The Diary Of A CEO with Steven Bartlett - The Scientist Who Scans Fathers' Brains: Parenthood Shrinks Your Brain, And Drops Testosterone 25%!

Episode Date: August 24, 2026

What actually happens to your brain, and how fast or slow do you age when you become a parent? Dr. Darby Saxbe reveals the surprising science of the "parental brain" and how fatherhood physically reshapes a man's mind, why dads lose grey matter, what really happens to testosterone, and why the "dad bod" might be nature's design. Dr. Darby Saxbe is a professor of psychology and a leading researcher on the neuroscience of parenthood. She is the founder and director of the NEST (Neuroendocrinology of Social Ties) Lab at the University of Southern California, where her pioneering work studies how the transition to parenthood changes the brains, hormones and relationships of both mothers and fathers. Her research has reshaped how scientists understand fatherhood, men's mental health, and what it really takes to raise a child. Chapters 00:00:00 Intro 00:02:13 Role Of Fathers In Parenting 00:06:10 What Happens To The Brain When You Become A Father? 00:09:09 Why Testosterone Drops When Men Become Fathers 00:11:22 Should Men Be Worried About Lower Testosterone? 00:15:39 What Fatherhood Can Change In A Man’s Personality 00:19:00 The Upsides And Downsides Of Parenting 00:21:30 What Happens When We Make Parents Fight? 00:23:48 Why The Birth Experience Can Shape Your Relationship 00:27:25 Are People Waiting For The Perfect Time To Have Kids? 00:30:44 Why Fewer People May Be Choosing Parenthood 00:35:12 Ads 00:37:34 Do Parents Actually Have Healthier Brains? 00:45:02 What Does Daycare Really Mean For Children? 00:47:17 Why Mothers Become The Default Parent 00:49:10 Maternal Gatekeeping And Weaponized Incompetence 00:52:04 What Really Happens To Relationships After A Baby 00:54:27 Why Fathers Can Experience Postpartum Depression 00:56:45 Can Your Personality Predict Whether You’ll Divorce? 01:00:51 Why Women’s Ovulation May Be Harder To Detect 01:03:06 How Can You Increase Your Chances Of Conceiving? 01:04:03 What Every New Father Needs To Know 01:04:51 Ads 01:05:51 How Should Parents Divide Baby Care? 01:07:54 What Couples Should Do Before Having Kids 01:13:26 How To Protect Your Relationship After Having Children 01:15:24 Is The Dad Bod More Attractive? 01:18:36 What Does Your Childhood Teach You About Parenting? 01:20:30 How Divorce Can Affect Children 01:20:47 Are Humans Really Meant To Be Monogamous? 01:22:09 What Are The Biggest Concerns About Modern Parenthood? 01:23:54 What Systemic Change Could Transform Parenting? She explains: ◼ Why a father's brain physically shrinks when you become a dad ◼ Why testosterone drops in new fathers ◼ Why the "dad bod" may signal a more attentive hands-on father ◼ Why men experience postpartum depression ◼ Why raising a child was never meant to be done by two people alone Follow Dr. Darby Saxbe: X: https://x.com/darbysaxbe NEST Lab: https://www.nestlab.ca Her research: https://dornsife.usc.edu/nestlab/ Her book ‘Dad Brain: The New Science of Fatherhood and How It Shapes Men's Lives: https://a.co/d/03Qhspxt Join her US based ‘Daddy Stroller Social Club’: https://daddystrollersocialclub.com The Diary Of A CEO: ◼ Join DOAC circle here - https://doaccircle.com/ ◼ Shop The Diary Of A CEO collection: https://thediary.com/collections/shop (https://link.thediaryofaceo.com/5IB1H6E) ◼ Get email updates - https://link.thediaryofaceo.com/5IB1H6E ◼ Follow Steven - https://link.thediaryofaceo.com/AGU9QP4 Sponsors: Shopify - https://shopify.com/bartlett Linkedin Talent Solutions - http://linkedin.com/DOAC Pipedrive - https://pipedrive.com/CEO

You've discovered something about the brain, I think, is quite surprising. So we found that in fathers, the brain is actually shrinking, and I'll explain why. But also there are studies that find that both men and women who report having had more kids have markers of a younger-looking brain age. And then also typically men, when they do this show about a 25% drop in testosterone. The next studies of single women have found that, you know, if you show them a series of body types, dad bought is the most popular. And that's proven by science. If I go out and get a dad, but you're telling me the science that says I'm going to be more attractive. Yeah, go for it.

Let's see what my fiance says. The other thing that's worth talking about is... Have you done any studies on that? Yes. That is one of the most robust findings in parenthood research. And my lab found actually that... Wow. So I've always been really interested in families

and becoming a parent is one of the biggest transformations that you can experience. But I'm concerned about the declining birth rate. And I think that we've managed to mark... market it as an undesirable choice. According to the CDC and Pew Research data, the US total fertility rate just hit an all-time recorded low. Yeah, I mean, the transition to parenthood can be really challenging. You are sacrificing yourself.

It can be very isolating. You're leaving your sleeve. But becoming a parent, you are benefiting from this sense of connection and purpose. You will rediscover your priorities in a way that will ultimately bring a lot of value. So if all goes well, next year I will be a dad. And I would like you to give me some advice on becoming a full. father based on all the research that you have. So great fathers are made not born. There's a lot you can do. I'm going to write it down. Love it. So first, guys, I've got a favor to ask before this episode begins.

It's the algorithm, if you follow a show, will deliver you the best episodes from that show very prominently in your feed. So when we have our best episodes on this show, the most shared episodes, the most rated episodes, I would love you to know. And the simple way for you to know that is to hit that follow button. But also, it's the simple, easy, free thing that you can do to help us make this show better. And I would be hugely grateful if you could take a minute on the app you're listening to this on right now and hit that follow button. Thank you so, so, so much. Dr. Darby, Saxby. You've discovered something about the brain that I think is quite surprising to a lot of men and women as it relates to what happens to a man's brain when they become a father. And I've got the report here in front of me,

but I have a model brain over there. Could you explain to me what exactly it is that you discovered? Yes. So we found that in fathers, and this is similar to what's been observed in mothers, the brain is actually losing gray matter volume. So it is shrinking. So if I had stronger hands, I could probably squish this brain and make it look tinier. But the parts of the brain that are shrinking the most are in what we call the mentalizing network. And that's a part of the brain that helps us understand other people's feelings and intentions. Those areas are kind of concentrated around the midline of the cortex, which is kind of what we're seeing here. And then you also see volume reduction in the visual areas, which is the back of the brain, which is really important for understanding when you look at an infant's face, what kinds of emotions it's trying to tell you. And so we see changes to those parts of the brain and new dads. In moms, we see changes to these same parts of the brain. We also see changes in moms to what's called the subcortex, which is this part of the brain that kind of controls our gut feelings and our sense of reward and is really strongly

linked with our hormones. So moms are kind of changing all across the brain. Dads are mostly changing in this top layer, the cortex, which kind of controls our higher order thinking, reasoning, and executive functioning. And that tells us something about fatherhood, which is that fathers choose to engage in parenting. It's a sort of cognitively mediated investment that dads are making. What does that mean? So if you think about a mom who's been through nine months of pregnancy, she is flooded with hormones when her baby is born. And she has a really high investment in the baby's survival. Just thinking about the number of calories that it takes to sustain a pregnancy, it's thousands. And so there's a very high floor from maternal investment. And moms are

undergoing plasticity all across the brain that reflects that. In dads, there's a tremendous amount of cross-cultural variability. So there are cultures in which dads participate in child care and are very hands-on with babies from the moment of birth. There are cultures in which they're prohibitions against men picking babies up. You don't pick babies up in the first year in some cultures. You don't pick babies up because it's considered unmanly. Okay. So there's a tremendous amount of variability.

And dads calibrate their investment according to what the culture says. and what the context looks like. If mom becomes unavailable, dad is often needed to step in and provide more of the care. And so this sort of top layer of brain changes reflects that, you know, dads are modulating their investment depending on what they're learning from the environment. And the word that biologists use for this is facultative. So a facultative adaptation is an adaptation that is optional but extremely useful. You could think about an animal that walks on four legs, suddenly having something really important to grab, and switching to walk on two legs so that it can use its hands. Hands are really useful for that animal. Fathers are really useful for humanity. But are you saying

they're optional? But they're very depending on situation. And I don't want to say that fathers aren't important. They're incredibly important. They're dads who are primary caregivers and even sole caregivers of children. But dads vary and they vary depending on what is needed for children to thrive in their specific local context. And a woman's brain shrinks as well, but it shrinks a little bit more. Yes, it covers more of the brain. And it also shows a larger across the board volume reduction. And I should explain volume reduction. We often think about deficit, mommy brain, you're forgetting things. Volume reduction is not a bad thing.

What it means is that the brain is actually working more efficiently because it's building better connected pathways and better channels for communicating information. Is it accurate to say that the brain is focusing? Yes, exactly. So it's reshaping in a way that enables more efficient communication. It's learning. It's consolidating. So it's kind of like if you think about the director's cut of a movie that has lots of interesting extra scenes and characters, and then you watch it in the theater and it's like this lean, mean, two-hour cut, right? Like many of us prefer the theatrical release because it's easier to follow. And by getting rid of certain parts of the brain, that means more energy can be used in the other parts of the brain. Is that broadly accurate? Exactly. So that we're better able to focus on.

on what matters. And when we become parents, what matters is our children and the inputs they're giving us. The interesting thing is the way that you described the part of the brain that the man loses when they become a father made it seem like they're losing empathy. No, they're actually improving in their empathy because they're becoming more efficient processors of social information. So the fact that where we see the biggest changes are in these what we call mentalizing social cognition networks tells us that those networks are really important for dads to use when they become parents. And they're getting a lot of practice, putting those networks into use. I thought you said that section of the brain shrunk. Yes, because the brain is becoming more efficient.

So it's losing all the extra pathways and you're sort of building a super highway for that specific social information. It sounds a bit counterintuitive because I imagined that my brain would grow when I get better at something. You would, but in this case, the brain is actually shrinking. And I know it sort of feels like a puzzle to wrap your head around, but it actually does reflect that the brain is working better. And is there a relationship between how hands-on the father is and the amount of shrinkage that happens in their brain? Yeah, and my lab found that relationship. So when dads told us before birth that they felt more bonded to their unborn baby, when they wanted to take more time off after work, and when they told us three months after birth that they enjoyed their babies more, they felt more connected and bonded to them. And they were spending more time taking care of their babies.

They had more profound brain shrinkage. All of this seems to support the contention that the shrinkage is really adaptive and it's enabling men's adjustment to parenthood. Is there any other biological changes that take place when someone becomes a father? So we also see changes to men's hormones. I talk about this in the book. Men typically show a drop in testosterone. I've got a big thing here. Yeah, let's talk about testosterone.

So typically men, when their hands-on as fathers, show about a 25% drop in testosterone. And some of the best studies of this have been done longitudinally in the Philippines. Before we had longitudinal studies, people said, well, maybe lower testosterone men are just choosing to become fathers. And so looking across time lets us tease that out and see, is there something about fatherhood that's actually changing testosterone? And so when you look across decades, you find that testosterone is typically pretty high before pregnancy happens. And it's adaptive to have high testosterone. You know, testosterone's been studied a lot in birds. It's also been studied in rodents and in other mammals.

You want high testosterone at the start of breeding season when it's time to maximize your chances of producing offspring. You want to compete. You want to build status. You want to fight off your rivals. High testosterone is your friend. Once you've accomplished your reproductive goal and you've caused a pregnancy and you want your offspring to survive,

you want to be investing and nurturing. that new baby. And this is what we saw in the men in the Philippines, that as they were spending more time taking care of kids, they showed a sharper drop. And then you typically see some rebound when the baby is getting older. And again, this is not unique to humans. We see it all over the animal kingdom. So during the pregnancy, something, some chemical tells my body that I need to make less testosterone, even though the baby's not here yet. Yeah, it might just be your proximity to your pregnant partner. Interesting. Yeah. Our lab found expectant dads and expectant moms had correlated levels of testosterone during pregnancy. And the more strong that relationship was the more dad showed a drop

in testosterone after birth. But I want to caveat because I think a lot of men are really concerned about the idea that testosterone might drop. And I think we have a really strong narrative right now that testosterone sort of like equals successful masculinity. And masculinity is not a about a particular hormone. It is about a body that is responsive to our goals and that sets us up to meet the demands of our environment. And so having a biology that fluctuates across the lifespan as our reproductive strategy shifts is really adaptive. We want to be flexible. And that doesn't always mean maxed out testosterone. So high levels of testosterone actually decrease our sperm count and they are bad for our immune system.

I think some men might be concerned that dropping testosterone might make them worse in the gym or it might make them less ambitious or less able to pursue their goals in life. Is there any truth to that? There's definitely a link between testosterone and men's muscle mass and their motivation, their drives. But these are not one-to-one relationships. So the human hormone literature is messy, and a lot of these are weak correlations. So testosterone doesn't necessarily equal success at work, for example. And high testosterone can get in men's way in multiple ways.

So there are links between men's testosterone levels and relationship satisfaction in the couple relationships. So my lab did a study where we found that men who had relatively higher testosterone after their baby's birth had partners who were more dissatisfied in the relationship and reported more intimate partner aggression. So the dads themselves reported more parenting stress. So there's a little bit of a mixed bag of high testosterone. And what it looks like you want is to hit a sweet spot. You don't want testosterone levels that totally crash. My lab is also found that when testosterone is really low after a birth, men have higher postpartum depression symptoms. You don't necessarily want testosterone levels. You don't necessarily

want testosterone levels that are sky high either because that can cause problems in your intimate relationship and it can make it hard for you to switch into nurturing and parenting mode. So the men who seem most successful in our study were men who had mid-range testosterone levels that could be flexible and that could adapt to different life changes. And am I right in thinking that the more time you spend hands on as a father in those studies that they did on men, the lower your testosterone. will go? Yeah, so the longitudinal work in the Philippines found that when men spent more time changing babies, doing hands-on care, sharing a sleeping surface with babies, they had more of a

testosterone drop. So the testosterone, the hormones are responsive to the context and to what we're doing. But testosterone does rebound, you know, after birth. So it's not necessarily the case that testosterone is going to bottom out and it's going to stay low forever. You know, you said a second ago that men that had crashes to their testosterone during the pregnancy and thereafter had a high likelihood of experiencing postpartum depression themselves. Are you implying that that means that there's an ideal amount of time and hands-onness that a father can spend with their child to make sure their testosterone hits that mid-range point? Yeah, it's a really good question.

I mean, I don't know that we know for sure if there's like a dose of, parenting involvement that sort of lends itself to an ideal amount of testosterone, it's hard to optimize your way out of these natural changes. I don't want to discourage dads from being hands-on with their kids because they're worried they're going to pay some kind of physiological tax. I think it's more like make sure you're protecting your sleep, which we know is linked with overall health. Make sure you're getting time to exercise and to socialize, you know, to participate in activities that bring you joy. Like those are ways to help mitigate your risk that I think will be more successful

than trying to hit a particular hormone level. My brother is a year older than me, and he has three young kids under the age of seven now. They were actually just here. They've just left. But I noticed a remarkable difference in him when his wife, Giulio, got pregnant. Would you notice? Just a total shift in what he wanted. out of life.

Yeah. And so before growing up, I remember one day seeing him on the computer figuring out which job would pay the most money. And he was very, very smart. He, I mean, he is very, very smart. And he picked, he sort of orientated his career towards the job that would make the most money. And then he was successful.

He went to LSE, got the job. And then shortly after graduating university, met someone. They got pregnant unexpectedly. And I watched my brother go from someone who was like really striving for material goals to someone who suddenly placed the material goal immediately after, how do I retire and spend the maximum amount of my time with my kids? Yeah. His kids are number one, above all anything else.

And it's something I admire a lot about him. But the most remarkable thing is someone that's not gone through that transition because I've not had kids yet, is just watching how profound the change was in him in terms of his stated goals and ambitions. Yeah. Like, what is this? I'm so glad you said that because that's something I heard from so many of the fathers. that I interviewed for the book is that you experience this profound shift in your values and your priorities. And a lot of men, you know, if you survey parents, you say, what are the most meaningful priorities in your life? Men are just as likely as women to say, my kids.

And I think fathers increasingly are recognizing that the parenting role is really central to their self-concept. And, you know, like we're in a culture where I think it can be hard for men to find a sense. of meaning and purpose and connection to other people, being a parent can give you that sense of meaning and purpose. And so, you know, I think that's a really important framing around, you know, your testosterone level might change or your brain might shrink, like things that maybe sound a little scary and negative, but they're in the service of this larger goal, which is building a more meaningful life. And I think, you know, like a message to men and also to women, to moms and to dads, is anything that's worth doing is hard. Being a parent is really hard. You know, you are sacrificing

yourself, you're losing your sleep, you are getting extra wrinkles, ask me how I know, but you are benefiting from this sense of connection and purpose that, you know, it sounds like your brother has been totally transformed by. And I think we're in a lot of ways like selling young men on this message that you should be optimizing your bank account and your, you're body fat percentage and you should be out there hustling as much as possible. And I think that can be a little bit of a hollow message because what we keep learning again and again from the longevity studies is that the quality of men's relationships is the best predictor of their well-being in old age. So men with healthy marriages, men who have positive relationships with their kids, those are the men

who age well, not necessarily the men who've maxed out on, you know, riches or the perfect. body fat score. It is, it's really a remarkable thing because when you, as you look forward into becoming a parent, you often see the sacrifices you'll have to make. You hear about, okay, you're not going to sleep as much as you used to. You'll hear about, um, the anxieties of being a parent and loving something so much more than yourself and all these things. But that's what a profound psychological, biological, biological hormonal shift, you kind of just have to believe in it. Yeah. People like tell you about it as if it's like a, almost like a, like, a religion. I say that because you have to have faith that the profound upside will be worth the very obvious cost that you see parents, you know,

the sacrifices they have to make. Yeah, I think that's exactly right, because I think a lot of the downsides are really visible. Yeah. Like, we've all been on a plane with a crying kid and we've seen the frantic parent trying to calm them down. We've all seen a tantrum in the grocery store, right? Like, that stuff is right in your face. But the upsides are sort of invisible. You know, just like the joy of seeing your child's face as they discover something new. Or, you know, getting to snuggle late at night and feeling this sense of closeness that you've never had, right? That, like, love that's bigger than yourself. And I think it's important to speak about the benefits as well as the downsides because we humans crave connection.

And, you know, we crave care. And I think becoming a parent is an opportunity to, provide care on a scale that's hard to find in other ways. I also want to hear from you about how the mother's brain changes through pregnancy and beyond. Yeah. Because Julia, so my brother's wife, she was here as well. And she's remarkably different now that she's had these three beautiful children. And I was asking her last night, because she was in a sort of corporate world before I was saying, you know, when they grow up and they leave home, which again is probably the worst thing you could probably say to a mother who has three young beautiful children and who's already like anxious that.

someday they're going to fly the nest. I was like, what will then be in the place of these three kids in your life? Would you want to go back to like the corporate world? Do you want to do something else? And how has it reordered your sense of meaning? But tell me, how does the mother's brain change? Yeah, the mother's brain change is really profoundly as well. Moms are losing about two and a half percent of their brain volume from before pregnancy to after birth. Dads in our studies, we found they lose about 1% of their brain volume. So similar pattern in similar parts of the brain. but the magnitude is different and there's more variability in the dads. And how did you conduct these studies?

What was the methodology? So we recruited a bunch of first-time parents. These were all couples that we recruited during pregnancy. Our only rule was that you had to be cohabiting and you had to be planning to continue cohabiting after the birth because we really wanted to capture the dads and get their experience, you know, being in proximity to their babies. And so we brought them into the lab.

We asked them every question we could think of. We sampled their blood, their saliva, their hair. We had them fight with each other on camera. We scanned the men's brains. And then about six months after their baby was born, we brought them back into the lab, blood, saliva, hair. This time we got a breast milk sample. We got a sample of baby poop. And we had them fight again, and we scanned the dad's brains again.

You had them fight again? We had them fight again. We wanted to see how do couples communicate with each other? And does that change across the transition to parenthood? And also what communication styles are going to predict better couple level adaptation to becoming parents? How did you get them to fight? I need to make sure I don't do that. So we gave them a whole list of different topics.

We said these are topics that couples commonly argue about, which are hot button issues for you and your partner. And so we had both the mom and the dad fill these out independently. And then we went through and we saw what are the issues that both people are endorsing. And we said, we want you to talk about this issue. Don't hold back. We're going to give you 15 minutes in this room. And we, you know, watch them talk through it. They weren't, you know, like punching each other.

But the conversations were often contentious because they were talking about issues that were frequently objects of conflict. Okay. And what did you discover? So we discovered that when couples fought more nuanced. negatively with each other, they subsequently reported more difficult birth experiences. And it's interesting because birth is a time in which moms need a lot of support. And the partner's often a primary person who's in the room providing that support. So when couples have, you know, sort of like a toxic, difficult relationship, that can really

color mom's experience of the birth. Are you saying that because the person that they fought with and don't have a good conflict resolution strategy with, it was in the room they had a bad birth experience or did something actually happen in the birth experience? Did like the husband make a comment? Yeah, no, I mean, we didn't record their conversations during the birth, but we actually did get the charts from the hospital or the birth center after the baby delivered and we looked at complications. We looked at how medically complex the birth was. And we found that when couples fought more negatively and less positively during pregnancy, during pregnancy. So, you know, they're about six months into pregnancy.

A few months later, when it's time to deliver the infant, they had more medically complex births. And they also appraised the births as more stressful. So the conclusion is it's thinking about the couple relationship is actually important when we think about birth. there's been a huge sea change about how we deliver babies. You know, like, it used to be that men were never in the birthing room. So babies were typically delivered with the assistance of a female midwife and female relatives. And it really wasn't until birth moved into hospitals in, you know, the late 19th century, suddenly you had a male physician who's presiding over the birth. And then really it wasn't

until the 60s and 70s, the dad started to advocate for their inclusion in the birth room. They said, you know, we don't want to miss this. We want to be present. But because historically, dads have really not been part of the birth experience, we haven't necessarily thought about the couple relationship as a place to intervene. If we want to make birth go more smoothly, we actually want to be thinking about dad's mental health and we want to be thinking about couples' relationship functioning because those things might actually affect mom's psychological experience of birth. So you're saying don't fight during pregnancy? Yeah.

Or just find more effective ways to fight. You want to figure out ways to calm each other down, validate each other, not necessarily, you know, imp each other up and get into these really negative spirals. I guess I want to push on a point of nuance here because I'm concerned that expectant parents might be looking at each other right now as they listen to the septupt. So I imagine we've got a lot of expectant parents listening and they're thinking, fuck, we had a fight last week. And we got the both coming up in a couple of months.

Yeah. There's nothing wrong with fighting. In fact, I'm a big believer that it's good to air out your concerns and grievances. What we were looking at specifically were negative conflict behaviors. Okay. Things like criticizing, showing contempt, stonewalling, so like refusing to listen to see the other person's perspective. actually one of my really smart grad students is working on a project right now where he looks he's looking at like what is kind of like a magic ingredient that helps couples shift from being negative with each other to being positive with each other during these conflict tasks he's like literally looking at the same task and he's finding the ingredient is validation so just conveying to your partner I understand what you're saying I see where you're coming from I'm

right here with you, I get it. Like those kinds of behaviors make a huge difference because they sort of take like a lot of the tension and frustration out of the conversation. As soon as you feel really heard by your partner, you know, the wind is a little bit out of your sales for being furious. I sometimes worry that a lot of people are waiting for perfection before they step into the next season of parenthood. Maybe I'm guilty of this. My myself a little bit to some degree. I think me and my partner talk about this sometimes, me and my fiancee about like it doesn't feel like there's ever going to be a perfect time to have kids. Yeah. When you look at the nature of my life and her life, you go, look, crazy, crazy schedules.

There really is no time right now. But I reflect and go, well, everything that I do now, including this podcast, at the time that I did the first episode, there was no time. Yeah. But I made the time. Yeah. And I sometimes worry that as young people, we are in a culture, that is waiting for more perfection than is coming in terms of our romantic partner or our circumstances. And of course, there is a fundamental sort of basis of security that everybody needs to be able to bring a life into the world. And often people don't have that. Yeah. But I'm wondering what your thoughts are on that.

Yeah. I mean, I had this conversation with my grad school advisor. I said I would love to have kids. What do you recommend? When is the right time? And she laughed. And she said, there is no right time. You just have to do it.

You just have to make it work. Because once the baby shows up, you'll figure it out. And that was tremendously good advice. And, you know, led me to start having kids within the next few years after that conversation. Really? Yeah. Yeah. I was like, okay, I guess I'm just going to go for it.

I'm going to make it work. And it was hard. But we did, in fact, figure it out. And I think, you know, when you optimize everything and you feel like you need the perfect conditions I need to own a house, So it has to be this many bedrooms. I need, you know, this level of stability. Yes, all those things are terrific. But historically, you know, people had kids young and, you know, often they found that having kids gave them a really strong impetus to get those things together.

We used to think about having kids as like a cornerstone of a life. It's like a foundation. You know, you do that and then you sort of build your career and everything else. Now we kind of think of it as like a capstone. It's like your crowning achievement. You've got everything perfectly set and now it's time to have kids. And I think the problem with that is, first of our biology doesn't always agree. You know, we can sort of lose our best window in which to have kids. And I also think, like, having kids isn't just an individual responsibility. We need to be thinking about it as it's a collective responsibility. It's societal. We are an aloe parenting species. So what that means we're cooperative breeders. We raise our, kids and community. That's how we evolved. That's if you look at hunter gatherers. That's how they raise their kids. We are not designed to do this in isolation. And I think, you know, when you think about like, what does a healthy society provide for parents to reduce stress, right? Like,

generous maternity and paternity leaves, you know, job protections, child care. Like, I'm a big believer in having strong policies that make it easier to have kids. Because I think in the absence of those policies, you feel like it's your job to get everything completely lined up. And that time might never come, especially not in a, you know, tempestuous economy. And I think we're seeing some of the symptoms of exactly what you've described there. A landmark 2024 study published in the Lancet projects that by the year 2100, 97% of all countries and territories will have fertility rates too low to sustain their populations. The global fertility rate has plummeted from an average of five children per woman in 1950 to just 2.2 today. According to the CDC and Pew Research data,

the US total fertility rate just hit an all-time recorded low of 1.6. This is far below the replacement rate of 2.1 children per couple, I guess, required to keep the population stable without immigration. CDC data shows total US birth rates dropped yet again by 1% in 2025, falling to roughly 3.6 million babies, continuing a nearly two decade downfall slide since the Great Recession. And lastly, because the fertility rate is crashing in high-income nations, but remaining comparatively high in specific low-income regions, it is predicted a massive shift in human demographics will take place and by 2,100, one in every two children born on the planet

will be born in sub-Saharan Africa. It's all quite shocking to hear, isn't it? I think. It's inconceivable. I thought growing up, everyone was talking about too many people being on the planet. Right, there was this narrative of the population bomb, which was this really popular theory in the 60s,

that we had too many children. Yeah. And we needed to, you know, adopt contraception and we needed to prevent too many children from being born. We all took that too literally and maybe overcorrected because now you have this population drop. And it's concerning because what you don't want is a society with what's called an inverse age curve,

which means that you have many more old people than young people. Because then you don't have enough caregivers for the older people. You don't have enough people to sustain the economy. You don't have innovators. You don't have, you know, the folks who are sort of building your future, you've depopulated that and you have a very aging population. And that can create a lot of instability. So I think we need to be thinking about, you know, how do we make parenting easier and more desirable for young people?

Because I think that we've managed to market it as an undesirable choice. How do we make it easier and more desirable for young people? So I think part of it is the conversation we're having right now. We're talking about the meaning, the purpose, the benefits that you can get from your relationships with others. I think we need a cultural reframe around care to raise the value of care. One of the reasons I'm interested in fatherhood is because I think seeing men as talented caregivers kind of unlocks this appreciation we have for the importance of care. The shift you described your brother undergoing where he went from church. transactional, how can I make the most money to my kids matter? How can I spend the most time with them?

Yeah. I think is a really valuable shift in purpose that, you know, at scale would make society's healthier and more empathetic. So there's like two things I think are worth saying here from my perspective. The first is I think it's important that we express the fact that a, not everybody can have kids because of, you know, reasons beyond their control. I think the second thing is not everybody wants or should should want to have kids, you know, depending on their circumstance. And the third thing is that I do feel in my personal circumstances, when I think about what I want from my life, again, this is about me, I do feel tremendously, positively jealous of his life. And that's a, it's a strange thing because, you know, he has a couple more grey hairs than me, even though he's

only a year older. So, you know, everything in life is a trade-off. But the, like, deep sense of meaning and purpose that even I experience when those kids are here, like they were at my house for the last couple of weeks and it's it's everything seems yeah incomparable in terms of like meaning to these beautiful children yeah they're just endlessly curious and fascinating and you know there's very little you can get from scrolling on a screen that you know that to me is as fulfilling as what you can get from watching a baby learn something it used to be that working for yourself was a massive massive risk but that world has completely changed. If you've got a business idea that you can't stop thinking about,

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operation consistent when we were a team of five or when our commercial team was a team of 50. Over 100,000 companies are already running their sales on it. So if you'd like to join them, sign up at pipe drive.com slash CEO, where you'll get an exclusive 30 day free trial instead of the usual 14 days and there's no credit card needed at all. Head to pipe drive.com slash CEO. Am I right in thinking that parents have different brains as it relates to? to the brain being protected? Yeah, so there's this really interesting emerging body of research suggesting that being a parent is neuroprotective in late life.

So there are studies, the UK Biobank is the biggest, big repository of brain scans from people in their 50s and 60s. And they find that both men and women who report having had more kids have markers of a younger-looking brain age. So if you do a machine learning algorithm that adjust for your chronological age and then, you know, takes what the scans looks like and uses that to estimate what they think your brain age is, you look relatively younger when you report having had more kids. It seems like the greatest benefit is at two or three kids. After that, it kind of levels off. You don't necessarily get a big benefit from having had six kids compared to having had two. But it suggests that there is something about the problem. practice that you get to your social brain and to your empathetic brain that is really beneficial to your brain plasticity and functioning later in life.

That's quite surprising because you'd think, you know, parents go through a lot of stress having lots of kids. So you'd assume that they'd be sleeping less. You'd assume that would be bad for the brain. But you're telling me there's evidence that it's actually protective to be a parent of two or three kids. Yeah, I think it's healthy to think about the short-term cost and then the long-term benefit. So, you know, like, there are plenty of studies that have found that moment to moment parents of young kids say that they're less happy. They're more tired. They're more stressed. They're more going on. We've talked about the, you know, brain changes, hormone changes. But then, you know, if you look longer in later life, people will report more fulfillment. So it's like you're you're doing something that's not very fun. It's taxing. It can be very isolating. And yet you're kind of reaping this longer term benefit. in terms of the power of those relationships and that sense of connection with other people.

That's social integration. And that practice trying to understand others that is really beneficial, like it's a glue for creating good relationships. What is it exactly about being a parent, though, that's going to make my brain more protected when I get older? You know, one of the theories I had was that because, you know, when those three kids were here, they had me playing all kinds of bloody games. They wanted to play hide and seek for seven hours.

and it is somewhat, you know, actually picking them up all the bloody time because there's three of them. And one of them's eight, I can't really pick her up easily. Yeah. The other two, I can get them up. And then she starts complaining that I've not picked her up. So I have to pick her up. And I'm like, wow, what a workout. Yeah.

It is both a cognitive and a physical workout when they're around. Yeah. Is it that like I'm building up brain reserve because they're challenging me and having tantrums and they're wanting to play and they're engaging me all the time. Is that why it's protective? Yeah. I think it's like Sudoko for your social cognition, right? It's like you're doing crossword puzzles, but instead of like, you know, the sort of practice that you're getting for putting warts together, you're getting practice understanding people's minds and intentions and communicating and responding to them and being sensitive to them. And all of that is putting you through a workout and it's also a full body workout because kids are really embodied. And there's actually interesting research that dads especially play in these physically demanding kind of vigorous ways with young kids.

That was my job. My job was to pick them up and throw up. as high as I possibly can. Yeah, and kids love that. Yeah, and then me now. And then I like, I threw that and then it's like, me now. And then I just, I was like, I'm going to lose weeks throwing these kids in the air, but also I'm going to break something. Yeah. I mean, I think my husband never had to see the chiropractor until, you know, he became a dad and all of a sudden you're throwing them up in the air all the time. But that kind of play is really good for kids because it's testing their limits. It's challenging them. And it's actually helping them build

their risk tolerance. So like think about like the moment of fear that you have when you're thrown up in the air and then the relief when you're caught. Like you're basically practicing your emotion regulation skills on a small scale so that when you're thrown into a scary situation at school, you have a stronger sense of confidence. My other theory around why having children would be neuroprotected for the brain was around oxytocin. I say that because I sat with Robert Waldinger, who's done that sort of that long Harvard study on human happiness. And the conclusion is that one of the single biggest predictors of longevity is whether you have strong relationships.

And again, I had another scientist say to me that oxytocin, the bonding chemical, is neuroprotective. So I imagine having three children is going to equal a lot of oxytocin, which is going to equal some neuroprotectiveness. I mean, we are social animals. We are designed to bond with each other. we pair bond, we bond with our kids, that's really healthy. I love Waldinger studies. I cite those in the book when I talk about, you know, if you really want to think about what creates longevity and well-being late in life, look at your relationships. And, you know, I feel like he shows that really well with

this 80-year study that he's been doing. There are all these like brain changes and hormone changes that are designed to facilitate to help us build those bonds. And that's a lot of what is sort of going off in early parenthood is like we are sort of reorganizing to become more sensitive, more attentive caregivers. It's not like, you know, some people are just destined to be great parents and some people aren't. It's like as we put in the experience, as we get the practice, we put in the reps, we're building that brain and body that helps make us really great sensitive caregivers. And then that, I think, can transfer over to our other relationships too. if you've learned how to calm a kid down from a tantrum, you are probably going to be a very effective

manager at work. If you have, you know, negotiate with three kids who all want to pick you up at different times, you know, you're probably going to be a better problem solver in your couple relationship. Like those are just skills that you're building that can cross domains. I was just looking at some of the research on this and it says that research shows that oxytocin actively downregulates harmful pro-inflammatory cytokines in the brain. It acts on the brain's immune cells, making toxic inflammatory responses lower. And studies on aging mice demonstrated that long-term oxytocin treatment concurrently enhanced the brain's plasticity, which directly improved learning and made them better with memory as they aged.

And in terms of Alzheimer's, in animal models of Alzheimer's, oxytocin has been shown to reduce the toxicity of amyloid beta plaques, the toxic protein clumps that are the hallmark of Alzheimer's disease, which is fascinating. And that's the chemical that is produced from bonding. Yeah, that's a pair bonding chemical. It's an affiliative neuropeptide. So it sort of helps us shore up our social bonds. Touch is really important, isn't it? Yeah. You know, it's such an important thing. Yeah, my lab found actually that when dads engaged in more physical touch, there's a type of touch that's called proprioceptive touch, which is exactly what you were just describing, like picking babies up, moving them around, playing with them, like in space. It's that sort of like vigorous

touch that we often associate with fathers. When dads did more of that, they subsequently had higher oxytocin levels when we did a blood jaw in our lap. And that's been found in some other labs as well. Do you know Erica Comisar, who's been on my show? I do. One of the things she says, which has been a little bit controversial, is that she's argued that placing children under the age of three in daycare causes profound separation trauma and elevates cortisol to dangerous levels. So she's quite against daycare. So I politely disagree. I both my kids went to daycare where they thrived. And I am a big believer in this idea of aloe parenting, which is this idea that we collectively raise kids. We are designed to help each other out and share care. And so the model of single parent, single child, isolated in a

suburban home is a very weird model in the context of human history. And so I think this idea that, you know, we can't participate in shared care that kids can't do well in group care settings, to me is a little exaggerated. I do think it's very true that it's about timing and when is the right window to, you know, put kids in group care settings. It's, you know, ideally when kids can benefit from some social interaction, which is usually a little older in toddlerhood. So, you know, 18 months and beyond, very young babies often do better when they have a single caregiver. They have a a more stable attachment figure that they can bond with. But babies can form really strong attachments with their dads, with a caregiver. It doesn't necessarily have to be the case that mom is the only

person that needs to be present for every moment of an infant's life because I think that model is not terribly sustainable for parents. And parenting stress is really bad for kids. You know, and this goes back to the birth rate conversation. I think we need to need to be thinking about parenting in ways that are sustainable that allow us to get help. And we also, you know, if we really think that we don't want kids in a lot of early child care, we need to support that with universal paid parental leave, which is not available for most parents in the United States. So a lot of moms are coming up against a reality that doesn't fit with what some of the parenting gurus are telling them is the only way to raise their kids.

And I think that creates a lot of anxiety. If you think about the early phases of a child coming into the world, like year one, year, two, year three, is there any differences in when either parent plays a different type of role? There's a little bit of difference. And it sort of depends on, you know, what the parent's styles are and what the kid's situation is. But there's a chapter in my book where I talked with Richard Reeves, who's done a lot of great work on masculinity and manhood. and he says he thinks dad should be able to get paternity leave up to their kid's 18th birthday. Because a lot of the time dads find that their sort of best relationship with their kid happens later in childhood, even in adolescence. You know, he talked about taking his kids on trips, teaching his sons how to drive.

And so I think like dads can kind of come in at different points along a kid's development and provide a lot of value. I think early in infancy, if mom is breastfeeding, it's important for the baby to get that sort of regular access to milk. You know, of course, moms can pump, dad's can do feeding. But it is often a source of challenge for couples when a baby's firstborn and dads feel like mom has a really big biological head start. You know, she has had the pregnancy. She's been able to build a bond with the child. Fresh feeding is like this magical formula that she can give the baby to help soothe. And so I think a lot of dads struggle to find their place in early parenthood in the first year or two

because they're like, what am I supposed to do? You know, it takes a little while for dads to kind of come online as parents. You know, dads need, I think, some space and opportunity to figure things out. And you often get into this dynamic where mom is kind of the default parent in the early years and dads are waiting for their instructions. When you've gone out in the booktrain, you've spoken to both fathers and mothers, what is the like central point of contention that you discover? It's funny. I was just at a friend's book club meeting and it was a mix of couples. It was moms and dads. And the thing that they all got into was this concept of maternal gatekeeping

and sort of male malingering, which is this like double-edged kind of sword. And so maternal gatekeeping, it's a somewhat controversial term, but it just refers to anytime a mom consciously or unconsciously sort of puts up a roadblock to dad's fully participating in parenting. And it could be as simple as the baby's fussy and crying. And mom says, hand him to me. You know, I know what to do. But over time, that kind of spiral into a pattern of mom becomes the authority figure. Dad is seen as like the bumbling, hapless, kind of a.

appendage. And dads ultimately feel like their contributions aren't valued or, you know, mom doesn't really want them to have a lot of independent time. Maybe it's because mom doesn't trust the dad, right? Which is an area where I think having communication and making sure there's trust before the birth is really important. But, you know, the flip side of maternal gatekeeping is what's called weaponized incompetence or husbandly malingering, which is when, you know, dad who's a totally competent, let's say project manager at work who can handle lots of different spreadsheets and a whole workflow suddenly doesn't know what to put in the diaper bag or you know when we were at the book club meeting one of the moms was saying their baby was a couple days old there was a giant diaper blowout

and she had gone out for a 10 minute walk and her husband called to be like what do I do she's like I've been a parent for exactly two days that's exactly as long as you I have no idea you got to figure it out he's like but the poop's on the wall she's like you're like you're I'm sorry, you can use the wipes. You know, that same husband, she told me later, was in charge of packing lunches. And at a certain point, he said, do you give the kids anything but chicken nuggets? She said, well, there's fruit. You can cut up some avocado, you know, like throw stuff in.

So I think that is sort of like when dads act like they just have no idea and it's mom's job to solve the problem. And so I think a lot of moms are sort of frustrated with what they see is that dynamic happening. At the same time, I've talked to a lot of dads who said, I would love to have done more. But my wife insisted on organizing everything, scheduling everything, telling me what to do, I never felt like I got an opportunity to fully step up.

So I think that's an area where couples really need to iron some of this out, even before the baby comes, who's going to do what, and how are we going to balance it in a way that we both get some ownership? We both have some opportunity, and we can trust each other. talking about that parents often report is that post-pregnancy there is a change in their relationship and intimacy. Have you done any studies on that? Yes, and that is one of the most robust findings in transition to parenthood research is that there is a drop in couple relationship satisfaction, often around the birth of a new baby. And it's not surprising. You take two people who are having fun together.

You sleep-deprive them. you give them a lot of extra responsibility, and then a baby who's crying and demanding that, you know, they get out of bed at multiple times during the night. So you often get a lot of conflict around who's going to do what, you know, who's more connected to the baby. And, you know, I think it's one of those things where forewarned is forearmed. If couples know that this is going to be a risky time for their relationship, they can do more to shore up their community. before a baby's born. Have you ever quantified how different the relationship is on the other side of giving birth? We have definitely given lots of different couple relationship questionnaires and we've measured them and we've looked at that dip and we've seen that there is in fact a statistically

significant drop in relationship quality. And sex life. And sex life. Yeah, I mean, because of course, right, like you've got an extra person in your bed a lot of the time or near your bed. And And if you have delivered the baby vaginally, there's also a lot of stuff that's sore and might need to get stitched up and even more so if it was a C-section birth. And does that at some point go back to pre-birth levels in terms of relationship satisfaction? Yeah. So there is a lot of variability in couples' relationship trajectories. So there are some couples for whom relationship quality continues to dip and often the relationship it dissolves. There are also couples who report they have a better quality relationship after

having parented together. You know, there's a richer relationship. Like, I feel that with my husband. Like, I appreciate him so much because I've seen him negotiate with terrorists in the form of our young children. So, you know, I think, like, how well couples fare is going to diverge sort of depending on how well they can kind of muscle through some of those early years. Earlier on, you said that men experience postpartum depression after the birth of their child sometimes. And that's quite a unconventional thing to hear. When we think about postpartum depression, typically it's in the context of what the woman is experiencing. Yeah.

So it's quite interesting to hear that that is a big issue for men as well. So technically, postpartum depression just means depression that occurs after the birth of a baby. That's what postpartum means. So that term, postpartum, doesn't necessarily mean that, you know, it's the person that's delivered the baby. It just means this is the time period after birth. And there's some evidence that dad's prevalence rate for depression. So in new dads, it's about twice that of the general population. So if you look at non-fathering men, they have about half the risk of depression as new doubts.

So there's a big uptick in depression risk. That doesn't mean that every new dad is depressed. and new dads have lower depression rates than new moms, just to be clear. But it's also not a competition. It's not a zero-sum game. And I think there can be a lot of consternation, understandably, from moms who feel like we have fought for the term postpartum depression to be widely recognized by the medical community.

We've advocated for this. Now that we've succeeded, men are sort of trying to take it over. And I'm sympathetic to that argument. And a lot of moms have said, why don't we call it parinatal depression? Fine. I think that's totally okay. Paranatal just means around the birth of a baby. And that's legitimate, too. But if you think about what are the risk factors for depression, either in moms or in dads, like in the period following a baby's birth, it's a combination of factors. It's multi-determined. It's hormone changes. It's sleep changes. It's identity changes. It's relationship changes, like relationship conflict. Changes. Changes. to, you know, how you show up at work to your extended family. It can reawaken childhood traumas that were unresolved about how you yourself were parented. So all of those things are coming to the fore and you're preoccupied by what can be very isolating and repetitive care for a young baby. And it creates kind of a perfect storm of mental health risk.

You've studied cortisol changes in couples, right? Yeah. And how they, and how their cortisol interacts with each other. Is there a biological divorce predictor in terms of a specific way a couple's cortisol sinks up or clashes in that sort of first year of parenting that tells you if their marriage is going to fail before they realize it themselves? Yeah. So I have looked at cortisol interconnection in my lab between couples. So how cortisol levels become correlated over time. I found that when couples had really strongly linked levels of cortisol, they reported lower marital satisfaction. And you'd think like, okay, they've got more similar hormones. That's probably a good thing. We found the opposite in our lab. And I think it's because you don't actually want to be

contagious to other people's stress. When one person is really stressed, it's helpful to have a partner who can modulate that, who can calm you down. So you don't necessarily, They want to be exacerbating, like amplifying the stress date. Interesting. This is fascinating. There are some other labs that have found that especially in a transition to parenthood context, more synchrony in cortisol can actually be a good thing if you're looking from prenatal to postpartum. But outside of childbirth.

Yes. So this is interesting for me because I was having a conversation with someone the other day. And she was telling me that she emotionally is a little bit more variant. than her partner. Yeah. And I was expressing a similar sentiment saying that I think actually the reason why my relationship works with my fiancee Melanie is because Mel is a little bit emotionally variant and I'm kind of the like prefrontal cortex sounding board.

That kind of brings us back down. Yeah. Yeah. So her emotional variance is super useful because she's almost like a threat detector. Right. In every regard. So if our relationship is drifting a little bit or if we're disconnected, she'll know first. Whereas I take a little bit more time to like to, to. sort of have empathy to these kinds of like shifts in our relationship. She's like very in tune.

It's like a sixth sense she has. Yeah. However, sometimes that can mean some things are harder to deal with. And maybe she's more prone to worry sometimes. And I've often felt it actually because she's expressed this to me, she's expressed the gratitude of me being able to like bring her back to a place of calm. Yeah. I've often felt that that's kind of like my job. Yeah. And I've often thought that our it works because you do have two different types of people. Yeah. And actually, this is not a plug, but I'm an investor in a company called Whoop. And on there, they have the stress measure.

Again, it's not a perfect measure and nothing is a perfect measure. But I was looking at our differences in the stress response according to Weep on the devices. Yeah. And mine is very stable and has is much more unstable. Right. But I imagine that opposites attracted in this regard. Yeah, I mean, it's interesting because you could think if you were paired with somebody who was super stable, life might feel boring. If she was paired with somebody who was really volatile, life might feel too chaotic.

So we frequently are drawn to people who compliment something about ourselves and who are sort of different enough that it can sort of expand our worldview. And I worked with a couples therapist. This is sort of his theory that it's often the differences that. that drive us together, they can ultimately polarize us when things go awry. So you can imagine a future where she's always the emotional one and you're always the calm one and nobody gets a chance to break out of that and that becomes really entrenched in a way that like pulls you apart. But you could also imagine a future where you meet in the middle. Yeah.

Like you become more emotionally attuned. Yeah. And she becomes calmer and more stable. Yeah. And that's sort of the ideal, right? That's what you want is you want to, you want to, you know. want to be joining around those differences. I would say that's definitely what's happened.

Yeah. So that's good. That's a good sign for your relationship. Yeah. Time to have a kid. I think so. Yeah. I'm trying.

Good. He froze our embryos. Excellent. So we've got them in a freezer. Fantastic. Which is a really interesting process. I think this is probably worth spending some time on because I think I was living under the assumption that like in my early 30s, I could just sort of decide when

to have a kid and I could just, you know, have sex during that little window. They talk about where she's ovulating and the kids would appear. It's not necessarily how it works. Yeah. Turns out. No, it's actually a little trickier. It's tricky than I expected. There's actually a chapter in the book where I talk about paternity uncertainty.

One of the things that's really unique and interesting about humans is we conceal our ovulation. So that makes us different from a lot of other animals where when a female is fertile, you know because she changes color. She starts dancing in a certain way. She smells different. There are all these really obvious cues. and as a result, males sort of know exactly what window to jump in on. And because we conceal our ovulation as humans, it's always a little bit murky. Why do we do that?

For one thing, it encourages pair bonding because you can't just as a man, like, just show up, like the one day that it's time to cause a pregnancy and then take off. So you have to court a woman. You need a lot of repeated opportunities. So if a man actually wants to cause pregnancy, he's much better. are off sticking with one woman and really investing in that relationship, then he is like going out every night to find a different lady. We form stable monogamous relationships because that's actually adaptive for spreading our genetic material. And it also reduces aggression. So there's one theory that it reduces rivalry between women. If you know that one of the ladies in your group is fertile

and you have it out for her, you want to take her out during her fertile period, right? So concealing ovulation actually reduces that rivalry, that aggression. Oh, okay. It also makes everybody a little bit more invested in babies because no man knows exactly who's caused which pregnancies. And as a result, everybody has a little bit of an altruistic stake in the future of our children. I'm not sure if this is an area of research you've covered, but, and maybe I'm asking for a friend here. Yeah. Do you know what increases the probability of conceiving a child?

Because I think about this a lot in terms of stress and feeling comfortable and all these kinds of things. Like I'm often thinking about like, don't argue with how keep her safe, make her feel really secure. Yeah. I mean, I think those are all good instincts. Is there research on this? There is research on reducing stress for sure, right? Like we know that stress makes it harder to conceive. Of course, the last thing you want to tell someone who's struggling,

to conceive is reduce stress because that's so invalidating because you're like, I'm stressed about how hard it is to conceive. Like, don't, you know, telling somebody be less stressed is frequently not that helpful. But I think your intuition is right that you probably want to make the environment calmer and safer. And, you know, like, you can optimize nutrition. There's a lot you can do. But there's also a lot that is, you know, not up to you. And sometimes more intervention is needed. What advice would you have for new father? This is kind of like one of the themes in my book, Great fathers are made not born. You might feel like you don't have the qualities to become an amazing dad, but it's really about your time, your investment, the practice that you get. And the extent that you care that is going to shape you, it's going to build a brain and it's going to build a body that will make you a tuned in parent. You know, give yourself grace. Like the transition to parenthood can be really challenging. But you can. You can become an expert in your own child. And there is a reward there. You will find enrichment.

You will find meaning. You will rediscover your priorities in a way that will ultimately bring a lot of value. Every I talked to new founders, they all carry the same belief that the biggest threat to their small business is having a bad product. It's not. The biggest threat they face is hiring the wrong person for their small team because bad hires put the handbrake on growth and rapidly infect company culture. And I get it. When you're starting out, you need A-Players to grow your company, but you don't have 40 spare hours to spend sifting through interviews. So you hire fast to fill the seat, but this ends up costing you even more in the long-term. What any small business actually needs is a reliable and efficient way to find the right talent without stalling momentum. That's where our long-term

sponsor, LinkedIn and LinkedIn Hiring Pro can help you. It streamlines the entire hiring process from drafting a job description to shortlisting candidates and conducting AI-powered interviews for initial screenings. Nearly 60% of hirers who've used this tool have found a candidate to interview within a week. Hire right the first time around and get started by posting your first job for free at LinkedIn.com slash DOAC. That's LinkedIn.com slash DOAC in terms and conditions apply. Well, you've done so many studies. Yeah, probably too many. What are the studies that we haven't talked about that are most, well, most formative or surprising for you? We did a study where we look at couples' plans for how they wanted to divide a baby care.

So we gave them this questionnaire that we called a who does what, where they were given 10 common baby care tasks, like changing diapers, feeding a bottle. And they indicated on a slider how much mom was going to do and how much dad was going to do. And then we brought them back into the lab about six months after birth. We had them do the same scale. And it was really interesting because couples weren't actually great predictors of how much dad was going to do. So every single couple expected dad would do more before birth than dad was actually doing after birth. And there are a lot of reasons for that.

That doesn't mean that anybody's a villain. It just means maybe mom got more time off from work. Maybe she was breastfeeding. And so the baby, you know, she was with the baby more, right? Like there are a lot of reasons why that is the case. But we found that when dads were doing more, they reported that they were happier in their couple relationship. But one thing we looked at actually was how moms and dads talked about how they wanted to divvy up baby care. We measured how many times did they say the pronoun we compared to when you use the pronoun I where you're talking about yourself.

When you're using we, you're talking about, you know, you and your partner. The more weeness the dads were showing, the more happy they were in their relationship after birth. So their investment, their willingness to chip in, even if they didn't totally realize all their plans, was still linked with their satisfaction. And that was controlling for how they felt about their partner before birth. And it's a little counterintuitive because you might think, you know, if you get to sit back and relax and your partner is doing more, that's a winning strategy. But it was actually the dads that did more who told us they were happier. If all goes well, next year, I will be a dad. I hope so.

I hope so too. Yeah. So I've written on this sort of slide in front of me here, advice for Stephen. And I would like you to give me some advice, some actionable advice on, you know, becoming a father, what I need to do pre-posts during, based on all the research that you have. Love it. I'm going to write it down. Okay. So first take advantage of the window before birth to work on your communication with your partner.

Okay. Think about how you want to divide up baby care. You know, a lot of the time people say, well, just wing. it once the baby comes. And that can be a recipe for frustration because moms feel like they're doing everything. Dads feel like they're set out from care. So, you know, have those conversations sooner. So before the baby comes, have a conversation about how we're going to divvy up responsibilities and make sure both people are clear. Exactly. And think about two, like, what are we going to do about our extended families? What religion do we want to raise our kids in? What do we think about

education? Like if you haven't had those conversations about values, have them now. Because then I think you're going to ward off conflict that is going to crop up later on. The other thing is, and I would do this before birth, too, build up your social support network. A lot of men's primary confidant, their primary intimate relationship is with their partner. After the baby comes, mom is really preoccupied, and dads are like, what about me? So, you know, we know when we look at depression research that having a strong social support network is one of the best buffers.

So you want to be thinking, what are my friendships that I can count all? and who can help me. We really need community support. So think about how can my mom help? How can my friend help? And maybe like, you know, your brother's got his own kids. He's too busy to take yours. But he can help in some other way, right?

Like, how do you plug the people into your life into what your social support needs might be? I think a lot of people would cite this as being one of the reasons why they haven't had kids yet. Now more so than ever we don't live in communities. Yes. Now more so than ever, we are lonely, isolated, living in four small white walls in a city where we can barely pay our rent and we're struggling enough to take care of ourselves. Our parents often live far away now because we're living in such a globalized world. So feeling like you don't have the support around you to give birth when you're like scraping through in a job, it doesn't make a lot of logical sense as to why people won't choose to have children.

Yeah, it's a huge problem. And I think a lot of parents really struggle with feeling lonely and isolated. And so when I say, you know, like take the time before birth to build up your social support network, that doesn't just mean with your existing friendships and family, right? Like sometimes we end up far away from those people. It also means build community with other expectant parents, with your neighbors, right? Like, we thrive when we build community. One nice thing about becoming a parent is there are a lot of mechanisms for doing that. There are many more for moms than there are for dads.

So when I became a mom, I could go to breastfeeding support group. I could go to baby wearing support group. I could go like walk around the park with the Silver Lake Moms Club. Like I had all these things to plug into. Dads did not have as many of those organic kind of community building structures available. So, you know, take advantage of the ones that are there. I just talked to these guys that founded the daddy stroller social club. They've got chapters all over the country. They just meet up and they go for stroller walks with. their kids and it's like an amazing way for dads to connect with each other. So, so build that as much as you can. So what do we say? So build your friends, work on your couple relationship, think about how you want to balance things out. When the baby does come, first of all, protect your sleep. That's really hard. Everyone says sleep when the baby sleeps. Your sleep is going to be totally scrambled. But when you have healthy routines and good sleep hygiene even before birth, you're going to fare better after birth.

I think that I can hear parents screaming through the cameras saying, easier said than done. Yeah, I'm not trying to gaslight any of years. But I think when you have a good foundation of healthy sleep hygiene, you're probably going to. So things like really obvious things. Like, don't be on devices right before it's time to go to bed. Like, dim the lights.

Like make sure your room is the right temperature. Like, try to dial in your sleeping environment because the sleep is going to be the hardest thing, the first thing to go. A bit of a paradox here that when you're, I guess, stressed. or sleep deprived, we often reach for things that are dopamogenic, I think the term is, which is like foods that maybe are a little bit higher in, you know, not the good stuff. Yeah, yeah. And there's almost a paradox there.

Yeah, it's a total vicious cycle for sure. And I would say, like, think about becoming a parent like you're preparing to run a marathon. You know, not to the point that you become totally neurotic about it, but think about being healthy, having things that are going to prepare your body for this big shakeup that you're going to undergo. And then once the baby comes, like, take any opportunity. to bond. Like, I think a lot of men feel like I'm going to avoid as many diapers as possible. Changing diapers seems gross, but it's also a chance to make eye contact with your baby and, like, really get to know them in a different way. So, you know, jump into those baby care opportunities,

like find your own style and, you know, make sure, like, the more windows you have to bond, the better you're going to feel like you know your baby and the more confident you're going to be. And then I would say give yourself grace. Like know that this is hard. Know that it's temporary. And know that you are, you know, you're sacrificing in the short term for a lot of long-term benefit. One of the things that might be a little bit absent from this list is an effort towards holding my relationship together with my fiancé. Also important.

I mean, that's part of what you want to do before the baby's born, right? You want to be shoring up the communication and having those hard conversations. Like the date night thing. Yeah. Yeah, yeah. Date night's probably going to be the first thing out the window. Yeah, that is a thing that goes out the window. But you know what?

One nice thing about newborns is they'll sleep pretty much anywhere. So, you know, when our babies were little, my husband and I would just like put the baby in a car seat and go eat in a nice restaurant. You know, it was like the last time we got to do that for a few years because once they start walking around, they're much less portable. So, like, take advantage of some of the early baby stuff that you can do to travel and to make sure that you get out. That advice was all advice for me. Yeah. For Stephen. Yeah.

Would there be any different advice if my fiancé was sat here and you were advising her? Oh, that would be fun. Yeah. Yeah. I mean, I would say that sort of giving yourself grace thing would go double, right? It's like know that Stephen is going through a lot, and then you need to know that she's going through a lot. Like her whole sense of self is going to be an upheaval.

Because, like, we go through this thing. It's called metrescence. There's also patrescence. which is just the idea that becoming a parent kind of, you know, changes your priorities. It changes your sense of who you are. So she's going to go through a lot of transformation, as you will. And so sort of like hanging in with each other during that period of transformation is really fundamentally. Sometimes couples can grow apart where dads are jealous that the baby's getting all the attention. He feels left out.

Moms are frustrated that dad isn't doing more to help. Like all of those things can lead to conflict. And you can know that those are going to be hot spots for conflict and try to talk your way through them even ahead of birth. Darby, what's the most important thing we haven't talked about that we should have talked about as it relates to your work? For all the people that are listening now that have gotten this far in the conversation. Yeah, let's see. We didn't talk about dad bod. Dad bod.

That's a fun topic. Okay. Something we frequently joke about. We think about Homer Simpson. but it's been found across both animal and human studies that males tend to gain weight when they become fathers. Is that just the cortisol and the lack of sleep? So it's a mix of all the hormones. It's prolactin is a hormone we haven't talked much about, but that is rising.

Sleep deprivation, changes in physical activity, changes in our diet, right, because of stress and some of the dietary choices that we're making. Like, I joke in the book, like my husband and I basically ate peanut butter pretzels from Trader Joe's, like, every day that our kids were babies. So, you know, a lot of stuff is happening all at once. It's kind of a perfect storm. And yet, you know, there's evidence even from animal models that you see weight changes around the transition to fatherhood. These ones here.

Yeah, yeah. These are the tamarin monkeys. So there was a study that looked at tamarin monkeys that were expecting offspring. And it fed them a standardized diet and it compared them to tamarin monkeys. who didn't have partners that were expecting offspring. And they found that the expectant dads actually gained more weight, even though they were eating the same diet, as the comparison monkeys who weren't about to have a baby.

And so there were these like body changes that happened even before birth in the male monkeys. Why would that be? It's probably adaptive. Like if you think about increasing your body size to be more imposing and to better ward off a tax. from rivals. And you also want to buffer in case there's scarcity, right? Like you want extra fat. It looks less adaptive in a kind of modern context when we have a very obisogenic environment. And, you know,

you can start to see more cardiometabolic risk. But one thing I talk about in the book is women actually like a dad bot. Studies of single women have found that, you know, if you show them a series of body types, the dad bot is the most popular, you know, sort of like a my or mildly, you know, kind of like a lightly marbled male torso. Lightly marbled. I don't know if you remember like the Ali Mures, the British singer who like did a big tone up at the gym and posted selfies. You know, he had like a 12 pack or something. And all these women online were saying like we liked the before picture.

So, you know, there's something to be said for the reproductive signal of a dad bought. But part of it is if you show women torsos of different kinds of male body types. the sort of dad bod is one that women say he's more likely to be a hands-on father, he's probably going to be more attentive, he's going to be more caring, and those are things that are really attractive to women. And that's proven by science. So if I go out and get a dad bod, you're telling me the science says I'm going to be more attractive. Yeah, go for it.

Yeah. Yeah, worth a shot. See what my fiancé says. Yeah. How much of your work has been influenced by this? Oh, this is my dad. So much of my work. My parents got divorced when I was nine. And my dad became a solo parent to me and my brothers. My parents ultimately worked out a joint custody schedule. So we were one week with my dad, one week with my mom. We switched off every week as I was growing up. And he became a really great dad. Like he had a major learning curve. He wasn't a hands-on dad. He was like an 80s dad. who showed up for the big stuff. But when he was alone with the four of us,

he suddenly had to be the guy making our meals, the guy helping us with our homework, the guy driving us to sports practice. He really rose to the occasion, and I'm still really close with him. How do you think that's influenced your overarching mission and your focus on, you know, dads and parenting? Yeah, so I've always been really interested in families.

And, you know, they say, like, psychologists are always trying to fix the thing that went wrong in their lives. So I'm probably, like, as someone who's interested in couples and families, wanting to reverse, like, my own parents, divorce. But I also like seeing my dad be a great caregiver and then realizing how much parenting research is solely focused on moms makes me realize there's, like, a real gap in the literature. Like, you know, men play a really important role in parenting, and I think deserve a lot of recognition and respect for that. It's interesting that I'd never heard before that there's really any changes that took place in a... Yeah. Man's brain when a man becomes a father.

I mean, I think it's not something that gets talked about a lot, which is why I wanted to write about it. But, you know, we are dynamic. We're plastic. We humans adapt. And becoming a parent is one of the biggest transformations that you can experience. Have you ever done any research on the impact that divorce has on children? Not a lot, no, which is ironic because I am a child of divorce. But there is some research about it, and there's definitely some evidence that it can create some challenges for kids. And have you ever done any research on the or do you have a view on whether humans are supposed to be monogamous? Well, okay, so the best way to describe humans is we're sort of monogamous with benefits.

And, you know, you can see that if you look at the difference in our body size. So, like, male humans are a little bit bigger than female humans, but they're not like twice as big. So like gorillas, male gorillas are way bigger than female gorillas. There's like a huge size differential. And, you know, that says that, you know, like the male gorilla model is one of like harem dominance, right? Fully monogamous animals are exactly the same size. Like prairie vol males and females are almost exactly the same size as each other. They have like no size differential.

So that's like real pair bonding. So we're sort of like somewhere in between. There are a lot of societies with different models. You have polygamy, which is one man with lots of women. You have polyandry, which is more rare. That's one woman with lots of men. Only a few societies that have that model. But monogamy is actually the most common across lots of different cultures and societies.

And I think it because it brings us some benefits, in part because of the concealed ovulation piece that helps motivate men to be more invested in a single partner. But also because it generally is good for kids. What are you concerned about? I mean, our future as a planet. Which part of our future as a planet? So I definitely am concerned about what we've been talking about, the declining birth rate. I'm concerned not just because it portends problems, you know, in our future societies,

but because it would signals, I think, about young people's hopefulness for the future, right? I think when you look at the world and you say, I don't. want to reproduce. I don't want to bring children into this world. It to me suggests like a nihilism and a darkness that concerns me. Like marriage rates are dropping. Like young men and young women seem to be on different paths. Part of that is like we're in these algorithmic echo chambers where the kind of content that we're absorbing is really different. So you see increasing political polarization, not just in the U.S. but in other countries too. It's like there's more adversarial. kind of interaction. And I don't think that's good. You know, going back to the idea that having a

healthy late life is about building strong relationships and that that's a good predictor of our longevity. I want us to be in a world where we see ourselves as being on the same team as each other. Are you hopeful? Yeah, I'm super hopeful. I'm a very optimistic person. What would have to happen for that to be the case? I'm hopeful I have teenagers. You know, I'm hopeful for them. I think they're going to take over and hopefully they'll be wiser than my generation has been. That's them with my husband. That's from a few years ago.

I was going to say, you're your boy's a bit older now, right? Yeah, he's 14 now. 14, okay. Yeah. Dr. Darby-Sachby, Ph.D. Yep, that's me. We have a closing tradition on this podcast where the last guest leaves a question to the next guest, not knowing who they're leading it for.

Who? Question left for you is, people are increasingly distrustful and lonely. if you could flip a switch and make one systemic change to turn the tide, what would it be? Oh, to make people more socially connected. Well, I think building a better policy environment around parenting, so I'm a big advocate for parental leave to protect time and space to bond. I think that would be a really positive change for a lot of parents in the U.S. who don't get access to leave. Well, as a Brit, you know, I've moved over here.

And we, you know, we're hiring a big workforce here in Los Angeles, New York, and around the United States. But hearing about the parental leave policies here is like mind-blowing. What is the current parental leave policy in the United States? Yeah. So we are a huge outlier compared to the rest of the world, right? So like, we do not have a universal paid leave policy for parents that's at the federal level. There are some different policies at the state level. So every state has slightly different policies. But frequently, what's most available to parents is unpaid disability leave that's provided by the state. It's not available to every parent. If you're a shift worker, if you're a gig worker, if you're at Walmart, you probably don't have access to that paid leave.

And as a result, a lot of new moms in the U.S. are back to work within a couple of weeks of birth, which I think is totally bonkers when you think about what does it take to build a healthy society. The baseline federal protection is the Family Medical Leave Act. It guarantees up to 12 weeks of unpaid leave. Your employer must also maintain your group health insurance during this time. So they don't pay you. Yeah. Yeah.

And that's a big problem because it's expensive. They're really expensive. To raise kids. It's so surprising that they haven't passed law in this direction because it's not a partisan dispute. No, that's what's so surprising is. that it's one of the best polling issues. It's bipartisan, right? Both Republicans and Democrats say they support leave. I think it's something like 80% of Americans are in favor of it, yet we haven't found the political will to make it happen. Well, maybe we need a woman in office. Well set.

Or just a man, which? Or just an empathetic man. Let's get hands-on dads to rise to power and Marks. Thank you so much for writing this book because you're shining a light on so many issues that have been mystified through, I guess, pop culture in a way, but you're bringing to light the reality that men are both important in the raising of children, but also you're doing it through a lens of storytelling, through adjacencies in different animals and through science in such a rigorous way. And I think it starts a conversation about the upsides of being a parent. And those are, as we said, they're less obvious than the pain of being a parent. Yeah. And I think the more we can sort of rebalance that equation, the more likely we are

to raise a healthy generation of kids. And again, I do pause a lot because I realize I've got friends close to me that both either don't want to have kids for whatever reasons or just can't have kids. Yeah. So there's often the sort of stigma can go both ways in some regard. But I'm someone that wants to have kids. And it was fascinating learning about your work. And it helps me to prepare for what I hope will be the most fulfilling journey of my life. So Dr. Darby, Saxby, thank you so much for your work. If everyone wants to go get your book, I have two versions here. I have the UK version and I have the US version.

I'll hold both of them up here. And I'll link it below for anyone that wants to have a read. Absolutely fascinating. And the great thing about your work is you do the sort of first-party research yourself. And you're at the very forefront of what we know about what it is to have a dad brain, but also more broadly about couples, how they interact and where they can sometimes go wrong. Thank you. Thank you so much for having me.

This was a delight. It's been a pleasure.