How Different Are Men and Women, Really?

A new book says the scientific research on the question has often been too biased by gender inequalities to tell us.

A funny female mask on the left, a funny male mask on the right.
Photo illustration by Slate. Photo by Thinkstock.

A majority of Americans believe men and women are fundamentally different in their physical abilities, how they express their feelings, and their personal interests and hobbies, a recent Pew Research Center survey found. And while women and Democrats are more likely to say differences are the result of social and environmental factors, a majority of men and Republicans believe they are biological. Beliefs about sex differences and gender roles remain very much a flash point in American cultural and political controversies today, from the #MeToo movement against sexual harassment, the persistent pay gap, the conspicuous absence of women from positions of leadership and power, and men from the playground, kitchen and carpool pick up, or the controversial Google manifesto.

The nature vs. nurture question has divided not only the general public, but also scientists themselves. British science journalist Angela Saini digs into those divisions and what they mean for what we think of as “normal” or “proper” behavior and life choices for men and women in her new book, Inferior: How Science Got Women Wrong – And the New Research that’s Rewriting the Story.

This interview has been condensed and edited for clarity.

Brigid Schulte: You write that, throughout history, mostly male scientists, including Charles Darwin, created studies or speculated that women were less intelligent than men, the weaker sex, and so forth based on their own biases—failing to see that if women weren’t scientists, perhaps not being admitted to universities could be a reason why, rather than an innate biological imperative. Is this what got you started digging deeply into the science of sex difference?

Angela Saini: I came to it by accident almost. When I went back to work after I had my son, the Observer newspaper here in London asked me to write a story about menopause. I come from an engineering background, and I’d always written hard, physical science stories. I tended not to do biology. The approach I took was looking at the explanations in evolutionary biology for why menopause happens. And what astounded me was that different people had different theories, and that they could sometimes run along gender lines.

There were groups of male scientists saying that women experience menopause because older men don’t find them attractive. And there were women—and some men—on the other side, saying the reason we live such long and healthy lives after we’re unable to have children is because grandmothers are so crucial to the survival of families.

Now, why would it be the case that men tend to have one view, and women tend to have another view? That’s very strange. Because if science is free of bias, it shouldn’t make any difference. It’s science. And that fascinated me.

Sex differences are still one of the hottest topics in scientific research. Some of the research reinforces what you call “the myth” that the gaps between men and women are huge—that women are more empathetic, that men are better at math and spatial reasoning, as well as more promiscuous, that men and women’s brains are structurally different, and so on. How different, really, are women and men, and where do those differences come from?

One of the important things that biology has taught us over the last 50 years is that nature and nurture can’t necessarily be separated. And there is biological feedback that happens as a result of the environment. So, for instance, if you give a very young child mechanical toys to play with, stuff that exercises their ability to build things and make things, they will be better, biologically better, at making and building things because of the experiences they’ve had. So a social interference produces a biological effect.

That goes a long way in explaining the sex differences that we do see. When parents say to me, “My girls prefer dolls, and my boys like to play with trucks.” Well, you have to ask them, what kind of toys did you give them growing up? Because I have a son. And when he was growing up, he didn’t receive a doll until he was 4. So, of course, for those four years, he didn’t play with dolls. We forget the kind of input we have as we’re raising children produces a profound effect in gender disparities that we see later on.

We assume everything we see is biological, when in fact the social and cultural inputs are huge. I’m not saying that they account for everything in terms of gender difference. But as far as we can tell, they certainly account for a lot more than we thought they did.

The amount we’ve been socialized, the amount that we’ve been affected by teaching and education and upbringing in the course of our lives, mean we will exhibit differences as adults, obviously, because we live in a very gendered society. So it’s very difficult to disentangle biology from the effects of society, culture, and the environment when we’re studying sex difference.

I was so struck by an influential study you mention by a researcher named Simon Baron-Cohen. He purported to find that women were “empathizers” and men “systematizers,” and that these sex differences show up on the first day of life. Yet you wrote about the way he came to that conclusion: by having a postgraduate student stand over the bassinet of newborn babies in a maternity ward and see whether the babies looked at her face, which would somehow mean they were more empathetic, or whether they looked at a mobile with lots of little pictures of her face, indicating some kind of systematic preference. The study showed a large proportion of the babies showed no preference at all. And yet the study has been cited and written about as evidence of deep biological sex differences. I’m not a scientist, but can babies even see at that age? That study just seemed ludicrous to me.

Studies like Baron-Cohen’s are already so difficult to trust because of the nature of the experiment. It’s very difficult to gauge where babies are looking. Can they even see? There is a multitude of ways that study could be flawed. We can’t rely on it. And that’s one of the big takeaways for me after having done this research: Don’t take everything you read at face value, because single studies are not enough.

And there is an issue with some researchers wanting to see sex differences, and going out of their way to see it. This happens in the realm of speculation. So even if they have a study that may show, for example, small structural differences between the brains of men and women, that’s one thing. To then infer from that, that that women are better at multitasking, or are more empathetic, or that men are more rational. We can’t do that. The newer science just isn’t there yet. The brain is such a complex organ. That kind of speculation is dangerous. All it does is build on stereotypes. It’s very unscientific. You need a lot more data to be able to draw such big, grand, sweeping conclusions.

You write about how some of the best research now is taking on some of these older and more biased studies. Like Angus Bateman, the geneticist, who in 1948 studied the mating habits of fruit flies and became the inspiration for “Bateman’s principle,” which, when applied to humans, suggests that men, with their millions of sperm, are more promiscuous and will mate widely in order to reproduce, while women, with their limited supply of eggs, have to be, as you wrote “pickier and more chaste.” That “principle” has had enormous influence on the lives of men and women.

There’s some really good research coming out of a frustration with the lazy research that happened in the past. And that’s very encouraging. Patricia Gowaty, an evolutionary biologist in California has replicated Bateman’s famous fruit fly experiment that was initially done in the 1940s that seemed to show that females are less promiscuous than males. She showed that it was flawed. She went back, did the exact same experiment and showed Bateman must have gotten it wrong—that female fruit flies went toward males as often as males went toward females. And when I called scientists like Robert Trivers, who popularized Bateman’s idea, he said she was probably right. And that’s quite amazing. Because if we think of the body of work built on Bateman’s principle, it’s incredibly influential, and it really does shore up our stereotypes about men and women.

I’m not saying [Gowaty’s work] unravels the principle. It certainly doesn’t overturn it completely. There are many species who do follow Bateman’s paradigm. But humans may not be one of them. And if they’re not, then we may need to fundamentally rethink human sexual behavior and these Darwinian ideas we have around male and female sex roles and male and female roles in society.

The question of sex differences, and whether they’re biological have such enormous implications. There is a school of thought that, if differences are biological, if women are just genetically wired for nurture and caregiving, and men to go out into the world and build things, why bother changing workplace cultures, social policy, or gendered caregiving norms? If biology is destiny, men should go to work, women should stay home, and we should be done with it.

I think approaching that question of who should do what in society in a biologically deterministic way is very dangerous. We have decided as a species that we’re all equal and we deserve equality irrespective of our abilities. That is a good thing. It’s a sign of moral progress as a civilization. So in that sense, legally and morally, the science actually makes no difference, really.

Where I think the science matters, and the reason I wrote Inferior is because there are still people who claim that, biologically, what we’re fighting for, equality, is impossible. That we’re never going to see it and we shouldn’t push for it because it’s in our makeup, our nature, that we’re cognitively different, psychologically different. They imply that we should give up on campaigns and policies to help drive equality forward.

And that’s where I think having good science is important. Because, actually, the science doesn’t say that. It’s actually quite emphatically ambiguous. If we’re going to read anything into the science, it’s that we don’t really know very much right now. And what we do know suggests that the psychological differences between the sexes are really small, and that cognitively, in intelligence terms, they are almost nonexistent. Biology certainly can’t account for the great gender disparities we see in many societies.

We forget that in hunter-gatherer societies, historically, people tended to live relatively egalitarian lives, where women were able to do everything that men did, there wasn’t always this sharp divisions in roles. As long as some women are denied the chance to do what all men can do, then there is still a fight to fight.

Even in the armed forces. One of the reasons that women have been prevented from taking on combat roles in the armed forces roles is a strength issue, that women have half the upper body strength of men. But that’s an average. Again, we may never see parity, but that doesn’t mean the women who are strong enough to do that job should be barred from it, when men who are weaker than these women are still allowed to do it. That isn’t fair.

So the message of my book isn’t that we should have equality because science says it’s possible. No. The message is, there’s no reason why we can’t have equality if we want it. Science doesn’t say that equality is impossible. We are adaptable and plastic as a human species. We can have society any way we want.