It may seem like a banal question, but it has exercised intellectuals for centuries. “One is not born, but rather becomes, a woman,” Simone de Beauvoir wrote, reminding us that most of what we think of as femininity is something we are inducted into, not born with. All but the most blinkered reactionaries would today recognise a certain slipperiness in cultural notions about gender, but many still can’t help but believe that an unbending biology sifts people at birth into two simple physical categories of sex—male or female—and that these categories matter in a fundamental way.
It’s this belief that underlies a bitter debate currently raging within some corners of, specifically, British feminism about whether transgender women should be welcomed within the circle of womanhood or should occupy a place outside it. JK Rowling is the most famous figure to have entered the fray. “I spoke up about the importance of sex and have been paying the price ever since,” she wrote on her blog after experiencing online abuse. There is no missing the heat of this argument. What’s less appreciated, though, is the absence of light: temperatures rise as they do because there isn’t universal agreement about what sex truly means.
Science is frequently drawn into the tussle. As someone told me with some frustration recently: “isn’t it obvious who is a woman and who isn’t?” If it were quite so obvious, would “science” need to be invoked at all? The fact that it is defensively reached for perhaps betrays how uncertain the boundaries truly are.
Popular opinion, “common sense” and the closely related priors of scientific enquiry have never been reliable guides when it comes to decoding human difference. After all, European biologists once thought it was obvious that colour-coded races were different species or breeds that had evolved separately on each continent. It was obvious to taxonomist Carl Linnaeus that monster-like and feral races of humans surely existed somewhere in the world. More recently, neuroscientists were happily insisting that women were innately less intelligent than men because they had smaller brains. A few neuroscientists still do.
History shows that many supposed “facts” about human nature were actually always cultural constructions. Race is one. Gender is another. Now, some researchers believe that sex—generally seen as determined by anatomy, including chromosomes, hormones and genitalia—may to some extent be constructed, too. Binary categories of male and female, they say, certainly don’t fully encompass all the natural variation and complexity that we see in our species. It’s an approach that undercuts the whole debate by asking whether thinking about people as only men or women, and in significant respects as homogeneous within each category, is the problem to begin with.
“In many instances, a binary model is inadequate to capture the full range of biological diversity of sex-related factors in their embodied and ecological contexts,” I’m told by Sarah Richardson, the Harvard historian and philosopher of science who directs the GenderSci Lab and thinks critically about scientific research on sex difference. “I see more medical and clinical researchers reaching to look beyond the binary.” She adds that simply introducing a third category, non-binary or intersex perhaps, isn’t enough. What is also needed is more interrogation of male and female categories themselves, and an appreciation of the enormous biological breadth that sits within them.
It was the pioneering transgender biologist Joan Roughgarden who almost 20 years ago provocatively called on scientists to accept gender and sexual diversity as natural rather than aberrant, not just in our own species but more broadly in the animal kingdom. “The fundamental problem is that our academic disciplines are all rooted in western culture, which discriminates against diversity,” she wrote in her 2004 book Evolution’s Rainbow, anticipating a discussion only now maturing within the sciences, as researchers look to the cultural limitations of their own historically binary ways of interpreting biological difference.
Richardson showed how necessary this conversation is in her 2013 book Sex Itself: The Search for the Male and Female in the Human Genome, which highlighted how quickly researchers attached all kinds of gendered stereotypes to the XX and XY sex chromosomes after they were discovered at the turn of the 20th century; using words like “sociable” and “motherly” to describe the female X and “macho” and “lazy” to describe the male Y. We still know relatively little about the full impact of the sex chromosomes on the body or behaviour, how they work in concert with other parts of the genome, and how they do or don’t shape development in individuals. Despite the uncertainty, they’re often assumed to hold the key to everything that we need to know about the differences between women and men.
Furthermore, not all humans have XX or XY sex chromosomes. A small proportion of people are born with other combinations: XXX, XYY or XXY, for example. An unknown number are observed at birth to have an indeterminate sex, or outward physical characteristics that don’t match the expectations of their genetic sex. Sex hormone levels, too, vary from person to person, as shown by the case of Olympic athlete Caster Semenya who has a difference of sex development that results in higher natural testosterone levels. She can no longer compete internationally against other women at some distances unless she agrees to have those levels artificially reduced. She isn’t a man, but under the rules of international athletics, she also isn’t woman enough as she is.
Some will respond by trying to count the category-defying cases, arguing that a low tally would mean they are only exceptions to the rule. But numbers are besides the point, and a rigid binary also risks distracting us from the vast diversity that lies within each group. What if the problem lies with the categories themselves?
In India, where my parents were born, there has always been space—as marginalised and even feared by others as it may be—for transgender, non-binary and intersex people. The existence of the hijra community, as it’s known, cannot be forced away because it is visible and was long ago woven into the cultural fabric of Indian society. Here in Britain, there was little accommodation for the existence of individuals who defied ready categorisation by sex. That doesn’t mean they weren’t there; only that, through fear of ostracism and abuse, they have had to hide their true selves.
We find it hard to accept what we’ve never seen. For those who have grown up as (or with) people who are openly non-binary, intersex or transgender, what is “obvious” about sex and gender is very different than for those who haven’t. As ethnic minorities know all too well, it is too easy to demonise the unfamiliar. Sophia Siddiqui recently highlighted the troubling willingness of some feminists in parts of Europe to form alliances with far-right organisations against transgender rights. “Arguments that demarcate who is a ‘woman’ and who is deemed ‘other’ play directly into the far-right agenda [and] moral panic” by, as she puts it, “drawing lines around who is entitled to rights and who is not.”
Those who have experience of being on the wrong end of acts of categorisation know full well how it can be part and parcel of efforts to restrict and control. In her research looking at India’s sizeable hijra communities under British colonialism, historian Jessica Hinchy at Nanyang Technological University has documented how categorisation was used by mid-19th-century colonial officials to assert power. They compiled “registers of eunuchs,” she writes, with the aim of eliminating hijras altogether, believing them to be unnatural and immoral. Fear and hatred were harnessed by the colonial state in an effort to suppress people who only wanted to be who they were.
“What I think needs to happen is we need to accept there is no easy answer,” says Anick Soni, a British Asian intersex activist and researcher. Soni would like to see a world that doesn’t lean on sex or gender boxes the way it does now, but instead accepts individuals as they are without forcing them into categories in which they don’t neatly fit. “If we unlearn our reliance on it, it will be easier in the long run,” he says. His ethos is: “If it exists, let it exist.”
Yet as more enlightened researchers are finally beginning to see the value in thinking beyond the binary, there’s also a growing movement within science and wider society calling for more research into the biological differences between men and women because of fears that neglecting these differences will fail women’s health. “There is a deep tension,” explains Richardson—one that is heightened by “new mandates requiring the study of ‘sex as a biological variable,’” including the expectation that data should be disaggregated by binary sex—even in situations where it’s not immediately clear that sex is relevant.
The problem, as Richardson and her colleagues at the GenderSci Lab have stressed, is that sex differences can’t be assumed. They have to be proven. And it’s notable how few assumed sex differences, after decades of research, have really been demonstrated. Even in aspects of cognition that are associated with strong gender stereotypes—such as spatial awareness or verbal skills—testing has overturned the old assumptions about profound intellectual disparities. Those differences in average aptitude that are seen are statistically tiny and impossible to disentangle from the effects of social conditioning. They are certainly not enough to account for the enormous gender gaps in occupations we see in society. Biology can’t explain the dearth of female physics professors.
The thing many people—including some feminists—find harder to accept is that our bodies don’t fit standard “male” and “female” patterns either. Overwhelming variation within the sexes is downplayed or overlooked, while differences are emphasised—even when there is reliable evidence to the contrary. It has long been assumed, for instance, that women are far more likely to suffer atypical heart attack symptoms than men—it’s an orthodoxy that I repeated in my 2017 book, Inferior: How Science Got Women Wrong. But 2019 University of Edinburgh research, funded by the British Heart Foundation, has corrected me as well as others. It found that men and women were equally likely to suffer typical symptoms. One problem, they learned, was that people didn’t believe that women were having heart attacks when they had these symptoms, because we culturally associate heart attacks with men. The issue was one of presumption—of sexism rather than sex, culture rather than biology.
“Scientific research in any one chosen population will always be limited by the vast variation within it”
That’s not to say there is no need for research specifically on women’s health. There is, particularly when it comes to reproductive health and autoimmune diseases that disproportionately affect women. But scientific research in any one chosen population will always be limited by the vast variation within that population. It’s impossible to generalise about all women, or all men. Yet time and again, essentialist ways of characterising women’s and men’s minds and bodies creep into the public debate, with even avowedly progressive campaigns and research agendas resorting to old-fashioned ideas about the supposed nature of the sexes. In June 2020, two economists at the universities of Liverpool and Reading asked if nations with women leaders fared better during the pandemic because women possess a natural empathy and aversion to risk. The authors were trying to make a positive case for female leadership, but reached for age-old stereotypes instead.
“Naturalist ‘explanations’ choose the biology of the moment,” wrote the French feminist Christine Delphy, who has for many decades challenged efforts to reduce masculinity and femininity to some biological root. It isn’t only misogynists who look to science to denigrate women with claims of natural inferiority, she warned as long ago as the 1970s; it is also certain feminists, who use it to make the case that women and men have innate qualities that make them distinct. “Naturalism is, of course, even more obvious in anti-feminist thinking, but it is still present in large measure in feminism,” Delphy wrote.
The commitment to the sex binary exists right across society, even among some transgender activists, for whom transition has the meaning it does because there is something physically tangible to transition from and to. On the other side, some feminists focus on defending those they class as “natural” women, a category they say you can only be born into. Either sex is the most fundamental thing one can change, or it is something too fundamental to change. No wonder the debate is so fraught.
People’s attachment to the sex binary is understandable in a world that requires us to constantly assert a clear, recognisable identity. And the binary can have a degree of biological salience sometimes. But the problem is with how fundamental it has become. The risk of essentialising women is ever-present, not to mention particularly acute in an age in which small chunks of information circulate on social media without much context. One of those moments came during the height of the pandemic in the UK last year, when it was revealed that there wasn’t enough PPE available in smaller sizes, leaving those with smaller frames at a possibly greater risk of infection. Women’s rights activists, such as Caroline Criado Perez and some health professionals, quickly declared that special PPE “designed for women” was needed.
But which women did they mean? Yes, women in the UK are on average around half a foot shorter than men, but we need only look around us to recognise that not all women or men fit the average. And such averages also vary between times and countries—the average man in South Asia is currently around the same height as the average woman in the UK. Across the globe as a whole, the mean gender gap in height is actually an inch and a half less than it is in the UK; in the Gambia, the gap between the average man and woman is less than two inches. Everywhere, some men have smaller frames and faces than some women, and individual women have very differently sized faces from each other. My brother-in-law, who is a doctor in a hospital just outside London, found the PPE he was supplied with couldn’t fit him either, because it came in a limited number of generic sizes and he—no doubt like many others—did not fit the particular proportions it was designed for. The idea of a single “female face” rests on the assumption that women are a homogeneous physical group.
In the rush to build a unifying portrait of women, the extent of biological differences from person to person are forgotten. We fall back on (literally) reductionist stereotypes of women as being generally “small” rather than appreciating the truth our own eyes relay: namely, that women come in all shapes, some of them taller, bigger, stronger and faster than some men. There may be statistically such a thing as an “average woman”—on particular dimensions, in a given society, at a particular time—but how many real women’s bodies even approximate those averages?
Categorisation papers over natural biological variation. It creates the illusion of homogeneity within groups. People are individually very different, whether they are described as women, men or another term. Having only two narrowly delineated biological categories also leaves some out in the cold. In April, Alexis McGill Johnson, president of the Planned Parenthood Federation of America, admitted that “when we focus too narrowly on ‘women’s health,’ we have excluded trans and non-binary people.”
Where does this leave the question of who gets to be a woman?
“Feminism has always been committed to the proposition that the social meanings of what it is to be a man or a woman are not yet settled,” gender theorist Judith Butler explained in an interview with the New Statesman last September. That sentiment could be usefully extended to science, too. For the biological meaning of sex has not been exhaustively settled, either. Until it is, if that’s even possible, whatever meaning it has is whatever meaning we have chosen to give it. It remains up to us.
“I was still alive and still employed,” Joan Roughgarden wrote near the beginning of her book. That simple statement revealed the precarity of her survival as a transgender woman in a world that didn’t yet fully accept her. While some of her ideas remain controversial, her work stands as a passionate reminder to biologists not to automatically pathologise that which they find unusual, and to recognise that their pronouncements aren’t just theoretical, but impact on real lives. Her hope was that scientists might draw intersex, non-binary and transgender people more firmly within the circle of what we understand to be normal.
There has been woefully little research on the biological and psychological effects of gender transitioning, no doubt because it was seen as an aberrant phenomenon for too long. But as social attitudes are shifting away from a rigid interpretation of sex and gender, this has begun to change—and in doing so it may well disrupt our categories. There is no single meaning of sex and there probably never will be. As Anne Fausto-Sterling has written, the debates about whether “sex is fixed and binary or complex and changeable, appear to be about scientific truthiness. But they are really part of the for-the-moment unsettled process of world-building.”
If there is one thing that makes us human, it is our ability to build new worlds. We are able to conceptualise society in fresh ways, and use technology and medicine to reframe the boundaries of who we are and what we can do. It isn’t always easy to see our worlds change, as Anick Soni acknowledges. For many children and younger adults, the enormous shift in how we think about sex and gender can feel like second nature, even anodyne. They tend to be more used to seeing, interacting with and existing within more fluid notions of gender and sex. To many people of my generation, on the other hand, it can feel as though a rug is being pulled out from under us. That sense of instability, of losing something that felt so tangible before, may help to explain why some retreat by clutching onto their traditional gendered stereotypes more tightly: the aisles of toy shops have never been more distinctively pink and blue, and “gender reveal” parties for babies still in the womb have become a trend.
In the meantime, who we include in our categories is often more a reflection of social than scientific choice. It depends on where we decide to draw the lines, because the lines themselves do not automatically and definitively exist in nature. An appeal to “science” is of no use when scientists themselves, often conditioned by the same priors as everyone else, are still negotiating what sex and gender really mean. How wide we draw our circles, then, is about the willingness to see beyond our stereotypes and show empathy with those who challenge our preconceptions.