The Cognitive Differences Between Men and Women,

I first started reflecting on what would eventually become my newly published Stanford Medicine journal article, “Two Minds: The Cognitive Differences Between Men and Women,” in 2013, when I attended a campus symposium on the question of whether such differences exist.

Numerous interviews and seminars and many dozens of slow digestion research reports later, the answer is clear. An excerpt from the article:

Scientists routinely acknowledge that the presence or absence of a single DNA base pair can make a medically important difference. How about a complete chromosome? While the genes housed on the X chromosome and the Y chromosome (about 1,500 on the X chromosome, 27 on the Y chromosome) may have once had equivalents on the other, that is the case only for some of them. Every cell in a man’s body (including his brain) has a slightly different set of functional sex chromosomal genes than those that operate on a woman.

So it should come as no surprise that, over the past 15 years or so, new technologies and new hypotheses have generated increasing evidence that there are inherent differences in how men’s and women’s brains connect and how they function.

And even, at least to some extent, in what men and women want. Findings in this line of animal and human studies continue to accumulate. Again, from the article:

In a study of 34 rhesus monkeys, for example, males preferred wheeled toys over stuffed animals, while females found stuffed toys cute. It would be difficult to argue that the monkeys’ parents bought them sex toys or that the ape society encourages their male offspring to play more with trucks. … [In a very recent study,] boys and girls ages 9 to 17 months – an age at which boys show little or no sign of recognizing their own or other children’s sex – show marked differences in their preference for male stereotypes versus stereotypically female toys.

Nor do the differences between men and women stop at the limits of normal cognition and behavior. On the contrary:

Women are twice as likely as men to experience clinical depression in their lives; similarly for post-traumatic stress disorder. Men are twice as likely to become alcoholic or drug dependent, and 40 percent more likely to develop schizophrenia. The rate of dyslexia in boys is perhaps 10 times higher than in girls, and they are four to five times more likely to obtain a diagnosis of autism spectrum disorder.

It now appears that bursts of sex hormones in the womb, which permanently affect brain structure and function, may differentially predispose men and women to these mental disorders.

At the 2013 event I alluded to earlier, a prominent speaker whose talk particularly caught my attention was molecular psychiatrist Nirao Shah, MD, PhD. At the time, Shah was located at the University of California, San Francisco. He’s at Stanford these days, and he proved to be a key source for my article.

Trying to assign exact percentages to the relative contributions of “culture” versus “biology” to the behavior of free-living human individuals in a complex social environment is difficult at best. But it is safe to say that the role of culture is not zero. The role of biology is also not zero.

Formerly: Stanford Medicine magazine reports on sex, gender, and medicine, Tomayto, tomahto: Separate genes control male and female differential behaviors, typically male Y chromosomes in men tell colorful stories of conquests, expansions, and having a copy of the ApoE4 gene variant doubles Alzheimer’s risk for women but not men

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