A WEIRDo’s Guide to Exercise


Date Published: April 13, 2021

If you're WEIRD—Western, Educated, Industrialized, Rich, and Democratic—chances are you aren't getting enough exercise. And it's not because you're bad or lazy; it's because you're normal. In this episode, Harvard paleoanthropologist Daniel E. Lieberman, PhD, explains how evolution designed humans to avoid unnecessary physical activity, i.e. "exercise" in the Western sense. In his new book, "Exercised," he busts 10 common myths about sleep, sitting, and physical activity, using the latest scientific research. If you've ever wondered whether sitting is the new smoking, or if you're getting enough sleep or exercising enough—this episode is for you.

Podcast Transcript 

Host: 00:00
From the Mount Sinai Health System in New York City, this is Road to Resilience, a podcast about facing adversity. I'm Jon Earle. My guest today is Dr. Daniel Lieberman. He's a paleoanthropologist at Harvard University, where he studies the evolution of the human body, especially in regard to physical exercise. Dr. Lieberman's latest book is "Exercised: Why something we never evolved to do is healthy and rewarding." In it he uses scientific research to dispel 10 common myths about health and exercise. So if you've ever wondered whether you sit too much or get enough sleep, or exercise right, keep listening. Dr. Lieberman, welcome to Road to Resilience.

Dr. Daniel Lieberman: 00:42
Thank you so much for having me.

Host: 00:45
Everybody knows that it's important to exercise, but most people in America and throughout the industrialized West do not get enough exercise. And I think the culture is very shaming. It says that if you don't get enough exercise there's something wrong with you personally. You're lazy or you don't plan ahead or something to that effect. But you do not get into the shame game, which is something I really appreciate. You blame evolution.

Dr. Daniel Lieberman: 01:12
Well, I wouldn't say I blame evolution, but I think we need to, if we want to try to help people understand both how we are and why we are the way we are and how to make the world a little bit of a better place, I think that the current medicalized, commercialized, commodified way in which we approach a lot of topics doesn't really work because they don't really explain how and why things are the way they are. And evolution and anthropology give us important lenses to view the world in a better, more broader, more holistic way. And the topic of exercise is no exception. I think it's actually very important to think more broadly about exercise. And when you do, you learn that people aren't lazy because they don't want to get on a treadmill. They're actually being totally normal.

Host: 02:05
That's extremely reassuring. Say more about that. What do we learn from evolution in terms of our non-predisposition to exercise?

Dr. Daniel Lieberman: 02:14
Two things. The first is that, remember, our bodies weren't designed, they weren't engineered, they evolved. So if you want to understand why we are the way we are, you have to understand that evolutionary history. And then secondly, it's important to make a distinction between physical activity, which is just moving, right, just doing stuff. All animals have some degree of physical activity. But exercise is a very special kind of physical activity. It's discretionary and voluntary. It's the sort of stuff that you choose to do. And until recently nobody did that. Nobody chose to be physically active for the sake of health and fitness. I mean, that's really what exercise is, right? Instead, people were active because they, you know, in order to get food or avoid being somebody else's food, or they were active when it was socially rewarding, like dancing with friends and stuff like that. But getting on a treadmill for 45 minutes because it'll prevent heart disease or something like that is a really strange, modern phenomenon that until recently nobody ever did. In fact, it was a bad idea.

Host: 03:17
Why was it a bad idea?

Dr. Daniel Lieberman: 03:19
Well, because until recently energy was limited. Most people until recently, almost everybody until recently, I should say, struggled to get enough energy to survive. You know, life is a very simple equation. It's basically: energy in, babies out. That's what life is all about. And until recently the energy that was available for life was limited. And all the only thing that natural selection cares about is how many babies you have who survive and reproduce. Unfortunately, that's all mother nature really cares about. And so when you spend a limited resource on one thing, then you can't spend it on something else. I went for a five-mile run this morning, and the five miles I ran cost me about 500 calories. And if I was energy-limited, those would be 500 calories I couldn't spend on taking care of my body or reproducing. It would be wasted. It would be a really bad idea. So nobody goes for a five-mile run in many parts of the world where people are struggling to get enough food, whether they're working in fields or they're out hunting and gathering or whatever, this is something that we choose to do now in the modern, developed world, the Western world, where we've created all kinds of machines that do our labor for us. So today we have to choose to be physically active, because our world is such that we can avoid physical activity all the time.

Host: 04:41
So nonindustrial people don't have this discreet thing called "exercise" they do from 7 to 10 and lift weights that only exist to be lifted, that sort of thing?

Dr. Daniel Lieberman: 04:50
Yeah, it's a completely modern, strange, Western thing.

Host: 04:53
So how do they get their exercise? It sounds like simply in the course of normal life they move a lot.

Dr. Daniel Lieberman: 04:59
Well, I mean, they wouldn't call it exercise. They get physical activity. They get up and they have to go get food. They have to work in the fields. They have to go hunt. They have to gather, they have to take care of their children. They have to make things. Until recently all work was done either by humans or by animals. And all of a sudden, in the last few generations, we've created these machines that do all our work for us. You can sit all day. You can get up in the morning and, magically, everything is there for you. You don't have to do anything. You can go through your entire day without lifting, raising your heart rate, or breaking a sweat.

Host: 05:35
And I think it gets at one of the myths that you bust in the book, which is this myth of what nonindustrial people are like. There is certainly this idea floating around in the culture. Anytime the word "paleo" comes up, I think we imagine these prehistoric He-Men who are climbing trees and running around and look like Arnold Schwartzenegger. But they're not like that at all, are they? Our preindustrial ancestors were not like that, and it makes sense that they weren't.

Dr. Daniel Lieberman: 05:59
Yeah, we've mythologized them in all kinds of ways that are actually, I think, problematic. Because first of all, it dehumanizes those individuals, treating people from other parts of the world as somehow super athletes who are somehow endowed with special capabilities. It's just not true. They're human beings just like you and me, and for them to run long distances requires just as much effort and trouble and determination and willpower, etc. They don't just magically get up and run ultramarathons or whatever. And they're not ripped and jacked like Arnold Schwartzenegger. But the other problem is it makes us feel somehow bad, like somehow we've been contaminated by civilization so that the shoes that you wear or the Gatorade you might drink or whatever, whether they're good or bad, somehow they've turned us into wimps. And that if we just got rid of those things, we would suddenly, magically be able to swim the English Channel or whatever your fantasy is, and that's not true at all either. And I think it's sort of damaging. I think we end up being very non-compassionate not only to others, but also to ourselves. You know, we've all experienced being in a subway or a mall or an airport or something like that where there's a stairway next to an escalator. And there's that little voice in your head which says, "Take the escalator." We all know that voice. Even though escalators obviously didn't exist in the Stone Age. And that's because it's a deep and fundamental and basic instinct to avoid unnecessary physical activity. And then we make ourselves feel bad or make people feel bad for that little voice. But we need to understand that that's a perfectly normal instinct. And it's just that we now live in a very strange modern world where all of a sudden it's now beneficial to overcome that instinct. And it didn't used to be that way.

Host: 07:49
Sitting is another thing that people obsess about.

Dr. Daniel Lieberman: 07:53
Well, yeah, partly because of the way in which health information is provided to the public. We demonize sitting. The expression that is common these days is, "Sitting is the new smoking." Or, "Your chair is out to kill you." And I think that's really problematic for a number of reasons. The first is, look, you don't have to be a PhD in exercise science or a physician or whatever to realize that's hyperbole. Your chair is not out to kill you. It's not a toxin like a cigarette. And furthermore, if you travel around the world, I've had the good fortune to spend time in various places where people don't have chairs even. They just sit on the ground, or if they have chairs, they're just simple benches and stools, there's no seat back to their chairs. And they turn out to just sit as much as we do! It's normal to sit. My dog spends her day sitting all around the house. I mean, let's not demonize sitting, or say that somehow sitting is a strange, modern Western thing. It is true, however, and we can learn from studying in other cultures, that there are better and worse ways to sit. There's more active sitting, where maybe not having a backrest. And so you're using your muscles in your back, or you're sitting on the ground and you're using your leg muscles a little bit. And also, certainly, getting up every once in a while, what we call "active sitting," so interrupting long-term bouts of sitting. In the old days, people didn't have movies to watch where they sat completely inert for two hours at a time. They had to get up all the time to take care of their kids and the fire—all that little occasional getting up is really healthy. It's really good for you. So let's relax a little bit about sitting. Yes, it's good not to sit all day long. It's good to get physical activity, but let's not scare people and make them feel bad for something as natural and normal as sitting.

Host: 09:40
And fidgeters can rejoice, too, can't they?

Dr. Daniel Lieberman: 09:42
Oh, fidgeting is good for you. There's no question about it.

Host: 09:45
One of my favorite parts of the book was the sleep chapter. Man, sleep is something for me, personally, I obsess a lot about. I'm all about getting the right mattress, creating the right circumstances. A lot of stress associated with sleep. And you have this great line that I want to read. You write, "If you require quiet and dark to fall asleep, you are evolutionarily unusual."

Dr. Daniel Lieberman: 10:09
Yeah, in the modern Western world we make people stressed about sleep. And if you go to different cultures and just think about how people sleep in hunter-gatherer groups, or various villages, etc., all over the world, people sleep in very chaotic conditions. They sleep together, there's outside sounds, etc. But we've created this world in the West where we isolate ourselves and we make sure it's pitch dark and there's no sounds, etc. We get really nervous about it. And when we hear things, it makes us upset. Of course, when you get upset and nervous, what happens? Your cortisol levels go up. Cortisol is a stress hormone. It's an arousal hormone. And it goes up when you're stressed. It doesn't make you stressed. But it keeps you awake. It keeps you alert. Because it's a fight or flight hormone. And, of course, once you're stressed, then your sleep has gone. Sleep has vanished. And so, so much of what we do about people's sleep today makes them aroused and nervous. We tell them they need eight hours of sleep. We tell them they need to have the perfect mattress, they need to—people can sleep in boats, they can sleep in airplanes, people sleep in piles of human beings and stuff like that. If we just help people relax about sleep, everybody would sleep better. And one of the worst things we do is we tell people they need eight hours of sleep. And that's just a fiction. It turns out that people in—the idea is that in the modern Western world, where we have telephones, iPhones, electric lights, all these things that keep us up that we now don't sleep as much as we used to. But when you go out and study people who don't have iPhones and TVs, it turns out they don't sleep eight hours. They sleep like six to seven hours. And furthermore, even epidemiological data show us that there's nothing magical about eight hours. In fact, seven hours turns out for most people to be actually better associated with long-term health outcomes than eight hours.

Host: 12:14
And it's completely normal, too, for people to be morning people, not morning people. That all makes evolutionary sense, right? To have groups of diverse sleepers.

Dr. Daniel Lieberman: 12:22
Yeah, some of us are larks. Some of us are owls. It turns out to be genetic and there's a lot of variation within populations. And it's actually a really good idea because it helps make sure that somebody is awake all the time in a camp. So that if hyenas or lions come, somebody is awake. It's a good thing. So if you're a lark or you're an owl, don't fight it. Go with it.

Host: 12:44
And there's no virtue associated with it.

Dr. Daniel Lieberman: 12:46
No, there's so much virtue signaling associated with health in general, about diet, and the people with the 26.2 stickers on their cars and whatever.

Host: 12:56
The 10,000 steps.

Dr. Daniel Lieberman: 12:56
Yeah, I mean, the virtue signaling doesn't help. Well, it maybe makes the virtue signaler feel better, but it doesn't help the rest of us.

Host: 13:03
You must go through the world with a perpetual eye-roll

Dr. Daniel Lieberman: 13:08
Or, yeah, and perhaps I create a lot of eye-rolls, too. But there we are.

Host: 13:12
Again and again in the book, and this is one thing I love about it, it's just like, what you think is normal, forget that. Lots of things can be normal. Lots of things can work. There are very few, if any, in this book, I think, lines to the effect of, "Something, something is normal. That's the way it's done. That's the way I recommend it." It's always, well, there's a diversity of things that work for people, and that's very reassuring.

Dr. Daniel Lieberman: 13:36
That's right, and that's how evolution works. Look, a colleague of mine coined the term WEIRD: Western, Educated, Industrialized, Rich and Democratic. And that's the world in which most of the readers of my book and the listeners of this podcast are in. We're in the WEIRD world. But weird people, which comprise 90 percent of the data that we have on human behavior, on human health, comprise only about 10 percent of the world actually. And, of course, it's only very recently that we've been WEIRD. And so there's an enormous benefit to step out of our shoes and realize that, you know, how people live in New York or Boston or LA or whatever you happen to be, or even Duluth or Des Moines or wherever you want to be in the U.S., but that's not a normal way to live from an evolutionary perspective or from an anthropological perspective. And it doesn't mean there's anything wrong with the way we live, but we have a lot to learn by looking at variation.

Host: 14:32
It makes me think of a question that I wanted to ask you, which is, you travel around the world studying nonindustrial people—what's the reaction, or the range of reactions, typically, when you show up to do field work and you have your instruments and you're measuring feet and you're asking people to do things that they maybe think are a little strange. What do they make of your curiosity?

Dr. Daniel Lieberman: 14:53
First of all, we always try to work with communities. We don't just show up. We always work with people and try to make sure people feel valued. But, of course, when you show up with weird machines, you're a bit of a curiosity. And sometimes they think I'm pretty funny, like when I go for a morning run in some of these places people laugh and tease me. And they wonder why I'm asking these strange questions. But, you know, people are people, and we understand that the world is very different, and people come from different cultures and they're curious about me just as I'm curious about them. They understand it. The more I travel and the more I experience different cultures, the more you see how variable people are and how varied cultures are. But on the other hand, you also realized that, scratch below the surface, and people are people and there's a lot more that unites us than divides us. And I guess I don't think about that very much.

Host: 15:53
This is jumping ahead a little bit to some of the advice that you do give, because you're very cautious about giving straight up advice. You talk about making exercise social among other things as a way to get over the evolutionary hump. And one example you give is dancing. I love the part on dancing you write, "I know of no nonindustrial culture in which men and women didn't dance for hours on a regular basis."

Dr. Daniel Lieberman: 16:18
It's true. And even in the West dancing is a cultural universal and when people dance, they do it for long periods of time. They don't just do one five-minute song. I can think back on wonderful occasions in different parts of the world that I've been to where people just dance all night long. I'm actually often a wimp and I'm sometimes the first to go to bed. But yeah, I mean, in Africa and in Asia and in Central America, people dance and we did too. I think I mentioned in the book Jane Austin novels. She describes dances and how people dance till three, four in the morning. There's something very strange about the modern world in which we're now so isolated and insecure, and I don't know what's going on, but we've stopped dancing in the same way that we used to. And, I mean, a few people do, but most of us don't. That's another weird thing about modern, Western, American culture.

Host: 17:16
So let's get into some of the prescriptions. Tell us about some of the ways that people can overcome evolution and actually get moving. Well, first, let me ask you what exercises people actually need to do. What is scientifically based?

Dr. Daniel Lieberman: 17:33
So that's the Western approach to exercise. What do you need? How many pills should I take, doctor? And that's part of the problem. I think that's a really bad approach. I mean, yes, I understand why we do it and it's part of our culture and so on. But the truth is that any physical activity is better than none. So if you are completely physically inactive and unfit, and you just do just a little bit more, you'll get some benefit out of it. And the World Health Organization and the American Heart Association, and the Surgeon General and every major health organization on the planet recommends a minimum of 150 minutes a week of moderate exercise, which is 21 minutes a day, or 75 minutes a week of vigorous exercise. So moderate is like a brisk walk. Vigorous is like a run. And if you do that, the epidemiological data from large samples suggest that your mortality rate will decline by about 50 percent. But if you do just 60 minutes a week, so that's just eight minutes a day of moderate exercise, you can still lower your mortality risk by about 30 percent. I mean that's still an improvement. So there is no minimum. Anything is better than none. And there's nothing magical about 150. That's just a general benchmark that everybody's sort of agreed on, but there's no magical number there. If you do more, you'll get even more benefit. Another thing that I think everybody knows is that mixing it up is good for you. Nobody got fit just doing one thing. You know you need to do some strength training to stay strong. Aerobic physical activity is the bedrock of pretty much any exercise routine. So that's also important. And it's good sometimes to do a little bit intense, get your heart rate up. So it's pretty simple: Some is better than none, more is a little bit better than some if you can do it, mix it up, relax, do the stuff that you enjoy, because if you don't enjoy it, you're not going to get any reward, you're not going to do it again. And keep it up as you get older, because the older we get, the more important physical activity is. It doesn't become less important. It actually becomes more important.

Host: 19:48
Right. True. But since we're talking to our Western selves, you seem to jive if I'm understanding correctly with the 150 minutes in terms of what the research says is that this is sort of a good benchmark, not a perfect benchmark, but a good one for beginning to really cut into risks of things like cancer and heart disease, etc. Is that accurate?

Dr. Daniel Lieberman: 20:10
Correct. I'm not opposed to the 150-minute benchmark. I mean it's a very good sensible, normal benchmark. But there's no magical number and it's not a magic bullet. But it will decrease your vulnerability to a wide range of diseases substantially.

Host: 20:27
Talk about that part a little bit, because I don't think that's something we've touched on so far. Certainly I have a vague idea in my head of "exercise reduces your risk of a wide range of diseases." Can you take us through that a little bit?

Dr. Daniel Lieberman: 20:40
Sure. Well, there's two issues. One is the epidemiological evidence. How much exercise on the X axis and how much it reduces your risk of, say, Alzheimer's on the Y axis. And there's just tons of data which showed that, for example, if you're worried about Alzheimer's, pretty much the only thing you can do actually to prevent Alzheimer's is exercise. And it's by far the most beneficial thing. Estimates vary, but you can lower your risk between like 30 and 50 percent by exercising moderately. Nothing comes close. The same is true for cancers. Breast cancer, for example, there's a lot of studies which show that, again, the amounts vary, but you can lower, women can substantially lower their risk of breast cancer by 30, 40, some estimates up to 50 percent by moderate levels of regular physical activity. Why don't we tell more people this? And the list goes on, right. But the question really is why is that the case? And the reason for that is two-fold. First exercise, physical activity, prevents our bodies from spending excess energy on things that make us sick—you know, too much fat or too many hormones. When you exercise, your levels of estrogen and progesterone, for example, go down to actually normal levels. A better way of saying that is if you don't exercise your levels of estrogen and progesterone rise to abnormal levels, that's actually a more correct statement. And, of course, those hormones are mitotic, they cause cell division and increase your chances of cancer. But the other equally important way that exercise is good for you is that it causes stress. But it's good stress, the stress that the body's used to. So every time you exercise, you're producing little reactive molecules called reactive oxygen species that can cause damage throughout your body. It can cause mutations in DNA, it can cause damage to cells, all that causes inflammation, it causes a whole range of pathophysiological processes. But because we always were physically active, our bodies evolved an incredible range of mechanisms to deal with every single one of those stresses. When you exercise, you produce antioxidants. When you exercise, you tamp down inflammation, in fact your muscles are the major organ that regulates inflammation in your body. So all that physical activity does is turns on all these repair and maintenance mechanisms that keep us healthy. And here's the thing, we never evolved to turn them on to the same extent in the absence of physical activity, because we were never permanently sedentary. So that's why being relentlessly physically inactive makes you much more vulnerable to this incredibly wide range of diseases.

Host: 23:23
Is it also true that if you are physically active and physically healthy, you are better able to deal with adversity, whether it's disease or traumatic events or things like that. Have you looked into that at all?

Dr. Daniel Lieberman: 23:35
Well, I'm not an expert on mental health, but there's a lot of data which shows that physical activity has incredible short-term benefits for mental health. We've been talking right now about the long-term benefits in terms of heart disease and diabetes and cancer, etc., but everybody knows that you can go for a walk or run or a swim or something like that and climb a mountain, and you feel better. Everybody knows that. And it's not simply because you were outside and were talking to friends, though that's part of it, it's also because physical activity turns on a whole host of processes in our brains that are good. You produce dopamine, you produce serotonin, you produce epinephrine, you produce this molecule called Brain-derived neurotrophic factor, BDNF, which has been described by some people as Miracle Grow for the brain and it really is. And you produce all kinds of good stuff that happens that has immediate effects on mood. We all know the experience. I often go for runs early in the morning with a friend of mine, and we often arrange to meet at six or seven, some horrible hour early in the morning. And I never want to be there at six in the morning. Never, ever, ever, not once have I ever wanted to run at six in the morning. And yet I'm always glad afterwards that I did. Because when I get back from the run, I've got all this good stuff floating around in my brain that makes me kind of happy.

Host: 24:59
So let's just go through the things that you do at 6 AM to get yourself out the door. So you've made it social, you have a plan and a schedule. Do you lay out your clothes or do some of those other tricks that you include?

Dr. Daniel Lieberman: 25:10
Yeah, so I always leave my clothes out. So when I get up to walk the dog and stumble to the bathroom, I put on my running clouds. And then I don't have an excuse not to go out the door. But also, again, if I have to meet my friend on the corner, I have to be there otherwise my friend will be irritated that I'm not there. So there's a kind of self-coercion. I sign up for races, not so much because I love the races, but because it forces me to train. It gives me a goal. It's a carrot or a stick, depending upon your perspective. And also, by being social about it, I kind of then become responsible to others. In my particular case, it's well-known that I run and I study running and physical activity. So if I don't do it, I'd be a hypocrite. You laugh, but it's true. It actually is an important motivator. Nobody wants to be a hypocrite. For example, when I get to my building and I want to take the elevator up to the fifth floor, but if I take the elevator and anybody catches me, I'm in trouble. So I can't, so I take the stairs and I'm usually glad by the time I get to the top that I did take the stairs, although I kind of grumble for the first few flights.

Host: 26:30
What was the most fun part of the book to work on for you?

Dr. Daniel Lieberman: 26:33
Well, I enjoyed some of the trips I did, which I did in order to write particular chapters. So I really enjoyed going to the Bjorn Borg Sports Company. That was hilarious. For those of you who haven't read the book yet, I hope you do, that's a company in Sweden, it's the only one in the world, I think, that requires all of its employees to exercise. So I went there to see what that was like. I ran in the Man Against Horse Race in Arizona. That was kind of fun.

Host: 27:00
How did that go?

Dr. Daniel Lieberman: 27:00
I beat most of the horses. It was great. Even a middle-aged professor like me. I went to a mixed martial arts fight, which I would never otherwise do to see what that's like. So I do a lot of participant observation. Once I knew I was writing the book, of course I had been doing lots of stuff beforehand, too. But all of that made it kind of fun because trying to put yourself in somebody else's shoes or try new experiences. And there are certain chapters of the book I really enjoyed writing. I particularly enjoyed writing the chapter on sports and fighting because I really hadn't thought much about that. And I'm really most proud about the chapter on aging, because I think really in some ways that's the most important part of the book, which is the idea that we evolved not to not to get less active as we get older, but to become more active as we get older, just how important that is for our health.

Host: 27:50
So no passive retirement?

Dr. Daniel Lieberman: 27:52
That's a very modern, weird thing. That's for sure. There's this idea out there that until recently humans died young, that lives were nasty, brutish, and short. But that's actually not true. Before the Agricultural Revolution, before people started farming, hunter gatherers lived typically about seven decades. And that means that people generally lived about two decades after they stopped reproducing. But those grandparent years of 20, 30 years of being a grandparent, weren't about just retiring and going to Florida and playing golf and basically doing nothing. Those were times when people actually worked to help their children and their grandchildren. So foragers who are elderly, grandparent foragers, go out every day just like when they were younger, and they go out and they hunt, and they gather, they forage, or they work in fields if they're farmers. And they help provide food and they help take care of children and grandchildren and provide food and calories. And that was normal. And this idea that we can just take it easy when we get older really works to our detriment because it starts this vicious cycle of physical inactivity and then we become frail and then that frailty makes you less likely to be active. But also it doesn't turn on those critical repair and maintenance mechanisms which keep senescence, which keep us from aging as fast as we do. And so the evidence is clear, there's no question about it that numerous studies have shown that as you get older, physical activity is more important for preserving health, not less important. And that has an ancient, deep, and basic evolutionary origin.

Host: 29:28
What's a mystery that remains for you, something that you're puzzling over or exploring that you haven't quite answered yet?

Dr. Daniel Lieberman: 29:35
Oh, well I think that an easy one to answer. The biggest mystery still is how do we help people, motivate people who are disinclined to exercise, how do we go help them help themselves? I mean, almost everybody wants to do it. I've very rarely met anybody who's inactive who says, "I'm happy being an active." They talk about how they're stressed, they find it hard to find the time. They just don't enjoy it. They don't get a reward out of it. And although I've been thinking about it, none of us have yet really come up with a really good solution to that problem. How do you help people exercise? That's to me the key issue. And it may be an unsolvable problem, but I think we need to be much more creative and find solutions. Because what we're doing today just isn't working. I mean, it works for a few people, but for the vast majority of people in this country, 80 percent approximately according to the CDC, are just not getting minimal levels of physical activity. So we have a lot of work to do.

Host: 30:36
Do you have any sense of what the solution might look like? Is it a policy solution?

Dr. Daniel Lieberman: 30:41
I think it's going to be a kitchen-sink approach. There's going to be no one solution. I think it's gonna be a cultural solution. I think it's going to have to be policy. I think schools have to step up to the game. It's just outrageous how few schools actually have sufficient levels of physical activity for kids. And people develop their habits not just when they're youngsters, but also in college. And colleges are outrageous. It used to be that every college in America required some kind of physical education, physical activity, and now most don't. And those that do have just basically pitiful requirements. And you try to, you know, at Harvard, for example, I've just talked about my colleagues, and they look in horror and shock like, "Oh, my God, you'd require them to be active?!" And yet these are colleagues who have no problem requiring people to learn languages and learn calculus and learn this, learn that. We're great at coming up with requirements, but somehow, the body—we have this idea that minds and bodies are totally different things, and they're not, they're intimately connected. And so we need to change our culture in a variety of ways and stop being so dismissive of prevention and preserving health, and think more about treating causes, not just symptoms.

Host: 32:03
Thanks so much for being on the podcast, Dr. Lieberman.

Dr. Daniel Lieberman: 32:04
My pleasure.

Host: 32:06
Dr. Daniel Lieberman is a paleoanthropologist at Harvard University. His latest book is "Exercised: Why something we never evolved to do is healthy and rewarding." That's all for this episode of Road to Resilience. If you enjoyed it, please rate and review us on Apple Podcasts and tell a friend about us. We've also got a listener survey going where you can tell us what you think about the show and recommend guests. We'll put a link in the show notes. The podcast is a production of the Mount Sinai Health System in New York City. It's made by Nicci Cheatham, me, Jon Earle, and our executive producer, Lucia Lee. From all of us here, as always, thanks for listening, and we'll see you next time.