Inferior: How Science Got Women Wrong—and the New Research That's Rewriting the Story

by Angela Saini

At the moment at least, the verdict of politicians and scientists seems to be that including sex as a variable when carrying out medical research can improve overall health.

In 1993 the US Congress introduced the National Institutes of Health Revitalization Act, which includes a general requirement for all NIH-funded clinical studies to include women as test subjects, unless they have a good reason not to. By 2014, according to a report in Nature by Janine Clayton, just over half of clinical-research participants funded by the NIH were women.

We know that around the age of two or three, children start to become aware of their own sex. Between the ages of four and six, a boy will realize that he will grow up to be a man and a girl that she will be a woman. It’s also by then that children have some understanding of what’s appropriate for each gender according to the culture they’re in.

by the age of five, children already have in their heads a constellation of gender stereotypes.

Critics pointed out, for instance, the bias in language being used to describe masculinity and femininity. Anything tomboyish, for instance, was interpreted as a girl behaving like a boy. But who was to say that this wasn’t in fact a normal, common feature of being female?

This was part of the problem with his work on testosterone and the brain, he adds. Geschwind’s eminence in his field made it easy for his theory to be published in important journals, even when it turned out that the evidence for it was worryingly thin.

“When I was born, my sex wasn’t determined at first look,” he explains. “I had a penis but it was very, very small.” It used to be common in cases like these for doctors to advise people like Michael to live their lives out as girls, because surgery to make their genitals appear female is simpler than constructing a penis. When

People with conditions like Michael’s are today described as “intersex.”

They’re not eunuchs or hermaphrodites. They don’t fit the binary categories of male and female, but instead occupy a biological middle point, which many people have yet to accept or understand.

Her findings reveal three areas that show a statistically marked difference. Starting with the obvious first, “for gender identity, the differences are huge. Most men think of themselves as men and most women don’t,” she states. “The second thing is sexual orientation. Most women are interested in men, and most men aren’t.” The third one is childhood play behavior. Studying girls with congenital adrenal hyperplasia, with higher than normal levels of testosterone, she found, “Rough-and-tumble play is increased in girls exposed to androgens. They like boys’ toys a bit more, girls’ toys a bit less, and they like to play with boys more than the average girl does, but not as much as the average boy. That’s been replicated by seven or eight independent research teams.”

The fact that research is replicated is crucial. A lot of work in the field of psychology, even the most widely reported on in the press, hasn’t been.

She and others found in study after study that boys on average really do prefer to play with trucks and cars, while girls on average prefer dolls. “The main toys are vehicles and dolls. Those are the most gendered type of toys,” she says.

It’s more evidence, she implies, that the differences they’ve seen in toy preferences aren’t purely due to social conditioning but have a biological element, too. This difference in toy choices, however, is a far leap from the theory that the brains of men and women are deeply structurally different because of how much testosterone they’ve been exposed to.

Tallying all the scientific data she has seen across all ages, Hines believes that the “sex difference in empathizing and systemizing is about half a standard deviation.” This would be equivalent to a gap of about an inch between the average heights of men and women. It’s small. “That’s typical,” she adds. “Most sex differences are in that range, And for a lot of things, we don’t show any sex differences.”

concluded that the psychological gaps between women and men were far smaller than the differences that existed in society among women and among men.

In 2010, Hines repeated this exercise using more recent research. She found that only the tiniest gaps, if any, existed between boys’ and girls’ fine motor skills, ability to perform mental rotations, spatial visualization, mathematics ability, verbal fluency, and vocabulary. On all these measures, boys and girls performed almost the same.

Beyond gender identity and toy preference, on pretty much every other behavioral and cognitive measure that scientists have investigated (in a field that has left few stones unturned), girls and boys overlap hugely. Indeed, almost entirely. In a study by Hines exploring color preferences, for example, she found infant girls also had no more of a love of pink than boys did.

In every case, except for throwing distance and vertical jumping, females are less than one standard deviation apart from males. On many measures, they are less than a tenth of a standard deviation apart, which is indistinguishable in everyday life.

When it comes to intelligence, too, it has been convincingly established that there are no differences between the average woman and man.

At the same time, the authors point out that the biggest effect is seen at the bottom end of the scale. Those with the very lowest intelligence scores tend to be male. This is partly genetic. X-linked mental retardation, for instance, affects far more men than women. “Mainly it’s at the bottom extreme because they have more developmental disorders,”

in some social environments, they don’t get encouraged at all, but I think in affluent, educated social environments, there is still a tendency to expect more from boys, to invest more in boys,” she tells me. This observation is backed up by recent research into how people often think of genius as being a male feature.

She tells me that she remains intrigued by the idea of empathizing and systemizing brain types, but believes that it’s only at the extremes where researchers seem to find any discrepancies. “It’s all a bell curve. . .and for the kids in the middle there’s almost no sex difference there at all,” she says.

gender differences fall on a continuum, not into two separate buckets.”

The scientific picture emerging now is that there may be very small biological differences, but that these can be so easily reinforced by society that they appear much bigger as a child grows.

“My opinion is that you will find differences wherever they were reinforced, because we love categories,. . .we need to have categories. And so once we’ve decided, once we’ve labeled ‘this is a girl,’ ‘this is a boy,’ then we have so many culturally strong biases that we maybe produce differences in abilities. So for example, in physical abilities, if we push boys to be more active and to deal with danger, then of course later in life when they’re children, they will look different. But that does not mean the differences were in the biology,” says Gliga.

In a beautifully clever and witty letter eventually published in Popular Science Monthly, she revealed that all her experts couldn’t distinguish between a male and female brain at birth. Even among adults, it would be a mere guess whether a given brain was male or female. The overlap between the sexes was just too big. Her sharpest observation was that the weight of a person’s brain couldn’t be a measure of intelligence, anyway. It was the ratio of body weight to brain weight or body size to brain size that was important.

Today it’s well established that brain size is related to body size.

“If you correct for skull size, there are very tiny differences between the two sexes, but their brains are much more similar than they are different.” The missing five ounces are accounted for. But that hasn’t stopped scientists, even today, combing brains for evidence that women think differently from men.

It stated that the brain-wiring differences shown by the Gurs and their colleagues indicate that men are better at carrying out a single task while women are better at multitasking. Ruben Gur himself admits to me that he hasn’t seen any scientific evidence to support this claim, and he’s not sure how it made it into the press release.

More women than men tend to suffer from depression or have eating disorders, and she found that, time and again, their illnesses were being explained as something innate to them as females that made them vulnerable. She was instead convinced that there were stronger social reasons for their mental problems. This sparked a fascination with how biological explanations are used and misused, particularly when it comes to women.

“It has been claimed and demonstrated that many (and possibly most) of the conclusions drawn from biomedical research are probably false,” the article began. The authors explained that one big complication is that scientists are under enormous pressure to publish their work, and journals tend to publish results that are statistically significant. If there’s no big effect, a journal is less likely to be interested. “As a consequence, researchers have strong incentives to engage in research practices that make their findings publishable quickly, even if those practices reduce the likelihood that the findings reflect a true. . .effect,” they continued.

The problem has at least been recognized. Even so, Gina Rippon believes that sex difference research continues to suffer from bad research because it remains such a hot-button topic. For scientists and journals, a sexy study on sex difference can equal instant global publicity. The vast majority of experiments and studies show no sex difference, she adds. But they’re not the ones that get published.

In her 2010 book Delusions of Gender, psychologist Cordelia Fine coins the term “neurosexism” to describe scientific studies that fall back on gender stereotypes, even when these underlying stereotypes are themselves unproven.

Study after study has shown almost all behavioral and psychological differences between the sexes to be small or nonexistent. Cambridge University psychologist Melissa Hines and others have repeatedly demonstrated that boys and girls have little, if any, noticeable gaps between them when it comes to fine motor skills, spatial visualization, mathematics ability, and verbal fluency.

Certainly, more recent studies suggest that sex differences in parts of the brain are not as big as scientists once thought. A 2016 paper in the journal NeuroImage established that the hippocampus—a brain region that many researchers have claimed is bigger in females—is in fact the same size in both sexes.

“Sex differences in the brain are irresistible to those looking to explain stereotypic differences between men and women,”

For Gina Rippon, this has become a tiresome battle. “There are people like Larry Cahill who call us ‘sex difference deniers,’ but it’s the same kind of attack that gets put on feminism at each stage, or whatever wave you think you’re in,” she tells me. “I’m not paranoid or a conspiracy theorist, but there is a very strong, quite powerful backlash in this area. It’s kind of acceptable in an odd way, which is not true if you’re talking about race or religion.” As someone outspoken about sexism in science, she occasionally receives misogynistic e-mails from men who disagree with her. The worst ones attach photos of their genitalia.

According to social psychologist Cliodhna O’Connor based at Maynooth University in Ireland, Ruben and Raquel Gur’s study on white matter is a textbook example of how research into sex differences can quickly become absorbed into people’s wider gender stereotypes. When the paper was published in 2014, she decided to monitor reaction to it. What she found was shocking. “It was covered in all the major national newspapers,” she tells me. “The main meaning that was taken out of it was just the fact that men and women are fundamentally different in some very essential, primitive, unavoidable way.”

“As a conversation evolved, cultural and gender stereotypes were progressively projected onto that scientific information, to the extent that people were describing the research as the discovery of stuff that wasn’t even mentioned in the original scientific article,” she says. People latched on to the idea in the press release, but not in the paper, that women are better at multitasking. Before long, they were using the study to argue that men are more logical while women are more emotional. “That dichotomy wasn’t mentioned either in the press release or the original article, but it was kind of spontaneously introduced when people were discussing the research,” she adds. O’Connor

Another factor that prompts people to behave this way is that we like to justify the social system we’re in. If everyone around us thinks that women are less rational or worse at parking, even the thinnest piece of information that reinforces that assumption will be pasted into our minds. Research that confirms what appears to be obvious seems right. Anything that contradicts it, meanwhile, is dismissed as aberrant. This is why, when theories come along that challenge gender stereotypes, we may also find them more difficult to accept.

Neuroscientist Eleanor Maguire at University College London discovered that the mental feat of memorizing the layout of twenty-five thousand streets and thousands of landmarks, known as “The Knowledge,” could be changing the size of a cabbie’s hippocampus, a region associated with memory. This piece of research had enormous implications. It helped confirm an idea that scientists had already been developing since the 1970s, particularly through animal studies: that the brain isn’t set in stone in childhood but is in fact moldable throughout life.

plasticity is a phenomena that has been oddly ignored when people talk about sex differences in neuroscience. “Our brain actually absorbs a lot of information all the time, and that includes people’s attitudes to you, expectations of you,” says Rippon.

Rippon, Fine, Jordan-Young, and Kaiser have argued that biology and society are “entangled”—that they work in concert with each other, through mechanisms like plasticity, to create the complicated picture we call “gender.” Their ideas are supported by a growing body of evidence on how gender differences shift over time.

We know, for instance, that playing with certain toys can actively affect a child’s biological development.

On the flip side, exposing someone to bad stereotypes can impair their performance.

Looking at the brain and behavior as a whole produces very different results when it comes to sex difference. Joel’s research reveals that, depending on the study, between 23 and 53 percent of people show variability in their brains, with features associated with both men and women. Meanwhile, the proportion of people in the studies she has analyzed that have purely masculine or purely feminine brain features is between none and 8 percent.

We are all, each one of us, a mix. Our brains are intersex.

“The problem with this question of difference and similarity is that we’re all different and we’re all similar,” explains Daphna Joel. “When people want to study sex in the brain, they immediately translate this to studying sex differences. But already here they make many assumptions, and the first is that there are two populations of brains, male and female.

Writing our evolutionary story isn’t easy and it’s also plagued by controversy. As Charles Darwin’s work in the nineteenth century proves, the narratives have often been shaped by the attitudes of the time.

Hrdy believes that being a woman in her field is one reason she noticed behavior that hadn’t been recognized before. She was driven to investigate what others may have chosen to overlook.