The Science of the Sexes
- I recall the foaming hostility of liberals when the Jessel and
Moir book (Brain Sex) came out. Again, enlightenment ideology has
required the doctrine of free will and equality, making creative
capacity and other incommunicable knowledge ineffable (i.e.,
politically irrelevant). The better approach has been to embrace
the biology and probe development. But this implies
acknowledgement that people could have been better parents-->
emotional roadblock. Denial has been the politically correct
response. Now the biology is overwhelming the agenda. Time for
others to take development seriously.
Step one: there is a fallacy to look at current biology and infer
necessity. Example: girls who are nurtured to engage in more
cross-pattern activity than they are hormonally disposed to do,
have the same brain scans as most boys when doing math.
The really interesting fact is the effect of lateralization on
belief revision (the Creationism study and the lateralization
genes). As a society, we might want to "breed" (in the
Nietzschean, non-genetic sense) highly lateralized "explorers"
who have one-track minds with impaired holistic belief revision
(typical uncultivated male pattern) and to breed less lateralized
holistic thinkers with greater capacity for integrating wisdom
(uncultivated feme pattern). The possibility of early
cultivation, rather than random distribution through genetic
disposition and accidental social factors, creates very
interesting justice issues concerning diversity within society
and the Enlightenment sentiment that all persons should have all
options. If the window for becoming a first-rate drone or a
first-rate integrator is the first few years, who is to make the
Murray J. Braithwaite, Ph.D.
Subject: Science of sexes - brain differences
The science of the sexes
New research into brain capacity suggests that men and women
really are on different wavelengths. Science Editor Roger
Highfield assesses the evidence
SCHOPENHAUER, the German pessimist philosopher, wrote in 1851
that only a man overcome by his sexual impulses could have given
the name of the fair sex "to that undersized, narrow shouldered
broad-hipped and short-legged race".
Despite the many differences between the sexes, from average
weight and height to body fat, there has been an assumption that
these are only skin deep and that intellect is essentially the
This week saw the publication of the latest in a growing body of
research demonstrating that our brains are different too,
fuelling the fear that science may provide an antidote to demands
for women's emancipation: if male dominance is all nature's
fault, then patriarchy is inevitable.
Feminists can, however, breathe a sigh of relief at the new
findings, which provide the first evidence from measurements of
electrical activity that the brain of a woman can work faster
than that of a man.
Manfred Fahle, of the University Eye Clinic in TYbingen, Germany,
measured the activity by attaching electrodes to the scalp. When
the subjects were asked to categorise letters, the resulting
activity was significantly faster in women.
Women's brain potentials have a higher frequency
"In these instances, the women seem to perform faster, and their
brain potentials have a higher frequency," he told me.
Importantly, this difference does not occur for all tasks. When
the subjects were asked to search for a shape among various
objects, he found brain activity was the same.
Scientists have understood the underlying cause of the difference
for some time. In 1990, two British teams found that the
difference between the sexes was triggered by a scrap of genetic
material. The men who led the research - Robin Lovell Badge, of
the Medical Research Council, and Peter Goodfellow, now at
Cambridge University -were yesterday rewarded with the 1995 Louis
Jeantet Prize for Medicine.
Residing on the male Y chromosome, the gene switches on a cascade
of genes that make testicles. These in turn bathe the body in
testosterone. "Many of the differences in male and female rodent
behaviour are testosterone-derived," said Prof Goodfellow.
"If you give a female rat a short burst of testosterone shortly
after birth, you end up with a female that demonstrates male
behaviour. But there is a lot of argument about whether a similar
thing occurs in humans."
Women have 11 per cent more brain cells in the regions near the
It was only last year that scientists announced they had found
differences in the thin rind on the surface of the brain
responsible for higher intellectual abilities. Sandra Witelson,
of McMaster University, told the US Society for Neuroscience that
women had 11 per cent more brain cells in the regions near the
temples, one crucial for understanding language in the left
hemisphere, and for recognising melodies and tonal qualities of
speech in the right.
This apparently dovetails with the claim of Moir and Jessel that,
as a result of different levels of exposure to sex hormone at
birth, brains work along different lines so, for example, girls
acquire verbal skills more quickly, and boys develop greater
But most scientists are shy of extrapolating from hormones to
human society. It is rarely possible to control all relevant
factors, such as the influence of parents. And even if hundreds
of studies show that males tend to outscore females on tests of
spatial ability, how can we unravel the many other cultural
The debate will be inflamed by the increasing use of brain
scanners. Prof Nancy Andreasen, of the University of Iowa,
reported on the use of one technique, positron emission
tomography (Pet), to measure blood flow in the brain, thus the
regions used for thinking.
Women have a higher flow of blood to their brains
In a study of 41 men and 31 women, she found that women have a
higher flow of blood through their brains - and thus greater
metabolic activity - than men, independent of brain size. Prof
Andreasen also found, in a comparison of long-term memory for
words and faces in 13 men and 21 women, that slightly different
regions of the brain tended to be used by women.
In studies using another type of scanner, magnetic resonance
imaging (MRI), the brain volume of 48 young men was compared with
that of 44 young women. Prof Andreasen found that men have larger
brains, even when body size is allowed for.
"The finding does not suggest that men have superior brains or
superior intelligence," she said. When she used MRI to measure
the complexity of the brain's corrugated surface, men and women
did not differ, "consistent with the observation that they do not
differ in overall intellectual abilities".
Though such studies will help the understanding of which gender
differences are inbuilt and which are due to social factors, she
still felt the similarities were more striking than the
A different approach is being taken at the University of North
Carolina in Wilmington, where William Overman has carried out
parallel studies of monkeys and children to try to disentangle
nature from nurture. "Our results show that, in fact, there are
significant differences in mental abilities of girls and boys as
young as one to three years of age," he said. "These differences
are not learnt but are probably due to the way sex hormones
direct the growth of particular areas of the brain."
In one task he found boys learnt more quickly than girls; in
another, he found the gender advantage was reversed. Although
there was a considerable overlap in ability between such groups,
this is the first demonstration that children show such
differences. "The findings are important because they parallel,
almost exactly, earlier data in infant monkeys whose mental
gender differences are known to be linked to influences of sex
Perhaps we should abandon the pursuit of equal opportunities
Some go as far as to urge that we abandon the pursuit of equal
opportunities to celebrate such differences. However, these
differences are not in dispute. What liberals have said, rather,
is that they should have nothing to do with equality and human
There is more work to be done, says Overman. "We do not know
whether this gender difference in mental abilities is linked to
those found in adolescents and adults. We do not know the exact
nature of the action of the sex hormones on brain development.
And the present results in children cannot be used to predict
performance in later life on any known educational test or mental