The New Sex Scorecard declares that “It’s safe to talk about sex differences again.”:
Get out the spittoon. Men produce twice as much saliva as women. Women, for their part, learn to speak earlier, know more words, recall them better, pause less and glide through tongue twisters.
Here’s an interesting anatomical difference:
Gur’s discovery that females have about 15 to 20 percent more gray matter than males suddenly made sense of another major sex difference: Men, overall, have larger brains than women (their heads and bodies are larger), but the sexes score equally well on tests of intelligence.
Gray matter, made up of the bodies of nerve cells and their connecting dendrites, is where the brain’s heavy lifting is done. The female brain is more densely packed with neurons and dendrites, providing concentrated processing power — and more thought-linking capability.
The larger male cranium is filled with more white matter and cerebrospinal fluid. “That fluid is probably helpful,” says Gur, director of the Brain Behavior Laboratory at the University of Pennsylvania. “It cushions the brain, and men are more likely to get their heads banged about.”
White matter, made of the long arms of neurons encased in a protective film of fat, helps distribute processing throughout the brain. It gives males superiority at spatial reasoning. White matter also carries fibers that inhibit “information spread” in the cortex. That allows a single-mindedness that spatial problems require, especially difficult ones. The harder a spatial task, Gur finds, the more circumscribed the right-sided brain activation in males, but not in females. The white matter advantage of males, he believes, suppresses activation of areas that could interfere with work.
The white matter in women’s brains is concentrated in the corpus callosum, which links the brain’s hemispheres, and enables the right side of the brain to pitch in on language tasks. The more difficult the verbal task, the more global the neural participation required — a response that’s stronger in females.
Women have another heady advantage — faster blood flow to the brain, which offsets the cognitive effects of aging. Men lose more brain tissue with age, especially in the left frontal cortex, the part of the brain that thinks about consequences and provides self-control.
“You can see the tissue loss by age 45, and that may explain why midlife crisis is harder on men,” says Gur. “Men have the same impulses but they lose the ability to consider long-term consequences.”
This should come as little surprise:
Women’s perceptual skills are oriented to quick — call it intuitive — people reading. Females are gifted at detecting the feelings and thoughts of others, inferring intentions, absorbing contextual clues and responding in emotionally appropriate ways. They empathize. Tuned to others, they more readily see alternate sides of an argument. Such empathy fosters communication and primes females for attachment.
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Men focus first on minute detail, and operate most easily with a certain detachment. They construct rules-based analyses of the natural world, inanimate objects and events. In the coinage of Cambridge University psychologist Simon Baron-Cohen, Ph.D., they systemize.
The superiority of males at spatial cognition and females’ talent for language probably subserve the more basic difference of systemizing versus empathizing. The two mental styles manifest in the toys kids prefer (humanlike dolls versus mechanical trucks); verbal impatience in males (ordering rather than negotiating); and navigation (women personalize space by finding landmarks; men see a geometric system, taking directional cues in the layout of routes).
Autism is fascinating:
In his work as director of Cambridge’s Autism Research Centre, he finds that children and adults with autism, and its less severe variant Asperger syndrome, are unusual in both dimensions of perception. Its victims are “mindblind,” unable to recognize people’s feelings. They also have a peculiar talent for systemizing, obsessively focusing on, say, light switches or sink faucets.
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Autism overwhelmingly strikes males; the ratio is ten to one for Asperger.
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The more testosterone the children had been exposed to in the womb, the less able they were to make eye contact at 1 year of age. “Who would have thought that a behavior like eye contact, which is so intrinsically social, could be in part shaped by a biological factor?” he asks. What’s more, the testosterone level during fetal life also influenced language skills. The higher the prenatal testosterone level, the smaller a child’s vocabulary at 18 months and again at 24 months.
Lack of eye contact and poor language aptitude are early hallmarks of autism. “Being strongly attracted to systems, together with a lack of empathy, may be the core characteristics of individuals on the autistic spectrum,” says Baron-Cohen. “Maybe testosterone does more than affect spatial ability and language. Maybe it also affects social ability.” And perhaps autism represents an “extreme form” of the male brain.