Delusions of Gender (17 page)

[C]ultural beliefs about gender act like a weight on the scale that modestly but systematically differentiates the behavior and evaluations of otherwise similar men and women. While the biasing impact of gender beliefs on the outcomes of men and women in any one situation may be small, individual lives are lived through multiple, repeating, social relational contexts.… The small biasing effects accumulate over careers and lifetimes to result in substantially different behavioral paths and social outcomes for men and women who are otherwise similar in social background.
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These gendered paths and outcomes then become part of the social world that entangles minds – gendering the very sense of self, social perception, and behaviour that will then seamlessly become once again part of the gendered social world.

But it happens imperceptibly. And so we look for answers elsewhere.

For two millennia, ‘impartial experts’ have given us such trenchant insights as the fact that women lack sufficient heat to boil the blood and purify the soul, that their heads are too small, their wombs too big, their hormones too debilitating, that they think with their hearts or the wrong side of the brain. The list is never-ending.

—Beth B. Hess, sociologist (1990)
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T
wenty years later, and it’s business-as-usual for that list. And somewhere near the top of it is ‘too little foetal testosterone’. Or is it that males have too much of the stuff? At first, it might seem as though the tables have at last turned and that it’s
males
’ inherent deficiencies that are now under scrutiny. According to Louann Brizendine, for instance, the effect of male levels of testosterone on the foetal neural circuits is like nothing so much as the ravaging of a village by enemy soldiers:

A huge testosterone surge beginning in the eighth week will turn this unisex brain male by killing off some cells in the communication centers and growing more cells in the sex and aggression centers. If the testosterone surge doesn’t happen, the female brain continues to grow unperturbed. The fetal girl’s brain cells sprout more connections in the communication centers and areas that process emotion.

A consequence of this ‘fetal fork’, Brizendine explains, is that ‘[g]irls do not experience the testosterone surge in utero that shrinks the centers for communication, observation, and processing of emotion, so their potential to develop skills in these areas are [
sic
] better at birth than boys”.
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Girls, it seems – at least for the time being until we take a closer look at the data
³
– have not so much a deficiency of foetal testosterone as a lucky escape.

But really, this kind of portrayal is just new ‘advertising copy’ for the old stereotype of females as submissive, emotional, oversensitive gossips.
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And a different, nicer way of saying that females’ brains are designed for feminine skills rather than those necessary for excellence in masculine pursuits. Simon Baron-Cohen, willingly assisted by those who also popularise his work, has been doing a brilliant marketing campaign for foetal testosterone. It is rapidly becoming the must-have accessory for the budding hard scientist or mathematician. For example, in a recent article for BBC News, Baron-Cohen asks ‘why, in over 100 years of the existence of the Fields Medal, maths’ [equivalent of the] Nobel Prize, have none of the winners ever been a woman?’ Over the course of the article, he circles around an answer … because women don’t have the same testosterone-saturated in utero environment. So confident is Baron-Cohen about this link between foetal testosterone and mathematical ability that he expresses concern that a future, hypothetical prenatal treatment for autism that blocks the action of foetal testosterone might reduce ‘that baby’s future ability to attend to details, and to understand systematic information like maths’.
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This foetal testosterone certainly seems to be potent, sex-segregating stuff. So let’s take a closer look, if we dare, at what it actually does.

At the beginning of life in the womb, male and female foetuses both have the same unisex primordial gonads.
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But at around the sixth week of gestation, a gene on the male Y chromosome causes the male’s primordial gonads to become testes. In the female the
transformation is to ovaries instead. Shortly after, at about week eight of gestation, the testes of the male foetus start to produce large amounts of testosterone, often referred to as gonadal testosterone, which peaks at about the sixteenth week of pregnancy. (Researchers sometimes, more accurately, use the term ‘androgens’ rather than ‘testosterone’, because testosterone is one of several very similar hormones secreted from the testes, ovaries and adrenal glands, known as androgens.) By around the twenty-sixth week of gestation, there is once again little difference in testosterone levels between the sexes until another, smaller, testosterone surge in newborn boys that lasts for about three months. No one seems to be sure what this second, postbirth surge does. But the testosterone surge in utero is essential for bringing about male genitalia.
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A genetic male without sufficient testosterone during this critical period will end up with feminised external genitalia, while genetic females with abnormally high testosterone in the same period are born with external genitalia that are masculinised – sometimes even to the extent that the baby girl is mistaken for a boy.

Such discoveries led to a brilliantly elegant idea known as the organizational-activational hypothesis. What if the same hormone involved in building male genitalia, a gift to be enjoyed for a lifetime, also permanently ‘organises’ the brain in a masculine way? (The other, activational, part of the hypothesis proposes that after puberty the circulating sex hormones activate these circuits.) Certainly, testosterone receptors have been found in many regions of the brain, in both males and females, and research with experimental animals is exploring how testosterone acts on the brain to influence its development.
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And so, neuroendocrinologists have investigated the intriguing idea that prenatal testosterone organises the brain. They manipulate the hormonal environments of experimental animals during the critical period that brain organisation is thought to take place, and see what happens to their brains and behaviour.
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Probably the neatest support for the organizational hypothesis comes from songbirds like the zebra finch and canary, in which
often the male sings but the female doesn’t. In these species, the vocal control areas of the brain are much bigger and better in males, which makes perfect sense. What’s more, treating female zebra finches to a male hormonal environment masculinises both their brains (in the vocal control areas) and their behaviour (they sing). Hormone, brain, behaviour –
snap!
(Actually, even here the picture can get a bit messy.)
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But, while to perch on a branch and warble a song may be the best possible way to set yourself apart from the fairer sex if you happen to be a zebra finch, the same does not apply to the human case. And so this kind of result, fascinating though it is, can only get us so far.

When it comes to rat research, there are a few more points of contact. In rats, by the way, the surge of testosterone that appears to be involved in brain masculinisation actually takes place shortly
after
birth. Researchers have found that male rats castrated at birth are more similar to females in various ways, such as their propensity for aggression and how easily they become dazed and confused in a maze. Immediately, the cogs start to spin. Could prenatal testosterone in humans create permanent sex differences in the brain that lie behind gender differences in cognition and behaviour?

It’s plausible but, as some researchers have pointed out, there are dangers in extrapolating from rats and birds to humans. Working from an implicit we’re-all-God’s-creatures framework that we do not apply when it comes to the right to not be killed and eaten, enjoy access to education or drive a car, there’s a tendency (especially among some popular writers) to assume that what goes for the rat can be readily applied to humans.
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Often, of course, this is the case. But while there
are
important similarities between all mammals great and small, there are also critical differences. As Melissa Hines points out (although she puts it rather less crudely), a penis is a penis, whether tucked between the legs of a rat or a man. Suitably scaled for size, it serves much the same function in both species, and the mechanism by which it’s produced may be much the same in the two species. But a rodent brain, even expanded to suitably grand proportions, would serve a human
extremely poorly indeed. Whereas in the human brain the so-called association cortices, devoted to complex and clever higher-order thinking, have taken over much of the available space, in the rat brain the association cortex has to squeeze in where it can among the neurons devoted to smell, sight, sound, touch and movement. It’s for this reason that Hines cautions that ‘one cannot assume that early hormonal influences on neural development in other mammals, particularly those involving the cerebral cortex, are preserved in humans.’
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Likewise, the very point of the slur ‘birdbrain’ is to indicate that the thinking skills of the person in receipt of the insult are, in some important way worth commenting on, inadequate.

There are several other important dissimilarities, too, between how early hormones affect rats and humans.
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All in all, some researchers think that rat data may not be very helpful in illuminating what goes on in humans.
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That’s not to say that the same principle doesn’t apply – that foetal testosterone has some important effect on the brain. But it’s wise not to extrapolate too enthusiastically from rats. So what about primates? Unlike rats, female rhesus monkey infants treated prenatally with testosterone are no more aggressive than untreated females. In fact, even normal female infants are no less aggressive than males when they are reared in a normal social group.
¹⁵
However, female infants experimentally treated prenatally with testosterone are keener than untreated females on rough-and-tumble play.
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And when prenatal testosterone is blocked in males, early in gestation, these males are a bit less interested in rough-and-tumble play.
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Researchers hypothesise that the changes they see in behaviour as a result of their hormonal manipulations are brought about by testosterone-induced changes in the foetal brain (or, in the case of the rat, the neonatal brain). But I say
hypothesise
because it has proved harder than you might think, even in the relatively humble rat, to connect the dots between prenatal hormones, brain changes and behavioural change. For example, more than twenty-five years ago it was discovered that a certain region of the rat brain (part of
the preoptic nucleus) is much larger in male rats than in female rats. Treating female rats with androgens early in life makes this region bigger, and depriving male rats of androgens prevents the normal male supersize appearance of the preoptic nucleus.
¹⁸
So far – hormone to brain – so good. But getting from brain to behaviour has proved a challenge. In 1995, the pioneer in this research, Roger Gorski, lamented, ‘We’ve been studying this nucleus for 15 years, and we still don’t know what it does.’
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Nearly a decade later, neuroendocrinologist Geert De Vries pointed out again that scientists have ‘not gotten an inch closer’ to working out how this sex difference in the brain translates into behaviour. And not for want of trying.
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Demand a story that includes a clear hormonal beginning, a neat neural middle, and a convincing behavioural end and the best that researchers have to offer involves a small area of the brain stem that innervates the penis. Without wishing in any way to denigrate the painstaking work of neuroendocrinologists (or, for that matter, the glory of the male machinery), so far they are falling way behind in the schedule of scientific discovery that Brizendine and others blithely attribute to them.
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