February 2, 2012

New genetic study of male and female behavior

American scientists develop an interesting model of how genes and hormones influence sex behavior, a model that might also throw light on transgender conditions.

Regular readers of this blog know my skepticism towards reducing human gender behavior to biology alone.

The interaction between cultural factors, personal experiences, the body itself and the genetic variables is just too complex to be reduced to a simple "one gene determine all gender behavior" kind of theory.

Indeed, we now know that not only is the brain "plastic" in that learning changes it; we also know that genes may be switched on and off because of stress and various environmental influences.

On the other hand, the discussion of the transgender conditions taking place on this blog and in other online forums,  as well as my own personal experience, has led me to believe there is some kind of biological core to at least some of these experiences, including my own crossdreaming.

The social pressure to conform to traditional gender stereotypes is extremely strong, so strong in fact, that these transgender traits should have disappeared if they were anchored in personal experiences only.

I can see a clear parallell in homosexuality. I have many homosexual friends who get seriously angry when someone suggest their experience is based on "mother complexes" or teenage seductions. As one gay friend told me: "If that was the case, ten years of therapy would have cured me!"

Then, of course, there is the large number of heterosexual men with similar childhood experiences.

In other words: homosexuality as well as transsexuality are most likely to have a strong biological basis.

That does not mean, of course, that there are no same-sex relationships or no types of cross-gender behavior that are not anchored in these kinds of hormonal or genetic starting points. Humans behavior is amazingly diverse, and I suspect that both sexual orientation and gender behavior are quite flexible.

Simplistic biological models

There has been a tendency among biologist to fall into the trap of social projections.  That is: They take the social stereotypes of their own culture and projects it onto animal behavior.

Their interpretation of animal behavior is then taken as proof of the social stereotypes being based in biology. Nature trumps nurture, and sexism trumps humanism. (See my series on Joan Roughgarden for examples).

These studies are often based on a simplistic reductionism where all "masculine" behavior is understood as the effect of one single factor (for instance a gene or prenatal hormones).

Ray Blanchard's transgender theory is, for instance, reductionistic in the sense that sex identity, gender specific behavior and sexual orientation are chained together. A transwoman can only be feminine if she (or "he" if we use Blanchard's vocabulary) is attracted to men. If she is attracted to women, she is per definition masculine, ungainly and ugly.

The Nirao Shah study

A new study done by Nirao Shah and his group at the University of California, San Franscisco, is interesting in that it brings a new level of complexity to the sexual behavior arena.

According to them sexual behavior in mice (which are much less complex organisms than human beings) cannot be reduced to one single gene. Instead each gene regulates a few components of a behavior without affecting other aspects of male and female behavior.


The idea is that genes may trigger a wide variety of hormone mixes from life in the womb to old age, and that different "mixes" leads to different combinations of "male" and "female" behavior.



In these experiments the researchers are looking at pretty simple behavioral dimensions. Still, even these dimensions add up to an amazing complexity:

Their website reports:

"Scientists have long suspected that sex hormones ultimately influence gene expression in the brain. About six years ago, Shah and his colleagues set out to find such genes by using DNA microarrays, a routine laboratory assay, to analyze sex differences in gene expression in the hypothalamus, a region of the brain known to be involved with hormone sensing.

"They found 16 genes that were expressed differently between males and females in the hypothalamus and showed that such differences were regulated by sex hormones. But in identifying these 16 genes, Shah and his colleagues also discovered they could tease apart classic, male and female hormone-driven behaviors into individual elements—each governed by its own genes." (...)


Breaker switches

Shah & Co compares the sexual behavior of mice to a  main electrical box with many breaker switches. Male and female behaviors in mice are actually made up of many behaviors, like sex drive or an inclination to fight.

Shah and his colleagues were able to turn off genes with drugs and by other means. They found that they could selectively knock out some male behaviors so that males continued to fight and mark territory normally, but altered their mating routine with females. Likewise they could modulate female mouse behaviors to make them maintain active interest in sex but spend less time caring for their young.

In the case of humans you would have to add cultural and social factors to this mix, which would -- of course --  make the number of variables mindbogglingly large. Still, if you do so, you end up with a model that is very close to the slider model presented by Natalie and myself.

In other words: In humans male and female behavior cannot be reduced to one and only one combination of traits and behaviors, and because of this it is also impossible to develop one "ideal" stereotypical model of how a woman or a man (trans or not) ought to be.

Sexual orientation is, for instance, separate from mating behavior (the copulatory instinct) and -- in the case of humans -- from a sex identity.

(I have no idea of knowing whether a mouse has a sex identity.)

It should be possible, though, to identify a core of genetic and/or hormonal triggers that might lead to the development of a transgender condition.

And as several such triggers exist, the idea that a transwoman is "a woman trapped in a man's body" may make sense. But we would also have to accept that there are people out there with a mix that makes it close to impossible for them to identify with one gender only.

For more on Shah, see my post On hormones, gender, mice and men.

The article, "Modular genetic control of sexually dimorphic behaviors" by Xiaohong Xu, Jennifer K. Coats, Cindy F. Yang, Amy Wang, Osama M. Ahmed, Maricruz Alvarado, Tetsuro Izumi, and Nirao M. Shah appears in the February 3, 2012 issue of the journal Cell.

Abstract:

"Sex hormones such as estrogen and testosterone are essential for sexually dimorphic behaviors in vertebrates. However, the hormone-activated molecular mechanisms that control the development and function of the underlying neural circuits remain poorly defined. 

"We have identified numerous sexually dimorphic gene expression patterns in the adult mouse hypothalamus and amygdala. We find that adult sex hormones regulate these expression patterns in a sex-specific, regionally restricted manner, suggesting that these genes regulate sex typical behaviors. 

"Indeed, we find that mice with targeted disruptions of each of four of these genes (Brs3, Cckar, Irs4, Sytl4) exhibit extremely specific deficits in sex specific behaviors, with single genes controlling the pattern or extent of male sexual behavior, male aggression, maternal behavior, or female sexual behavior. Taken together, our findings demonstrate that various components of sexually dimorphic behaviors are governed by separable genetic programs."

5 comments:

Iris said...

Just as a note, this is the sort of thing I was talking about regarding hormones and regulation of sex and gender. It's NOT simple, and if one goes deeper into developmental biology/regulatory biology, it's really a sort of elegant complexity - I think anyone interested in sexual dimorphism and the onset of sex/gender differences would do well to pick up a developmental biology textbook and gain a grasp of basic molecular developmental biology. From what I read, this study doesn't really demonstrates anything groundbreaking, but just reinforces ideas already reasonably established in the scientific community. That's pretty much why psychology without biology never really proves much, for me, and why I really dislike the misconception that genetics functions exactly like an on-off switch for every trait - there's a huge network of signaling, regulation, and so forth behind every observable trait. There is no single gene in control of sex - there isn't even a single chromosome composed of countless genes which controls gender/sex by itself - not even the famous X and Y.

But that's also why I don't feel it's wrong to call certain things "abnormal". Overexpressions/underexpressions or other regulatory abnormalities can easily cause some abnormalities in gender/sex roles, but that doesn't erase the fact that they are atypical. To an extent, it's almost as though people take "abnormal" to be negative, when it really just means, at a biological level, that something is contrary to the norm, and doesn't make it any less or more nature... To me, it just demonstrates the plasticity and tolerance of the human condition as it is now, that such a diversity is allowed for.

Jack Molay said...

@Iris,

I agree: We need to combine an understanding of biology with and understanding of culture. Unfortunately the way our university departments are organized makes it hard to find scientists that are able to bridge that gap.

As for rare conditions being "abnormal". Well, language is stigmatizing. English is not my first language, but i sense some seriously negative connotation to the word "abnormal". This is why I would prefer words like "atypical" or "rare" to describe the outliers of the natural diversity of nature.

That being said, I am pretty convinced crossdreamer and transgender conditions are much more common than people believe. Due to stigmatization most crossdreamers make sure not to tell other people about it.

Anonymous said...

"Unfortunately the way our university departments are organized makes it hard to find scientists that are able to bridge that gap."

There is a distant hope with slowing growing scientific semiotic community.

"I am pretty convinced crossdreamer and transgender conditions are much more common than people believe."

I again feel it (again) necessary to emphasize a viewpoint I am pretty certain of. That crossdreaming, a constructed arousing notion centred around ones self identity, often has a massive influence on ones habits and general feeling of self identity if they are open to it.

Just a thought... My time being a part of the crossdreaming community has made me ever more feel incredulity in regards to self-identity.

-wxhluyp

Iris said...

@Jack

I agree: We need to combine an understanding of biology with and understanding of culture. Unfortunately the way our university departments are organized makes it hard to find scientists that are able to bridge that gap.

You are right about that. The majority of biosciences are fully detached from psychology. Neuroscience and endocrinology, both most relevant to the case of psychological issues, are almost solely focused on disease (and at least IMO, rightfully so - crossdreaming can't really be compared to, say ADSL deficiency in terms of quality of life or life expectancy). I'm always surprised, meanwhile, that psychology requires so little in the way of biology, given how much the two are related...

As for rare conditions being "abnormal". Well, language is stigmatizing. English is not my first language, but i sense some seriously negative connotation to the word "abnormal". This is why I would prefer words like "atypical" or "rare" to describe the outliers of the natural diversity of nature.
It might be that I'm too used to those terms, then, since I've never attached a negative connotation to them in my own mind - I think it's because clinically/scientifically, "abnormality" means exactly what it says - not normal.

That being said, I am pretty convinced crossdreamer and transgender conditions are much more common than people believe. Due to stigmatization most crossdreamers make sure not to tell other people about it.
To be honest, I don't think that the average person is even much aware of its existence, so I'm not sure that's saying much... On a side note, I do think that sometimes, people who are simply "effete" or "boyish" end up labeling themselves crossdreamers/transgendered these days, as though being effete as a male or being boyish as a female is unnatural. It's a strange dichotomy that I have to admit, I don't quite understand - it seems almost like sometimes, people among the transgender/crossdreamer communities have more clearly defined gender boundaries for certain psychological/sociological traits than society generally does... That is, taking for truth that submissiveness and nurture and being lusted after is inherently feminine in nature, or that dominance and chasing after lust is the dominion of men, when it seems as though they would be the ones to argue that the most.

It's certainly been interesting following along the conversations and insights thus far, even though my ability to understand these topics is limited by not being a crossdreamer/transgendered person myself.

Jack Molay said...

@Iris

"t seems almost like sometimes, people among the transgender/crossdreamer communities have more clearly defined gender boundaries for certain psychological/sociological traits than society generally does."

This is a very good point. The sciences stive hard to find exact definitions of masculine and feminine. Natural language, however, is immensely flexible when it comes to defining who is a man and who is a woman.

The problem for transgender people, and in particular transsexual people, is that they stretch natural language beyond the breaking point. Because of this they have to struggle hard to define a new type of identity.

If this is not possible, they try to adhere to the gender stereotypes of the day, and at that point the flixbility of normal language is of no use.

When "normal" people are forced to define what it is to be a man or a woman, the flexibility is lost.

Instead you end up with narratives like "Men are from Mars, and Women are from Venus."

Many transwomen therefore try hard to become the stereotypical woman (handbag and effeminate mannerisms included) to avoid bein ostracized.

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