Newsflash: Male, Female Brains Differ, in 100s of Ways

male and female brain differencesScience and sociology: The two fields often find themselves at loggerheads. That is the case with ADHD.  And, it’s increasingly the case when it comes to accepting that there are differences between the male and female brain.

Personally, I’m siding with science. Perhaps after you read a sampling of staggering statistics below—continued fully in the next post—you will, too.

But first, a bit of stage-setting.

In social media and elsewhere,  sociological theory threatens to crowd out scientific facts. The sociological theories seem “intuitive,” therefore alluring. Intuition may be quick and easy. The human brain generally doesn’t like to think; it’s too hard! All the same, intuition is not proof.

Gender and ADHD: Both “Social Constructs”?

Many sociologists and social psychologists have long issued intuitively inviting claims about ADHD. They call it a “social construct.”  The implication is that ADHD is an invention of social norms—or Big Pharma. Unfortunately, sociology is not a life-science field.

To these sociologists and social psychologists, I ask, “Are eyeglasses the product of social norms, too?

Would the vision of people prescribed eyeglasses be just fine if they didn’t want to read, drive, create, and not walk into walls? Should we all just go back to the good ol’ pre-Guttenberg Press days?”  I would also refer them to my four-part series:  Eyeglasses, ADHD, and Stigma

This post attempts to address (in a tiny and gingerly way) another claim made by the non-scientifically inclined: There is little difference between the male and female brains; the differences largely spring from culture.

This complex topic evokes strong feelings. We cannot bring a binary mindset to exploring the topic of male-female biological differentiation. Human brains are like snowflakes: No two are alike.  But it’s a topic worth exploring. Brains drive both physiology and behavior.

Please consider this a short blog post meant to spark thought—not a comprehensive treatise. As always, I welcome your thoughts.

male and female brain differences

Sex Begins in the Womb

The so-called Decade of the Brain, the 1990s, brought us revolutionary brain-imaging technology. This technology made possible the unprecedentedly precise study of the human brain. The evidence has been mounting ever since. It points to inherent differences in how men’s and women’s brains are “wired” and how they work.

Add this to what we’ve known it for years:  All humans develop from the same starting point in utero.

Yet—and this is critically important— that ends at about 6-9 weeks. That’s when fetuses with a Y chromosome start developing male sex characteristics in the brain and genitalia.

Excerpt from Sex Begins in the Womb (U.S. Institute of Medicine US, 2001):

During early development the gonads of the fetus remain undifferentiated; that is, all fetal genitalia are the same and are phenotypically female.

After approximately 6 to 7 weeks of gestation, however, the expression of a gene on the Y chromosome induces changes that result in the development of the testes. Thus, this gene is singularly important in inducing testis development.

The production of testosterone at about 9 weeks of gestation results in the development of the reproductive tract and the masculinization (the normal development of male sex characteristics) of the brain and genitalia.

In contrast to the role of the fetal testis in the differentiation of a male genital tract and external genitalia in utero, fetal ovarian secretions are not required for female sex differentiation. As these details point out, the basic differences between the sexes begin in the womb

Now For A Caution

Nothing about fetal development is straightforward or binary. That’s human biology for you. External influences can interfere with all aspects of fetal development—for example, nutritional deficiencies or toxins, the mother’s stress, illness, or trauma. 

In other words, the full expression of inborn genetic programming is not clearcut; it depends upon the full range of environmental factors. Yes, that includes culture—but also includes much more than culture. That’s true from conception to death.

Consider a Brief Example: Autism

Autism spectrum disorder (ASD) is 2 to 5 times more common in male individuals than in female individuals. That’s a very clear difference.

No doubt many girls with ASD go undiagnosed, but there’s no evidence that contributes to this disparity. There is evidence, however, of structural brain differences between male and female study subjects—and between female controls and females with ASD. In fact, some research has shown that the brains of girls with ASD more resemble male brains than female brains.

Consider this 2017 study in JAMA Psychiatry: Association Between the Probability of Autism Spectrum Disorder and Normative Sex-Related Phenotypic Diversity in Brain Structure.

Researchers imaged the brains of 98 individuals ages 8 to 22 with autism spectrum disorder and 98 control subjects. Each group contained roughly equal numbers of male and female subjects. Confirming earlier research, the found that the pattern of variation in the thickness of the brain’s cortex differed between males and females in the control group. But the team also found that the great majority of female subjects with ASD had cortical-thickness variation profiles similar to those of typical non-ASD males.

(What is cortical-thickness?  It is the outer layer of the cerebrum, or the cerebral cortex; it is composed of folded gray matter and thought to play an important role in consciousness and intellectual ability. For more info: Associations between cortical thickness and general intelligence in children, adolescents and young adults)

Did you get that?   Having a typical male brain structure, whether you’re a boy or a girl, substantially increases the risk for ASD. Obviously, more boys than girls have this brain profile. That likely explains ASD’s two- to fivefold preponderance among boys compared with girls. It’s not culture; it’s the brain structure and function.

male and female brain differences

 

Autism and the Empathy-Systems Polarity

While we’re on the topic of autism. Autism researcher Simon Baron-Cohen has called autism “extreme male syndrome”.

In 2004, I was greatly impressed by his book, The Essential Difference: Male And Female Brains And The Truth About Autism. He details his research linking fetal androgens (testosterone) with autism. These hormones can be both endogenous and exogenous— that is, issuing from the fetus or from the uterine environment.

(When I read that previous inhabitants of that uterus can leave their own hormonal mark for future occupants, I thought about my siblings. What else besides coats and old schoolbooks did those three brothers and three sisters pass down to me?)

He also explains his rationale for what he calls the “systems-empathy” polarity. One end of the spectrum is empathy, and the other end is systems. (Systems is, simply put, the drive to analyze and construct systems that follow rules; think math, science, finance, engineering).

Based on his research, Baron-Cohen maintains women are generally higher in empathy and men generally higher in systems. That is a brain-based difference.

Again, this is a spectrum. There are many men with higher empathy than systems ability, just as there are many women with higher systems ability than empathy.  Think of it as being similar to height; men as a group are taller than women as a group, but some women are taller than some men.

Now for The List:  For Every 100 Girls…

To be clear:  Human sexual differentiation is not binary; it is also a spectrum. For purposes of research, though, large numbers indicate differences between the general groups of male and female.

Which brings us to the staggering list of statistics.

Tom Mortenson first compiled this list in 2006. He gave me permission to share the most current version with you.

Mortenson is currently a Senior Scholar at the Pell Institute for the Study of Opportunity in Higher Education in Washington, D.C. and an independent higher education policy analyst.  In 2003, he wrote a fact sheet: What’s Wrong with the Guys?

The next post will include Mortenson’s entire list, with charts.

Birth and Death: Male Versus Female

Some bullet-point statistics below clearly document the physiological and behavioral differences between male and female, because they manifest at birth.

Others likely have a cultural overlay. Teasing out which comes first should be grounded in careful thought and study, not preconceived ideology or intuition.

Research by Russell Barkley et al shows that untreated or poorly managed ADHD is associated with premature death.  The brain is obviously driving behavior.

Let’s start with birth statistics that point to greater male mortality. For every 100 girl babies that:

  • Are born alive, 105 boy babies are born alive.
  • Are born dead, 106 boy babies are born dead.
  • Die in the first 28 days of life, 117 boy babies die in the first 28 days of life.
  • Die after the first 28 days of life but before they reach their first birthday, 124 boy babies die.

Mortality and suicide from childhood into young adulthood. For every 100 girls age:

  • 1 to 4 years that die, 125 boys the same age die.
  • 5 to 9 years that die, 123 boys die.
  • 5 to 14 that commit suicide, 225 boys kill themselves.
  • 15 to 24 that commit suicide, 433 boys commit suicide.

The disparate effect crosses ethnic boundaries, too. For every 100:

  • White, non-Hispanic girls ages 15 to 19 that die, 216 white, non-Hispanic boys the same age die.
  • Black girls ages 15 to 19 that die, 310 black boys the same age die.
  • Asian girls ages 15 to 19 that die, 203 Asian boys the same age die.
  • American Indian girls ages 15 to 19 that die, 180 American Indian boys die.
  • Hispanic girls ages 15 to 19 that die, 287 Hispanic boys ages 15 to 19 die.

Statistics based on data from 2011, the source is the U.S. National Center for Education Statistics.

difference between male and female brains

difference between male and female brains

Look to my next post for the full list.

—I welcome your comments. It’s easy.

No annoying forms to complete.

Gina Pera

 

10 thoughts on “Newsflash: Male, Female Brains Differ, in 100s of Ways”

  1. Interesting topic! The post sent me off to do more reading. Found a few more articles about gendered brain structure differences, such as neural fiber development. Also references to “female protective effect” which will be interesting to hear more about.

    My son suffers from tuberous sclerosis complex, which is one of the leading known genetic causes of ASD. However, with TSC there is not a strong difference in ASD diagnoses between male and female. One reason I suppose this group is of great interest to autism researchers.

    I like the description of the “systems” brain. While my son does not have ASD, he certainly resembles the description of wanting to construct systems with rules, math, science, etc. He doesn’t seem un-empathetic, but does often seem to be studying us for the appropriate response. Perhaps I’ll learn a little more empathy towards him, in times of frustration, by understanding better how his brain is wired 🙂

    1. Hi Cristy,

      After all this time, I did not realize that TSC is linked genetically to ASD.

      There used to be several websites sharing Simon Baron-Cohen’s empathy and systems quotient tests. That was around 2005, I think. They seem to have largely disappeared now.

      This site merges the two tests. I don’t know how valid it is. But it might be worth a look.

      https://openpsychometrics.org/tests/EQSQ.php

      In the back of his Essential Difference book are photos of faces depicting various emotions. The higher your score incorrectly assessing emotions, the lower odds of ASD.

      Of course this is just one metric. But I find his work very interesting.

  2. Josemanuel Navarro

    I’ve read this article with great interest. Having concluded my reading, I am lost as to its conclusions or what you intended to do with it. I’d appreciate a clarification,

    1. Hi Josemanual,

      haha! I figured someone would say that.

      I tried, obviously not entirely successfully, to explain in the first paragraph:

      Science and sociology: The two fields often find themselves at loggerheads. That is the case with ADHD. And, it’s increasingly the case when it comes to accepting that there are differences between the male and female brain. Personally, I’m siding with science. Perhaps after you read a sampling of staggering statistics below—continued fully in the next post—you will, too.

      But first, a bit of stage-setting.

      Perhaps you are not aware of the growing insistence from a growing number of ideologues. That, as I write, the only difference between males and females comes from the culture, not biology. That any “bad behavior” from men is always volitional.

      That is simply not the case. The male brain from birth to death is more vulnerable to dysfunction, illness, and injury.

      For example, impulse-control disorders are higher among men, and poor impulse-control is associated with the group of sexual disorders called Paraphilias.

      Another example: Learning and intellectual disabilities are more common among males.

      Fewer male fetuses, compared to females, make it to delivery, and they suffer from higher rates of physical disabilities, accidents, etc.

      If we don’t understand these vulnerabilities, we draw the wrong conclusions and implement the wrong solutions. We also fall for ideological claptrap.

      In Part II of this post, I will be sharing an immense body of data comparing how males and females fare in a range of areas, from mental illness to education and life span.

      I hope that clarifies a bit. Thanks for asking,

      Gina

  3. Fascinating Thank you Gina! I’ve been immersing myself in info on ADHD Dyslexia, and a wide spectrum of issues we face trying to figure out this line between life experience and genetics. Epigenetics has explained one hell of a lot but there’s a point I feel we get to that crosses the line of what the western world has misunderstood for generations as we’ve concentrated on competition based idiologies, extrinsic values and an image considered to be success. We’ve seemed to lean so far toward a systems ability that systematically maintains an unrealistic view of “survival of the fittest” rather than heart based values that nurture all of life in order to accept neurodiversity. Our unchanging education systems has allowed for that. I believe our teachers as well as our children are obtaining an insufficient systems based curriculum intended to divide rather than to accept, integrate and collaborate as we did during the renaissance era whereby natural science, creativity and humanism were of high interest. The fact that conformity is viewed as top priority rather than individualism is the very essence of what it takes to dehumanize society. We’ve seen time and again the devistating effects of man/women trying to control nature yet in order to learn from nature and histories past change is always necessary and takes people who either aren’t able to conform or eventually decide not to. Many times these people have been called deficient, rebellious, heretics, artists, saints, musicians, poets, writers, genius’s, outside the box thinkers, open minded, stars, obsessive, free thinkers, and every label known within learning disabilities and mental illnesses since conforming is more painful than complacency when the spectrum between the systems ability based modal of freedom doesn’t seem to fit the feel within the empathy based modal of freedom which is based on unity rather than attrition. A balance is based on equality and that’s found by searching for the positive abilities in each other rather than continually trying to control human nature which is what we do to perfectly imperfect children in our education system. Allowing them to think or believe their deficient by an extrinsic charting system as if that directly relates to their purpose or passion in life. Self soothing by any means is the next very logical step.
    It would seem by the charts that nature might have a tighter hold on which way she feels this world needs to go since there’s a reason for everything under the sun and cause and effect rule. What we think can’t over ride what we feel there has to be balance. Humans have in fact been tampering with this very fact with damaging effects.

    1. Hi Bonnie,

      Thanks for your comment.

      I appreciate your sentiments. I’ve also seen, living here in the SF Bay Area, how “humanistic” perspectives can be carried too far. With the ideology overriding concern for the person suffering from challenges that leave them unable to function in school as many other children do, too.

      I’ve seen “celebrating neurodiversity” dominate over compassion and access to treatment for highly treatable conditions. I’ve seen adults with ADHD who came up in schools dominated by that ideology see their life options unnecessarily circumscribed. And I find it heinous, the inherent selfishness to let people suffer as long as one’s ideology is preserved.

      There is much gray area to tread here, and treading gray area is not a human strong suit.

      “Nature” has many goals. The ultimate one is survival. That doesn’t always put a premium on humanistic qualities.

      If we let “nature” stay in the driver’s seat, we will stop attempting to cure disease and elevate human lives.

      Gina

    2. Betsy Davenport

      There is nothing so dehumanizing as to be endowed with a brain that can’t keep itself on track to do things one needs to do to be successful at human things like, say, nurturing a child. Neurodiversity sounds interesting until one realizes that one’s diverse – and divergent – neurology has got one two years behind on filing income tax returns. There is no “positive ability” under the sun that is going to matter to the IRS, and we do live in the real world. Stop romanticizing faulty brain function.

      If one places a high value on autonomy, on having choices, on self-actualization, then not obtaining diagnosis and treatment for one’s anomalous brain function is anathema. It has nothing to do with conformity and everything to do with effective functioning. If all the grocery stores were run by “neurodiverse” individuals, there would be no regular hours and poorly stocked shelves. We have to be able to rely on structures in order to function nominally well SO THAT we can go from the everyday basics to doing something interesting and beneficial with our lives.

      And let us not pretend that every neurodiverse person has rare talent, or special genius. Most are regular people who can’t get the laundry done. There is nothing romantic about standing in the middle of the kitchen in your pajamas at the exact time you should be in the car getting your kid to school. Most of life is mundane; most of life is maintenance. In special moments – if we have gotten the maintenance out of the way – there is room for brilliance or creativity. But the person with, say, ADHD who never gets chores done is relegated to a life of discouragement and despair.

      So, as a person who has suffered this condition all my life and watched family members unable to reach their natural potential, and as a clinician who has assisted people to find the right diagnosis and treatment, so they can live more fulfilled lives, I say: you have a funny idea about what’s going on here. You aren’t really paying attention to what’s being said but are leaping to an inaccurate conclusion that someone wants to make everybody the same and be damned with their interesting differences.

      The opposite is true: we want people to be ABLE to express their uniqueness in the world, and the ones who are anomalous, and in need of a diagnosis and treatment, are generally unable to do exactly that.

    1. Hi Alana,

      That is exactly the kind of ideology (not neuroscience) that concerns me.

      Most psychologists have little study of life science. That is, “hard science.” And Ms. Fine seems to be one of them.

      I prefer to consider the science, not anti-science, self-serving ideological polemics.

      It is also important to note that she starts with the premise of a strawman argument, as described in her book’s product details:

      Drawing on the latest research in neuroscience and psychology, Cordelia Fine debunks the myth of hardwired differences between men’s and women’s brains, unraveling the evidence behind such claims as men’s brains aren’t wired for empathy and women’s brains aren’t made to fix cars. She then goes one step further, offering a very different explanation of the dissimilarities between men’s and women’s behavior. Instead of a “male brain” and a “female brain,” Fine gives us a glimpse of plastic, mutable minds that are continuously influenced by cultural assumptions about gender.

      No legitimate scientist makes those bold claims. She is being dishonest here, in a very self-serving way.

      excerpt from the blog of evolutionary biologist Jeffrey Coyne: …As I’ve said several times, while the book [Testosterone Rex] has good bits, especially its calling out shoddy research, Fine can’t bring herself to call out shoddy research that supports her book’s hypothesis: that there are no innate biological differences between the male and female brains or bodies caused by hormones. (She’s made her living on the thesis that there are no evolved genetic differences between men and women.) Further, many of the “critiques” that Fine leveled against previous research on sex—including her claim that in humans male variance in reproductive success is equal to that of females (WRONG), as well as her denying of the importance of sexual selection in humans and other species (WRONG)—bespeak a deep confirmation bias derived from The Sexual Blank Slate.

      https://whyevolutionistrue.wordpress.com/2017/09/28/a-new-critique-of-cordelia-fines-testosterone-rex/

      Gina

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