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12655The Science of the Sexes

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  • Murray J. Braithwaite
    May 31, 2001
      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
      spatial ability.

      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

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