Well I dont have any studies I know of off the top of my head. But I do think there is a more fundamental problem with gender differential studies. Namely how do we know what differences are caused by genetics and what differences are caused by socialization. For this reason measuring differences in any group of people outside of infants is highly problematic.

I've never read any but I don't generally go around reading studies in any case so that should show you what my answer is worth. Why not just ask him? If he point some out to you, you can seek them out and read them in order to access them for yourself. The studies he refers to probably do exist but the important question to ask is if they are reliable studies. Looking at the methodology behind them is important.

Your friend refers to a period at birth before the baby is exposed to a sexist society. Does this period of time truly exist or is the baby exposed to a sexist society as soon as the baby is born? Another question is whether the baby has exposure to a sexist society in utero? Does society behave differently towards mothers who it knows are carrying one gender or another?

The most recent (not the current one on display, I think) issue of Scientific American Mind included a reprint of an article about the differences between men and women's brains. The article talks about several studies involving adult humans, particularly the size/neuron density of various parts of the brain; and a bunch of studies on the behavior of animals. The article was focused on studies that deal with DIFFERENCES between how women and men process emotions, looking towards possible targeted treatments for PTSD, schizophrenia, etc., so obviously the studies mentioned in the article were strongly tilted towards the ones that showed strong differences. Still, here are some of the conclusions and a couple of critiques:

In the studies of ADULT humans, one of the things researchers look at is the size and neuron density in various parts of the brain *relative* to the size of the rest of the brain. In general, they find that women often have larger/thicker frontal cortexes and limbic cortexes, which are two areas of the brain often associated with higher-processed emotional responses and morality. On the other hand, men on average have a larger/thicker parietal cortex, which is associated with space perception, and a larger amygdala, which is the part of the brain that responds to more 'primal' emotions (e.g. fear). HOWEVER. These conclusions are from studies that look at *adults*, and differences in brain structure size are typically thought to reflect their relative importance to the human. So it is reasonable to think that at least *some* degree of the difference (I don't know how big it was in the first place, sorry) is due to societal conditioning/expectations rather than natural biology. I don't know of any studies that have been done on infants but would love to hear about it if anyone else knows.

As far as studies on animals goes, there is the famous "toy experiment" in which young female and male monkeys are exposed to toys that, in the human sphere, are typically considered "female" (mainly, dolls), "male" (trucks, balls, etc), and "gender neutral" (picture books). One study showed that the female monkeys gravitated towards the "female" toys and the male monkeys towards the male toys. In a different study, however, researchers actually observed the male monkeys sticking with the "male" toys while the female monkeys played with all of them equally. The hypotheses drawn from the first study were that males tend to look for toys that will help them hone behaviors for hunting (chasing after balls and such) and securing a mate; females are more prone to look towards toys that will help them develop skills they will eventually use as mothers. So I suppose that unless your friend is really enthusiastic about running after wild game and slaying it with his bare hands...

What I thought was one of the most interesting studies mentioned was one that looked at stress responses in rats. Male rats tended to perform better (learn tasks more quickly) than female rats under situations of acute, non-prolonged stress. However, over time female rats dealt better with chronic stress.

There were more, but now I feel like I'm rambling. I've got a good chunk of neuroscience websites bookmarked; I'll check and see if there is anything more recent than the studies mentioned in the Sci Am article.

It's been a while so I don't remember any off the top of my head, but I have encountered studies discussing the difference in learning styles between girls and boys. I think this is a perfectly legitimate area of scientific research.

The thing people tend to forget, is that any research on human behavior is going to be dealing with averages.

The average girl might be more inclined towards learning style A, while the average boy may be more inclined towards learning style B. However, this important detail is often omitted when people use the argument "girls learn better with teaching style A, and boys learn better with teaching style B," in support for gender segregated schools.

These arguments obscure the fact that there is a ton of overlap, and that the differences within genders are much greater than the differences between them.

As long as we live in a sexist society, people will continue misrepresenting science to justify their sexist goals.

Why So Slow?: Notes on the Progress of Woman by Victoria Valian is a great resource. It is older, but she references some impressives studies of how gender is imposed on children from the moment of birth, literally. She speaks of one study where parents told a new baby was a boy, judged it to be bigger, stronger and firmer than a baby they were told was a girl. Valian is a social psychologist I think her book is brillent.

Joan

Why So Slow?: Notes on the Progress of Women by Victoria Valian is a great book; in it, she talks about how gender is imposed on very young children, starting at birth. She talks about one study that showed parents judging infants they were told were male as bigger, stronger and firmer than infants they were told were female- even when their was no diffrence in weight or size. It is great book.

Joan

One of the issues with any studies on neural differences between genders as adults is the principle of brain plasticity. What we think and what we do actually changes the structure of our brains. I don't have the studies at hand on that, but I remember being fascinated by the idea, which is by now pretty well-accepted as fact. So if you're studying the brain of an adult woman and an adult man and they appear neurologically different...that *may* be inherent, and that *may* be a result of living a lifetime of sexism.

I am way out of my area in this. I'm a sociologist, not a neuroscientist. But you could look up an article called "Biological Limits of Gender Construction" (which said female and male brains ARE different) and then look up all of the rebuttals written to it.

To me, I have no idea how you could even begin to measure brain and genetic differences from birth.

I'm no expert, merely shooting from the hip, but, would like to add this...yes, in general terms there are differences in mle and female brains, BUT, nature (human or otherwise) is very adept at adapting to the surrounding environment.

An extreme example of this would be to state that the strengths and skills that we use today are very diffent to those when humans were hunter gatherers.

For this reason, I believe that to fully understand neuro-genetic differences would mean the impossible task of studying the brains of humans through the centuries.

Also, as humans (and therefore human brains) adapt through life experience, it would be interesting to see studies broken down by different groupings, such as race, class, sub-culture and so on. The only problematic part of this being that it could give an open door those with prejudices.

Good question, fgbm. I'll have to get a copy of Why So Slow?: Notes on the Progress of Women by Victoria Valian, so thanks for the reference Joan, it looks intriguing.

I am no expert either, and I don't know of any studies off the top of my head. But something very important you need to establish with your friend before citing any studies or discussing any biological differences between men and women, is that GENDER and SEX are two different things. Sex is purely biological, while gender is a social construction. Gender is a term denoting which social group an individual is placed in at birth by society, and the social construction of gender is the defining, valuing, and channeling of individuals into their respective roles in society.

This may help frame your discussion better. There are several articles and books devoted to analyzing the social construction of gender that you can easily find through Google or Amazon or your local library if you need credible sources.