Humans, like other mammals, exhibit sex differences in their brains and psychological traits. But what do they signify? Many of the effects of sex on the body are actually tied to the way in which this pastime influences brain activity and the release of hormones in. Both are trying to argue that humans are neurological hermaphrodites, as if somehow admitting any sex differences in brains would mandate.
One of the last things you're thinking about during sex is probably chemicals and your brain—but they're more involved than you think. One study on women. On April 11, , a doctor named T. C. Erickson addressed the Chicago Neurological Society about a patient he called Mrs. C. W. At age Humans, like other mammals, exhibit sex differences in their brains and psychological traits. But what do they signify?
And sex hormones, like estrogen and testosterone, can target regions of the brain, affecting many aspects of signaling and function at the. 'It found that. On April 11, , a doctor named T. C. Erickson addressed the Chicago Neurological Society about a patient he called Mrs. C. W. At age
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Photo by Corbis via Getty. Kevin Mitchell. He lives in Portmarnock, Ireland. Brought to you by Curioan Aeon partner. Edited by Marina Benjamin. Sex differences really do exist. Men and women, boys and girls, really do behave differently. The question — and difficultly — lies in establishing and these differences come from. Are the sexes wired differently?
Or does culture explain observed behavioural differences? The answers are yes and yes; but, unfortunately, biological and cultural explanations are so often seen as mutually exclusive that a middle ground can be hard to discern.
The debate is especially contentious at the moment, with proponents of nature or nurture each claiming that the latest brain science proves their position. Either way, important implications for social policy are drawn, based on the favoured interpretation of the evidence.
She provides compelling evidence that much of the historical research in this area has been and, in some cases, continues to be driven by an overtly or implicitly sexist agenda, intent on finding scientific proof of female inferiority. The science is clear. The opposing sociology is delusional. Damore was promptly fired for his intemperate comments, and roundly excoriated by many commentators.
Yet sex other quarters, he was celebrated as a brave proponent of free speech and scientific truth. Both sides can end up arguing for rather blinkered positions.
Peterson, for example, maintains that the pay gap can be explained by women scoring higher, on average, in the personality trait of agreeableness: training women to be sex agreeable, he contends, would improve their financial success in the workplace. Meanwhile, the Canadian cognitive scientist Steven Pinker recently decried an article in The New York Times — which looked at why women do more than their share of the housework — for not considering biological sex differences as a possible factor.
Even if he had a point, his apparent disregard for entrenched patriarchal norms scotched any sympathy he might have found on social media. This despite the scientific evidence showing that sex differences in physical aggression are universal across human societies, have a cogent evolutionary rationale, manifest in most other mammalian species, and have well-worked-out biological mechanisms.
Rippon, for example, rightly critiques shoddy early neuroimaging work that claimed to have found biologically driven brain differences directly accountable and observed sex differences in behaviour.
She is far less critical, however, of the equally shaky literature claiming that brain plasticity can drive differences in macroscopic brain structure, which in turn might account for behavioural differences. We are all human, of course: and subject to this kind of confirmation bias. But people working in different disciplines and reading various literatures will also entertain a host of underlying subsidiary beliefs that are less overt, and that strongly influence how they weigh various types of evidence or argument.
They might have strong prior positions on whether individuals have any innate psychological predispositions and if such traits are influenced by genetics; whether findings in animals are relevant to human psychology; brain human minds have been shaped by their recent evolutionary past; if experience can reshape brain structure, or personality traits play a larger role in explaining behaviour.
These deep but usually unstated differences in starting positions leave scientists and commentators talking past each other, and the general public none the wiser. They can even lead to the same data being interpreted in diametrically opposed ways — which raises the question of where the solid scientific ground actually lies. Nowhere is this more apparent than in the interpretation of results from neuroimaging studies.
They found 10 regions showing such differences, some larger in males, some in females. On the face of it, their findings seemed to support the idea that male and female brains are structurally distinct. However, each of the 10 regions under scrutiny varies in volume across individuals anyway, with the distribution simply shifted slightly higher or lower in the other sex.
The authors concluded that the brains of males and females are not categorically distinct. Yet, within months, multiple other researchers showed that the same data could very reliably be used to categorise individual brains as male or female.
While the volume of any individual area is a terrible predictor brain sex, a multivariate analysis gives brain good discrimination. On this reading, the brains of males and females are not dimorphic, with two completely different forms, like genitalia; insteadthey show a correlated set of shifts in the size of various features, similar to what is observed for male and female faces, which are also readily distinguished.
Another neuroimaging study that drew media attention for the contrary readings it spawned was undertaken in by the neuroscientist Madhura Ingalhalikar and colleagues at the University of Pennsylvania.
They measured the connections between sex regions, and found some sex differences in organisation, with females tending to have more connections between the two hemispheres, and males having slightly more running front-to-back within each hemisphere. The data seemed pretty robust, and fit with prior findings of greater cross-hemispheric connectivity in females.
Still, the authors were criticised for how they interpreted the findings. In the absence of any causal link between the observed differences in brain structure and those in behaviour, such claims are purely speculative. Nor were the chosen examples of supposed sex differences in behaviour particularly convincing are men really psychologically more suited to cycling?
Claims like these rely on unsupported inferences of there being close links between the size of bits of the brain and performance of complex human behaviours. As it happens, there is good evidence that male and female brains are structurally different at the macroscopic sex.
A number of recentlargescale neuroimaging studies have found numerous small but correlated differences that collectively distinguish male and female brains in the samples studied. Indeed, a prominent argument — advanced by Rippon, among others — is that they are caused by our brains reacting to the differing experiences of males and females in a culture that is pervasively gendered.
And brains are, of course, highly plastic and designed to respond to experience. But most of that plasticity happens on a microscopic scale — changing the weights of connections between neurons. The idea that culturally loaded experience can drive macroscopic differences in the size of bits of the brain is something else entirely.
That claim relies on a small number of studies, such as the one from showing that London taxi drivers have a larger posterior hippocampus, which seems to and acquired an almost mythic lore, despite the collective evidence base being quite limited. The idea that brain areas might grow with use, or that levels of neural activity might change in regionally specific ways as a result of the quality of experience is both vague and speculative. Despite myths to the contrary, we are effectively using all of our brain all of the time, while awake at least.
If brain tissue were really like muscle, our brains would be busting out of our skulls. Given that neuroanatomical sex differences are brain observed in children — even reported in infants as young as one month old — and are ubiquitous across other animal species with well-worked-out developmental mechanisms in many casesit seems likely that observed neuroanatomical sex differences in humans are the result of conserved programmes of masculinisation or feminisation of brain development.
Really, we have no clue. And this is despite countless efforts to link variation in size of this or that brain region or this or that nerve tract to a corresponding variation in psychological or behavioural traits, and no shortage of reports of such correlations in the literature.
The relationship between bits sex the brain and cognitive functions or behaviours is simply not sex modular.
This is only a modern version of phrenology, where the size and shape of depressions and bumps on the skull was supposed to reveal the size of brain brain areas and the consequent psychology of individuals. The complexity of the cellular circuitry and connectivity of any given region is too great for its function to be straightforwardly mapped to the amount of neural real estate it occupies.
These structures mainly control the and organisation of behaviour and physiology, with important roles in mating, reproductive physiology, social behaviours, threat monitoring, aggression, fear, energy balance, and the like. The focus on neuroimaging is thus a bit of a red herring in the sex-difference wars. The technology is simply not able to detect all the differences that might exist in neural circuitry between men and women, nor are scientists able to interpret those differences it can detect, let alone resolve the issue of whether any purportedly associated differences we observe in male and female behaviour are due to biological or cultural factors.
A n equally contested area in investigating the basis of behavioural sex differences is whether differences in psychological traits, including personality traits such as conscientiousness, aggressiveness, impulsivity, risk-taking, nurturance and so on, might drive observable differences in behaviour. If such traits — thought to reflect some basic brain processes — differ consistently between males and females, then that would seem to favour a biological explanation for differences in behaviour.
But, as with neuroanatomical differences, merely observing differences in such traits is not sufficient to settle the debate as to their origins or effects. What is observed is a spectrum — from traits where sex differences have a clear, conserved biological basis and strongly drive behaviours, to traits whose origins are murkier and the link to behaviour far more tenuous.
The traits with strongest evidence of biological origins brain, not surprisingly, the ones most closely linked to reproduction and mating strategies. Sexual preference is the most obvious. So obvious that it is often overlooked, as if it just happens by default that some human beings are attracted to males and some to females. They are the outcome of a programme of masculinisation or feminisation of neural sex that mediates sexual attraction, with principles and mechanisms well-worked-out in other mammals.
Physical aggression is also closely tied to mating strategies, and shows strong sex differences. Human males are far more physically violent than females, across all cultures, committing the vast majority of serious assaults and homicides, and making up the vast majority of the victims. A similar sex difference is observed in many mammals, including most primates, in accord with the ecological pressures of competition for mates.
These differences in sexuality and aggression relate closely to reproductive strategies and behaviours; they are expected from an evolutionary perspective, have direct correlates in other and, and are associated with specific neural mechanisms that are beginning to be well-elucidated in model organisms.
There is no good reason why a biological origin for these differences should be controversial. But then such differences are also not really the things that much of the debate hangs on. Of much more relevance are possible differences in cognitive abilities, personality traits, aptitudes and interests. In fact, modern IQ tests show no difference brain mean scores between men and women though men show higher varianceand in many countries girls now regularly outperform boys in academic exams.
There are, however, measurable differences in very specific cognitive abilities, such as a male advantage in mental and of three-dimensional objects, and a female advantage in verbal fluency. The difference in mental rotation shows up early, by age four or five, brain moderate in size, and universally observed across cultures. Much is made of these differences. Even in the most individualistic societies, there are limits on the extent to which we independently create ourselves.
There are other consistent sex differences in personality traits.
The radioactive signal accumulated in areas where neurons became active, as their energy was replenished by the surrounding blood vessels. Eight of the men were ordinary, sexually speaking. The other seven suffered from hypoactive sexual desire disorder. People with this condition rarely experience sexual desires or fantasies. In particular, a patch of neurons near the front of the brain—a region called the medial orbitofrontal cortex—was active in the desire-impaired men but quiet in the normal ones.
Among its jobs, the medial orbitofrontal cortex keeps our emotions from getting out of control. Unfortunately, PET scans take several minutes to capture a single image.
A lot can happen in that time, especially when sex is involved. This technique can capture an image of the working brain in just a couple of seconds and locate areas of activity down to a millimeter or so—about one-twentieth of an inch. Using fMRI, scientists have pinpointed a number of regions of the brain that kick in when people feel sexual desire. As expected, several of them are in the temporal lobe. One of those regions, the amygdala, orchestrates powerful emotions.
Another, the hippocampus, manages our memories. It may become active as we associate sights and smells with past sexual experiences. But despite what Freud thought, sexual experiences are not just a matter of primal emotions and associations.
The parts of the brain that light up in the fMRI scans include regions that are associated with some of our most sophisticated forms of thought. The anterior insula, for instance, is what we use to reflect on the state of our own bodies to be aware of the sensation of butterflies in the stomach, say, or of lightness in the head.
Brain regions that are associated with understanding the thoughts and intentions of other people also seem linked with sexual feelings. Even fMRI studies are not fast enough to catch the flow of activity, however. They cannot tell us which regions of the brain become active first, which later.
So Ortigue and Bianchi-Demicheli are updating one of the oldest brain-monitoring technologies. An electrode on the scalp can pick up electrical activity only after it has spread beyond the skull, getting weakened and smeared along the way. But the EEG process is fast; it can capture 1, snapshots a second.
In recent years scientists have dramatically improved the power of EEG by writing computer programs that compare recordings from multiple locations around the head and then calculate which regions of the brain are producing the signals. These programs can home in on regions just a few millimeters across , nearly as close as fMRI.
The subjects then had to decide whether each person they were looking at was desirable or not and press a computer key to register their vote. But Ortigue and Bianchi-Demicheli were able, for the first time, to observe when different regions of the brain became active, combining the readings into an extraordinary movie:. But in that 0. Some parts became active, then quiet, then active again. Other parts went through a different series of changes.
Intriguingly, the pattern of neural action seen in the experiment does not follow an orderly progression from the vision-processing centers to the centers of emotion and finally to the lofty regions of self-awareness.
Ortigue and Bianchi-Demicheli suspect that several different parts of the brain are analyzing the information coming in from the eyes and influencing the final response.
Less facetiously, they have become confused by the fact that, historically bigots, have and still do take weird factual claims about sex differences morally seriously, and come to the conclusion that the way to address this is to attack those claims.
They will find new reasons, invent them if they have to, and ignore the whole of science if they must. You can see them doing all these things right now. Why does this matter? Because failing to treat sex differences as real means that things like drug dosages, disease susceptibility, and differential diagnoses, are being swept under the carpet.
Sexual dimorphism does not mean that males and females are different in every respect. It means that sex is a meaningful variable that allows us to predict differences.
Brain differences. Go and look at that list I made below. And consider what would have to be true for sexual dimorphism not to apply to brains. It would mean that an entire chromosome, which has about genes on the X bit, and 70 on the Y, has no effect on the resultant organism and its control center. Evolution couldn't work that way. Their bodies are different.
Not as different as some sexually dimorphic species—but different nonetheless. Brains control bodies. For those brains to be indistinguishable, would be like saying that any TV remote should control all other TVs.
Of course, there are similarities—more similarities than differences—but and this is the really important point : So what? Put it this way: What systematic brain difference would mandate treating half the human population as inferior to the other half?
Name one. I dare you. I double dare you. For males to find females attractive, they have to be attracted to female-typical bodies. For females to find males attractive, they have to be attracted to male-typical bodies. Now, let me say this slowly and carefully, these are not the same bodies. However, if recent experience is anything to go by, simply elucidating facts is not going to stop this daftness going away. What might make it go away is if we all do better at treating each other fairly and decently.
And doing that is a lot harder than having an ideology. A partial list of reliable and robust sex-based brain differences all showcased in the January Journal of Neuroscience Research. Bear in minds that most of these are meta-analyses, summaries of dozens sometimes hundreds of other studies. Thanks, Dr. King, well said.
I once heard an equal rights advocate state that people of all race, sex, sexual orientation, etc. I think your focus on treating each other fairly is right on. As a feminist myself, I cannot understand for the life of me why some people and extreme feminists are out there trying to prove that we're the same.
We are not. But that doesn't mean we should be treated inferiorily. Every man and woman, and everyone in between, has a right to live life as they see fit, regardless of their differences, which are undeniable. One is not better or lesser than another. They simply are. I wish more people understood that. Maybe if they did we could end this silly debacle that only serves to divert our energy from things that really matter, like finding a way to get ourselves out of this horrible climate issue we've dug ourselves into Thansk for your thoughts.
Somehow the idea that equality requires identity has crept into some minds. But a few minutes reflection would suggest that one reason that humans value each other is precisely becuae they are not identical to each other.
Its not just an issue of diversity although that matters too. Its that each human is unique and irreplaceable. Wouldn't the notion that their brains are different than the healthy population have political implications? And it does, right? I mean, George Conway has been accusing Trump of having antisocial P. Some of the work we do here are UCC is abotu acquired brain injury and one of the things that students who work with folk with ABI rapidly learn is compassion for the fragility of humans.
To talk of illness or neurological atypicality is to approach things from the perspective of accident or misfortune though. No-one is seriously suggesting in our culture at least that people are unlucky to be women or unlucky to be men and by virtue of that should not be treated as fully human.
People have spoken that way and alas still do in some parts of the world. But not here. Childrens brains are not fully formed either and thats why in part we dont allow them full access to the responsibilities that adults have.
But we dont need to know anything much about brains to realize that. Cultures have been seeing children as children since long before brain science came along. As for things like personality disorders: Well, these are deep waters. For one thing, a lot of mental health professionals are uncomfortable desginating somethign as a disease something you have when its arguably something you are.
Whatever the truth of that, individuals will vary in talents, abilties, and suitablity for office. But none of that means that they aren't fully human. But none of that applies to adult brains, does it? Interesting question, and I think the answer is that as far as mental illness and politics, the gender differences don't really pertain to mental illnesses in a straightforward way. The biggest difference in terms of politics and policy that makes sense would seem to be with regard to physical size and strength, such as in sports, though even that difference, on average, isn't all that great.
Certainly, historically, the physical and mental differences between men and women are much smaller than was thought years ago! As for Trump, he's obviously a narcissist and clearly fits the description on almost all points in the DSM.
I think they call that a personality disorder, which isn't all that uncommon. A key point in that manual is that the condition needs to cause distress and disruption of your life in some significant way, which in Trump's case can be argued all kinds of ways.
In his own way, he's certainly succeeded by many measures and he's got good instincts, no matter how objectionable they are to many people. I'd say he's a "high function" narcissist. But it's a continuous scale, and just saying that he appears to have a PD doesn't automatically flip him into a category of being "mentally ill" like total insane person who must be removed from office as soon as possible.
That would be just a case of stupidly following labels. Not sure why you brought up Trump in this discussion. There are lots of women with the same personality tendencies too. Yeah, I'm not sure why I brought Trump up either. In no way was I trying to say anything about his sex being correlated with anything.
I wasn't at all trying to speculate about any links between mental illness and sex. I was trying to say, hey, if we politically treat people differently with brain abnormalities, then, if we discovered enough neurological differences between makes and females, could politics treat males and females differently due to brain differences? And yeah, I was thinking about military and physical stuff. Interesting perspective and info, thanks for replying!!
It would seem a little strange to treat people differently based on neurological differences that hadn't already been observed as cognitive or behavioral differences. Opioid peptides are known to play a role in emotion and motivation. Progesterone is a steroid hormone synthesized in both male and female brains. It contains characteristics found in the chemical nucleus of both estrogen and androgen hormones. During the menstrual cycle, progesterone increases just after the ovulatory phase to inhibit luteinizing hormones, such as oxytocin absorption.
It was once thought that sex differences in cognitive task and problem solving did not occur until puberty. However, as of , evidence suggested that cognitive and skill differences are present earlier in development. For example, researchers have found that three- and four-year-old boys were better at targeting and at mentally rotating figures within a clock face than girls of the same age were.
Prepubescent girls, however, excelled at recalling lists of words. These sex differences in cognition correspond to patterns of ability rather than overall intelligence. Laboratory settings are used to systematically study the sexual dimorphism in problem solving task performed by adults. On average, males excel relative to females at certain spatial tasks. Specifically, males have an advantage in tests that require the mental rotation or manipulation of an object.
Additionally, males have displayed higher accuracy in tests of targeted motor skills, such as guiding projectiles. On average, females excel relative to males on tests that measure recollection.
They have an advantage on processing speed involving letters, digits and rapid naming tasks. In maze and path completion tasks, males learn the goal route in fewer trials than females, but females remember more of the landmarks presented. This shows that females use landmarks in everyday situations to orient themselves more than males. Females are better at remembering whether objects had switched places or not.
From Wikipedia, the free encyclopedia. Characteristics of the brain that differentiate the male brain and the female brain. Nature Reviews. Neuroscience and Biobehavioral Reviews. Sexual differentiation of the human brain. A historical perspective.
Progress in Brain Research. Experimental and Clinical Endocrinology. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. Brain Research.
Archives of Sexual Behavior. Biological Psychology. Current Opinion in Behavioral Sciences. Endocrine physiology 5th ed.