[Paleopsych] NYT: Gray Matter and the Sexes: Still a Scientific Gray Area
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Mon Jan 24 21:32:30 UTC 2005
Gray Matter and the Sexes: Still a Scientific Gray Area
NYT January 24, 2005
By NATALIE ANGIER and KENNETH CHANG
When Lawrence H. Summers, the president of Harvard,
suggested this month that one factor in women's lagging
progress in science and mathematics might be innate
differences between the sexes, he slapped a bit of
brimstone into a debate that has simmered for decades. And
though his comments elicited so many fierce reactions that
he quickly apologized, many were left to wonder: Did he
have a point?
Has science found compelling evidence of inherent sex
disparities in the relevant skills, or perhaps in the drive
to succeed at all costs, that could help account for the
persistent paucity of women in science generally, and at
the upper tiers of the profession in particular?
Researchers who have explored the subject of sex
differences from every conceivable angle and organ say that
yes, there are a host of discrepancies between men and
women - in their average scores on tests of quantitative
skills, in their attitudes toward math and science, in the
architecture of their brains, in the way they metabolize
medications, including those that affect the brain.
Yet despite the desire for tidy and definitive answers to
complex questions, researchers warn that the mere finding
of a difference in form does not mean a difference in
function or output inevitably follows.
"We can't get anywhere denying that there are neurological
and hormonal differences between males and females, because
there clearly are," said Virginia Valian, a psychology
professor at Hunter College who wrote the 1998 book "Why So
Slow? The Advancement of Women." "The trouble we have as
scientists is in assessing their significance to real-life
For example, neuroscientists have shown that women's brains
are about 10 percent smaller than men's, on average, even
after accounting for women's comparatively smaller body
But throughout history, people have cited anatomical
distinctions in support of overarching hypotheses that turn
out merely to reflect the societal and cultural prejudices
of the time.
A century ago, the French scientist Gustav Le Bon pointed
to the smaller brains of women - closer in size to
gorillas', he said - and said that explained the
"fickleness, inconstancy, absence of thought and logic, and
incapacity to reason" in women.
Overall size aside, some evidence suggests that female
brains are relatively more endowed with gray matter - the
prized neurons thought to do the bulk of the brain's
thinking - while men's brains are packed with more white
matter, the tissue between neurons.
To further complicate the portrait of cerebral diversity,
new brain imaging studies from the University of
California, Irvine, suggest that men and women with equal
I.Q. scores use different proportions of their gray and
white matter when solving problems like those on
Men, they said, appear to devote 6.5 times as much of their
gray matter to intelligence-related tasks as do women,
while women rely far more heavily on white matter to pull
them through a ponder.
What such discrepancies may or may not mean is anyone's
"It is cognition that counts, not the physical matter that
does the cognition," argued Nancy Kanwisher, a professor of
neuroscience at the Massachusetts Institute of Technology.
When they do study sheer cognitive prowess, many
researchers have been impressed with how similarly young
boys and girls master new tasks.
"We adults may think very different things about boys and
girls, and treat them accordingly, but when we measure
their capacities, they're remarkably alike," said Elizabeth
Spelke, a professor of psychology at Harvard. She and her
colleagues study basic spatial, quantitative and numerical
abilities in children ranging from 5 months through 7
"In that age span, you see a considerable number of the
pieces of our mature capacities for spatial and numerical
reasoning coming together," Dr. Spelke said. "But while we
always test for gender differences in our studies, we never
In adolescence, though, some differences in aptitude begin
to emerge, especially when it comes to performance on
standardized tests like the SAT. While average verbal
scores are very similar, boys have outscored girls on the
math half of the dreaded exam by about 30 to 35 points for
the past three decades or so.
Nor is the masculine edge in math unique to the United
States. In an international standardized test administered
in 2003 by the international research group Organization
for Economic Cooperation and Development to 250,000
15-year-olds in 41 countries, boys did moderately better on
the math portion in just over half the nations. For nearly
all the other countries, there were no significant sex
But average scores varied wildly from place to place and
from one subcategory of math to the next. Japanese girls,
for example, were on par with Japanese boys on every math
section save that of "uncertainty," which measures
probabilistic skills, and Japanese girls scored higher over
all than did the boys of many other nations, including the
In Iceland, girls broke the mold completely and outshone
Icelandic boys by a significant margin on all parts of the
test, as they habitually do on their national math exams.
"We have no idea why this should be so," said Almar Midvik
Halldorsson, project manager for the Educational Testing
Institute in Iceland.
Interestingly, in Iceland and everywhere else, girls
participating in the survey expressed far more negative
attitudes toward math.
The modest size and regional variability of the sex
differences in math scores, as well as an attitudinal
handicap that girls apparently pack into their No. 2 pencil
case, convince many researchers that neither sex has a
monopoly on basic math ability, and that culture rather
than chromosomes explains findings like the gap in math SAT
Yet Dr. Summers, who said he intended his remarks to be
provocative, and other scientists have observed that while
average math skillfulness may be remarkably analogous
between the sexes, men tend to display comparatively
greater range in aptitude. Males are much likelier than
females to be found on the tail ends of the bell curve,
among the superhigh scorers and the very bottom performers.
Among college-bound seniors who took the math SAT's in
2001, for example, nearly twice as many boys as girls
scored over 700, and the ratio skews ever more male the
closer one gets to the top tally of 800. Boys are also
likelier than girls to get nearly all the answers wrong.
For Dr. Summers and others, the overwhelmingly male tails
of the bell curve may be telling. Such results, taken
together with assorted other neuro-curiosities like the
comparatively greater number of boys with learning
disorders, autism and attention deficit disorder, suggest
to them that the male brain is a delicate object,
inherently prone to extremes, both of incompetence and of
But few researchers who have analyzed the data believe that
men's greater representation among the high-tail scores can
explain more than a small fraction of the sex disparities
in career success among scientists.
For one thing, said Kimberlee A. Shauman, a sociologist at
the University of California, Davis, getting a high score
on a math aptitude test turns out to be a poor predictor of
who opts for a scientific career, but it is an especially
poor gauge for girls. Catherine Weinberger, an economist at
the University of California, Santa Barbara, has found that
top-scoring girls are only about 60 percent as likely as
top-scoring boys to pursue science or engineering careers,
for reasons that remain unclear.
Moreover, men seem perfectly capable of becoming scientists
without a math board score of 790. Surveying a
representative population of working scientists and
engineers, Dr. Weinberger has discovered that the women
were likelier than the men to have very high test scores.
"Women are more cautious about entering these professions
unless they have very high scores to begin with," she said.
And this remains true even though a given score on
standardized math tests is less significant for women than
for men. Dr. Valian, of Hunter, observes that among women
and men taking the same advanced math courses in college,
women with somewhat lower SAT scores often do better than
men with higher scores. "The SAT's turn out to underpredict
female and overpredict male performance," she said. Again,
the reasons remain mysterious.
Dr. Summers also proposed that perhaps women did not go
into science because they found it too abstract and
cold-blooded, offering as anecdotal evidence the fact that
his young daughter, when given toy trucks, had treated them
as dolls, naming them "Daddy truck" and "baby truck."
But critics dryly observed that men had a longstanding
tradition of naming their vehicles, and babying them as
though they were humans.
Yu Xie, a sociologist at the University of Michigan and a
co-author with Dr. Shauman of "Women in Science: Career
Processes and Outcomes" (2003), said he wished there was
less emphasis on biological explanations for success or
failure, and more on effort and hard work.
Among Asians, he said, people rarely talk about having a
gift or a knack or a gene for math or anything else. If a
student comes home with a poor grade in math, he said, the
parents push the child to work harder.
"There is good survey data showing that this disbelief in
innate ability, and the conviction that math achievement
can be improved through practice," Dr. Xie said, "is a
tremendous cultural asset in Asian society and among
In many formerly male-dominated fields like medicine and
law, women have already reached parity, at least at the
entry levels. At the undergraduate level, women outnumber
men in some sciences like biology.
Thus, many argue that it is unnecessary to invoke "innate
differences" to explain the gap that persists in fields
like physics, engineering, mathematics and chemistry. Might
scientists just be slower in letting go of baseless sexism?
C. Megan Urry, a professor of physics and astronomy at Yale
who led the American delegation to an international
conference on women in physics in 2002, said there was
clear evidence that societal and cultural factors still
hindered women in science.
Dr. Urry cited a 1983 study in which 360 people - half men,
half women - rated mathematics papers on a five-point
scale. On average, the men rated them a full point higher
when the author was "John T. McKay" than when the author
was "Joan T. McKay." There was a similar, but smaller
disparity in the scores the women gave.
Dr. Spelke, of Harvard, said, "It's hard for me to get
excited about small differences in biology when the
evidence shows that women in science are still
discriminated against every stage of the way."
A recent experiment showed that when Princeton students
were asked to evaluate two highly qualified candidates for
an engineering job - one with more education, the other
with more work experience - they picked the more educated
candidate 75 percent of the time. But when the candidates
were designated as male or female, and the educated
candidate bore a female name, suddenly she was preferred
only 48 percent of the time.
The debate is sure to go on.
Sandra F. Witelson, a
professor of psychiatry and behavioral neurosciences at
McMaster University in Hamilton, Ontario, said biology
might yet be found to play some role in women's careers in
"People have to have an open mind," Dr. Witelson said.
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