This one's a Brain link. From the BBC :
Scientists say they have proof that the sex of the brain makes men and women more prone to different diseases.Tell me about it....
Doctors know that women are more likely than men to have depression, anxiety or an eating disorder, while men are at higher risk of Parkinson's disease.
Post-mortem and brain imaging studies show that male and female brains are physically different.
Now scientists say they can to link the two together and suggest future disease cures may be "gender-specific".
The sex of a brain is decided in the mother's womb and depends, among other factors, on hormone levels.
Higher levels of testosterone makes a male brain and oestrogen a female one.
Professor Dick Swaab from The Netherlands Institute for Brain Research in Amsterdam, said the proof for this comes from studies of transsexuals - people who know, often from a very early age, that they are born in the wrong gender body.
"The theory is that the sex difference in the sex organs develops early in pregnancy - in the first few months while in utero - while sexual differentiation of the brain occurs later in the second half of pregnancy and postnatally."
That would mean certain factors could interfere with the sexual differentiation of the sex organs and brain in an independent way because there is a time lapse between the two.
"If that was true you would expect to see female structures in male brains. That is indeed what people have found - a reversed sex difference in the brain of transsexuals."
He said that because men and women's brains are different "we should be looking at diseases as male and female".This would also explain what is an almost universal feature of Male-to-Female transsexuals : Clinical, and often totally debilitating, Depression. Looks like we're set up that way. Plus a lifelong stressor of enormous effect, wrong type brain for the body. How Depressing. :-)
"There is a different sex ratio for neurological and psychiatric diseases.
"In depression, it is very clear that sex hormones are directly interfering with the stress axis in the brain.
"We have shown that sensitive proteins [receptors] for sex hormones are present in the cells that form the stress axis. In women there are more oestrogen receptors and in men more androgen receptors present.
"That results in higher prevalence of depression in women compared to men because the stress axis is more sensitive.
"The oestrogens are directly affecting the production of the stress peptides.
"So for the same amount of stress in the environment, women are more prone to develop depression than men."
So how come Transsexuals exist? I mean, it's a fairly awful thing to have to deal with (trust me on this...). Here's one hypothesis, one I came to independantly, before I read the article.
Imagine our human species from a high, utterly cold, and godlike perspective, watching it only as an animal upon the earth, and consider that which might benefit it. In primates, such as the Bonobo chimpanzee, homosexuality helps to bond both males and females with members of their own troop, reducing inter-group competition and aggression. I suggest that transsexuality serves a useful purpose in the scheme of things as well.Or of course, this could be a way of fooling ourselves. We're different, outsiders, and extremely lonely and marginalised at school. Fitting in neither with male nor female society, finding refuge in books, (lately) computers, exploring alone, and mechanisms of all sorts. Sort of a Geek Redux. This hypothesis may be just be compensation for endemic feelings of Inferiority.
Consider the benefit to the animal human, to possess the capacity to produce the occasional individual that, while perhaps not contributing to the gene pool commonly, instead contributes socially, just like homosexuality does in primates. The value of a human with generally superior intellect and creative abilities, curiosity and drive to match, a brain capable of intersexed functioning - and thus an unusual viewpoint - with the additional benefit of being a reproductive dead end...and thus expendable biologically... cannot be underestimated.
Since we have learned that transsexuality can be caused by - among other things - stress affecting pregnancy, it is tempting to consider that there is survival benefit in transsexuality.
A population of highly stressed and struggling paleolithic humans, perhaps at some great impasse, might well be saved by the cross-hormonally induced birth of transsexual members. A hyper intelligent and creative disposable personage would be the most likely to try new things, even highly dangerous things, things that no ordinary individual would think to try. The tormented transsexual would have less to lose, and be less of a loss to the gene pool if the new idea had fatal results. Ultimately, the transsexual would be very likely to find a solution, a way, that would otherwise be missed.
I suggest that transsexuality is a natural function, a way for human animals to produce a subset of their population effectively suited to discovering new and useful survival options, with minimal loss to the genetic pool overall.
In effect, the transsexual is Nature's Little Wild Card. The disposable enhanced Survival Scout, who tends to be generated in proportion to the overall stress the population endures, and which serves a valuable function in the scheme of basic animal survival. Transsexuals are the Hyper-Homosexuals, the guardian angels of the primate world. They not only function as homosexuals do for social bonding, but go a great step further...finding new ways that no others are constructed to find.
Admittedly, it is a cold and mechanical value, but then I asked the reader to consider it from the Blind Watchmaker's position, the dispassionate and living machinery of Nature.
I submit, that from the position of pure survival, of cold hard reality, that gender dysphoria may well be a useful evolutionary development...a "deliberate" (as though Nature had the faculty of choice!) mistake that can serve a vital function for the survival of the Whole, with no concern whatsoever for the agony of the individual.
There can be found a gentle nobility in being an Evolutionary Angel, an emergency Wild Card. Who know how many catastrophes the paleolithic transsexual may have averted?
Perhaps it is no random thing that all early societies revered the transsexual, and made place for and wonder of them. The closer to the struggle for survival, the more aware of what is valuable and what is not....at least for those who are consistent survivors.
So Why Me? Perhaps it is not just bad luck. I suggest the existence of transsexuality serves a real value to any social species.
If this theory has value, it would help to explain the existence of transsexualism in non-primate species, such as rats, dogs, wolves, and the like.
On the other hand, it is as good an explanation as any as to why many Transsexuals are in IT, Academe, or the military.
I taught Computer Science at ADFA.....
And darnit, objectively there is a ridiculously high proportion of us with high IQs, and creativity likewise (though that's more difficult to measure - I aggregated military planners, systems architects, engineering/construction architects and artists to get the estimate). Lower bound estimate of prevalence is 1:2500, upper bound 1:500.
So the hypothesis is that there are basically 3 genders: Hunters, Gatherers, and a salting of, what, Neuters? Soldiers? Protectors? Brain bugs? Expendables? Mechanicians? Scouts? Shamen? Viziers?
All of the above, I guess.
The proportion of the latter increasing with societal stress.
May I say how thoroughly uncomfortable it is to look at the situation logically, objectively, and rationally, and realise that I was probably born to be expendable? And that a really uncomfortably large part of my personality is hard-wired? And in common with many women, a maternal instinct a mile wide? Some so-called Secondary TS women marry and have kids, even though we're really not wired up for a male role, and are often infertile. Can't be a Mum, but Dad is about as good, and desperately desired.
As I said, I'd come to exactly the same conclusion based on the available evidence, before I was aware of the article's existence.
I suspect Larry Niven had too.