a rat's brain, which led to instant behaviour as the opposite gender? What's even more amazing is they were also able to revert the cellular gender back to the original one. Pretty scary stuff

Well it cannot be directly compared because their brain structure is different.
Things that work for them do not work for mammals.

[Cindy]

Without reading the article, but to add an interesting fact to the idea of brain gender, did you know that not too long ago, scientists, through the careful application of hormones, were able to completely switch the cellular gender of neurons in a rat's brain, which led to instant behaviour as the opposite gender? What's even more amazing is they were also able to revert the cellular gender back to the original one. Pretty scary stuff

Well it cannot be directly compared because their brain structure is different.
Things that work for them do not work for mammals.

Ahhh when I did my Zoology degree, rodents were mammals!

[Kellam]

Firearms are not gender role signifiers. It's absurd to make that inference. Most of the cis Females locally own firearms, hunt, wear cammo, drive trucks, ride ATVs. Redneck hillbilly working-class has no particular gender boundary when it comes to guns.

Speaking from my personal experience you are absolutely right. My younger brother and I weren't allowed toys that had anything to do with violence. Toy guns were a no no. My father had been an antique gun seller though and still had two pieces left by the time my brother and I were in schools. I always initiated the seeking out of these guns for play. It was I who loaded and fired the one that had bullets in our basement. My brother showed no interest without my leading the way. I also got my rifel shooting merit badge in Scouts. My brother did not care. He is happily very cis and very male.

Just sayin' in my case...

[Rejennyrated]

Nothing about this is new or in any way dubious... Gooren Et Al demonstrated these effect in the human brain a long time ago (like thirty years!) Since then my own colleague Dr Dakin has replicated and extended many of these results, as have Dr Vincent Harley in Australia, who has gone some way toward explaining how they apply to the trans community and has postulated a possible Aetiology, along with several others.

It is well on the way to being well proven science and I see no reason to doubt it just because its inconvenient to the arguments of certain groups with an agenda of their own which may or may not be helpful to us.

[Laura_7]

Well it cannot be directly compared because their brain structure is different.
Things that work for them do not work for mammals.


Ahhh when I did my Zoology degree, rodents were mammals!

Yes... a bit clumsy expressed...
there seem to be differences in their neuronal responses which make results not directly comparable.
There were a few results where other species reacted differently, especially concerning action of hormones.

[iKate]

Firearms are not gender role signifiers. It's absurd to make that inference. Most of the cis Females locally own firearms, hunt, wear cammo, drive trucks, ride ATVs. Redneck hillbilly working-class has no particular gender boundary when it comes to guns.

You had me up to redneck hillbilly. I know plenty of urban pistol packin women too. I shoot with some of them, in fact. Shooting is fun, for starters. Women are also getting guns for self defense.

[ActionLiz]

You had me up to redneck hillbilly. I know plenty of urban pistol packin women too. I shoot with some of them, in fact. Shooting is fun, for starters. Women are also getting guns for self defense.

Yep.  Another gun-toting lady here.   I've been a firearms enthusiast for years and am hoping to get involved in our local ladies' shooting scene post-transition.  New Hampshire has a great gun culture populated by friendly, tolerant folks.

[Deborah]

I have a closet full of guns including the "evil" assault ones that I used to shoot a lot but I haven't touched any of them for several years.  But shooting is one of those things once learned and never forgotten so if I ever have the need I am a very accurate shot.


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[HughE]

Without reading the article, but to add an interesting fact to the idea of brain gender, did you know that not too long ago, scientists, through the careful application of hormones, were able to completely switch the cellular gender of neurons in a rat's brain, which led to instant behaviour as the opposite gender? What's even more amazing is they were also able to revert the cellular gender back to the original one. Pretty scary stuff

It's true that exposure to external hormones at the appropriate stage of development can induce opposite-sexed brain development, however this can only happen if the exposure occurs during the critical period when your prenatal development is taking place, and it's not a reversible process. This isn't a recent discovery, it was first demonstrated in experiments carried out in the late 1950s.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146061/

During the 1950s, Phoenix, Goy, and Gerall working in W.C. Young's lab at the University of Kansas administered testosterone, a testicular androgen, to pregnant guinea pigs. The dam's female offspring had ovaries and masculinized genitalia and thus were called hermaphrodites (Phoenix et al., 1959). In adulthood, the prenatally testosterone-treated females behaved more like males and less like control females. They were said to have "masculinized" behavior because they showed more male-like mounting behaviors in response to testosterone, and they showed less lordosis behavior in response to the ovarian hormones estradiol and progesterone...In their paper, Young and colleagues (Phoenix et al., 1959) also presented evidence that this effect of testosterone was both specific to the prenatal period and permanent.

In other words, exposure to external hormones during prenatal development can be a cause of intersex, and it can also induce cross-sexed brain development. This is something that's been known for a long time, and I think the only reason it's a "mystery" as far as the public are concerned, is because doctors and the pharmaceutical industry either didn't take note of the research or chose to ignore it, and went ahead and administered hormones with gender bending properties to millions of pregnant women. By the time they realised their mistake, several million people had already been exposed to these hormones for part of their prenatal development, and have ended up intersexed (or more commonly with opposite-sexed brain development) as a result. Rather than own up to what happened,  the US regulatory authorities, the pharmaceutical industry and the medical establishment have all closed ranks to keep the public in the dark about it. That's what I think has happened anyway. It's an undeniable fact that high doses of hormones that have subsequently been shown to induce cross sexed development in animals, were used in several million human pregnancies.

While all the hormones with the worst gender bending properties (DES, ethinyl estradiol and first generation progestins) had largely been withdrawn from use by about 1980, I think there must be some remaining in use that don't affect genital development too badly, but can nonetheless still induce cross sexed brain development, and that's why the number of younger people being born trans has continued to increase.