Of boys and girls
Sex is more than socialization
By Andrea Runyan
Opinions Columnist
Thursday, August 18, 2005
last updated August 18, 2005 12:37 AM
Editor’s Note: This article is the first in a series of columns
about men and women.
Last weekend, I had the privilege of spending an evening with,
among others, a three-year-old girl and her one-year-old
brother. Their parents remarked and my observation affirmed that
the children were incredibly different — more stereotypically
male and female than they or I expected. I might have dismissed
their observations as stereotypes, if the girl and her brother
(let’s call them Anne and John) didn’t remind me so much of what
I’ve seen of myself and my brother in family videos.
Anne and I were both voluble and volatile — quick to cry,
enamored of clothing, sensitive, easily scared and constantly
whining. John and my brother rarely made a sound, were mostly
calm and would have been very easy babies if only they weren’t
so mobile and prone to manipulating things (e.g. John turned the
fax machine on and off several dozen times, came close to
knocking over everyone’s beer can and opened the dishwasher,
pulling out hefty vegetable knives).
Seeing these children reminded me that, as politically incorrect
as it is to say so, male and female minds are fundamentally
different. Certainly, social expectations have some affect on
people’s interests and expectations for themselves. However, I
had to wonder whether a girl who was barely old enough to
communicate with adults could be picking up her love of dresses
and chatter from them, or whether a boy too young to talk could
be getting the idea from adults that such behavior wasn’t
expected of him.
Indeed, children show marked gender differences in their
behavior far before they could reasonably be interpreting
different societal expectations.
Early in life
• At one day old, boys look at mobiles longer than newborn
girls.
• At 12 months, girls look at human faces longer. Researchers at
Cambridge found that girls look at faces longer than boys.
• The same Cambridge team found that one-year-old boys preferred
watching a film showing cars to one showing a person. Girls
showed the opposite preference.
• At a few hours, old girls are more sensitive than boys to
touch. Tests between the sexes of tactile sensitivity in the
hands and fingers produce differences so striking that sometimes
male and female scores do not even overlap, with the most
sensitive boy feeling less than the least sensitive girl.
• When it comes to sound, infant females are much less tolerant
— one researcher believes that they may “hear” noises as being
twice as loud as do males. Baby girls become irritated and
anxious about noise, pain or discomfort more readily than do
baby boys.
• According to Anne Moir and David Jessel in “Brain Sex: The
Real Difference Between Men and Women,” “[a]t four months, most
baby girls can distinguish photographs of people they know from
photographs of strangers; baby boys cannot.”
• Researchers found three- and four-year-old boys to be better
at mentally rotating figures than girls of the same age. — ibid.
• Doreen Kimura, the co-author of the 1994 paper, “Cognitive
Pattern in Men and Women Is Influenced by Fluctuations in Sex
Hormones,” “[f]or the past few decades, it has been
ideologically fashionable to insist that these behavioral
differences are minimal and are the consequence of variations in
experience during development before and after adolescence.
Evidence accumulated more recently, however, suggests that the
effects of sex hormones on brain organization occur so early in
life that from the start the environment is acting on
differently wired brains in boys and girls.”
Different aptitudes?
• Boys outnumber girls four to one in remedial reading classes,
according to the book “Brain Sex.”
• “When asked to judge when someone might have said something
potentially hurtful, girls score higher from at least seven
years old. Women are also more sensitive to facial expressions.
They are better at decoding non-verbal communication, picking up
subtle nuances from tone of voice or facial expression or
judging a person’s character,” writes Simon Baron-Cohen in an
article in The Guardian. He writes further that men tend to show
“direct” aggression such as hitting whereas women show covert or
relational aggression, such as gossip or verbal insults. His
thesis in the book, “The Essential Difference: The Truth about
the Male and Female Brain,” is that women’s brains are designed
for empathy whereas men’s are built for understanding and
building systems.
• The amygdala, the brain’s emotion-control center, shows
significantly higher levels of activity in males viewing sexual
visual stimuli than females viewing the same images, according
to a study led by Emory University psychologists Stephan Hamann
and Kim Wallen.
• Women might have better short-term memories. They can store
greater amounts of irrelevant and random information than men,
who seem to need the information to be organized in order to
remember it.
• Doreen Kimura writes in “Sex Differences in the Brain” that
“[m]en tend to perform better than women on certain spatial
tasks. They do well on tests that involve mentally rotating an
object or manipulating it in some fashion, such as imagining
turning [a] three-dimensional object or determining where the
holes punched in a folded piece of paper will fall when the
paper is unfolded. Men also are more accurate than women at
target-directed motor skills, such as guiding or intercepting
projectiles. They do better at matching lines with identical
slopes. And men tend to do better than women on tests of
mathematical reasoning.”
• On the other hand, “Women tend to perform better than men on
tests of perceptual speed in which subjects must rapidly
identify matching items ... When reading a story, paragraph or a
list of unrelated words, women demonstrate better recall. Women
do better on precision manual tasks — that is, those involving
fine motor coordination — such as placing the pegs in holes on a
board. And women do better than men on mathematical calculation
tests.”
• Vanderbilt researchers find that among a sample of 40,000
“gifted” 12- to 14-year-olds who took the SAT, about twice as
many boys as girls scored above 500 on the math section; four
times as many scored above 600; and 13 times as many boys than
girls scored above 700. Boys and girls performed approximately
the same on the verbal portion.
• UCLA researchers performed brain scans on people who scored in
the 99th percentile on the math portion of the SAT and found
that as they worked on problems, the men relied on grey matter
in the cerebral and parietal cortices, whereas women showed more
activity in areas with white matter, sparking the observation by
Richard Haier, a professor of psychology at the UCLA Medical
School that “Maybe [the women] are doing the math using the
white matter.”
Structural differences
• Haier and his colleagues at the University of New Mexico and
the UCI Brain Imaging Center found that men have about
six-and-a-half times the amount of gray matter related to
general intelligence than women, and women have nearly 10 times
the amount of white matter related to intelligence than men.
“These findings suggest that human evolution has created two
different types of brains designed for equally intelligent
behavior,” Haier said. Gray matter is used for information
processing, while white matter consists of the connections
between processing centers.
• Rex Jung, a co-author of the study, suggested that this
difference in white and gray matter between the sexes might help
to explain why men excel at local processing tasks while women
tend to be good at integrating and assimilating information from
distributed gray-matter regions.
• In this same study it was found that 84 percent of gray-matter
regions and 86 percent of white-matter regions involved with
intellectual performance in women were found in the brain’s
frontal lobes, compared to 45 percent and zero percent for
males. Thus, most of women’s brain matter involved in
intelligence is in the frontal lobes, whereas the grey and white
matter involved in men’s intelligence is distributed throughout
brain regions. The researchers remarked that this finding that
women’s intelligence processing is concentrated in the frontal
lobe is consistent with findings that frontal brain injuries can
hurt women’s cognitive performance more than men’s.
• A similar study at McMaster University found that women have
up to 15 percent more brain-cell density in certain areas of the
frontal lobe, which controls so-called higher mental processes
including judgment, personality, planning and working memory.
• Parts of the corpus callosum, a major neural system connecting
the two hemispheres, as well as the anterior commissure, another
connecting structure, are larger in women, which might enable
better communication between hemispheres.
• Men seem to have greater asymmetry between brain hemispheres,
and damage to one hemisphere often has more of an effect on
cognition than a similar injury in women.
Hormones affect the brain
• Canadian researchers found prenatal testosterone levels were
positively correlated with skills on a mental rotation test
(imagining objects being rotated).
• Males with IHH (idiopathic hypogonadotrophic hypogonadism)
have small testes (and therefore low levels of testosterone) and
are worse at spatial reasoning.
• Male babies with androgen insensitivity (AI) syndrome are also
worse at spatial reasoning.
• Females with CAH (congenital adrenal hyperplasia) have high
levels of androgens and enhanced spatial systemizing.
• Researcher Elizabeth Hampson of the University of Western
Ontario found that women’s performance on certain mental tasks
varied throughout their menstrual cycles. High levels of
estrogen were correlated with decreased spatial ability but
increased speech and manual skills.
In the day or two that I’ve been looking things up for this
column, I’ve been astounded not only at the number of
differences between male and female brains, but also at the lack
of scientific arguments that the brains are essentially equal.
Certainly, people have written that men and women have equal
ability, etc. during the Larry Summers ordeal, but among people
who study the brain, the consensus seems to be that while
intelligence (however it is defined) might be equal, the male
and female brains are altogether different animals.
As Moir and Jessel write in “Brain Sex,” “Men are different from
women. They are equal only in their common membership of the
same species, humankind. To maintain that they are the same in
aptitude, skill or behavior is to build a society based on a
biological and scientific lie.
We might condone that lie if it helps women to believe that they
can perform in technical subjects just as well as men or if it
encourages the homogeneity and androgyny our society seems to
desire. But there can be huge costs to assuming that besides
sexual responses and the like, male and female brains are the
same.
I’ll address these consequences in a later column in this
series.
Given that Andrea is prefers talking to writing in solitude and
also loves Moonbeams’ tea, she’d love to talk with you over hot
beverages about sex differences. E-mail her at
arunyan@....
http://daily.stanford.edu/tempo?page=content&id=17742&repository=0001_article
.
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