Woman: An Intimate Geography (44 page)

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Authors: Natalie Angier

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BOOK: Woman: An Intimate Geography
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1000, when Scotland was more pagan than Christian, dominated by Viking culture. Cast as a Viking, Lady Macbeth loses none of her brutality but gains much of our sympathy. Viking women were expected to curry ferocity, to be thick of blood and galled of milk. Viking men were away on raids for months or years. Viking women were in charge of the fiefdoms back home, and they had considerable power to make decisions about life and death, war and peace. But they had little time for pomp and mead parties. The plundering class is ever at risk of being plundered, and there were no laws, no local sheriffs, no Royal Canadian Mounties to protect a Viking's property or person. The only insurance against threats from the outside was kin and clan. A weak clan could not attract allies. A weak clan could be exterminated in a single spasm of slaughter. A Viking woman didn't have the luxury of indifference to status. Macbeth could always hop aboard a ship and take his middling thanely title and milk of human kindness overseas. For his lady, moored on the Scottish highlands, nothing short of a queen's crown looked strong enough to shield the clan, and there was no way to gain that crown but with the point of a knife.
Lady Macbeth is every actress's dream role, but we can be glad that we don't have to play the Norsewoman in everyday life. Our aggressions are more palatable, less indelible. Still, we have aggressions,
our
aggressions, and that we need them is what matters, and if we approach them without hostility or mental transvestism and search out their source and substrate, then we can forgive ourselves our woman's gall and blow a kiss to our friends.
Which brings me to testosterone, so formidable by reputation that you can practically hear its carbon rings clanking. There is no way to think about the source of aggression without looking testosterone in its cocky little eye. Testosterone the conquering concept has swaggered among us too long to ignore as a trifle. We have heard and heard again that testosterone mediates aggressive behavior somehow, in some way, we're not sure of the details, but nevertheless the hormone is surely a contender. Testosterone is linked to all those traits covered by the umbrella term
aggression
, such as the urge to dominate or attack another, to show off, to bluster, to leave heaps of dirty laundry in the middle of the floor. It makes leaders and it makes crooks, and if it can be hard to tell the difference between the two, well, that's testosterone for

 

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you as subtle as a sledgehammer. Testosterone is said to start its maneuvers young, pre-young, to shape the brain of a developing fetus and dispose the brain toward domineering, reckless, ham-handed behavior later in life. Testosterone is to aggression what breasts are to buttocks: think of one, and the other inevitably pops to mind.
Of course, lately we have all learned and been told that testosterone is not strictly a male hormone, that females have some too. But less of it, mind you, much, much less of it. The average levels of circulating testosterone among women fall between 20 and 70 nanograms per deciliter of blood. Half is made by the adrenal glands and half by the ovaries. Among men, 300 nanograms per deciliter is on the low side, and most men are in the 400-to-700-nanogram range in other words, they have ten times the amount found in women, and nearly all of that plethora comes from the cells of the testes. So men have more testosterone. So we think men are more aggressive than women. And so we think that testosterone is partly if not largely to blame or to credit for the putative aggression asymmetry.
We have also come up with a new creature called the high-T woman, whose testosterone quotient is on the upper end of the normal female range and who is more aggressive than the average woman, more dedicated to her career, more sexually assertive, less interested in children a
very
little mother. This high-T woman is a biologically tinted attempt to explain why some women behave like error variants, but there is in fact scant evidence to support the existence of the high-T gal, or, more precisely, the gal whose forceful, edgy, ambitious style is the result of elevated testosterone concentrations. Testosterone has been accorded vast powers, as the libido hormone, the aggression hormone, the dominance hormone. But if women had to rely on their testosterone to get anything done in life, to feel erotic or angry or noncomatose, they'd be a pathetic lot. There's so little there there. Even a high-T woman, with her 70 nanograms per deciliter, would not make a sub-passable man. It has been proposed that
because
women have low levels of testosterone, they are extremely sensitive to small variations and fluctuations of it. Can this be? Despite its reputation, testosterone is not a particularly active hormone; grain for grain, it is much less biologically potent than estradiol. Men appear to need great swells of it to subsist. Why should a woman be better equipped than a man to whip a feeble hormone into a

 

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source of behavioral power? The likely answer is, we aren't, and we don't need to be. We have paid a long and blind obeisance to testosterone the conquering concept, to the point where we assume it rules all rulers, male or female, present or wistful; but if we challenge the dominant paradigm and see how badly it fails us, we can begin to imagine a parallel universe, where the neural substrate of a Viking matriarch is not a booby prize but our birthright.
Testosterone is said to work in two stages on the brain, the organizational stage and the activational stage. Organization happens prenatally, when the testes of a male fetus begin releasing testosterone, which supposedly shapes the brain in male-specific ways. Much later, during adolescence, activation occurs; testosterone levels rise in a young man and switch on all the male-specific patterns that were set in the womb, and we are given the raw material for Fortune 500 executives (all but 10 percent of whom are male) or very large bruisers named Arnold (Schwarzenegger) or Norman (Schwarzkopf).
The female brain, by contrast, is the steady-state brain, the default brain, the plan we go with unless otherwise signaled. The female brain is not exposed to a burst of testosterone prenatally, because the female has no testes to release testosterone. The characteristic circuitry of the female brain is established by absence rather than presence. On reaching puberty and feeling the surge of estrogen and progesterone, that circuitry is activated in its female-specific conformation, forthwith to counsel behaviors like . . . well, it's hard to say, and naturally it differs from individual to individual, but in essence, all things muzzled not quite as aggressive as the male, not quite as ambitious, not quite as obnoxious, not as obsessed with sex. That, at least, is the persistent presumption of the standard organizational/activational theory of the sexing of the brain that the female brain is comparatively less primed to aggressive, dominant behavior and all accessories and permutations of such.
Now we can consider the blemishes and qualifications of the O/A hypothesis. First, testosterone as such may not be what matters during the prenatal imprinting. The thinking among many researchers is that much of the testosterone that reaches the fetal brain is promptly converted by the neurons to estrogen, and only as estrogen does it affect the sexual architecture of the brain. Yes, only as a ''female" hormone can the

 

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male hormone masculinize the brain. Which means that estrogen is what counts for the sexing of the brain and the dispensation of aggressive, dominant, or satyric behavior. Females know from estrogen. In this hormone, we can't exactly be ranked as deprived. Still, one can preserve the O/A hypothesis by insisting that what counts is not estrogen versus testosterone but the quantity of steroid hormone to which the fetal brain is exposed. Supposedly, estrogen in a fetus's blood, whether from the mother or from the fetal ovaries, gets bound up by a fetal protein called alpha-fetoprotein and is unable to penetrate the brain. Supposedly, testosterone from a boy fetus's testes doesn't get bound up by this fetal protein, so it
can
reach the brain. If it is then converted to estrogen before influencing brain architecture, so what? It is nonetheless cortically present and accounted for, and a girl's estrogen is not. The great steroid surge remains the ken of the male fetus. The female brain keeps its hormonal virginity.
Except that it doesn't. Most of the experiments suggesting that it did were performed in rodents, where alpha-fetoprotein is adept at waylaying blood estrogen. In humans, the protein doesn't distract estrogen from reaching the brain. And so estrogen from the mother is free to affect a girl baby's brain, and estrogen from the girl's ovaries may do the same. A drizzle of estrogen plies the female brain throughout gestation, and who can say how much is flowing or what its impact on the neuronal conduits may be? Scientists assume that the dose is still relatively low compared to the hormonal swell that reaches a male fetus's brain from his testes, and that, to put it schematically, low estrogen feminizes a brain while high estrogen masculinizes a brain, and high estrogen comes from prenatal ejaculates of androgen which are converted to estrogen in the brain. Yet there is no proof for this assertion. Even in rodents, the tidy dichotamous model doesn't pan out. Take female mice that have been genetically altered so they lack estrogen receptor-alpha and therefore have one less way of responding to estrogen than a normal mouse does. If a brain that is spared the impact of estrogen during development is slated for femininity, these mice should be the murine equivalent of the goo-girls on television commercials, superfemmes. But they're not. On the contrary, they're unusually aggressive. Some are infanticidal. They see another female's pups, and they attack. The receptor-deficient females are more aggressive than the

 

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male
mice that lack estrogen receptors. Those males appear somewhat feminized. They don't like to venture across open spaces, as male mice usually do. They mount females, but then they don't ejaculate. Their brains were also deprived of the developmental persuasions of estrogen; their testes made testosterone, but the testosterone couldn't exert its organizing influence on the brain because the hormone had to do its deed as estrogen, and the estrogen receptors weren't listening.
What, then, is the moral of our story? That if you're a chromosomal gal and you can't respond to estrogen in utero, you turn guyesque? But if you're a guy and you can't respond to estrogen, you turn gal? Or something like that, or something else altogether? Or is the moral that the old stories won't do, and that the female brain is made, not defaulted, and that if brain development in either sex is perturbed by a genetic anomaly, the resulting animal will defy expectations and laugh in all the wrong places?
Women have testosterone, but it's nothing to hang a helmet on. We can't count on testosterone, and there's a good chance we don't need to.
The studies that link testosterone to aggressive or dominant behavior in men are not pretty. They are a mess. Some studies have found that among male prisoners, the more violent the offense committed, the higher the man's testosterone level. Other studies have failed to find such a correlation. Among young adolescents, boys rated as "tough leaders" by their peers have been shown to have high levels of testosterone; yet one boy's "tough" is another boy's "tough luck," for the same study showed that those boys who had spent their childhoods getting into fights and trouble had fairly
depressed
levels of testosterone on reaching puberty. As a rule of thumb, a man's testosterone will rise right before a challenge, like a football game or a chess tournament, and if the man triumphs, his testosterone stays high for a time, but if he loses, it drops, and it has difficulty getting up again. Testosterone will rise when a man receives a medical degree or a professional honor. It will climb when he is awarded a cash prize for winning a tennis match, but not if he wins the same amount in a lottery and can't feel the peacock for it. The testosterone levels of male trial lawyers who must get up in court and shake their verbal scimitars and slash at any who doubt them are higher, on average, than the testosterone concentrations of tax

 

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lawyers, who do most of their work in the privacy of their office and may even keep an orchid plant on the desk.
But gearing up for a challenge does not always elicit a testosterone spike. Young men competing in a video game tournament show no detectable testosterone shift, neither beforehand nor in the wake of virtually exterminating their opponents. Before a male parachutist leaps from a plane, his testosterone
drops;
it sees what's coming, we can suppose, and swoons at the thought. A man's testosterone concentration also falls when he has fallen in love to the point where he is committed to the woman, and it falls when he is on the verge of fatherhood. Some scientists interpret these results to mean that men in a monogamous relationship don't need their testosterone. They don't want their testosterone. It does them no good if they're going to stay put and be a loyal lover and a devoted father. They don't need as much testosterone as they did when they were on the hunt and might be forced to rattle their chain mail at a rival en route. There are alternate storylines, though. Testosterone can fall when a man is under stress; that's presumably part of the reason why it dips with a drop in social status, or with the loss of a chess game. Is commitment not stressful? Is commitment not a match for the scream that precedes a parachute jump? And impending and new fatherhood are they stressful? If you have to ask, you are inert, and need neither testosterone nor oxygen.
We don't know the meaning of testosterone fluctuations in men. They rise and fall every day, throughout the day, peaking in the morning, subsiding by late afternoon, and rising again before bed. If you cut off the major source of a man's testosterone, his testicles, he may or may not become less aggressive than he was before. Some men who have been chemically castrated for the treatment of prostate cancer report extreme mood changes, usually in a more passive and depressed direction; but they have cancer, for Thor's sake, and why expect them to be out there pretending they are jujitsu masters? Men who were castrated to guard a sultan's harem were not unaggressive. They could be pissy. That's why they were good watchdogs. In ancient China, court eunuchs could be notoriously bloodthirsty, arranging assassinations of emperors and enthroning chosen successors; some were military strategists, others fought as foot soldiers. In this country, surgical or chemical castration sometimes is used as a treatment for sex offenders, particularly

 

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