SEX DIFFERENCES: Are boys really more aggressive and girls really more empathetic--or do we just see what we expect in them?
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In Brief
- Boys and girls are different, but most psychological sex differences are not especially large. For example, gaps in intellectual performance, empathy and even most types of aggression are generally much narrower than the disparity in adult height, in which the average man is taller than 99 percent of women.
- Researchers have found very few large-scale differences between boys and girls in brain structure or function. Boys have larger brains, and girls’ brains finish growing earlier than boys’ do. But neither of these findings explains why boys are more active and girls more verbal or reveals a plausible basis for any of the other emotional and cognitive differences between the sexes.
- Experience itself changes brain structure and function. Most sex differences start out small—as mere biases in temperament and play style—but are amplified as children’s pink- or blue-tinted brains meet our gender-infused culture.
Parents anticipate sex differences from the first prenatal ultrasound but then seem amazed when their son goes gaga over trucks or their daughter will wear nothing but pink. Boys and girls are obviously different, and in many cases the gaps between them seem stark. But stereotypes do not always hold up to scientific scrutiny. Are boys really more aggressive and girls really more empathetic—or do we just see what we expect in them? Where true sex differences exist, are those gaps inborn, as our current Mars-Venus obsession implies, or shaped by environment—that is, by us?
A natural place to look for answers is in the brain. If there is a neurological disparity between the genders, it could explain important behavioral differences. But surprisingly, researchers have found very few large-scale differences between boys and girls in brain structure or function. Yes, boys have larger brains (and heads) than girls—from birth through old age. And girls’ brains finish growing earlier than boys’. But neither of these findings explains why boys are more active and girls more verbal or reveals a plausible basis for the consistent gaps in their reading, writing and science test scores that have parents and teachers up in arms.
This article was originally published with the title The Truth about Boys and Girls.
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34 Comments
Add CommentAll I can say is THANK YOU.
Reply | Report Abuse | Link to thisThe clearest and most unbiased psych article I have read in a long time. Far too many of these studies have interesting results but then the authors make unwarranted leaps in the conclusions. I like that this one discussed the many possible causes of what we are seeing.
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Reply | Report Abuse | Link to thisI don't read a lot of articles about the mind or psychology of us humans because as a "male", I am more into technology and the physical world. But I did find this one interesting. A curiosity though. My wife and I had 5 babies with the first being female, the next male, then twin girls, and last a boy. There are 4 years between our first and second, 11 months until the twins arrived (2-1/2 months premature) and then 3 years for the last boy. We raised our children with little gender bias.
Reply | Report Abuse | Link to thisI am a car enthusiast and from about 3 years of age on, our oldest (a girl) was always perched on the fender of whatever car I was working on to see what Daddy was doing and she would try to please me at every turn. Handing me wrenches, taking out (or on) bolts, retrieving dropped tools, whatever it took. The second (a boy), while he did want to spend time with me, he quickly lost interest in mechanical projects (by this time our oldest moved on to more "girly" endeavors). We have one twin that is pink, butterflies and the perfect lady all the way. While the other (the older of the two) is NASCAR, football, and has worked in the automotive parts field basically her whole career. The youngest boy is working toward being a chef and the least aggressive (with the exception of the butterfly twin) than all of our children. Which brings me to my point? I didn't see in this article at all where sibling "position" plays any part of how the child develops. What are the percentages of the subjects studied multi sibling environments and what are they for "only child" environments? In my family at least, I don't see where many of the conclusions are pertinent. I understand that there are exceptions to any rule, but the variants I see within my own family are important and significant. We did not raise one twin different from the other. Obviously I think, (I could be wrong), there wasn't any difference in the testosterone level in the womb as they are twins (maternal not identical). Yet they display entirely different if no opposite characteristics. I think this article (while very well written and researched), left out a key element. Any thoughts?
Its only natural that people, family and society should expect behavioral differences among girls and boys: their statistically significant behavioral differences primarily arise from fundamental physiological distinctions.
Reply | Report Abuse | Link to thisThese physiological distinctions include many many that appear in babies and many that occur during puberty as a result of hormonal induced development, and many differences in their bodies, brains and minds.
While those fundamental differences may lead to unfair training and social opportunities that should be corrected, the physiological distinctions cannot be eradicated by training or modified rule enforcements.
I base these statement not on any bias towards my sons over my daughters, but my appreciation and love for each of them for who and what they are. What they are not does not make them any less for what they are.
""Researchers have found very few large-scale differences between boys and girls in brain structure or function. Boys have larger brains, and girls brains finish growing earlier than boys do. But neither of these findings explains why boys are more active and girls more verbal or reveals a plausible basis for any of the other emotional and cognitive differences between the sexes.""
Reply | Report Abuse | Link to thisGee, what a surprise. If you carefully examine Spartan apples as compared to crab apples you might find that your research "doesn't explain" why Granny Smith apples are green, either!
Unless there was very good reason to expect that the differences quoted WOULD explain different traits in boys vs girls, what is it you're trying to prove?
If this is scientific research then somebody's money just got wasted!
"""Researchers have found very few large-scale differences between boys and girls in brain structure or function. Boys have larger brains, and girls’ brains finish growing earlier than boys’ do. But neither of these findings explains why boys are more active and girls more verbal or reveals a plausible basis for any of the other emotional and cognitive differences between the sexes."""
Reply | Report Abuse | Link to thisNow let's write this information up a different way.
Researchers found that there are some large-scale differences between boys and girls brains in brain structure and function. Boys have larger brains, and girls brains finish growing earlier than boys' do.
The researchers were not, however, able to explain why boys are more active and girls are more verbal. Neither were they able to point to these two large-scale differences as being the basis for any other emotional and cognitive variation between the sexes.
Perhaps research into smaller-scale differences could throw some light on this subject.
Why do we continually obsess about differences in the sexes? Shouldn't these differences be treasured? What is wrong with boys being boys and girls being girls? The differences complement each other, don't they? As long as we continue to have respect for our differences and strive to assure equality, being different is a good thing.
Reply | Report Abuse | Link to thisPerhaps we do influence our children to be a certain way. So what!!! Thats what being a parent is all about. Should I be OK with my son wanting to wear a dress to school? Why do we have to raise this next generation with such gender confusion?
scribblerlarry - Gosh, I wonder if there might be some hormonal or other chemical differences between the sexes that account some of the variation between the sexes?
Reply | Report Abuse | Link to thisTo those whose favorite tool is a hammer, all problems appear to be nails.
Are psychological sex differences really that small? In fact, the standard measurement methods often lead researchers to underestimate them by a substantial degree.
Reply | Report Abuse | Link to thisFor example, the sexes reliably differ on most personality traits (e.g., extraversion, neuroticism, and so on). Differences on individual traits are usually small to moderate, so if you simply average those differences (which is what researchers usually do) you come up with a deceptively small estimate of the overall male-female difference. However, if you combine single-trait differences with the appropriate statistical tools, the overall estimate becomes much, much larger - almost three times as large in the case of personality.
For details see: epjournal.net/filestore/ep07264279.pdf
Nice opinion piece but not up to the standards that I've come to expect from Sci Am. More Pop Sci than Sci Am. The absence of finding is not the finding of abscence. The genetic difference between humans and chimpanzees is around 1.6 to 4% yet the physical and intellectual differences are significant. The brain differences between heterosexuals and homosexuals using the arguably subjective criteria of the author would be considered negligible. Socialization arguments to account for gender identification with same sex parents propose an identificatory mechanism. Given that this mechanism would be genetic in nature, this begs the question of why such a mechanism would exist if not for an evolutionary preference for gender. There are also questions concerning transsexualism as well as the observation that many males who are raised with masculine behavioral intention nevertheless exhibit femine personality which would be expected of females. Minor if any structural differences between their brains and those of more masculine males (be any criteria) are so minor as to be highly speculative. Even what constitutes a minor vs large scale difference between brains or what contitutes a minor or large difference in patterns of behavior between the sexes presents a broad gray area for subjective opinion.
Reply | Report Abuse | Link to thisIt is my opinion that a considerable preponderance of evidence indicates that neurological differences between the brains of males and females, transsexuals, homosexuals and effeminate heterosexual males; are determinant no matter whether these structural difference are judged minor by weight, volumn or morphology.
Nice opinion piece but not up to the standards that I've come to expect from Sci Am. More Pop Sci than Sci Am.
Reply | Report Abuse | Link to thisTwo quotations readily came to mind as I read this article. "The absence of finding is not the finding of abscence" and "Not everything that matters can be counted and not everything that can be counted matters." The genetic difference between humans and chimpanzees is around 1.6 to 4% yet the physical and intellectual differences are profound. The brain differences between heterosexuals and homosexuals using the arguably subjective criteria of the author would be considered negligible. Socialization arguments to account for gender identification with same sex parents propose an identificatory mechanism. Given that this mechanism would be genetic in nature, this begs the question of why such a mechanism would exist if not for an evolutionary preference for gender. There are also questions concerning transsexualism as well as the observation that many males who are raised with masculine behavioral intention nevertheless exhibit femine personality which would be expected of females. Minor if any structural differences between the brains of "effeminate males" and those of more masculine males (be any criteria) are so minor as to be highly speculative. Even what constitutes a minor vs large scale difference between brain structure or what contitutes a minor or large scale difference in patterns of behavior between the sexes presents a broad gray area for subjective opinion.
It is my opinion that a considerable preponderance of evidence indicates that neurological differences between the brains of males and females, transsexuals, homosexuals and effeminate heterosexual males are determinant no matter whether these structural difference are judged minor by weight, volumn or morphology. I however also believe that any intellectual differences between the sexes are nurture based almost entirely.
newtimer - Curious. So, do you also believe that intellectual differences between individuals are almost entirely nurture based (not produced by any physiological condition or chemical process, etc.) as well? It would seem likely that if there is any physiological basis for individual variations there may also be physiological conditions producing intellectual differences between the sexes as well.
Reply | Report Abuse | Link to thisIt took me a long time to realize that others don't necessarily process information using the same methods I do, and even longer to realize that women tend to think even more differently than other males. The best I can figure, it may have something to do with hormones.
Not that anyone is better than anyone else, only that we can only experience the universe from our individual perspective, from within the environment provided by our own bodies. But, that's just the way I see things.
You may be right, I may be crazy, but the gender differences atributed to education reflect in some way the cultural history of their parents ethnic background, give the children a sense of identity, and contribute to the shape of relationships with other persons and other groups, as global bonds are built in a stepwise way starting from very small to large groups; many times those who speak about internationalisms of all kinds have just destruction in the deep of their minds. Also some lernt behaviour connects us to the not so different animal world, for example mating rituals. I have the hunch that a thing some sex experts advised for a wedding night, both parts of the couple commiting masturbation one in front of the other, may be not a good innovation, and destroyers of old gender differences tend to easily start spreading their own inventions for the case
Reply | Report Abuse | Link to thisThe most obvious problem in any kind of study of this kind is that the differences in structure appear to be as a result of a mechanism that is totally independent of what genes the person has. Thus, you can find "male" brains in women and "female" brains in men. A "correct" study would need to do a two-way analysis, where genetic gender was one variable and brain gender was a second variable. Otherwise, how do you find out what contribution is made by the brain and how much is experiential? It becomes guesswork otherwise.
Reply | Report Abuse | Link to thisFor my think,this article write is very well
Reply | Report Abuse | Link to thisThe differences between boys and girls don't need to be huge to have a big impact. The frame of references in this article wreaks of the Standard Social Science Model (differences in individuals are due to culture/socialization).
Reply | Report Abuse | Link to thissacrednature - I strongly agree. Evaluating brains solely on the basis of structural development ignores critical distinctions in brain chemistry which may produce significant differences in processing.
Reply | Report Abuse | Link to thisThis is a minor fact check, but the average male is taller than roughly 95% of women, not 99%.
Reply | Report Abuse | Link to thisHere's the math: The average white American male is ~5'9", whereas the average white American female is ~5'4". The standard deviation for female height is about 2.5 inches. That means that a woman who is 2 standard deviations from the mean will be 5'9", and will therefore by in the 95th--not 99th--percentile. Assuming a normal distribution, the average male height would have to be almost 6' for the "99%" figure to be accurate.
A lot of it is psychological and socially implied, but a lot of it really does have to do simply with biology.
Reply | Report Abuse | Link to thisThink about it. Hormones play a BIG difference. Testosterone in high doses, either in men or women, makes an individual more aggressive and easily sexually aroused. But women tend to produce very little testosterone as compared to men who produce it in high doses (except Eunuchs and anorexic or andropausic men).
A lot of women tend (emphasis on "a lot of" and "tend") to produce more alpha brainwaves than men, whereas most men are more beta-geared. This correlates with the commonplace "female intuition" and "empathy" so commonly seen in women, and beta brainwaves have more to do with mathematical calculations and hard logic which is why men are more oriented towards these areas. Of course, mileage always varies.
This article was quite dissatisfying to say the least. I did not learn anything from it other than the obvious comment that social conditioning can make us act in very particular ways.
Also, I really do think that just having been born to a certain sex does not determine your personality.
Reply | Report Abuse | Link to thisI'm a girl and I've always preferred blue over pink. I rarely, if ever, wear pink; I usually stick to colors like blue, white, or black. I think big breasts are disgusting and do not look up to the modern "perfect girl" ideal as most girls do. I refuse to have children. I think gossipping and starting rumors is the lowliest, most pathetic thing anyone could ever do. I find shopping to be an extremely boring and selfish activity and find no pleasure in getting a new pair of shoes or getting a manicure. Who cares?
I'm also somewhat prone to aggressivity (although I control it) and enjoy kickboxing and running to let go of stress.
I am not a tomboy however, because I stil do "girly things" - i.e. I take care of my looks and try to present myself well-put together to others. But on the other hand, I find I'm deeply different from most women.
So I am living proof that you don't have to be like the sex you were born into. Maybe that is why some religions point out that the "soul" is inherently genderless?
Ana Dollika - Well put. I think that, since human behavior is so complex and to some extent dynamically self-determined, any characteristic studied by gender, race, religion, profession, residential region, etc. will produce a bell curve with a great deal of overlap. Characterizing any population group of humans is essentially a pointless endeavor in which mostly temporary conclusions are possible.
Reply | Report Abuse | Link to thisIt is very difficult to apply large scale statistical trends to individuals. People are far too complex. It is pointless to look at yourself or your children for proof or disproof of the article's premise. There are many applications of this type of study, the first that comes to mind is marketing, but I wouldn't use it as a ruler to measure your child's male/female-ness.
Reply | Report Abuse | Link to thisThanks for the response jtdwyer. I believe that the relative contributions of nature (genetic) and nurture to individual variations in intellectual ability, vary by individual to a degree which is currently much in debate. The aspects of personality which we tend to refer to as masculinity or femininity may receive a much greater infuence from genetics or the prenatal environment than intellectual ability does. As an illustration, even variations in height between individuals are a result of relative contributions between environment (nutrition) and genetics.
Reply | Report Abuse | Link to thisI agree with you that there are differences between individuals in the way we process information. Two individuals may have different styles of processing information yet be of equal general intellectual ability. I won't deny that it is resonable to generalize that men and women think differently at under certain circumstance, but I think of it more as a result of men and women having different cultural values. The etiology of disparate mens and womens cultures may be genetic but culture per se is learned behavior.
Along the lines of this particular nature vs. nurture discussion one might consider human language facility. You won't get much argument whether the human language facility is genetically determined compared to other primates. However, you won't find an "english gene", or "deutch" gene. I suspect that the kind of variation we can have in the expression of the language facility is constrained by genes. So, sometimes the question of whether behavioral differences are more nurture or more nature is a less important question than how nature and nurture for a particular behavior make their contributions and for what adaptive benefit.
Diversity is wonderful. As long as it's something trivial and meaningless like skin color.
Reply | Report Abuse | Link to thisnewtimer - You bring up a very interesting point regarding 'nature vs. nurture' and language development. As I understand, children are born with with a super-set of language processing abilities. Most languages only use a subset of those capabilities. The neuronal structures providing those unused abilities disappear around 5-6 years old. After that point, if the language you learned does not include specific features such as 'L' or 'R' sounds, for example, you will find it very difficult to simulate the ability to make those sounds later in life.
Reply | Report Abuse | Link to thisPerhaps similar capabilities are initially provided in other areas of intellectual or social development that are discarded in not used early in life...
However, this process is unlikely to explain the female propensity towards language that seems to become more pronounced around puberty and other developments apparently largely under the control of hormonal influences.
The bolts and nuts make no different when they are recycled.They don't know what to be next generation,but they have to study their mission when they were created again.NIRVANA.....
Reply | Report Abuse | Link to thisI always heard there were fairly large differences in the brains between boys and girls. For example, the corpus collosum is supposedly much larger in women than in men. Men have more neurons, but womens neurons are more connected, things like this. I didn't get the entire article, though, but those seem like pretty substantial differences. I could be wrong, though, I suppose...
Reply | Report Abuse | Link to thisIf to watch closely children, it is possible to find out a lot of interesting and inexplicable. Sometimes the child figuratively repeats of what you think.
Reply | Report Abuse | Link to thisDenying significant differences between the sexes, including differences between their brains, flies in the face of research previously published by many others, including contributors to Scientific American Mind.
Reply | Report Abuse | Link to thisFor example, the architecture of the corpus callosum has been extensively proven to differ in males and females. This alone accounts for many behavioural differences between the sexes.
Why shall we be so obsessed by trying to deny the significant differences between the sexes? Different doesn't mean inferior or superior. Being different creates opportunity for creative tension, interesting relationships, complementary skills and behaviour, etc.
I prefer to celebrate the differences between the sexes instead of trying to find feeble excuses why they don't exist.
I don't maintain there exiests any sex differents between girls and boys. Why their behaviours have so many disparities is just because of the way their parents treat them after they are born. The outer environment alters them.
Reply | Report Abuse | Link to thisSometimes small things can make a huge difference. If the force applied on an object lying on the ground is increased by 1% it may not make a big difference. By pressing a button on electronic gadget can make a significant difference. A single neutron can trigger an atomic blast and not to talk about even smaller things a single thought can make a huge change then there is also a question where the thought arises, free will, good & bad. A small change in single gene can have a potential impact a small change in nature and size of hypothalamus can make a big difference.
Reply | Report Abuse | Link to thisIt seems like this article was written in an attempt to provide evidence to support equality, giving cause to view the genders equaly. It almost seems like they are pussy footing around the obvious fact that women and men are infact different. Its like their two year old trying to change the shape of a hole so their block will fit. What is with the title, what truth have they revealed? The obvious truth is that we're different whether from gender, or personality, or culture. Trying to show that we aren't, takes away the significance of how our differences can compliment each other.
Reply | Report Abuse | Link to thisYou didn't read of understand the point of the article at all, did you?
Reply | Report Abuse | Link to thisSeriously, a quick skimming of the intro says flat out that PHYSIOLOGICAL DIFFERENCES ARE OVERSTATED.