In July 2021, Carole Hooven went on Fox & Friends to discuss an article in The Free Press about medical schools moving away from the words male and female. She defended the terms. She said biologists use them because they are scientifically accurate, and that respecting people’s gender identities does not require abandoning scientific language. The Director of her department’s Diversity and Inclusion Task Force called her remarks transphobic and harmful in a public tweet. The story metastasised. Hooven retired from Harvard in January 2023, eighteen months after the Fox segment, having been a lecturer in the Department of Human Evolutionary Biology for twenty years. The science she was teaching was not in dispute among evolutionary biologists.

She wrote about all of this in The Free Press in January 2024, in an essay subsequently cross-posted by the American Enterprise Institute, where she now holds a nonresident senior fellowship. She remains an associate in Harvard’s Department of Psychology, in the lab of Steven Pinker, and is an active member of the Council on Academic Freedom at Harvard — an institution her own case helped bring into being. Eleven months after her essay appeared, the Republican congressman Tim Walberg cited her case at a congressional hearing on campus free speech, asking Harvard’s then-president Claudine Gay why a call for violence against Jews was protected speech but a statement that sex is biological and binary was not. Gay did not answer the question.

Hooven is the author of T: The Story of Testosterone, the Hormone That Dominates and Divides Us, the kind of trade science book that earns reviews in both the Wall Street Journal and academic journals. She got into evolutionary biology via Richard Dawkins’s The Selfish Gene, and into testosterone specifically by spending eight months in Uganda following chimpanzees. She is a self-described lifelong Democrat. She has continued to write, teach, and speak publicly throughout the period covered by this story, including through a diagnosis of major depression and the loss of close professional friendships she has written about in detail.

The conversation below was recorded in autumn 2023, when Hooven had recently formalised her departure from Harvard and the Council on Academic Freedom was newly established. Joe Warner spoke to her for Unfiltered about the science of testosterone, the lived experience of hormonal transition described by transgender people she has interviewed, what cancellation actually feels like from inside it, the case for biological language in education, the toxic-masculinity backlash and her concern for boys, and the trans-in-sport question on which she has staked a clear and unfashionable position.

What follows is the unedited conversation, lightly cut for length. Hooven speaks here as she does on the page and on the podium — measured, scientifically precise, and willing to take positions that her own political tribe finds inconvenient. The reader can decide what to make of those positions on the basis of seeing them in full.

Your book Testosterone details the relationship between hormones, genes, environment, culture and behaviour. What was the seed that you had to explore?

So that’s a big question. There’s the inspiration for my interest in the topic, which I think is a separate question. At Harvard, I have been teaching — my main class was Hormones and Behavior. And in that class, we got to really dive into some of the sensitive questions about who we are and issues like free will, how males and females are different, how we come to be these different creatures biologically who inhabit a gendered culture and what that interaction is like.

This is all in addition to teaching about all aspects of hormones and how they affect behavior. And that also involves more — you know, less controversial aspects of our behavior, like appetite. But that also has really deep relationships with culture. So we would get into these very deep questions about biology and culture.

Something that kept me going, even when it became clear that what I was teaching about was sensitive and controversial — first of all, my undergraduates were always wonderful. One thing that kept me devoted to the science and to never sacrificing clarity, but always trying to cultivate an atmosphere of trust and sensitivity, was that students really long to know the facts and to understand themselves. And those facts of biology, it turns out, increase compassion for other people’s differences and help people understand themselves and how they got to be who they are. That just sort of automatically translates into understanding where other people are coming from. Even when you’re different, even when you disagree.

That perspective is something I’m more committed to than ever, especially after writing the book and talking about the book, even though I’ve had a fair amount of blowback — not really from the book itself, but from talking about it in ways that not everyone appreciates. But I know from firsthand experience that this is a perspective that helps people in the long run, even in fighting for things like social justice.

Was there a specific piece of research that made you completely convinced of testosterone’s effect?

No, it’s the entire framework of evolutionary theory that commits me to this idea. We are evolved organisms, like any other organism. And this perspective more than any other has more power to explain who we are and why we are the way we are. It explains things having to do with our own genes and how they are expressed and how our hormones work, but also why we love our children, why we’re attracted to each other, power hierarchies.

So it was really my understanding of — initially the first time I was exposed to it, through the book The Selfish Gene by Richard Dawkins. That changed my life. There was no sort of light bulb moment. If there was something after that that got me specifically interested in testosterone, that was studying chimpanzees and living out in Uganda and following them around every day for eight months, and seeing that their sex differences paralleled in many ways human sex differences, even though there was no human culture. That definitely cemented my interest in evolutionary biology as a really powerful way to explain who we are.

Were there any surprising findings from researching the book?

Something that I was surprised by during the research, and even more talking about the book, especially with transgender people who had transitioned hormonally. So it’s one thing to read about the effects of hormones — even reading studies on transgender people who have either been born female, lived in the female sex role, and then taken male typical levels of testosterone. You can read these big studies about how that changes someone’s appearance, of course, but also behavior and psychology.

What surprised me was that for males who transition — so trans women — the sex drive plummets. These are not universal changes. These are changes on average. And for trans men — so females transitioning to living as males — the sex drive increases. So maybe this is most interesting to me as a woman: not only does the sex drive increase, but the nature of sexual desire changes significantly.

People who had been born female and lived most of their lives in the female sex role, often resenting being the target of male sexual attention, described feeling first of all overwhelmed by the sexual urge. And it didn’t matter if they were attracted to males or females. Many of the trans men who had previously been attracted to females described feeling overwhelmed in the first couple years of taking cross-sex hormones — felt overwhelmed by sexual desire, but also viewed the target of their sexual desire not only as a potential romantic partner, but also as an object, basically with body parts that they wanted to access. And described having very intense and persistent fantasies, visual fantasies of body parts of the individual they were attracted to.

This was mind-blowing to me as a woman, because women do not do that to the extent that men do. That’s just a sex difference. It’s everybody knows it and it’s real. And women don’t understand what that is like to live with.

I’ve also talked to a lot of men who say that they have to constantly inhibit — and this sounds obvious to a man, I think, but not to women, because we don’t have to generally do this. They have to inhibit their desire. They have to inhibit their words and their actions very often in social situations, and in a way that can be exhausting. And they don’t notice how exhausting it is until they block their testosterone. So I just talked to a guy who is in his early 70s. He had prostate cancer. He had to block his testosterone for part of his treatment. He said it was a huge difference in his sex drive, and he felt a sense of relief that he didn’t have to constantly inhibit where his eyes lingered. So that perspective to me as a woman was one of the most interesting things that I learned, that you can’t learn from just reading. You could only really understand it if you go through it yourself.

Reading the book, what fascinated me as a man was the emotional response — that women who transitioned to men suddenly didn’t have access to the same range of emotional response, that anger or frustration became the go-to emotion. Are we missing something important in how we communicate?

Yes, definitely. And I think this is part of the value of understanding who we are biologically, that this is not just socialization. Socialization is extremely important — I cannot emphasize that enough. The gendered culture can mold or reinforce or inhibit, to a certain extent, different kinds of population-based patterns. And there are plenty of men who are extremely emotional, who cry a lot, who understand themselves and can articulate their emotions.

But the point is that relative to women, men on average are much — I don’t want to say worse, because I don’t want this to be a value judgment. And I think that’s part of the problem, that the different way that men understand their own emotions is stigmatized, and the masculine way is somehow held up as less moral than the feminine way. I think that, in itself, is problematic.

However, yes, I think if we understood that we come into the world with different predispositions — and it’s not that men do not have the feelings that women have. Well, maybe it is. Actually, it is, to a certain extent. Women do tend to be more empathetic than men. Women do tend to be able to understand and articulate their emotions in ways that men sometimes struggle with. Again, this can be heavily influenced by culture, but these differences are present around the world, and they do change when people take or block testosterone. So men may feel strong emotions, but the predominant emotion when felt strongly can sometimes be frustration and anger.

I just want to give an example of my 14-year-old, who is not an angry kid. He’s a gentle young man, I guess at this point. I’ve seen him get more frustrated recently and feel angry at himself in response to anything that stands in the way of his achieving some goal. I’ve seen him bang his fist playing chess when he messes up in chess, and I hadn’t seen this before in him. So we talked a lot about it, and he described feeling frustrated and angry most intensely when he can’t achieve a goal, when something is blocking his way to achievement, whatever it is he wants.

I thought this was really eye-opening and fascinating, that this is part of male reproductive strategies in a way. It’s a little bit different from female reproductive strategies, which have to do more with nurturing. Females are also competitive in our own way. But testosterone does seem to have this effect, which is present also in trans men, of putting the individuals somehow more in touch with those feelings of frustration. And the frustration isn’t met with tears. It’s met with: “I’m going to get this. I’m going to do what I need to do to get this.”

Why do you think there is such a vocal movement that downplays the significance of sex differences on behaviour?

So you’re right that there is a strong resistance to the kinds of explanations that I wrote about in my book.

I think there’s some good reasons for that resistance. I can understand why people who are very concerned about equality, and the way that science has been used historically to justify the subordination of women — using science to support claims about female inferiority in various ways, whether intellectually, or what a woman’s monthly cycle does to her ability to think rationally — there have been a lot of myths that science has ostensibly supported, or has been used to kind of justify subordination.

So those are good reasons. We have to be alert to that happening today. The way to be alert is to do really good science and clear communication about science and what it means.

There is actual scientific evidence that biological explanations for sex differences, for other kinds of group differences, can lead to an increase in certain negative stereotypes, which can have real-life impacts on what people think is possible for a given group — in this case, women or girls. So given that reality, you can understand why people want to play up social explanations and downplay biological explanations. Because it seems like, well, there’s something we can do about the social environment.

But what people are failing to understand is that even if males are biologically more physically aggressive than women — if men are more physically aggressive because of their Y chromosome, essentially more physically aggressive than women — that doesn’t mean that they always will be. It means we use culture to do what we can to promote a positive masculinity and reduce violence. But we have to know what’s going on first.

When I encounter those kinds of views, it just makes me more motivated to do the work that I do and talk about it and write about it. Because that, I think, is taking us in the wrong direction. It’s always better to know — to have the facts and be working with the facts — if we’re trying to improve society.

You took a leave of absence from Harvard after your Fox News appearance. What’s it like to be in the crosshairs of cancel culture?

No, no, I’m glad you’re asking, because people should know.

It’s personal. It’s people you like. I worked in my department for 20 years. I had friends and colleagues I respected, and I thought they respected and supported me. So to — I was doing my job, and I was doing it well. And part of my job is saying things like “male and female are real.” I mean, it was in the Department of Evolutionary Biology. So to not be supported when attacked publicly, and having my — you know, people who are in positions of power at academic institutions should be supporting their scholars who are trying to discover how the world works and communicate it. So the fact that that did not happen — and in some cases, I can’t talk about everything that happened, but — yeah, it’s very painful personally. It’s painful professionally, economically. And it’s just sad, because we need trusted institutions, like journalism and academia. We need to be able to trust these institutions to communicate the truth. And that’s not happening. The values that these institutions are supposed to be promoting and defending and manifesting seem to be crumbling.

Do you agree that science is under attack, stemming from a culture of telling people what they want to hear rather than the truth?

Yes. That is definitely happening. Because it’s really happening on such a huge scale, I can’t even begin to describe how it is happening in scientific journals, in the classroom, in news — the way that big news outlets like The New York Times or Scientific American report on the supposed science. So what is being taught, what is being published, what is being reported on is not a reflection of unbiased inquiry and knowledge. It is a reflection of what is safe to report or teach or study. What is the least likely to cause certain groups of people or activists offence. So it’s extremely biased.

There’s a huge over-representation of progressives or liberals in the academy and in media. And that’s dangerous because that means the science is heavily politicised, and my field is becoming hugely distorted. If I’m not allowed to say that male and female are real — and little kids are being taught this now in school.

There’s a tweet you commented on yesterday where kids in fifth-grade sex education are referred to as “people who produce sperm” and “people who produce eggs.” How dangerous is this?

I think it’s a type of dictatorship, and it’s scary when a small number of vocal activists have control of language and concepts. There is fear stoked in people who disagree, or who are curious, who can’t ask questions. Which means we cannot have liberal democracy, because that requires an openness to debate, to understand how the world works, form educated opinions and participate in a democracy.

If there’s a small group that is controlling — through whatever means — the language and instilling fear in people who just might have questions, [people who] cannot even get the facts about reality, that undermines democracy and disadvantages social progress and disadvantages, I think, the very causes that certain groups of activists are trying to promote. And [it serves to] divide society. Ultimately, if our institutions fail — which they actually are failing — I don’t know what comes next.

We need values. We need to train individuals in our democracy, or in the academy. At Harvard, what should be happening is that the most basic value is that we search for and communicate the truth, and that that should be defended and promoted. If we’re not doing that — and this is just the academy, of course there’s so many other institutions — but what matters now in its place is the individual, each individual’s values, each student’s sense of themselves and their authentic selves and their lived experience. Instead of having an institutional value that everyone’s participating in, that everyone’s buying into.

So things have gone topsy-turvy here. I’m trying to do what I can to uphold the values that I think made sense and that we should try to return to. At Harvard, we now have a Council on Academic Freedom that some of the professors are joining. So we’re making some progress.

Are we seeing a shift?

I mean, it’s not that the science needs to be at the forefront. But evidence and reason and logic and listening to people you disagree with, instead of calling them names and shutting down argument — that just means that the other person or group doesn’t really have an argument and is just saying “you’re doing violence” or “you’re transphobic.” This is no way to unite people in a common cause. Obviously, this is bullying, and it’s just bad for the functioning of a democracy.

In terms of where we’re headed, I do feel that political division is increasing. There’s a segment of liberal progressives — I’m a liberal person, I’m not a conservative. However, I am aligned with conservatives on free speech and biological reality. So there’s all these group divisions that, to me, do seem to be increasing.

The first step needs to be to have respectful conversations with people you disagree with. I think largely everyone is trying to do the right thing. Everyone is coming from a different place — whether it be the part of the country that they live in, their religious background, their political background, their socioeconomic status, their ethnicity, sexual orientation, transgender status. All of these things matter. All of these things shape deeply people’s views. And if we’re just in our little silos and not listening to each other, it’s just going to get worse and worse. So step one is conversation, and not stigmatising people who disagree.

Do you think gender-neutral terminology — chest-feeding, pregnant person, menstruator — is the correct approach?

God, no.

No, I think it’s a disaster. And it’s denying biological reality — that we are cohesive humans who come into sexes, and the sexes are meaningful. Male and female capture — the fact that there are two reproductive classes across organisms, that doesn’t mean that each organism is one or the other. Some are both at the same time. Some will be born one sex and then transition to another sex — certain types of fish. There’s so many different kinds of organisms. But still, there’s male and female, and they’re meaningful categories.

This relates to what we were talking about earlier, which is the fact that the existence of those categories does not by itself undermine anyone’s rights. However, it is a biological fact that is extremely powerful. That is why I wrote a book about how we’re different from a biological point of view.

And if we attempt to erase those differences, and erase the concept of male and female, we lose the ability to discuss any issue which has to do with that reality — like the fact that only women have babies, only women breastfeed. And that basic difference between women and men has huge cultural implications. Only women, for the most part, fear being raped almost every time they’re out alone by themselves in a city, on average after dark. Women have a constant fear of sexual assault. That’s just something that we live with, and we have to design our lives around that fact. This is because of our biology.

Men are bigger and stronger, and men do not carry the babies and breastfeed the babies. There are so many other really important differences that need to be acknowledged. But that does not mean that trans people don’t exist, or that trans people shouldn’t have any rights. Those facts have very few implications on their own for the rights of transgender people, who of course should live without discrimination, should have lives where they can freely choose how they want to live and live with dignity, and have the health care that they need.

The implications of being male or female are very important. The solution to our problems, the solution to these social justice issues, is not to pretend that reality doesn’t exist. This is dangerous. It’s manipulative. It reduces our ability to understand the world and ourselves. So I will fight for retaining clear language and being as sensitive as it’s possible to issues that transgender people face.

But it is a small portion of transgender rights activists who are sort of militant and demanding that certain terms be used, and even becoming very bullying towards people who don’t want to use those terms. I do not believe that people should be required to use the — I will say preferred pronouns. I use preferred pronouns because I know that it can be very difficult for trans people to be referred to by their biological sex. But I also understand some people who have a conscientious objection to that. I don’t think you can require other people to play into your own demands about how you want to be referred to.

But this — embodying human beings and starting to think of us as a constellation of disparate systems and parts — is extremely dangerous. We do need to acknowledge that we are whole individuals. We are made this way for a reason. And there is a danger in just trying to trade off body parts. We don’t know where that is going to lead. People who have penises and make sperm have a lot of other traits psychologically and physically that sort of work as a package. There are reasons for that. And I think we have to be very careful about messing around with these basic systems.

How worried are you about the world in which young boys are growing up, being told their natural behaviours are toxic?

I think it’s a huge issue. And I think it’s such an important issue that that’s what my next book is going to focus on.

The logical consequence for me of diving really deep into male-female differences, but mostly the biological forces that shape men and understanding what happens when we change our testosterone levels — that has taught me that, first of all, anyone could have been born male. It’s easy for women to judge men’s behavior and challenges. Of course, some of it should definitely be judged as unacceptable. There’s plenty of behavior that’s unacceptable. But there has to be an understanding that men face different challenges socially than women do because of their biology.

If there is only stigmatising of masculinity and the natural urges that men, and young men in particular in puberty, are facing — if there’s only negative judgment, if there’s shame about sexual urges or risk-taking or any of the things that women don’t feel maybe as strongly — that is stigmatising, that shames one half of the population for their natural impulses. No one should be shamed for how they feel. Shamed for how they behave is a different matter. But feelings — and becoming a man, I think, should be celebrated the same way becoming a woman is celebrated. It’s wonderful. And if you have a high sex drive, that can be a gift. You have to culturally have the support to learn how to channel those drives.

Men also need to be acknowledged for the things that I was talking about earlier, like men are the ones who are risking their lives, for the most part, to save the lives of strangers. And women typically aren’t doing that. Some women do, but men do that routinely, and that’s something that needs to be acknowledged and not taken for granted. That is the flip side of having a higher preference for risk-taking and for a kind of physical bravery that benefits us all. We see that all the time in the news. There are so many instances of men dying trying to save others.

The toxic masculinity movement is potentially alienating young boys, driving them towards social media influencers promoting misogyny. How do we break that cycle?

I think you’re right. I have a lot of work to do to try to figure out what we as a culture can do to better support boys. But this is something that historically — and even in deep history — a lot of cultures have recognised, that there has to be strong cultural norms to channel in a positive way that masculine energy. I think that’s super important. And that requires us to be able to talk about it, to do research and talk about it honestly, in a way that doesn’t result in people just saying, “well, you’re legitimising bad male behavior.” That’s not what it is at all. We have to be able to talk about, again, what the implications of biological differences are.

Where for a lot of people the rubber meets the road in trans issues is elite sport. What’s your comeback to people who say that athletic differences are purely cultural?

I think they’re disingenuous if they say that, because of course everyone can see that men are bigger and stronger than women on average. And what that doesn’t mean is that all men are going to beat all women in sports. That is, I think, a ridiculous comeback if that’s what people are saying. There are people who are able to publish articles in high-profile outlets and go on the BBC who say that this is psychological — women aren’t trying hard enough. That’s one response. I just think that’s ridiculous, because there’s so much evidence that testosterone increases muscle mass, increases hemoglobin, increases bone density, increases height, strength and power, to an enormous degree relative to women.

It depends on the sport, but there’s like a 10 to 50, or even 60% advantage of men over women. So then the question arises: well, to what extent does that advantage dissipate when testosterone is blocked? Those advantages accrue during puberty. There’s clear evidence that the full advantages are not retained, because if you block testosterone, you reduce hemoglobin to female levels. Hemoglobin makes a big difference in terms of VO2 max and powering the muscles used during exercise. Muscle mass drops too. But it drops nowhere near the — depending on the part of the body you’re talking about — 40 to 50% advantage. So strength advantages, muscle advantages, height, bone density — those are all retained to some degree.

But given that, people start arguing about the evidence — some will argue, well, the advantages basically disappear. They’ll just say there’s no evidence that trans women retain an advantage over natal women. First of all, I think that’s wrong. I think there’s evidence of a clear retained advantage. But the question I think we should be asking is: why open up the female category to people who are not female in the first place? What is the justification for doing that?

The argument from the trans activist seems to be that the onus is on people who want to keep the female category exclusive to females. The onus is on them to show that there is a retained advantage in trans women. I would say no, it isn’t. The sexes are separated for a reason — because women would never win in the elite categories.

Right now I’ll just say, high school boys blow away female Olympic world records in all kinds of track and field events. High school 15-, 16-year-old boys can beat Olympic gold medal women, depending on the event. The advantage is enormous.

So I would say no — the onus is on the trans activists who are males to participate in the female category. They need to answer: why should the female category be open to males regardless of how they identify? I hate to even use the word “male” for trans women, but if you’re talking about bodies — which we are here — yes, it’s about psychology, but it’s about the capacity, the physical capacity. It’s a female category. That means it is specifically designed to exclude males.

So if you’re going to open up the category, I think there needs to be a reason beyond how someone identifies. And I know this is very painful for people, but I don’t see that any male has a right by virtue of how that person identifies to compete against females, even if that male is not winning. That’s not the point. So evidence that a trans woman isn’t winning anything is not evidence that they should be admitted into a female category, in my view.

Looking forward — do you feel this is a battle that can be won? Can we find common ground?

Yes. I think it’s possible. And I think everyone who can say what they believe, even if it runs counter to their tribe, should do that. And should listen to — again, just listen without judging. Listen to people who disagree with you and have conversations. I think that’s the most important place to start. That’s what I’m trying to do.