Never Mind the Bollocks

Hilary Rose and Steven Rose

  • Brain Storm: The Flaws in the Science of Sex Differences by Rebecca Jordan-Young
    Harvard, 394 pp, £25.95, September 2010, ISBN 978 0 674 05730 2

Aristotle affirmed the essential difference between the sexes: men’s brains were bigger, women were more inconstant, emotional and compassionate, at least in part because they do not produce semen – whence men’s and women’s different behaviour and place in the social order. Symbolically, at least, biology’s long, continuing and often lamentable history of using its authority to define woman’s nature, in order to justify attributing her with inferior status, begins here.

According to naturalists, the origin of gender differences lay in men’s genitals and women’s menstrual cycle. That the testes produced masculinity was apparent from the effeminate nature of eunuchs; ingesting extracts of animal testes has long been assumed to enhance a man’s potency, bellicosity and intellectual pre-eminence. By the end of the 19th century the physiologist Charles Edouard Brown-Séquard was injecting himself with extracts of dog and guinea-pig testicles to restore his youth. (It failed.) In popular culture the scientist’s elixir was transformed into ‘monkey glands’, which had a long, if much satirised, vogue, still extant in the host of testes-related products sold as rejuvenators on the net and in health food stores. Similarly, it was the ovaries and their juices that conveyed a woman’s essential womanhood and accounted for her naturally nurturing role, while making her a stranger to such activities as war or science.

In the 1930s the active principles found in testes and ovaries – hormones – were isolated and their chemical structures determined. The endocrinologists saw them as specifically ‘sex hormones’, and named them testosterone and oestrogen. Alas for the complexities found in subsequent research, the names stuck. No matter that both sexes produce both hormones and that they have many and varied physiological effects; no matter that they are chemically very similar members of a family of steroid molecules readily converted into one another in the body. In popular accounts testosterone is the male principle, oestrogen the female, with the consequence that the Alastair Campbells of this world are invariably described as ‘testosterone driven’.

As for brains, even after the fashion for phrenology had declined by the late 19th century, the science that replaced it – craniometry – assumed that brain size was a powerful surrogate marker for intelligence. Men’s brains, Paul Broca reported, were on average 14 per cent heavier than women’s. Broca’s data were elegantly picked apart by Stephen Jay Gould in The Mismeasure of Man. Most of the difference is accounted for by differences in height and build between men and women, and once corrected for these, the gross difference evaporates. After Broca’s death – it turned out at his post-mortem that his own brain was disappointingly small – the enthusiasm for relating brain size to intelligence receded.

It wasn’t until the 1960s that more refined measurements began to reveal subtle anatomical differences between men’s and women’s brains. Men’s brains seem to be a bit lopsided: the hemispheres are slightly more asymmetric than women’s. There have been claims that the shape and size of the corpus callosum – the broad tract of white matter that connects the two hemispheres – differs between the sexes, but they have been vigorously contested. Even if such differences could be unequivocally substantiated no one has the slightest idea what their implications might be for the allegedly essential differences between the sexes. The myth of the left-brain cognitive male and the right-brain affective female still persists, while women’s supposedly thicker corpus callosum has been invoked to explain why men are more single-minded and women better at multi-tasking.

Modern imaging studies haven’t helped. Most such experiments involve putting people in an fMRI machine and setting them tasks to perform or problems to solve. Differences between the sexes in brain activity patterns are found fairly frequently. However, whatever the brain patterns, the time taken to solve the problems and the solutions offered do not generally vary between the sexes, so to infer behavioural or cognitive differences from some measurable difference in brain processes is a step too far. Indeed, the logic might work the other way round: that’s to say, the experiences of everyday life may influence our brain structures or activities. It has been found that the posterior part of the hippocampus of black-cab drivers is enlarged by comparison with a control group (though one London cabbie told us he didn’t believe a word of it as he’d been a black-cab driver for 30 years, like his father before him, and if it were true, then his brain would long ago have burst out of his skull).

It is the finding that certain clusters of nerve cells in the hypothalamus are more abundant in men than in women that links hormonal and brain accounts of sex differences, as these hypothalamic cells carry receptors that bind testosterone. But studying differences between adult brains doesn’t explain the origin of these differences: do they result from some internal programming that differs between males and females, or are they, like the taxi drivers’ larger hippocampus, imposed on the brain’s highly plastic structure and chemistry by everyday experience? A partial answer comes from the study of foetal brain development. The current consensus among biologists is that during early development in utero, male and female brains are indistinguishable. However, in the normal development of the male brain, there is a surge in testosterone production, which initiates the structural and biochemical processes that masculinise the brain. This is what has come to be known as brain organisation theory, a concept pioneered by John Money in the 1960s. It is currently the leading explanation for the essential difference between men and women.

The real world question, however, still goes back to Aristotle: do such differences legitimately naturalise the different places in which men and women find themselves in the social order? Among those insisting on the ‘Essential Difference’ is the autism researcher Simon Baron-Cohen. He believes that the testosterone surge makes men’s brains S-type (systematising) and women’s E-type (emotional), and that autism lies at the extreme end of the male range. Leave aside the fact that some men and women – the two of us, for example – may well find when they answer Baron-Cohen’s questionnaire that they have the brain of the other sex. For Baron-Cohen, as for other determinists, gender difference has to be understood within an ideology of diversity rather than inferiority. But such a celebration of diversity cuts little ice when reckoned against the persistent association of women with low paid work and with poverty in the developing world, which is more easily explained through neoliberal economics than through neuroscience.

Where, in this binary world, do intersex people, gay men, lesbians or transsexuals find a place? Their existence has long been a problem for essentialists – a problem solved culturally by pathologising them. Earlier versions of the American psychiatrists’ bible, the Diagnostic and Statistical Manual, defined homosexuality as a disease: it wasn’t until 1974, with the rise of the gay and lesbian movement, that it was officially depathologised. But still today intersex people have to contend with a powerful biomedical culture, which insists that the binary divide is fundamental to every aspect of life. Those whose bodies and sexualities fail to respect this divide are encouraged, or forced, to seek medical intervention with a view to locating them safely on one side or the other, by way of scalpels, hormones and psychotherapy.

As intersex people became more visible through clinical intervention and research, they were seen as offering a research opportunity: if differences between the ways men and women think and behave are a matter of brain structures and hormone balances, then intersex or homosexual people’s biology and thought patterns will also be intermediate. In that case ‘gay brains’ should resemble female brains, or at least be intermediate between those of straight men and women. In 1991, the gay neuroscientist Simon LeVay claimed, on the basis in part of post-mortem studies of gay men who had died from Aids, that he had found such an intermediate region in the hypothalamus. LeVay’s results have not been replicated, although the Dutch researcher Dick Swaab subsequently located ‘gayness’ in a slightly different region of the hypothalamus. Two years after LeVay’s report, the geneticist Dean Hamer claimed to have identified a ‘gay gene’ (or, more precisely, a chromosomal region which contained such a gene). Like LeVay’s, Hamer’s androcentric claim has not stood the test of time. But it was immediately welcomed by the US gay community, who saw Hamer’s research naturalising ‘gayness’ as legitimating their sexuality while in the UK it was resisted, as naturalisation was understood as biological determinism.

An alternative focus of attention for biopsychological researchers concerned with sex and gender has been on brain organisation theory. Could some factor affecting the foetal testosterone surge alter sexual orientation? One of the commonest causes of intersex, and one that takes centre stage in Rebecca Jordan-Young’s Brain Storm, is a recessive genetic condition, congenital adrenal hyperplasia (CAH), which affects one in 15,000 children in Europe and the US. CAH can result in an overproduction of adrenal hormones in utero. One of the many consequences of this is that genetic (XX) females are born with ambiguous genitals, sometimes including a miniature penis and scrotum (genetic – XY – boys born with the condition have enlarged penises and reach puberty prematurely). The medical world regards the condition as a profound sexual and personal problem for the child and its family, which medicine should help normalise. Confident that there are two sexes, and two sexes only, clinicians seek objective criteria by which to assign the child to its ‘true’ sex. Thus the size of the penis helps determine whether the infant should be designated male or female. Young boys should be able to urinate standing up, and men should have a penis big enough for vaginal penetration during sex – a distinctly male heterosexual view. In the pursuit of measurable and therefore scientific sex assignment, a baby born with a penis less than 1.5 cm long and 0.7 cm wide is to be made female, and reconstruction to transform these into ‘appropriate’ female genitals is begun not long after birth. The process requires a sequence of operations over many months – interventions based on the cultural norm, shared by doctors and parents, that sex is and must be binary. Such thinking is beginning to be challenged by the intersex movement in the US. However, if brain organisation theorists are right, the hormonal surge that occurs in CAH will have masculinised the otherwise ungendered brain, and as a consequence, irrespective of any surgical reconstruction to the contrary, the child’s behaviour will be masculinised – to be rectified only by lifelong hormone treatment.

For feminists this essentialism is nothing new. Fighting in the late 19th century to secure women’s admission to the universities, they were confronted by patriarchal science which argued that going to university would inexorably damage women’s reproductive function and so for the sake of her own happiness she must be barred from academic life. Feminists were passionate in their opposition to these arguments, but the forces that had successfully prevented them from studying science also prevented them from countering scientific arguments with scientific arguments of their own. By the 1970s, although women were under-represented in the universities – and massively so in the sciences – they were now in the lab, and enough of them were feminists to make possible a strong counterattack.

There were skirmishes over Steven Goldberg’s The Inevitability of Patriarchy (1973) in which he argued that men’s power in the world was a product of their testosterone-driven urge to succeed, regardless of the definition of success in any given society. But although he had based his arguments on the hormone research initiated by John Money and his colleagues, Goldberg was a sociologist. Feminist biologists moved to counter his arguments with science as well as political opposition. But the first real fight came with the publication in 1975 of E.O. Wilson’s Sociobiology, which claimed that a new evolutionary synthesis would reduce the social to the biological, entrenching women’s position. Feminist biologists responded in a special issue of the journal Signs, devoted to the science question in feminism. Among other pioneers in a multidisciplinary alliance, Ethel Tobach and Betty Rosoff launched the series Genes and Gender; Ruth Hubbard, Mary Sue Henifer and Barbara Fried co-edited a collection called Women Look at Biology Looking at Women and Anne Fausto-Sterling explored society in biology as well as biology in society, before turning her attention to hormone research and the construction of sex and sexuality.

Jordan-Young’s new book follows in this tradition. Writing as a socio-medical scientist, her immediate target is brain organisation theory, and the evidence on which its proponents base the claim that sexuality, sexual orientation and what she politely refers to as the ‘sex-typed interests’ are all determined by that fateful testosterone surge. Although well aware of the ethnographic work done on the social construction of scientific knowledge, her concern as an insider is principally with the practice of research. She quotes from interviews with leading researchers, and questions whether the many studies attempting to sustain the theory in practice meet the criteria of scientific method.

Although many inferences about human biology and behaviour are drawn from observations and experiments on animals, especially laboratory rats, whose hormone levels, genitals and brain structures can be manipulated, there are obviously limits to the extrapolations that can be made. As humans can’t be experimented on directly, students of sex differences have to rely on what Jordan-Young calls ‘quasi-experiments’. Genetic conditions such as CAH, or the rare surgical accidents that result in infant males having their penises destroyed and hence being reared as females, are the subjects of such quasi-experiments. Cohort studies follow the children through their development and into adulthood. Alternatively, one can use a case control approach, attempting to identify factors in an adult’s prenatal hormonal experience that might account for their current sexuality or sexual orientation.

In her exhaustive survey of the literature Jordan-Young discovers a hodge-podge of tiny samples, inadequate controls, conflicting data and extravagant conclusions. Prenatal stress can either increase, have no effect or reduce the likelihood of someone’s becoming gay or lesbian. There is a greater incidence of left-handedness among gay men, but left-handedness apparently goes with ‘hypermasculinity’ rather than the anticipated feminisation. Girls exposed in utero to high levels of progestins, which induce prenatal androgenisation, were described as being tomboys as youngsters, but showed ‘stereotypically feminine sexual behaviour’ as adults. And so on. But what shouts loudest in all these studies is the ways in which the researchers’ preconceptions of what counts as appropriate male or female behaviour shapes their research. Girls (and apparently even infant female vervet monkeys) are supposed to prefer pots and pans and dolls to trucks and Meccano. When girls turned out to be as interested as boys in playing with a construction kit called Lincoln Logs, a Lego aeroplane was substituted instead. It is hard to avoid the conclusion that these studies tell one more about the prevailing ideology of the researchers than about their subjects.

As Jordan-Young points out, researchers’ essentialist preconceptions lead them to ignore context – above all, the fact that gender identities do not spring fully formed from the genome or from the organisation of the newborn infant’s brain. She quotes the ethnographer Suzanne Kessler’s reports of the distress of both mothers and their CAH daughters at the child’s degrading vaginal examinations. How can the interminable intrusive medical procedures, the lifelong drug regimes, to which children with CAH are exposed not affect their sense of who they are? In the aftermath of the sequencing of the human genome even the most hardline geneticists are beginning to recognise that genes alone can’t determine developmental outcomes. They have found it necessary to reinvent epigenetics, the study of how genes are activated and regulated by environmental experience during development, originally formulated by C.H. Waddington seventy years ago and now returned to mainstream science. As Jordan-Young puts it, context is all.

‘Taking Context Seriously’ and ‘Trading Essence for Potential’ are the twin themes of her closing chapters. Earlier generations of critics, both feminist biologists whose work she builds on, and radical Marxist critics of genetic determinism such as Richard Lewontin, pioneered these more open theories of biological development. However, they saw ‘context’ as less circumscribed. For them, it encompassed the entire social framework in which science is embedded. These earlier scientist-critics sought to reveal and contest the social values – of sexism, racism and class – that lay within and behind biological determinism. Focusing on the micro-production of scientific knowledge, Jordan-Young ignores this larger context. Nonetheless, by meticulously revealing the flawed research behind brain organisation theory, she opens the way to a non-hierarchical study of sex difference that will be both more fruitful for science and less damaging for society.