Different, but why?
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Sex differences in the brain are sexy. As MRI scanning grows ever more sophisticated, neuroscientists keep refining their search for male-female brain differences that will answer the age-old question, “Why can’t a woman think like a man?” (and vice-versa).
Social cognition is one realm in which the search for brain sex differences should be especially fruitful. Females of all ages outperform males on tests requiring the recognition of emotion or relationships among other people. Sex differences in empathy emerge in infancy and persist throughout development, though the gap between adult women and men is larger than between girls and boys. The early appearance of any sex difference suggests it is innately programmed—selected for through evolution and fixed into our behavioral development through either prenatal hormone exposure or early gene expression differences. On the other hand, sex differences that grow larger through childhood are likely shaped by social learning, a consequence of the very different lifestyle, culture and training that boys and girls experience in every human society.
At first glance, studies of the brain seem to offer a way out of this age-old nature/nurture dilemma. Any difference in the structure or activation of male and female brains is indisputably biological. However, the assumption that such differences are also innate or “hardwired” is invalid, given all we’ve learned about the plasticity, or malleability of the brain. Simply put, experiences change our brains.
Recent research by Peg Nopoulos, Jessica Wood and colleagues at the University of Iowa illustrates just how difficult it is to untangle nature and nurture, even at the level of brain structure. A first study, published in March 2008 found that one subdivision of the ventral prefrontal cortex—an area involved in social cognition and interpersonal judgment—is proportionally larger in women, compared to men. (Men’s brains are about 10 percent larger than women’s, overall, so any comparison of specific brain regions must be scaled in proportion to this difference.) This subdivision, known as the straight gyrus (SG), is a narrow strip of cerebral cortex running along the midline on the undersurface of the frontal lobe. Wood and colleagues found the SG to be about 10 percent larger in the thirty women they studied, compared to thirty men (after correcting for males’ larger brain size). What’s more, they found that the size of the SG correlated with a widely-used test of social cognition, so that individuals (both male and female) who scored higher in interpersonal awareness also tended to have larger SGs.
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Reply | Report Abuse | Link to thisI find this study fascinating. But I would like to see the question posed slightly differently. I.E. "What differences show in the brain for highly skilled social interactors?" Particularly politicians -- here I mean all types of politicians. Those who run for public office, of course, but also those who are successful as business leaders, or in office politics, academic politics and/or family politics.
My experience is that those who are good at practising politics, are people not only good at public politics, but are also good at 'reading a room' or skilfully employing gossip.
I think only after you have established what part of the brain is involved in such social activity, what aspects of it are nature or nurture, one can begin to compare which sex is best at it.
If you are interested in this, I recommend reading Why Gender Matters by Dr. Leonard Sax. Awesome info!
Reply | Report Abuse | Link to thisIf you find this article fascinating, I recommend that you read Why Gender Matters by Dr. Leonard Sax
Reply | Report Abuse | Link to thisThe finding that this might be more related to personality factors/preferences rather than the Y-chromosome is easy to understand and predict (and apparently empirically true if this study is to be believed). However, just because it is not Y-chromosome linked doesn't lead to the conclusion that it must be more attributable to nurture, as the author implies. It appears that there are many genes whose actions underlie quite a number of personality preferences. Of course nurture is involved here, too, so i'm not saying that it is just one way. But it is non-sequiter to say that because it is not Y-chromosome linked that therefore it must be mostly due to nurture.
Reply | Report Abuse | Link to thisIt "raises" the question, actually. It can be an important distinction, so let's preserve it, shall we?
Reply | Report Abuse | Link to thisHard-wiring definitions of the brain will be changing over the next decade as the science of epigenetics moves into the research. Switching on and switching off factors in the individual genes in utero, are probably responsible for male and female brain differences in ways we can't even imagine.
Reply | Report Abuse | Link to thisThere are probably many more factors to discover that describe the differences between the male and female brain. One of those studies has already shown the sweat pheromone preference similarities of both male and gay females brain regions, and the corresponding preferences in female and gay male brain regions, as measured by brain imaging.
Could it be that a gay female is a women whose brain is more male-wired at birth in many different ways, and a gay male is a male whose brain is more female-wired at birth?
We know that a woman's uterus exhibits higher and higher levels of estrogen with each subsequent pregnancy. Many studies of gay males find them to be among the youngest born in the family sequence when the estrogen levels are known to be at their highest.
Could our increased use of estrogen pharmaceuticals for birth control be increasing our numbers of gay male babies - especially for those mothers that took the pills produced in the early 60's, and didn't wait the proscribed months before becoming pregnant, after ceasing their use of the earliest, high-level estrogen birth control pills?
Let's do a study of the SG region in gay males in that 1960's age cohort and see if there is any similarity to female brains in that same region?
Lot's of questions, but not many studies on this front as yet. I await the research.
Elizabeth Lowe
Integrative Health Specialist
Newport News, VA
elizllo@yahoo.com
Johnay, I agree with you that it raises the question, and that the distinction is important, and to be preserved. My objection was that the author was going from [not due to Y-chromosome] and leaping over [but may be due to the influence of other genes] and landing all the way over to [must be due to social upbringing]. It's very possible she is right, but there is a leap in logic that is unwarranted and I wanted to point that out. And the comment by Elizabeth Lowe regarding epigenetic factors seems very important to keep in mind, too. In utero switching on and off of genes is kind of a cross here. To the extent we think of that as a "nurture" effect, it is surely not the result of social upbringing, meaning that it is an even further leap to go all the way to such latter-stage nurture effects.
Reply | Report Abuse | Link to thisElizabeth, according to Dr. Sax, he says that the brains of gay and straight men are exactly alike and are obviously male. The same for female brains whether they are gay or straight women. Under a microscope brain cells of a male are different than those which are female brain cells. As to how those brains behave, he did not elaborate on that. It might be an interesting study.
Reply | Report Abuse | Link to thisIt does not follow that if some brain differences are small in an infant, then the differences which appear later on are not innate. Certain inherited traits may appear as the young person develops, due to those genes that control the behavior of other genes. These studies are interesting but most conclusions about the nature vs. nurture problem are premature. The article was however good in that it took up some such complications. The main issue is that whatever brain tissues are involved noone has as yet successfully 'nurtured' a boy into a girl, or the opposite. Besides this I would not agree that men lack empathy. Their empathy is just of another kind than those a of a woman. Besides, a woman is more sensitive to the emotions and signals of other women (!), which may reflect the evolutionary typical stage where men and women lived as separate communities, before the emergence of farming and the aristotelian idea of the happy husband and wife and children-family living on its own plot of land and forming the foundations of society.
Reply | Report Abuse | Link to thisI studied this, without the MRI advantage, in the 70's ... noting new seems to be forthcoming .... so the nature / nurture arguement is still alive and well ....
Reply | Report Abuse | Link to thisI studied this, without the MRI advantage, in the 70's ... noting new seems to be forthcoming .... so the nature / nurture arguement is still alive and well ....
Reply | Report Abuse | Link to thisI can't even begin to count all the things, my parents and other people have said over and over again, that I know for a fact... that I do not believe and have never believed from day one. Just because a person is exposed to something does not mean that they are sold on the package. Maybe these people have never taken the time to REALLY think about what they really believe to be true. Some people head off in a direction and that... that... go away my mind is made up!
Reply | Report Abuse | Link to thisThat's...that... I wish this had a Spell check. Sorry.
Reply | Report Abuse | Link to thisThe observation of a larger SG in grown -up women as per the study is most probably a case of nurture more than nature since women are brought up in an atmosphere in almost all cultures that favour development of social cognition,like peer approval,empathy for young ones ,and others,since that is part of the social training they under go as they grow up,learning to be more empathetic and giving more value to social cognition aspects,perhaps of the awareness that they are the weaker ,and fairer sex ,and family values largely derive from them.
Reply | Report Abuse | Link to thisSURESHKUMAR,ADVISER,NIIST,TRIVANDRUM[CSIR],INDIA
Hmmmm......
Reply | Report Abuse | Link to thisVery interesting. Thanks for publishing this.
Not sure I understand this nature vs nurture debate.
Reply | Report Abuse | Link to thisThe brains plasticity is part of it's nature. In relation to epigenetics, numerous studies have been done on a wide variety of mammals showing that an increase in estrogen levels during gestation will produce males that are homosexual, or for lower animals, do not demonstrate normal male behavior, i.e. no or little desire to mate, non-territorial and no inclination to compete for breeding.
Stress is known to increase estrogen levels in women and there was an ~100% increase in the number of homosexual men born to women in Germany during the air raids in WWII.
The nature vs nurture issue was resolved some time ago and shown to be a false dichotomy.
This is a gross over-simplification of the facts.
Reply | Report Abuse | Link to thisThere is a wide spectrum of gender-related differences in brain wiring, just as there is in height. In general, men are taller than women. This does not mean that every man is taller than every woman or that short men are more "feminine" or tall women are more "masculine". The same is true for gender-related differences like "empathy", verbal competence, mathematical and visuo-spatial prowess.
The large range of gender-related differences are modified by the fact that their correlation with gender also varies across a wide range.
At the top of the list is brain wiring that controls sensation in the genital area. This is nearly one hundred percent gender specific. Areas which control sexual preference are less differentiating of the genders: a significant number of humans and other mammals are attracted to their own sex. Verbal facility comes a long way down the list. Contrary to the gender-specific myth, most published authors are male, not female.
In other words, there is a lot of overlap on these items.
One of the most robust differences is that men, in general, tend to have brains which are more specifically wired than women's. The average woman distributes some functions across hemispheres while the cerebral hemispheres of the average man are more specifically dedicated. This is the reason why males are five times more likely than females to suffer from brain deficiency syndromes like dyslexia, autism, Asperger's disorder and so on. If a specific brain region is impaired the male brain, on average, has less plasticity and ability to reprogram. The fact that these conditions also occur in females should alert readers to the fact that these gender differences are not universal. There are many women with "masculine" style brains and many men with "femine" style brains in one or many of the gender-related areas.
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Reply | Report Abuse | Link to thisThe main thrust of the article is in accord with what I believe. Therefore, like everyone who reads something that they already believe, I like the article. However, I don't know about that straight gyrus thing! At the advanced age of 73, I suspect mine isn't so straight anymore, and I am not surprised if women's thing is 10% larger.
"However, the assumption that such differences are also innate or “hardwired” is invalid, given all we’ve learned about the plasticity, or malleability of the brain. Simply put, experiences change our brains."
Reply | Report Abuse | Link to thisThis is disingenuous.
Sexual preference is not a choice, nor is there any proof that it can be altered by experience. Yes, I have slept with women, but I prefer men. That has never changed. Pretending that sexuality is something that can be learned, like French, is the hallmark of a monotheist, not a scientist.
Why are we so committed and obsessed with continuing the binary of male and female. This study proves to me that there is so much in between! When a baby is born why is the first question always: a little boy or a little girl? What if we ceased applying so much importance in the gender black and white and embraced a freedom of self expression? Do we really think that wide spread panic would explode?
Reply | Report Abuse | Link to thisWhat about the transgendered? Who truly believe that they were either born in the wrong body or just never quite fit with the gender they were assigned at birth. I'd like to see scientific research into this phenomona!
Gender is a non-lineal spectrum that encompasses not only the extremes of masculine and feminine but also the myriad of expressions that exist within it.
Why are we so committed and obsessed with continuing the binary of male and female. This study proves to me that there is so much in between! When a baby is born why is the first question always: a little boy or a little girl? What if we ceased applying so much importance in the gender black and white and embraced a freedom of self expression? Do we really think that wide spread panic would explode?
Reply | Report Abuse | Link to thisWhat about the transgendered? Who truly believe that they were either born in the wrong body or just never quite fit with the gender they were assigned at birth. I'd like to see scientific research into this phenomona!
Gender is a non-lineal spectrum that encompasses not only the extremes of masculine and feminine but also the myriad of expressions that exist within it.
This article is so political; the VERY FIRST STATEMENT made is about how women are superior to men, without any reciprocation about male abilities. Then it goes on to tell you that sexual differences are societal because of research that hasn't been done yet!? This is just social indoctrination, not science.
Reply | Report Abuse | Link to thisI think the majority of the differences between Men and Women are related to social conditioning. I acknowledge that there are many difference in Men and Women however I believe when it comes to the way we act, think, learn, and communicate is primarily related to social conditioning. There has been a number of behavioural studies where the results appear to say otherwise however I think when you are doing a study on half of the population of the world vrs the other half you can not really have a clear-cut result without testing millions of people. I guess the problem is that we seem to find it easier to group people and to say if you are in this group you are more likely to do this. Anyway that’s my thoughts on the matter.
Reply | Report Abuse | Link to thisI completely agree with you. It really irritates me when we keep slotting people into a group and saying everyone in this group acts this way, thinks that way and is more likely to do this. We seem to not be learning the lesson that people should be thought of as unique individuals and treated based on their own actions and experiences. I refuse to believe that the way I think, act, learn, and feel is the same as 50% of the worlds population. Sorry I just had to get that out :) I feel better now.
Reply | Report Abuse | Link to thisThis article is very nice for me. I am the earliest female civil engineer in my country and work very well with women and men in my matter.
Reply | Report Abuse | Link to thisI don't know the sampling universe of this interesting study. I believe in the anthropological evolution of the societies and the influences of educational resources.
This article is very nice for me. I am the earliest female civil engineer in my country and work very well with women and men in my matter.
Reply | Report Abuse | Link to thisI don't know the sampling universe of this interesting study. I believe in the anthropological evolution of the societies and the influences of educational resources.
Some studies have revealed that certain brain regions differ in their circuitry for men and women.For example when it comes to blinking or thin slicing as usually found,women at better hunch makers.Similarly for repetitive jobs women have a better brain attuning.When it comes to acting on very little or limited information,in the face of uncertainty men many a times outsmart women.Where more analysis and calculative effort is required ,again men do better,mostly.But women brain has a better capacity to adjust to unfavorable or handicapped situations. Some of these could be the result of cultural conditioning and nurture more than nature.But the intrinsic screw in neural circuitry is undeniable,by and large.SURESHKUMAR,ADVISER,NIIST,CSIR,INDIA
Reply | Report Abuse | Link to this<i>a questionnaire that assesses each persons degree of masculinity vs. femininityregardless of their biological sexbased on their interests, abilities and personality type</i>
Reply | Report Abuse | Link to thisBut who decides what is "feminine" and what is "masculine" if this is not gender-based?
And who decides where on this putative psychological scale "feminine" tips into "masculine"?
Is it "feminine" to cook? Does that make Robert Carrier "feminine", and if so, by how much? Who decides the units on the scale?
Is Martha Stewart more "feminine" than a woman who lives on take-out? Or does Martha lose "femininity" points every time she wears trousers? Or goes to watch sports?
None of this is made clear in this article.