Oestrogen Expert: Birth Control Changes Who You Are...Would You Still Love Them If You Came Off It?! Oestrogen Makes You More Attractive!

Are you saying that you'd recommend that a woman looking for a partner gets off the birth control pill until they find one? Yeah, I mean researchers found when women who were partnered to attractive men went off hormonal birth control, they were more attracted to their partner. But for women who were partnered with less attractive partners, they became less attracted to their partners and reported being less sexually satisfied. It's quite frightening.

Dr. Sarah Hill is a leading research psychologist and professor. Uncovering the shocking effects the contraceptive pill has had on women, relationships, and society. And what we can do about it. There's been nothing more instrumental to women's ability to be able to achieve independence within the birth control pill.

And so we're very cavalier in just giving it to people. Oh, well, you should go on it for this, and you should go on it for that. But it has huge costs. And when I started to dig into the research, I found there's at least five different things the birth control pill does to change who we are. And these risk factors, they're swept under the rug, but their doctors weren't prescribing it. First, it changes our emotional states with increased risk for developing anxiety and depression.

And then it influences our ability to put on muscle mass. And it can also affect our sexual function because it turns off that estrogen surge that makes us feel sexier and makes us want to have sex. And there's warm, but we also know that it affects men in two different ways. And this is implications for society around us. And I'll tell you why. So what are the alternatives for women? Let's dive down into that. First,

Quick one before we get back to this episode, just give me 30 seconds of your time. Two things I wanted to say. The first thing is a huge thank you for listening and tuning into the show week after week. Means the world to all of us and this really is a dream that we absolutely never had and couldn't have imagined getting to this place.

But secondly, it's a dream where we feel like we're only just getting started. And if you enjoy what we do here, please join the 24% of people that listen to this podcast regularly and follow us on this app. Here's a promise I'm going to make to you. I'm going to do everything in my power to make this show as good as I can now and into the future. We're going to deliver the guests that you want me to speak to and we're going to continue to keep doing all of the things you love about the show. Thank you. Thank you so much. Back to the episode.

Dr. Sarah Hill, what is the mission that you're on? If you had to sort of encapsulate it into a couple of sentences, all of the work you're doing into a couple of sentences, and the impact it has on people like me, but also my partners, my mother, my sisters, who read and understand your work, what is that mission?

is to help women understand themselves. And I think that part of that is doing the science that helps to uncover the insights that help women understand themselves, and then also being able to communicate that to women. I think that for a very long time, because of the way that medicine has been set up, the focus has been primarily on men. And most of the things that we think that we know about health and functioning in the human body and brain is based on research conducted in men.

And so it's taking that back and helping women actually understand themselves as themselves. So would you say that this conversation is just for women? No, absolutely not. No, this is a conversation for women, for women's partners and those who love women, right? And so I think that it's a conversation for everyone. I have these conversations because I'm interested in the subject matter. And as I read through your work at the top of your work, I saw that, you know, you really have a focus towards women's health and women's issues.

But I can't explain how unbelievably fascinating and enlightening it was for me as someone who is a boyfriend and a partner to a woman. But also when we talk about the evolutionary psychology that sort of is intertwined throughout your work, I was able to understand so much about me as a man and the way I am and the way that I develop and my testosterone and all those kinds of things and also attraction and mating preferences and all these things from looking through your work.

Why? Why are you so focused on this subject matter? What is it? What's the sort of in your heart? I mean, for me, it's really fascinating to consider the way that hormones influence who we are and then to think about something like the birth control pill, which almost all women are on at some point in their life. And understanding that this actually, by changing women's hormones, has the impact of kind of fundamentally changing some really important things about themselves.

I mean, this is really huge, and this has consequences for everything ranging from who women are attracted to and might be choosing as partners to women's mental health, right? And it could end up having consequences on the shape of the world around us. We already know

that birth control has had an impact on women's ability to do things like go to school and get advanced degrees. And we see this played out when we look at college classrooms that are becoming increasingly female. And one of the big reasons for this is the birth control pill. It's like by allowing women to know with almost perfect certainty that they're not going to get pregnant.

This has allowed women to make plans, which means that they can dream bigger and achieve more than most of us would have ever dreamed possible, like 50 or 100 years ago. And so the pill changes everything. By changing women, we change the world. This has implications for women. This has implications for their partners. And this has implications for society around us.

We're seeing some of the downstream positive impacts of this. And then there's also some of the sort of downstream consequences, which I think society is now trying to understand and contend with. And I think one of them you mentioned there is that more women in classrooms, I think more women are college educated now in the US or becoming college educated, and they're running more and more and more. And it's interesting because there's a study which you cite in your work. I think it was in your book where I read it that shows women still have a preference for men who have more resources

And I was wondering, doesn't this create a little bit of a fundamental issue? Because if more and more women have more and more resources, in many cases, much more than men, but they have a preference for men that have more resources, isn't there an issue here?

Yeah, no, there is actually, there is an issue there. And in fact, there have been people, including my former mentor, David Bus, who have talked about this idea that there's a mating crisis going on. And that women who are becoming increasingly college educated and getting access to resources of their own, that they do continue to exhibit and increase preference for partners with resources.

Women are what we call hypergamous, which means that we like to mate up in terms of achievement and educational attainment. When you have a populace like we do in the US of women who are now on average more educated than men, it makes it more difficult to find a suitable partner. If you're a woman with an advanced degree and you want somebody who has at least as much education for you, that's going to lead to a more narrow pool of mates.

And in fact, what we see is that there are an increasingly large number of women who are just choosing not to get married and are choosing to stay single. And in fact, there's a wonderful book called All the Single Ladies that is about this very phenomenon. And women are increasingly choosing to opt out of long-term mating if they're not able to find the relationship that they want. So two questions there on the first point is how do we know that women are dating upwards and to the right?

We know that women are dating upwards because that's what women express a preference for, and it's also who women tend to marry. So when you look at, for example, data looking at the education levels of people who get married and age of people when they get married, women generally will marry somebody who's older.

and generally earns more money than they do themselves. And this is something that isn't specific to the US. This is something that we tend to find cross-culturally that women tend to express a preference for this. And yes, it has become more common for women to be open to partnering with people who earn less money than themselves, for example.

or have less education than themselves than what it used to be, but it's still not what it would be if women were actually more willing to make that trade-off. What we see is that instead of choosing to marry down, what many women are choosing to do is simply not get married at all. Are they making that choice, or is it just a lack of good options?

I think yes and yes. I think that they're making that choice because there aren't good options. I think that many women feel the constraint of the fact that there's not as many partners available that have the qualities that they're looking for and a long-term partner.

And as a result of that, they're just making the choice when it's between that, like, you know, just staying single and not partnering with somebody that they desire, or partnering with somebody who has fewer resources than they do or less education than they do themselves, they're choosing the former. They're instead choosing to be single instead of having to partner with somebody who doesn't, you know, sort of meet what their exacting standards are. Are they still having sex?

Yeah, you know, that's like, so sex is down. Like sex is trending downward. What we tend to see is that people are having a lot less sex than they used to. They're having sex later. They're having less, fewer people are not virgins, and that's a double negative.

More people are virgins when they're graduating high school and college than there were in the past. This is becoming increasingly common. It's also really interesting when you consider that in face of the fact that we have something like hormonal birth control, or we have birth control where you have an opportunity for men and women to be able to have sex without having to have the fear of pregnancy and yet people are having less sex. And that's a very complicated

issue that requires a lot of untangling to get to the bottom of. But one of those factors is the fact that it's harder for, you know, imagine that you're a college-aged woman and you were looking for somebody who at least is, you know, on par with you in terms of their educational attainment. Most college campuses are like 60% female and just simply playing the odds. I mean, women are going to have a harder time finding somebody within their pool.

that they can get together with and this is going to mean less dating for some of these women and less sex. If women have more money and more independence as a result of that money and success in education, why don't they just date down? As in why don't they date men that are broke?

Right. Yeah. Well, you know, we have inherited this mating psychology from our distant ancestors who are very much more reliant on men for things like provisioning, resource access, and even protection than what contemporary women need. And this is because throughout most of our evolutionary history, we spent our lives, you know, having to be pregnant regularly.

lactating, caring for young children. And we're very heavily dependent on the ability of our partner to gain access to things like food and the other resources that we're not able to get access to when we are very pregnant or dealing with young children. Like, I don't know if you've ever gone.

hunting before or met a two-year-old, but the two things don't mix. The children are loud. They're not going to allow you to sneak up on a buffalo. It's not an ideal situation for women. Women historically have been very dependent on men for resources. We've inherited that brain, because over the course of evolutionary history, women who would have placed an emphasis on choosing partners who have these kinds of qualities,

they would have been more likely to have surviving offspring who then passed that tendency or that preference onto their offspring who'd pass that preference down to their offspring. Contemporary human women, even though we're able to gain access to resources of our own, we still have that preference. We've inherited that preference from our successful ancestors because women who had that preference would have performed better than women who didn't pay attention to that sort of thing.

So oftentimes people think things are the way they are because of a patriarchy or because of sort of social factors. But you're saying that there are sort of innate biological differences and evolutionary differences in men and women that go beyond our sort of sexual organs and stuff. Yeah, no, absolutely. Yeah. And in fact, the patriarchy, which just refers to, you know, male control of resources,

wouldn't really exist if women didn't desire resources and their partners. Because the reason that men tend to control a lot of resources is because women demand resource access on the part of their partners. And if women didn't care, then men wouldn't work so hard to get access to them. There's this really great quote by Aristotle Onassis where he once said, without women, all the power and money in the world would be completely meaningless. And I think that there's a lot of wisdom in that.

Men work so hard to control the resources, not because men together are banding together and trying to hoard the resources and keep them from women. I don't think that that's really how the world works. And I think if you have a look around, we'd see that that's not really how the world works. Instead, it's an epiphenomenon of the fact that men are competing amongst whoever else has access to resources to get resources of their own.

And because women value this and their choice of partners, oftentimes men will go to greater lengths to get them. One of the reasons, not the only reason, but certainly one of the reasons that we see that more men tend to be in positions of being a CEO, for example,

is because oftentimes men are more willing to make the trade-offs that you have to make to get into those positions because men are wired that way, right? And the reason that they're wired that way is because they've inherited these tendencies to want this despite the costs because it would have paid off in terms of being able to attract better partners, a greater number of partners, right, and then being able to have your children do better.

And so the patriarchy, yes, that is something that exists. We do tend to see that men tend to control resources more frequently than women in most societies around the world. But this isn't because men are banding together and trying to keep exclude women. Instead, this is just a product of men's evolved psychology, trying to work as hard as they can to get access to resources, in part because women require them.

And men are much more likely to take risks, aren't they, as you say. As you were speaking, I was thinking about the gambling statistics that I read that said the vast majority of gambling addicts are men. So I was just thinking about that in the context of entrepreneurship and these kinds of things. Is that to say that men are going to be more entrepreneurial?

Yeah, I would think so, yes. And the reason being that it is about risk, right? And women oftentimes, again, a lot of this has to do with the psychology that we've inherited. And throughout most of our history, women were caring for young children. I mean, this was kind of what our bodies made us have to do. It's like, our bodies are wired for

having babies, right? And this doesn't mean that this is what women should do, right? Or what women need to do or that, you know, that this is somehow destiny in women to do one, you know, this set of activities. But instead, throughout most of our history, we spend a lot of our time pregnant and caring for young children.

And that has selected for our psychology to be very risk sensitive and risk-averse. And what we tend to see is that women are more risk-averse than our men. And we can see this play out in terms of things like gambling, right? We know that overwhelmingly,

Men tend to be the ones who are gambling addicts relative to women, but also in terms of good risks, because you do see something like being an entrepreneur, for example, which is something that does come with a pretty big risk attached to it, meaning that there's a big boom in bust. But the risk associated with the possibility of a bust is something that women's psychology is a little bit less tolerant of relative to men's.

I think one of the interesting observations I've had as an investor, but also as an entrepreneur myself, is then maybe data to support the fact that more men are likely to start businesses, but it doesn't necessarily mean they're better at it. And part of that links to what you said about this.

relationship with risk because being prone to risk in business doesn't necessarily mean you're going to be good at entrepreneurship. I often tend to find that when you have a woman leading a business, they're much more accurate and honest with their forecasting and much more realistic about what the business is actually capable of and men tend to over forecast

in terms of business performance. But then also I think it's interesting because I had Kevin O'Leary who's the shark on Shark Tank in the USA say that in his portfolio of investments from Shark Tank, the best performing investments that he had were women. And I think again, I think from memory, what he was saying was when it comes to forecasting and taking more calculated risks, women tend to be better at that than men.

Right. Which is an interesting, it's interesting. Yeah, no, I think that it's totally spot on. Men tend to be riskier and they tend to have a little bit more hubris. I mean, there's a tendency to assume that they're going to, and they have an exaggerated belief about how successful they're going to be because in part, I think it ultimately boils down to the differences in our mating psychology and then also the psychology of parenting

compared to provisioning. And I think that for men, seeing the world in a way that's distorted in terms of assuming that things are going to be better than they are is going to allow them to be able to better attract mates, for example, because they're buying their own story. It's like they're buying their own story about how great everything is going to be, even if it's not necessarily all that great. This leads people to take risks. And with big risks come big rewards. And historically, evolutionarily for men,

those rewards could potentially translate into additional mating opportunities that have a direct impact on men's ability to pass down genes. For women, it's not so much, because even if you have the best idea ever that's going to get you access to the greatest number of mates possible, the number of offspring that a woman can potentially have into the future

is dependent completely on the limits of her own reproductive biology. So a woman with access to 10 partners can only pass down the same number of genes as a woman with access to one, whereas the same hasn't been true for men. For men who have access to 10 partners, this can lead to 10 times as many offspring as what they can have if they have access to one. And this creates an asymmetry in the potential fitness benefits related to men and women from winning big.

And so men's psychology is geared toward wanting to do things, and having their brain tell themselves stories about how successful things are going to be, to act as a carrot that then leads them to want to pursue those types of things, even when it's highly risky. So if I become a billionaire, then I can afford to and I will attract.

potentially hundreds or thousands of partners and then I can have hundreds of thousands of kids because I can afford to and I'm going to have so much interest because I'm a high resource, high status male. Whereas a woman, if she becomes a billionaire, she can only have one kid every nine months or 12 months, whatever it is.

Yeah. Yeah. And that's actually there's an evolutionary biology. There's a principle behind that. It's called the Bateman principle. It refers to the fact that men's fitness can increase with each partner they have access to. And for women, it tops out after one.

So the potential reproductive returns from having access to novel partners is greater for men than it is for women. And this does not mean that this is what most men do. Most men don't translate their increased status and their increased access to resources.

by gaining access to an astronomical number of partners. But historically, that's something that men sometimes do. If we look at history, you'll see particularly in polygynous cultures where you have men who are able to have access to multiple partners at the same time.

Those men who have the most resources and have the highest status tend to have multiple wives. They tend to have a greater number of children. And we are the descendants of people who would sometimes make that decision. And so what we tend to see is that that is shaped men's mating psychology and shaped men's achievement motivation psychology in ways that helps to promote gaining access to resources in part because gaining access to resources

leads to a greater fitness return than what gets is available to women from doing the exact same thing. This wasn't a long time ago in human history either because my granddad in Nigeria, I've never met the guy. I don't believe he's still alive. I've never been close to him. But I was told that he had 10 or 14 wives. And so I was told that I have 30, 40 cousins in Nigeria.

Right, yeah. I mean, I'm doing OK financially, but I probably don't have the means to meet them all and become friends with all of them. But yeah, that's pretty striking. That's just sort of one generation above my dad.

was this a man that had multiple wives. And so when you say that that could be passed down to me in some way, that sort of proclivity to want to acquire more resources so that I can support more people. It's quite frightening.

I don't think that it's something to be frightened of. I think that when we understand the tendencies that we've inherited, I actually think that it gives us greater appreciation for the kinds of decisions that we actually end up making. Why is it that especially in cultures like the US and I think about in European culture,

We're monogamously mating species. We form these long-term pair bonds. And so then we also have to ask ourselves, given that this is something that is possible for men to increase their reproductive output simply by gaining access to new partners.

Why is it that most men don't do this? What are the benefits? When you look at contemporary hunter-gatherer groups where humans are living in ways that are more similar to the way that our ancestors likely lived than what we do currently, what you tend to see is that those children who have an investing father around, their probability of survival is vastly higher than that of the children of women who do not have an investing partner around.

One of the other parts of the answer is that women generally don't want to share, right? And so what you get is by men being willing to restrict their own, what we call reproductive value, which just refers to the number of potential children that they can have into the future.

That increases the quality of partner they're going to be able to have because most women don't want to share. And so if you are a woman who's of high value, meaning that you have a lot of the qualities that men desire in their partners, you can be really picky and say, no, I'm not going to share. And so if you want to mate with me, then that means that you're going to have to make some decisions.

Because imagine that you're a man and just based on all the qualities that you have, let's say that your mate value is, and let's assume that mate value has a 1 to 10 scale. So there's a 1 to 10 scale and you're a 7, all the qualities. I'm not talking about you, I'm talking about the royal you. What have I got to do to be an 8? The reason I'm making you, and again I'm saying the royal you, a 7 is because, so I'm just

Bear with me here. Imagine that you're a seven, right? And you're a seven without being willing to, I know, without being willing. I know it sounds sad, but just got to trust me here. Your value of seven is because you are not really willing to commit to a long-term relationship, right? So you're, you have all these resources and you have, you know, and you've got your attractiveness and you've got your good genes and all the other things, right? Yeah, but you're not willing.

Yes, exactly. You've got to podcast. You've got all this great stuff going for you. But you're not willing, you're not going to just commit your resources to one person. And you meet somebody who's just amazing. And she also has a podcast and she's gorgeous. And she's a nine. You can increase your value to her just by being willing to invest.

Because women desire that, because women generally place a priority on somebody's willingness to stick around and to continue to invest resources in just her, you can increase your value from a seven to a nine or a 10 just by virtue of being willing to commit.

How does a woman know if I am high status or not? Like on the ways that I can just like signal that I am, if I go to the gym and then I don't know, I got nice aftershave and perfume and I'm wearing, I don't know, a cool t-shirt. What are the cues? How does the brain know that I'm a good reproductive partner?

Right. Yeah. No, that's a really great question. It's really interesting because a lot of the qualities that men value in their partners, like for women are things that are immediately available just based on physical appearance because we know that men have placed a priority on cues related to fertility and reproductive value. And reproductive value is just essentially a person's reproductive shelf life. If you were my coach and you were trying to train me to be high value to women,

even though maybe I'm not. Like even though maybe I don't have a lot of money and I don't have a lot of resources. What kind of like things would you give me? What kind of advice would you give me?

I would probably encourage you to play up your nice guy attributes and your willingness to commit and your willingness to, for example, and interest and things like having children, for example, because these are qualities that women desire and their choice of long-term partners and being able to have those qualities, I think is something that can certainly give you a leg up in terms of made attraction. So you tell me to be a nice guy?

I would say to be a nice guy. Nice guys get laid. Nice guys do get laid. I think that I think that nice guys are less likely to have short-term, you know, casual sex. They probably have fewer casual sexual partners than non-nice guys, but it'll certainly get you access to women. Yeah. I mean, I was reading in your book about how

mating and attraction preferences change for a woman throughout her cycle. So throughout a woman's 28 day cycle, does she always want a nice guy?

No. So women's partner preferences and the types of qualities that women tend to prioritize in their choice of partners do change across the menstrual cycle. And this changes with our sex hormones. So during the early part of the menstrual cycle, both sets of sex hormones, so our estrogen and progesterone, which is our second primary sex hormone,

They are low. And then as estrogen begins to increase, which is something that happens as eggs start to mature in the ovary. And as the eggs are maturing, they release estrogen. And as an egg, as a dominant egg is chosen and begins to fully mature, so that way it will be released at ovulation.

which is how many days into the cycle? Usually estrogen really starts to surge right around day nine of the cycle, but it really hits its high point usually right around day 14, which is when ovulation occurs. So estrogen begins rising sharply around day nine of the cycle.

And again, the first day of the menstrual cycle is the day that, um, is the day that your period arrives. So that's day one, about day nine. So about a week and a half after your period started, most women will start to have a pretty dramatic increase in estrogen, estrogen will climb, climb, climb, climb, climb. It will peak around day 14, which, um, is when ovulation occurs. And this is when an egg, of course, is released and pregnancy is possible from sex. So from day nine till day 15,

Until day, yeah, until day 15, day nine to day 15 are usually like that's usually when we sort of bookend the fertile window. And during this time, not surprisingly, women experience a change in their sexual psychology.

Right, so women become increasingly attuned to all things sex. So what we tend to see is that women's sexual desire increases right around that time in the cycle. Women have more sex during that time in the cycle. Women masturbate more during that time in the cycle. And women become more exacting about who it is that they desire as a romantic partner or a sex partner.

And in particular, what we tend to see is that as estrogen is increasing across the cycle, so too does women's interest in cues that historically have been related to high genetic quality or genetic compatibility within their choice of partners. So two of the traits that we know to be particularly pronounced in terms of women's interest near high fertility in the cycle are cues related to testosterone and masculinity.

And the reason for this one is because testosterone is a known immunosuppressive, meaning that it has the effect of suppressing the immune system. And so people who have relatively high levels of testosterone, this is a cue that their bodies are in such good physical condition, right? Their immune system is so strong and robust that it can handle

being suppressed by testosterone. So people who have higher testosterone are believed to have greater immunocompetence relative to people with lower levels of testosterone. And what we tend to see is that low and behold, during that peak fertility time in the menstrual cycle when estrogen is high, that women exhibit a greater preference for cues related to testosterone in men. So we find, for example, that women desire

a more masculinized male faces, voices, and behavior at high fertility in the cycle compared to low fertility in the cycle. How do you test this? You test this by looking at what it is that women are looking for and you look at it over time. Just to give you an example of one of the most robust studies that's been done looking at this phenomenon, researchers had a group of women bring home a bunch of little plastic tubes,

in a freezer bag, and they had them spit into these little saliva collection tubes every day of the cycle across two menstrual cycles. On those same days when women were taking a saliva sample, they were also evaluating the attractiveness of male faces. And the thing that the women didn't know is that the researchers knew the testosterone levels of the faces of the men that they had them looking at. And because the researchers had men come into the research lab beforehand,

and it took their morning testosterone levels over the course of several days to get an average morning testosterone level for these men. And so when they got all the saliva samples from the women, they assayed all of their saliva, and they were able to look at women's estrogen changes across the cycle, and then how it related to their facial preferences for men. And what they found was first,

that of course estrogen tended to increase and peak during this fertile window. So days nine or so to day 15, women's estrogen levels were high. And during this time, what they also found is that women's preference for testosterone levels in the faces of the men they preferred also increased. And so there was this really beautiful overlap between women's estrogen levels and their preference for testosterone going to show that estrogen loves testosterone.

So women during this estrogenic phase in the cycle have a heightened preference for cues related to facial masculinity. They also have a greater preference for vocal masculinity. So women at high fertility in the cycle also like the sound of more masculinized male voices. They tend to like more social dominance in terms of behavior relative to what we tend to see when women are at low fertility in the cycle.

So I'm more likely to get laid if I... Yeah, there you go. I think that voice right there that you did. I think it's gonna get you all the girls. You think, okay. I do. I do. I would try that one out at the bar tonight. They must then find that, and I think I read this in your work, and well, I did read it in your work, I was just pretending I knew it. They also found that men who have high testosterone levels are more likely to be in a relationship the next year than men that don't have high testosterone levels.

Yeah, so we know from research that not only do women desire testosterone in their partners, women choose men with higher levels of testosterone as their partners. So they've done studies looking at whether or not men are partnered over time.

based on what their testosterone levels are at time one, and then looking at whether or not they're married at time two. And what we tend to find is that low and behold, men with higher levels of testosterone are more likely to be married at time two, suggesting that men are probably more likely to be chosen as partners when they have higher levels of testosterone relative to when they do not.

And something that I found really bizarre, no one's ever explained to me, is I also read, I believe it was in your book or I've been in a video I watched of yours. They found that man who had a baby.

had plummeting testosterone levels? Like how does the, how does the, my body know that I have a baby? Isn't that fascinating? Like the exact mechanisms, I don't know exactly what they are, but the connection between the brain and the rest of the body, I mean, it's, it's, it knows everything. I mean, it knows everything. And what the research finds is that yes, when men get into a longterm relationship, for example, a men's testosterone decreases a little bit, right? And we tend to, you know, culturally we have this narrative about testosterone where,

It's like more is better, right? And it's always seen as something that men should have a lot of. And you see, there's testosterone clinics on all these different corners, because, you know, this idea that men need lots of testosterone and to have lots of testosterone means that you have a problem. But it doesn't always mean that at all. And what we tend to see is that when men are good into a long-term relationship,

testosterone takes a little dip, and when men have children that they're caring for, testosterone takes another dip. And the reason for this is that it's not always in a man's best interest to have their foot on the gas pedal of sexual desire and attraction all the time. It's just not necessarily the best thing to do.

If you're a man engaged in a long-term relationship or you're a man who's caring for young children, it would be better to take some of that effort. They'd be spend, you know, looking at the next-door neighbor and, you know, looking at her shorts or whatever it is that you're looking at. And instead, using that effort to channel it toward caring for your children, caring for your partner. So nice, guys. Don't get laid as much.

So, nice guys might not get laid as much. And when you look at short-term casual sexual behavior in particular, we tend to find that the ones who are more successful with that as a mating strategy tend to be men with higher levels of testosterone. There's just no question about that.

Nonetheless, being somebody who's willing to invest and willing to have long-term relationships with women generally is going to get you in a good position to be able to find a partner. And this is something that anybody can do to increase their value to women. And so you could be somebody who has low testosterone, right? You're lacking these cues to high genetic quality or even genetic compatibility, right? Like let's say that you're

Immune genes, which is one thing that women also pick up on at high fertility is they tend to pick up on qualities related to somebody having different immune genes than themselves. Men who are lacking these things completely can make themselves desirable to women simply by virtue of being the type of person who's willing to invest in a committed relationship because that is something that women value.

This is a bit of a side point and I haven't seen this in any of your work, but it just came to mind because I just think I have a conversation with one of my friends. Attraction for me is such a delicate thing. It's almost, it's almost, it's when it is unconscious. And I, we often think of attractiveness as maybe, you know, this body part on the person is a certain shape or their face looks like this, but

The older I've gotten and the more I look back on my life, the more I've come to believe that there's almost like a thousand tiny little micro expressions or something in the air which makes us attracted to someone else. And so when we're giving people advice on how to be attractive, I wonder if most of the advice is pretty futile because it's deeper than that. It's so much deeper than that.

Yeah, so and you're totally right about that. I mean, the fact is attraction is idiosyncratic and finicky, right? So all of us, when we think about the things that we find sexy and attractive, there's going to be a lot of ways that you're going to disagree with other people, right? Like you're going to think that somebody like is so sexy to you.

And other people might say, yeah, she's all right, but it doesn't really do it for them. And there is an element to our attraction that is very person-specific and idiosyncratic. And might there be some evolutionary roots behind all of that? Maybe. So it could be, for example,

that the kinds of qualities that you find just really attractive in another person that make you feel so attracted to them might be cues that they are a really compatible mate for you. And maybe that's why you have a very sort of youth specific response to that person. But there are also dimensions that are shared. So we know, for example, that men tend to place a greater emphasis relative to women on cues related to physical attractiveness. And that physical attractiveness tends to be related to things that have historically been related to fertility.

So, for example, having an hourglass body shape, we know that this is something that's related to a woman's level of sex hormones and that women with higher levels of estrogen, for example, are more likely to put on fat around their butt and their thighs and less likely to put on fat around their waist relative to women with higher or lower levels of estrogen, as estrogen levels decline when women age.

their bodies become more straight up and down than they do our class. And this has to do with changes in estrogen. And so we know that that's something that men generally desire to a greater extent than women. We also know that men tend to place a greater emphasis on cues related to youthfulness. So the cues that are related to maturity in a face, that's something that women tend to have a heightened preference for. So if somebody has

sort of an older face. They tend to be seen as more attractive. So like 50-year-old George Clooney seems more attractive. Most women think that that looks more attractive than 25-year-old George Clooney. And we see that because our brains have inherited this tendency to find cues related to wisdom and status

and resource acquisition, all of which come with greater age, women have inherited that preference for those kinds of qualities because that would have given them a mating-related advantage relative to preferring a more youthful face. Conversely, for men, they would have been penalized

if they had a preference for maturity in the face of a potential partner. Because if you like women who have signs of maturity and wisdom and resource acquisition ability, you'd probably choose somebody who's approaching menopause, right? And that's not going to lead to any gene transmission at all, right? And so we tend to see that men have a heightened preference for cues related to youthfulness in faces.

And so even though, yes, there are differences between individuals and there is some idiosyncrasy that tends to characterize human-made choice, there are a lot of things that we can actually make some pretty strong predictions about too. So there are some overall themes that tend to characterize men's and women's partner preferences. Is it true that men are less attractive to a successful woman? Is there any sort of evolutionary basis for that?

I do know that research finds that men don't place as much of a priority on that compared to women, but I don't know that they penalize them exactly. If you had somebody, if you show a man, a photograph of a woman who's dressed like a CEO, and she's gorgeous, and you show a man, a picture of a woman who's dressed like a Burger King service person,

And she's dropped dead gorgeous. Men are going to find her similarly attractive in both conditions. It doesn't matter. The woman can be doing, it doesn't matter what the woman is doing. And there's been research that shows this. They'll show men and women photographs of people in different types of outfits. And the men's ratings of how attractive the women are has just everything to do with how attractive the women are. For women, rating men,

It all depends on what they're wearing, right? Do they show cues to resource access? Do they not show cues to resource access? And women tend to modulate how physically attractive they find men based on whether or not they have these cues related to provisioning ability.

So I don't know if there was a really attractive, and there are a lot of really attractive females in positions of power, men will find them just as attractive as they do somebody who's not in a position of power. Although they may be potentially less likely to choose them as a long-term mate, if there's issues related to power dynamics and that sort of thing that they don't want to mess with.

What about jealousy? And specifically, is the term intersects of women being jealous of women, men being jealous of men. You mentioned a second ago that if 60% of the college educated or college attendees or 70% of them are women, and there's only a pool of 30% which are men,

isn't there going to be a ton of competition amongst women? And what direction does that competition travel in? Is it low status women having competition with high status women, or is it what is it?

I mean, the competition when you have cases where there's an asymmetrical sex ratio and like we do on college campuses, I mean, women are very competitive amongst one another for access to the men that are available. And oftentimes the way that this like the form that this tends to take is that women become increasingly likely to be willing to do whatever men want of them in order to be chosen as a mate. And what we've tended to see on college campuses is because men are more oriented

toward casual sex and non-committed relationships, then women are. What we tend to see is that short-term hookups and casual sex tend to be very common on college campuses. And in part, this is the result of the fact that women are competing for access to mates. And one of the ways that they can compete for access to mates is to be willing to do whatever it is that men want in terms of providing the structure of their relationship.

And if men are only looking for casual sex, even though women tend to be more oriented toward long-term relationships, they're going to be more inclined to just give in to whatever it is that the men desire as a means to be able to get a partner. Are women more competitive with beautiful women or women that are less stereotypically and socially considered beautiful?

Oh, women are more competitive with beautiful women. I mean, there's just no question about that. And the reason for this is that given that this is something that men desire in their partners, this is the primary dimension by which women compete for access to partners, right? And so this is the big, this is the big one. Given men place of really

pretty strong priority on physical attractiveness and their choice of partners. And in fact, one of the biggest predictors of a woman's upward social mobility in the US is how physically attractive a woman is. And in fact, that's a bigger predictor of a woman's upward mobility than her education level or even her socioeconomic status of origin.

When you say upward social mobility, what do you mean? I mean, the ability to transcend the social class in which you were born. So if you're somebody who was, you know, working class or middle class or upper class, your ability to transcend those ranks of, you know, socioeconomic status is more strongly predicted by physical attractiveness than a woman's education level. And that's like a tough thing to have to, that's a tough nut, you know, a tough nut to crack, tough pill to swallow.

So women are more competitive against beautiful women in the lens of society and stereotypically.

Yes. And one of the ways that women compete against one another is by derogating their competitors, right? And derogating their competitors just meaning saying mean things about them or saying mean things to them. And a lot of times those mean things that they have to say have to do with a woman's attractiveness, right? They'll try to downplay how attractive she is to other people.

by saying things like, oh, she's had a lot of work done, right? That's the thing that you'll hear women say about each other or two men about other women. And this is something that's done to try to manipulate other people's perceptions of that woman's value. But because attractiveness plays such an important role in terms of a woman's ability to successfully attract a romantic partner, this is a dimension in which women are fiercely competitive.

even when they don't want to say that they are and want to pretend that they're not. I think that the Barbie movie was sort of got at some of these kinds of issues and just this idea that women want to pretend like none of this stuff matters, right? And that it's not that important and that we don't value this stuff. But nonetheless, this is still a very important domain of competition for women. Always has been, I think it probably always will be.

Are women more likely to trust a beautiful woman or a woman that is less stereotypically beautiful? Because I was thinking about this thing about gay male shopping sales associates. It was a test that you did, right?

Yeah, so this was, I have one of my former, this is digging deep, so this is one of my former students who was really into, and so he's a gay man, and just to set the stage for all of this, he became really interested in the

friendship that tends to form between gay men and straight women, which is actually, you know, there's a, this is something that happens everywhere. So having like the gay man and the straight woman friendship is something that's not just, you know, something that we see in Europe in the US. It is sort of cross-culturally ubiquitous. And he was trying to understand this relationship. And one of the things that he noted in his research is that, um,

the people who tend to form friendships, most frequently with gay men, are beautiful women. It's like attractive women who are more competitive and potentially may perceive more competition on the part of other women, and they form these friendships because

gay men can provide them with really important information that's relevant on the mating market that is not colored by one intersectional competition, right? So if you say to these pants, make me look fat, right? Your gay man friend isn't going to tell you, no, they look great even though they make you look terrible because they're trying to send you out and look terrible.

There's no thread of competition in that relationship. There's also not the fear that this person is just trying to get you in bed. There's this really nice trust that women can have with gay men. This is your brain on birth control. Why did you choose to write this book?

I chose to write this book because I was on hormonal birth control for more than a decade of my life, and I'm a psychologist who studies women and women's brains. And I had absolutely no idea that any of the things that the birth control pill does to the brain were happening to me. And so I went off of hormonal birth control after being on it for more than a decade straight.

And when I went off it, I felt like I woke up. It was like I had this moment. It was about three months after I discontinued it, where all of a sudden I realized that over the last three months, I'd been feeling things more deeply. I'd been interested in sex in a way that I hadn't been in a long time.

I was exercising and going to the gym again. I was downloading new music onto my, what was then, an iPod. For the first time, I know. It's like an archaic iPhone, people. I was downloading new music onto my phone and my iPod. I was cooking again. I was just interested in pleasure. I had more energy. I was feeling things more deeply. And I thought, what is this?

And I was on it, you know, during the time that I was on birth control, I never had any issues with it. Like, I wasn't one of those people who had a negative mood-related side effects. And I didn't know that I was experiencing any side effects at all. And it was only after I went off of it and started to realize how much more alive I felt.

that I started to dig into the research behind the way that hormonal birth control changes women. And it was then that I learned that people had been studying this in some cases for 30 years on the way that hormonal birth control changes the way that women think, feel, and experience the world.

And it was then that I knew that I had to share this information with other women because here I was as somebody who's on the pill, studies women, studies women's brains, I'd even published papers on the effects of women's changing hormones over the cycle and the way that they influence women. And it never even occurred to me that my birth control was changing me. And I knew that if I didn't know that the birth control pill was changing me, that nobody else knew it either.

And so that led me to dig into the science behind hormones, hormonal birth control, and how that changes women. And I put together that book to tell everybody the things that I learned. Pretty dangerous subject matter to take on.

It can seem like a dangerous subject matter to take on. And for good reason, hormonal birth control and having a reliable way to prevent pregnancy has been by far the biggest game changer that women have ever experienced in history. There's been nothing that has been more instrumental to women's ability to be able to achieve political and economic independence for men than the birth control pill.

And because of this, saying anything that is critical of the birth control pill can be seen very dangerous, right? Because it's like, oh no, don't say that too loudly, or else they're going to take our birth control away, or oh no, don't say that too loudly, like what else are we going to do? But this book was really important to me to be able to present to women all of the different ways that hormones influence us.

And the surprising ways that hormonal birth control can change who we are in the way that we experience the world and then give that information to women. So that way, when they're making decisions about whether to be on or off of hormonal birth control, they have all the information about the trade-offs that they're making. And this will allow them then to make decisions about whether or not to be on it.

depending on what's going on in their own lives. Because everything that I've learned about the way that the birth control pill changes women means that the answer that you come to when you're asking yourself the question, do I go on this or do I not go on this, is going to be very woman-specific. For some women, the decision is still going to be, yes, I'm willing to make these trade-offs.

And for other women, the answer is going to be no. I am not willing to make these trade-offs. And whether or not we make those sort of where we land on that is going to differ depending on where we are in our life and so on and so forth. And so it was really important to me to present this information as a way to really empower women to be able to make informed decisions about who they want to be and how they want to regulate their fertility.

Do you wish you were told? On that day when you first given that little packet of pills, what do you think if they were being completely honest with you and they knew what you know now, what is the sort of the list of things you would have said to a young Sarah about this decision? To me, the one thing, and then we can kind of dive down into what this all means, but the thing that

What have really made a difference to me is that your hormones make you who you are, and when you change your hormones, you change who you are, right? So the birth control pill is going to change you. It changes the version of yourself that your brain creates. And so if you're going to be going on this, you need to understand what that does. So this, of course, begs the question, what does it do?

And there are several things that the birth control pill does. And there's at least five different things that the birth control does to change who we are. It changes our sexual desire and who we're attracted to. It changes our emotional states. It can affect our moods. It can affect our ability to regulate and to manage stress.

It influences sexual desire and sexual function. It influences our ability to be able to put on muscle mass and affects our nutrition and fitness goals. It affects all of us and not knowing all of that and not knowing the potential risks of having side effects related to mental health and libido, all the way to everything, who a person is attracted to,

I wish I would have known that. That probably would have, you know, impacted again. Decisions that I would have made about staying on it when I didn't need to. Because there's no reason to change who you are if you don't need the contraceptive benefits. So on that first point then, it changes who you're attracted to, your sexual desire. How?

Well, so mechanistically, the way that this happens has everything to do with the hormonal changes that are initiated by the birth control pill. And so just to talk about the mechanics of this first and then talking about the downstream effects of it next, mechanically what goes on when you take hormonal birth control is you are suppressing ovulation.

And the way that birth control does this is it does this by giving you a combination of hormones or a single hormone that tells your brain not to stimulate the ovaries and not to ovulate. And it does this by way of a synthetic progesterone called a progestin.

and progestins, which are in all forms of hormonal birth control. When they get picked up in the hypothalamus in the brain, that sends a signal that the brain should not stimulate the ovaries and should not lead to egg maturation and egg development. And when this happens, when the brain is not stimulating the ovaries, this means the body is not producing estrogen, right? So estrogen levels are kept really low.

Instead, you get this daily dose of a synthetic progesterone or progesterone that is supplanting that. Many forms of hormonal birth control, in addition to having that synthetic progesterone or progesterone that turns off the brain's communication with the ovaries.

It also has a relatively low level of estrogen that is also added, so combination hormonal birth control pills contain progestin and a little bit of estrogen, but the estrogen levels are kept really low, and the progesterone levels or the progestin levels are the dominant hormone, and you get that same hormonal message every day.

When you do that, what happens when you flat line a woman's own production of hormones and replace them with a daily dose of synthetic progesterone, this does a few things to sexual, like women's sexual psychology. The first thing that it does is it turns off that estrogen surge that you get right prior to ovulation that's related to a heightened preference for sex

Like that estrogen surge is related to an increased preference for testosterone markers and mates. It's related to women's interest insects. It's related to sexual function. All of those things that increase prior to ovulation that help to promote reproduction, sexual reproduction, all of those things are turned off on women on hormonal birth control.

Because instead, they're getting the same daily message in which progestin is the dominant hormonal message and estrogen levels are really low. So that's the first thing that happens. But they're still horny, right? They're still...

Yes, I mean, they still will have sex and they still want sex, but many women report experiencing a real decrease in their libido when they're on hormonal birth control. That's a very common response. And the reason for this is twofold. One, one of the things that's a big factor in promoting women's sexual desire and libido.

is estrogen. And as estrogen is rising in the cycle, because when estrogen is rising, this is a time in the cycle when sex can lead to conception, this is something that's known to fuel the female sexual response. So women's sexual response and their sexual desire

all increases with estrogen levels across the cycle. So when you take hormonal birth control and that's flatlined, which is what it does, this means that sexual desire is kept more constant across the cycle. So you do tend to find that women who are using hormonal birth control

tend to have fewer peaks in valleys and sexual desire than naturally cycling women do, but on the whole it tends to be lower. The other thing that happens on hormonal birth control that can lead to a decrease in libido is that all of those synthetic hormones that are in hormonal birth control

they tend to lead to an increase in what's known as sex hormone binding globulin, which is a real mouthful. But what it does is that this is something that's released by the liver and it binds up free testosterone. So it binds up testosterone and makes it inactive in the body. And testosterone, even though we tend to think of it as like a guy thing, like this is a male hormone, it's actually really important in terms of promoting women's sexual desire.

And women who are on hormonal birth control have levels of free testosterone that are about 60% lower than that of their naturally cycling peers. And so what this means, again, is that you have another, you know, blow to women's sexual desire when they're on hormonal birth control, those low levels of estrogen, and then really low levels of free testosterone. Those two things work together to suppress

sexual desire in women. And it can also change attraction, because as we noted, when women are approaching ovulation, their estrogen levels increase. And this is something that research finds to be related to women's interest in testosterone markers in men. Researchers more recently said,

If that's true, what happens when you put women on hormonal birth control? And estrogen levels are kept really low. And what they find is that low and behold, women who are using hormonal birth control do seem to have a dampened preference for cues related to masculinity and testosterone in partners relative to what's observed in naturally cycling women.

which specifically means that a woman on birth control is less likely to be interested in a guy who is what? A guy who has really masculinized features. So for example, if you see a face that has high levels of testosterone, generally men will have like more deep set eyes. They tend to have a wider jaw. And in the bodies, they tend to have broader shoulders and a more narrow waist.

deep men with more deep voices, men who have cues to like behavioral cues to social dominance. That's also something related to testosterone. And what the research finds is that women who are using hormonal birth control do prefer a less masculinized male face relative to what is observed in naturally cycling women. I mean, this is slightly concerning if you're a man, right? Because if my partner's on the pill and then she comes off the pill, she might not like me.

Right, yeah. And that's a real important question to me. It's very provocative, because what does that mean? And there have been some research studies that have looked at that exact question. And one of the best studies that's looked at this question is one that was a longitudinal study of married couples. They followed women who were using hormonal birth control at the time that they met their partner, and then they just followed them over time to see what would happen when women discontinued the pill.

What happened when they discontinued was that there were real significant changes in how attracted women were to their partner, depending on whether they chose them using hormonal birth control. But what was interesting about it is whether the women became more or less attracted to their partner depends on how attractive their partner was. So what the researchers found is that women who were partnered to attractive men,

When they went off hormonal birth control, they were more attracted to their partner and were more sexually attracted to their partner and more sexually satisfied within their relationship relative to where they were beforehand. But for women who were partnered with less attractive partners, they had the opposite effect. So when they went off hormonal birth control, they became less attracted to their partners and reported being less sexually satisfied with their partners than where they were beforehand.

And so this suggests that yes, it is a very real possibility that if you have a partner who chose you when you're using hormonal birth control, that this can change attraction within the context of the relationship. But whether that's good or bad probably depends on a bunch of other dimensions that you need to take into effect, including partner's attractiveness.

So if you're not a very good looking guy, you probably want to stay on it. Run for the hills. Honestly, it's one of these things where you can really quickly become alarmed with this. The good news is this, and that is most women who choose their partners when they're on hormonal birth control

go off of hormonal birth control, and then there's really not a huge shakeup in their relationship, right? And the reason for this is the way that hormones influence us is they kind of nudge us a little bit one way or the other, right? They kind of nudge us toward preferring this type of mate or that type of mate. It's generally not these big sweeping changes where all of a sudden it's like the wool comes off your eyes and you're like, what in the world was I thinking?

These are little nudges. It's just that for some people who are teetering on the edge of not necessarily being attracted to their partner, going off hormonal birth control can tilt them out of attraction. I've talked to people who've had the experience

of feeling like they were lesbian and all of a sudden they feel like they're bisexual or women who are bisexual and then they go off of the pill and all of a sudden they realize that they're not interested in women anymore. I mean it's like sexual orientation, attraction of all sorts, whether it's who you're attracted to in terms of the sex you're attracted to or who you're attracted to in terms of the specific partners that you're attracted to, all of those things are influenced by sex hormones.

And, you know, when sex hormones kind of nudge you this way or the other way, depending on where you fall in that distribution of, you know, sort of where you are in terms of sexual orientation, or am I attracted to this mate or that mate, those people who are on the tails can get nudged into a place that puts them into the uncomfortable situation where they realize that they're no longer attracted to the person they chose on the pill.

As a man, is my attraction going to change if my partner comes off the pill? So there is evidence that suggests that women are more attractive to men when they're naturally cycling relative to when they're on hormonal birth control. And so chances are if you have a partner that you were attracted to when she's on hormonal birth control, when she goes off of it, it's actually going to lead to an increase in attraction.

So, there's a ton of research that finds that men find women sexiest. They think that they smell better. They think that they look more attractive. Men will tip women more at strip clubs when the women are at high fertility across the cycle, relative to low fertility across the cycle, meaning that men are queued into estrogen levels.

sent visual appearance and even just the way that women act and move. So they've done studies or they have men looking at women moving, just seeing their silhouettes move like behind a sheet, right? So they'll see women walking or dancing and they have them walking or dancing at high or low fertility across the cycle and men find the women more attractive when they just see their outlines moving.

at high fertility compared to low fertility. So men's brains are wired to pick up on estrogen cues. And this makes perfect sense when we consider the evolutionary process that designed us. Because over the course of evolutionary history, men who were really dialed into women's estrogen levels

they would have passed down more genes than men who didn't really pay attention to those cues. Because estrogen across the lifespan is linked with fertility, and estrogen across the cycle is linked with fertility. It's linked with fertility no matter which way you look at it. And so men who are really cute into estrogen levels, they would have done really well. And so if you are a man, your partner chose you when she was using hormonal birth control, and now all of a sudden she starts cycling again,

My guess is that most men will experience an increase in attraction to their partner, particularly at high fertility in the cycle, because there's so much research that suggests that this is exactly what should go on. Here's one where I've put a few dots together. If my partner is on the birth control pill, are my testosterone levels going to be lower?

That's a fascinating question and it's one I'm super interested in. So I actually was just, I just had this conversation not that long ago with my graduate students in my lab. There is research that suggests that men's testosterone levels increase in response to the scent of fertile women, right? So when women are at high fertility, if men sniff t-shirts that they were wearing or in one study, they actually had men sniffing the air that was being,

piped through a nebulizer that had a woman's pantyliner in it that was either worn at higher low fertility. So smelling women's vaginal secretions, both of those things have been shown in research to be related to an increase in testosterone levels in men. So it increases men's testosterone levels to be around these cues.

to high fertility. So what happens then when men are spending their time or are partnered with somebody who's on hormonal birth control, right? So given that estrogen levels can increase testosterone, does a lack of estrogen presence lead to lower levels of testosterone on average?

And this is a question that we do not have a research answer to, but it's one that's incredibly fascinating because here we are, right, 2024, almost 2025, and we have a testosterone crisis on our hands, right? Men's testosterone levels are much lower than what they used to be even 50 years ago. And it's possible that one contributor to this is the fact that so many women are using hormonal birth control

And when you have on average lower levels of estrogen in the population, might this then also predict lower levels of testosterone in men? And the answer to that is we don't know. Another possibility with that, by the way, and one that I think is so interesting is we talked about kids, and we talked about the fact that men's testosterone levels will decrease when men are in long-term relationships, and then they'll decrease a little bit more when men have children that they're caring for.

Another possibility for men's lowered levels of testosterone, in addition to all the trash that's in the water and all the chemicals that we're exposed to, is the fact that men are now responsible for more caregiving than they ever have been in history. With many women being in the workforce, men are having to also do more in the home.

than they ever did before. And so it's also possible that some of the differences that we see in testosterone levels that have changed over time may be the result of men, their bodies actually decreasing testosterone production in response to their changing roles in the home, which is also sort of a fascinating possibility. Are you at all concerned that there will be a bit of a population collapse if we don't start having more kids?

Gosh, I have thought about that. I can't spend, if you talk about something like that, it almost sounds like you can take the next step and say that it's everybody's obligation to reproduce and that women need to be having more babies.

If I say yes, I do think about that. I hasten to add that it's not women's responsibility to make sure that they're having babies. But I do wonder what's going to happen because people are not reproducing the way that they used to. And there's a lot of people now who are choosing not to have children at all. And so what is that going to do? I have no idea, but I don't think it's necessarily going to be good.

Every single time you eat, you have an opportunity to improve your health.

because Zoe combines my health data with their world-class science. Using these two things, Zoe guides me to better health every single time I make a food choice in eat, which means I have more energy, better sleep, better mood, and I'm less hungry. And the best part about Zoe is that it's backed by their recent clinical trial, something called the method study, which is the gold standard of scientific research. I started Zoe just over a year ago now, and I've been able to track my progress week after week, so I can learn how to be even smarter the week after.

And if you haven't joined Zoe yet, I'm going to give you 10% off when you join Zoe now. Just use the code Bartlett and check out. Just for a second, because I had so many conversations on this podcast about men's issues in the state of the world for men right now. It's quite an interesting moment with like the depression statistics and sociality and sexlessness and all these things. And I don't know if you've even got an answer to this question, but

What advice would you, have you got a son? I do. What advice do you give to a young man? How old is he? He's 15. He's 15, perfect. He's like right at the age where he's just about to figure out what it is to be a man. Right.

What advice are you giving to him about what is a good man in the modern world? Is it okay to be masculine? Yeah, no, I think there's room for masculinity. And honestly, sex demands it.

I mean, I teach a class called Evolution, Sex, and the Brain. And one of the things that we talk about is just how problematic sex has become because there's so much of a dance with seduction. Everybody knows when masculinity has gone too far. It's like, you know it when you see it.

you know, like touching a woman when she's asking not to be or harassing somebody. It's like we all know what that looks like. But then there's also, you know, seduction requires like the whole idea of seduction is this idea that men

can lead women into sexuality. And so trying to have a conversation with my son about, you know, it's like everything has to, you know, he has to make sure that if he's interacting with girls that there is consent and that it's consensual, any sort of a physical touch that goes on. But at the same time,

You know, like, I would never at the, you know, I can't imagine thinking, you know, is it okay if I touch your breast? You know, like, I can't imagine that. I can't imagine living in that world.

I mean, it's a really tricky world to be in. Being a male is hard. I mean, that's like a hard line to toe because on the one hand, you don't want to do something that's obviously going to be detrimental or hurtful to a woman or violate her in some way. But on the other hand,

you know, you can go too far with the permissions in a way that can be really bad for sex. And because attraction and sexual desire is all about sort of the push in the pull of the masculine and the feminine. But also if you're a low status male, like I was at the start of my career, when I'm 18, no money, working in a call center, you know, not really any friends, can barely, well, I couldn't provide for myself, let alone anybody else. Right.

And in terms of dating dynamics often hear that the top 10% of men are pretty much having all the fun.

Right, yeah, that's probably true. And then the bottom 50% of men haven't had sex for like a year or something crazy like that. So if you're in that bottom 50% of men, but that's not the case going the other way, is it? Because it's much easier for a woman to acquire sex if she sought it. I mean, you did studies on this, right? Right, well, yeah, I mean, if a woman is looking for sex, it's not hard to find. Like any woman who is listening to this right now, if she decided to go and have sex tonight, she'd probably be able to find a taker

What was the study of the actor, the beautiful actor on a campus? Oh, yes. No, that's a wonderful study. So that's a classic social psychology study that was done at the University of Florida a number of years ago. What the researchers did is they had a male and female model, so in a really attractive person, approach strangers on campus. And they would introduce themselves. They would just say, hello. I've been noticing you around campus and find you very attractive.

And after they made this introduction, they would then follow this with one of three requests. It would either be, would you like to go on a date with me? Would you like to go back to my apartment with me? Or would you like to go and have sex with me? And then they simply made note of what the person said. Did they say yes or did they say no?

And what they found was that for both men and women, 50% agreed to the date. So I've been noticing your own campus. I find you very attractive. Would you go on a date with me? 50% of men, 50% of women said yes. After that, the sex is diverged in pretty marked ways. What they found is that very few women, almost zero women, said yes to go back to the apartment with the person. And a full 0% of women said that they would go back and have sex with the person.

This isn't what they found for men, right? For men, what they found was that men were more likely to agree to go back to somebody's apartment with them than they were to the date. And men were most likely to agree to just have sex. Almost 80% of men agreed. Yeah, I would love to go and have sex with you. And the men who said no.

Usually, we're in a relationship, or noted that their parents were in town and they wouldn't be able to go back to their apartment. This goes to show some real differences when it comes to men's and women's tendency towards sexual opportunism.

And the fact is, historically, women have had huge costs related to sexual behavior just simply because women to reproduce have a minimum investment of nine months' time in pregnancy and then subsequent time spent breastfeeding.

And so for women who were sexually opportunistic, in other words, willing to consent to sex without strings or investment, women would have been penalized for that. Because throughout most of our evolutionary history, that could result in a pregnancy, and it could result in a pregnancy for which you have no one to help co-invest. For men, on the other hand,

Being willing to consent to sex without commitment, that's an evolutionary win, right? That's a potential gene transmission opportunity because short-term sex, of course, can lead to pregnancy. And if there is no expectation of further investment, it's very low cost, right? So the costs and benefits related to short-term casual sex are vastly different depending on whether or not you have a male or female body.

So if your son comes home one day and says, Mum, listen, I've tried my best. I can't seem to persuade a woman to give me a chance. Right. Then I would say, go to the gym and be a nice guy. Well, I mean, honestly, you know, be a nice guy for a nice guy. Well, no, but a nice guy can form relationships. Right. If he's looking for a girlfriend, I think one of the ways that you can get a girlfriend is by being willing to, being willing to

invest in a woman. If you're a jerk, you're going to have a harder time. Even if you're an attractive jerk, if you were an attractive nice guy, you'd probably do better as long as you're not too nice, because that might give off low testosterone cues. I'm not really sure.

bad boys. They seem to get a lot of this sort of sexual attention, right? What is that about? But that's like despite the fact that they're bad boys. I mean, so it depends on how we're defining bad boys. Okay, so being a little bit. Yeah, yeah. So a lot of those are cues related to testosterone, right? So having, you know, being risk tolerant, so being willing to do things that are really risky and, you know, and being a little bit arrogant because you know you're always going to succeed.

Those are cues related to status and related to sometimes testosterone levels. And so we know that women like both of these things and their partners. And so because of that, those men will tend to do pretty well on the mating market. For men who don't have those qualities, so men who are not

risk-seeking and are not arrogant, that's not necessarily going to not do them favors unless that also is an indicator that they have other qualities that aren't working for them. You can have somebody who's very successful and has high testosterone, who's not a jerk. That guy will do pretty well. Why would you tell your son to go to the gym?

I would tell my son to go to the gym because it's like one way that you can naturally increase your testosterone levels is by building muscle. And also another thing that does is that muscle mass is related to reductions in anxiety. And the reason for this is because if you're a big dude, it means that you're going to be able to protect yourself. And so your brain makes the adjustment and it makes you more confident and less anxious when you have some muscle mass.

And so I would say go and do those things and then also doing the things that you can to get access to resources and status, right? So study and work hard because ultimately people who do that tend to do well and people who do well financially and do well in terms of, you know, ascending the status hierarchy. They tend to also do well in the mating market if they're men. Have you got a daughter?

I sure do. Your daughter comes home. Mum, I've tried my best. And no one's interested. Right. Yeah. No. So for my daughter, then I would say, then you just need, you need to wait. Right. You were probably, you were probably in the wrong, you were probably in the wrong mating pool. Would be my, would be my advice to her. Why?

My advice is, well, because so a few things. So many of the things that women sort of possess, that men desire in their choice of partners, are things that women don't have that much control over, right? It's like a woman's like youth and reproductive value and these things related to fertility. You want to entertain at the gym?

I mean, I guess I might tell her to hit the gym. I might probably make her feel better, but I don't think that I would tell her, like, you know, you should probably go and get your hair done. And, you know, I'm trying to think, well, go off the birth control pill so that if she was on the birth control pill, but she is not. But I'm just thinking in an abstract way, like what I would tell her, like things that women can do to increase their attractiveness to men.

I mean, it's like, okay, go be more beautiful. Like, what are you gonna say? And so, like I said, my real advice, if my daughter said this, would I would say you probably need a different pool of mates. What if she was 35?

If she was 35, good question. So if she was 35, what would I recommend? Is this what I would actually recommend to my daughter? Or are you trying to get at what should a woman do? Because here's, I have two different answers. So if a woman is just looking for, if you want me to write

a pamphlet called 35-year-old woman, here are the things you need to do to find a partner. I mean, it would have a whole list of unsavory things that, you know, I mean, it would be like, consider Botox. Men are attracted to women who have features related to youth and fertility.

Consider having a Brazilian butt lift because men are also interested in this. Why don't you also consider spending time on your hair and makeup? But I don't think I would write that book. That's not the advice that I would give.

Do men find confidence attractive in women? Because I was thinking about this as you're speaking, because I can think of many people that I know, many women and men, but many women that I know that are, you know, maybe, you know, approaching their forties, and they're beautiful.

But they're single and they don't want to be single. And it's not necessarily a physical thing, it appears, but it seems to be more of like a self-esteem confidence thing. And I can see how in men confidence matters, like if they're stood up straight and they exert those signals of dominance or not dominance, but like a high status, that'd be attractive. Is it the same? And are men attracted to like confident women?

Yes and no. So women who are seen as more confident, like that is seen as more attractive, for example. Like somebody who has some self-assurance of themselves instead of sort of like kicking their toe on the ground, generally people find that attractive both men and women. But the degree to which that is prioritized is hugely different between the sexes. And if you are a woman and you sort of go out and exude those cues related to like social dominance, for example, and social status,

That's not going to necessarily get you a mate. And in some cases, it might actually detract from your attractiveness as a mate because people seem to view women who are in positions of power more negatively than how they perceive men. And women who are in positions of power, they're sort of a

There's definitely a double standard there. And this is something that has been fairly well studied, where they find that there's nobody more polarizing in the world than powerful women. So for example, somebody like Kamala Harris, who is running for president, people seem to either really love her or really hate her.

So, there's this polarization that happens with powerful women. This happens for anybody who's run for any political office that is a female. You get these sorts of issues. And women who are confident and direct and assertive are seen as being cold. And, you know, like we call girls bossy.

When they have these kinds of qualities, whereas if it's a boy or men, it's like leadership potential. There is a double standard in how we tend to perceive this. Over the course of evolutionary history, women did well when they chose high-status men. That would have given them preferential access to resources for themselves and their children.

we don't get that same kind of a pattern for men choosing women, right? Men who chose women who were high-end status and

you know, socially dominant. That doesn't necessarily translate into anything that's going to correspond to increased reproductive success. Bit of a sort of correlated but uncorrelated point. People talk about daddy issues. And in your work, I've kind of seen hints of an explanation for daddy issues. If my father isn't around, that has a big impact on who I am. Is there any truth to this idea that people can have daddy issues?

Yeah, no, there absolutely is. And so when I say this, you know, daddy issues just simply referring to the fact that women whose fathers are not invested in them or absent during childhood, that these women will tend to have more unrestricted or precocious sexual development and sexual behavior.

relative to what we see in women who grow up with investing dads. So just to give you an example of some research that's been done looking at this, research finds that women who grow up in a household without an investing dad, so dad is either gone or dad is there, but in name only, so he's not really investing in the family. Those women go into puberty significantly earlier.

They then do girls who grow up in two parent homes with investing fathers. They also tend to have an earlier age at which they begin having sex relative to women who have two dads in the home. And they tend to have a greater number of sexual partners sort of over time relative to girls who grow up with two parents in the home. Wouldn't they then also go into menopause area?

That's a really great question. And there is some evidence that suggests that there may be a decrease in ovarian reserve that might go on, but there hasn't been anything linking that to menopause just yet. Which is the amount of eggs they have in their ovaries. What role does the father play on our sexual preferences and decision-making? So if my dad, am I taking, as a woman, do I take cues on what a good partner is from looking at my dad?

I have not seen any research that has looked at that. I've seen some research looking at whether women prefer partners who are kind of similar to their dads, and they do seem to, which is interesting and in its own right. But I do not know anything about men and their preferences and whether or not their sons then tend to emulate those preferences as an interesting question.

So on the subject of stress, what is the impact that the birth control pill has on how women experience this stress?

Well, the research finds that when women are on hormonal birth control, that they have a blunted cortisol response to stress. And cortisol is a stress hormone, right? And we all know it as this bad guy, right? This idea of like, oh no, high cortisol, and that's, you know, seen as something that's bad because when you experience high levels of cortisol for a long period of time, it actually is bad, right? So chronic stress causes all kinds of problems, right? It makes you put on visceral fat, so it makes you put on belly fat.

It dumps fat and blood into your bloodstream in ways that can raise your triglycerides and put you at a greater risk for heart and cardiovascular problems. It's not good. But having dynamic spikes in cortisol in response to stressful events is actually incredibly adaptive. And it's something that allows us to be able to regulate

manage and cope with stress. There's a reason we experience cortisol and response to stress. And what research finds is that for women who are using hormonal birth control, that you get a no, you know, a blunted or absent cortisol response to stress. And this is the sort of thing that we tend to see in people who've experienced PTSD.

or trauma because people have experienced PTSD and trauma, their stress responses get shut down by their bodies because they've experienced so much stress that their body is like no more cortisol release for you because cortisol in the long term is not good, right? It is detrimental to the body.

And so what research finds is that people with PTSD and people who've had trauma, they have a blunted or absent cortisol response to stress because their body just doesn't allow them to release it anymore because it's chronically being released. And we see the same thing in women who are using hormonal birth control.

So they experience a blunted or absent cortisol response to stress. And this is something that can lead to dysregulated responses and everything ranging from their immune system, which is regulated in part by cortisol because that helps to regulate the inflammatory response that we have both to stress and also injury. And it can lead to things like our ability to regulate our emotional responses because we know that cortisol has something to do with that as well.

And we know from so much research now that women who are on hormonal birth control, that they have dysregulations in emotional responses oftentimes with these women being at an increased risk for developing things like anxiety and depression. And this may, in part, have something to do with the differences that we have in cortisol.

In your book, you mentioned that in a study in Denmark, women on the pellet were 50% more likely to be diagnosed with depression within six months of starting the pill compared to naturally cycling women. And researchers showed that women who were on the pill were two times as likely to have attempted suicide than naturally cycling women.

Yeah, it's pretty stark. I mean, there are some real risk factors that come up when women are using hormonal birth control. And these are things that oftentimes are swept under the rug by their doctors who are prescribing it. The fact is, especially for teenage girls,

Going on hormonal birth control can significantly increase your risk of developing a mental health disorder and significantly increase your risk of attempting or being successful at suicide. And this is something that's absolutely necessary, especially for mothers of young girls and young girls who are being put on these pills because they're the ones who asymmetrically bear the burden

of the increased risk of mental health related problems. And the thing about these girls is that we don't know whether or not these patterns are reversible because the teenage brain is still developing. And to go into a teenage brain that's still developing and suppress normal hormonal variation that occurs across the cycle and instead replace it with synthetic hormones,

We have no idea what this does to brain development. And this is an important question because brain development that occurs during the pubertal transition, that is when the brain is remodeling itself from its child version of itself into the grown-up version of itself, that remodeling job is being coordinated by sex hormones.

And so the idea that we're gonna replace that, you know, these naturally occurring variation in sex hormones, and replace it with synthetics, and that it's not gonna have any impact on brain development, doesn't seem realistic. How old is your daughter? She's 17. 17. So she's right, she's at the age now where she's making the decision. You mentioned Ellie, she's not on birth control. Yes. How did you feel when it came time to make that decision?

I mean, for me, it's all about what weighing the risks and the benefits. And so for me, the first risk and benefit question is, is there a risk that this person is going to get pregnant? And so if she's not in a sexual relationship, I don't have to worry about it. It's a no-brainer. You're not going on hormonal birth control. If she is sexually active, then the question becomes,

Is there a way that we can protect her from pregnancy that doesn't introduce these exogenous hormones, these synthetic hormones that are going to shut down her own hormone production and potentially impact brain development? Thankfully, there are options. So there's not great, right? And they're not for everyone, but for example,

There's a copper IUD, which is an intrauterine device that prevents pregnancy without changing women's sex hormones. And so I think that's a really good option for sexually active teenagers. Is that the coil? Yes, it's the coil. It's the copper coil because there's two different types of coils. Where does that go? It goes up into vagina. It goes up into the cervix.

Okay, and it sits there for a long time. It sits there for like five years is how long it can stay in there without having to be replaced. And it's a really great option for women to be able to protect themselves without having to think about it. Right. And that's really important when we're talking about teenagers, because a lot of times they don't make the best decisions.

Their frontal lobes are not done developing and because of this, they don't always plan and they don't always think things clearly, you know, think things through clearly. And so for a teenager who's not necessarily going to be all that on top of things when it comes to using things like condoms, which is a barrier method that requires that you actually use the condom.

You can't just have them and then protect yourself from pregnancy or something like the fertility awareness method, which is where women keep track of where they are in their cycle, and then abstain from sex or use a barrier method when they're at high fertility.

And then they don't have to worry about it at low fertility. I don't necessarily recommend those highly for teenagers if possible, just because it requires a lot of thought. And like I said, teenagers aren't always great at thinking through things.

What about that thing that goes in the arm? A lot of the girls in my school, when I was in secondary school, were getting the little thing in their arm. Yeah, so that is the implant. So that's here in the US, the one that people are on is called Nexplanon. And that gives a daily dose of a synthetic progesterone or a progesterone. And that daily dose of that hormone is, of course, keeping the brain from stimulating the ovaries. And so it's keeping hormones flatlined.

And so that is something that yes is incredibly effective. And yes, it is brainless because you don't have to think about it, which is great because the best birth control is birth control they don't have to think about. But you're getting a daily dose of this hormone that's shutting off your ovulation. And so you're going to experience all of the changes that women experience when using hormonal birth control when you're using that, right? It can change who you're attracted to. It can change your sex drive. It can change your mood.

It can change your ability to regulate your stress response. It can change your ability to put on muscle mass from working out. There's some new research that finds that women who are using hormonal birth control, who are doing the exact same exercises as women who are naturally cycling over a 12-week period.

right put on less muscle mass and had lower levels of testosterone relative to what you see in the women who are naturally cycling and of course that's what they find because women who are using hormonal birth control their testosterone levels are kept suppressed and this is one of the big stimulators that we know of muscle growth and same with AMPK levels are tend to be

high when estrogen is high, and that's also something that promotes muscle growth. And that's lower in women who are using hormonal birth control relative to natural cyclers. And so, you know, it also can influence that. It influences everything.

And so the idea that hormonal birth control is the answer for women when it comes to regulating fertility, I just don't think that it is. It's an answer, and it's one that we need to make sure all women have access to it, who need it.

But my whole message with everything with my book and everything else has always been, we need more answers. We need better answers. And it seems like things might be moving in that way. There's more research being done on things that mail contraception and not just mail hormonal contraception because I don't think that's the answer either because the idea of

suppressing men's hormone production to such an extent that they no longer produce viable sperm, which is how they're looking at it. By the way, I don't think that's the answer. That's just shifting. I really don't think men would sign up. It's not crazy. No, I don't think men would sign up either. I'm like, who would take this? I'm like, this is madness, but that's what they're working on, and it just shifts the problem. It shifts it onto men, but there are some really interesting things that are happening in terms of, for example, there's

Can I ask you a question on that? Do you think that if the shoe was on the other foot and men had to take the pill? So suddenly there was a thing that came out and it's like, oh, you're a man and you can take a pill. It messes with your hormones a little bit. They're going to be like artificially replaced with this pill. Do you think men would take it? No.

No, I don't. I think some men would, but do I think most men would take that? Absolutely not. No way. No way, Jose. I wouldn't take it. I'm just going to be honest. Yeah, no. I don't know any, but honestly, I don't know any men who'd say, yes, sign me up for that. I mean, the fact is, if you look anywhere... So why the women take it?

Women take it because we have no choice. Okay, because you're going to bother, yeah. It's like we're the ones who get stuck with the pregnancy. You know, for men, their other option, like if they say, no, I'm not going to take this, is that their partner will be on the pill. But then if the partner is not on the pill either.

You have the partners out on the pill, then they've got to figure something else out. But a lot of times what ends up happening is the women end up going on the pill. And it's because for women, pregnancy is so costly that it's hard for us not to be the ones who are bearing the price of birth control. Because the fact is, we're always the one who end up ultimately having to pay the largest cost.

Your daughter, she's 17 years old, you said that when you went on the birth control pill, it changed you. And after you came off it, you quote, unquote, woke up. So of course you're presumably you're scared if you lose changing your daughter. Right. And then I mean, under your analogy, it should be a sleep.

Right, yeah. Yeah, no, I don't want that. And I also especially don't want that when she's during this period in her life when her brain is still developing. Because like I said, there has been hardly any research that has looked at what happens to brain development when you introduce synthetic sex hormones to women when their brains are developing. And the research that does exist, looking at this question, doesn't paint a very good picture of it. It looks like it can put women on a long-term risk of

developing major depressive disorder over the course of their lifetime, even after they've gone off of it. The idea of having my daughter on hormonal birth control is not something that I want to have happen, especially when her brain is developing. She texts you now and says, I'm just going to start taking the pill moment. How'd you feel? How'd I feel? I would feel like if that was the best, I mean, if she really couldn't tolerate the IUD, the copper IUD that doesn't have the hormonal side effects,

then I would say better that than pregnant.

The fact is teenage pregnancy is one of the biggest predictors of a woman ending up in poverty. And that's a much bigger deal than whether or not a woman feels like she's awake or asleep. And so sadly, that's where we are. And it's my hope that as we move forward, and the more that we start to recognize that birth control as an issue for women hasn't been solved, right, and that we need more options besides just changing women's hormones,

it's my hope that things are going to get better and that we push for more options. I mean, I think that it's so long been considered, you know, we think that birth control is solved and it's not. And so I'm hoping that there's going to be more options. And so that way, you know, later on my daughter's daughters and her daughter's daughters daughters have more things to choose from than just change me or, you know, come at risk of a teenage pregnancy.

What kind of emails do you get? Like what's the most popular email you get from just the world?

The most popular email I get is, thank you. I knew that this was going on. I had absolutely no language to describe it. You nailed it. That's what I get the most. And it's not like you nailed it, Sarah, while you wrote such a great book. But instead, I knew that this had to be happening to me. I knew that I didn't feel the same and this is it. Of course, of course it happened. I mean, I think for a lot of people, we have a blind spot with the birth control pill.

Almost everybody goes on it. And we don't think about the fact that our hormones are an important part of what our brain uses to create the experience of being who we are. Right? And so we're very cavalier in just giving it to people. We're like, oh, well, you should go on it for this. And oh, you've got some acne. You should go on it too. And oh, your period, sometimes you spot between your periods. You should go on the birth control pill. It's like, we don't think about the fact that when we're making those changes, that's changing who women are.

Yeah, so the most frequent thing that I get is like, thank you for making me myself again. Thank you for helping identify what I knew was going on when I was on it. And I didn't have the words to describe it. Yeah, and I say this and I touched on the subject in particular because I've got so many friends who were in a relationship where their partner in their 20s turned around to them and said, I'm not interested in sex anymore or just their libido fell off a cliff. And they ultimately broke up.

and they never really had an answer for it. They just thought, you know, that person's broken or that, you know, women just don't like sex. It's funny, because when my partner turned around to me that night in bed and said to me, I remember where I was, I was in Jamaica. It sounds super weird. I was in Bob Marley's old house. Oh my gosh, I love it. That's what they told me it was anyway. Maybe that was just a sales pitch going to pay extra for that hotel. But they told me I was in Bob Marley's old house and yeah, she turned around to him bed and she said, I'm not interested in sex.

But loads of women aren't interested in sex either. I spoke to my friends, they're not interested either. And that was like the pitch of it. And I remember thinking, as a man, obviously, you just feel really emasculated by it, because you're like, it must be something to do with me. We ended up breaking up. She went off for a year and went to Bali, did her own thing, worked on herself. I think around this time is when she stopped the birth control pill.

Started thinking about a lot of other things and when she came back It was just a totally different person like we ended up getting back together just a totally different person like and I say this because I Don't want people to give up right when the libido gives up Right. Yeah. No, I know I know I totally know what you mean No, and I think that that's I think yes Yes, yes that she probably has a high sex drive demeanor. I'm just trying to keep up at this point Yes

I love it. No, I love it. I think that, especially with the birth control pill, it's like there's a tendency to fear that everything is permanent and like if you go on it, that it ruins you and that it's going to break you. And the research just doesn't quite point in that direction. Unless you're a teenager, if you go on it as a teen, we don't yet know ultimately what that does to brain development long term.

But if you go on it as an adult and then you discontinue it, you can go back to being the person that you were, right? And yeah, and that can include the recovery of your sexual desire, even if you think that it's lost. Dr. Sarah Hill, we have a closing tradition on this podcast where the last guest leaves a question for the next guest, not knowing who they're going to be leaving it for. And the question left for you is, okay.

What is the legacy that you want to leave behind? I want to make the world a place where women understand themselves and that women are understood as themselves and not as being some sort of a malfunctioning male.

Thank you. Thank you for all the work you do. It's so interesting for me, so interesting for me as a man. But as men, we have mothers, we have sisters, we have partners. So helping us understand women in all, in every facet of the word, understanding their health, their reproductive health, their sexual health, why they are the way that they are, helps us be better sons, better brothers, better husbands, better boyfriends, in a way that

I think is really, really important for both of us as sex is to get along. Because otherwise, before I understood the menstrual cycle and I had conversations about menopause and I've had these conversations with you today, it's so easy to jump to conclusions about the opposite sex when you're a man. It's so easy to misinterpret things.

understanding how pertinent hormones are to how we feel and how we behave in our mental health and our libido and all of these things. Again, I think it breeds empathy. It breeds empathy and understanding and awareness, which I think will allow us to have the relationships we hope to have with the people that are, you know, our mothers, our sisters and our partners and

Had I known some of the things that I know now from reading your book, but also from learning more broadly about the subject matter of like women's sexual health and women's health and women's reproductive health, a lot of my life would have been different. And that's coming from as a man. A lot of my life would have been different. And at some day, you know, I'm going to have a daughter, I hope, someday.

And I think that it's also informing me about how to be a better father for my daughter someday, which I think is really, really important. And sometimes I do hope that men click these episodes. And I hope they could probably look at the numbers, but I hope they understand the importance of understanding all this subject matter to them because, yeah, I mean, we live in, we inhabit this world together in 50% of the inhabitants of this planet are women and

And also, there's something which I was quite illuminating in your work, which is I think I used to be in the opinion that only women had fluctuations in their hormones and feelings. And I think I've joked before with my male friends that, like, we're all just like this, me and my friends, whereas our partners are like, woo! But I've come to learn that that's also not true.

No, that's also not true. No men's hormones change dynamically across the day and they're higher in the morning than they are later on in the afternoon. And they change in response to environmental cues. So beautiful women, you know, the win or loss of your favorite sports team, the win or loss, your favorite political candidate, the presence of a weapon.

All of these things can change men's testosterone levels, and so men's hormones change quite rapidly. And in ways that are more unpredictable than women's, because women's hormones do cycle, but they cycle predictably. And if you tell me a woman's age and the first day of her last menstrual cycle, I can tell you with almost really high degree of certainty what's going on with her primary sex hormones. And the same is just not the truth for men.

How the pill changes everything. Or this is your brain on birth control. I'll put them both below. I'll link them both below the UK and the US Virgin. I guess the US Virgin's gonna change the UK title, right? Well, no, it's called, this is your brain number control. How the pill changes everything. Oh, okay. It's not on here. I know, that's because they changed the subtitle when we went to paperback. Oh, okay. I know, it's all very confusing.

I'll link it below anyway, so everyone can have a readout. Thank you so much for writing such a preeminent book on this subject because it's so, so important. And I'm so excited to see the science and the conversation evolve on all of these subject matters. Where do people find you if they want to ask you questions or send you emails or learn more? Yeah, well, they can find me online at sarahehill.com. And that's Sarah with an H and I am on Instagram is my most active platform. And it's Sarah Ehill PhD. And that's my handle.

Thank you so much, Sarah. Thank you.

I'm going to let you into a little bit of a secret. And you're probably going to think that I'm a little bit weird for saying this. But our team are our team because we absolutely obsess about the smallest things. Even with this podcast, while we're recording this podcast, we measure the CO2 levels in the studio because if it gets above a thousand parts per million, cognitive performance dips, this is the type of 1% improvement we make on our show. And that is why the show is the way it is. By understanding the power of compounding 1%, you can absolutely change your outcomes in your life.

It isn't about drastic transformations or quick wins. It's about the small, consistent actions that have a lasting change in your outcomes. So two years ago, we started the process of creating this beautiful diary and it's truly beautiful. Inside, there's lots of pictures, lots of inspiration and motivation as well, some interactive elements. And the purpose of this diary is to help you identify, stay focused on, develop consistency with the 1% that will ultimately change your life.

We're only going to do a limited run of these diaries. So if you want one for yourself or for a friend or for a colleague or for your team, then head to the diary.com right now. I'll link it below.