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Humans Weren’t Made to Exercise – Dan Lieberman

Humans Weren’t Made to Exercise – Dan Lieberman

Real Talk: The Charles Mizrahi Show podcast

Humans Weren’t Made to Exercise – Dan Lieberman

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It turns out that humans weren’t made to exercise … But we should still do it. Harvard professor Dan Lieberman has dedicated much of his career to exploring how physical activity has evolved over time, distance and cultures. Lieberman discusses his fieldwork, discoveries and the importance of making physical activity rewarding with host Charles Mizrahi.

Topics Discussed:

  • An Introduction to Dan Lieberman (00:00:00)
  • Field Work in Africa & Mexico (00:02:17)
  • Calories Across Generations (00:07:12)
  • Avoiding the Blame Game (00:09:00)
  • Physical Activity: Optional or Necessity? (00:12:36)
  • Exercise & the Class Divide (00:19:52)
  • Myth-Busting (00:21:54)
  • Making the Necessary Rewarding (00:35:48)
  • Youth Exercise Programs (00:44:12)
  • Improving Exercise for the Rest of Us (00:47:29)
  • Treating Exercise Like Education (00:53:08)

Guest Bio:

It may be a tall order, but Dan Lieberman wants us to make exercise fun. Lieberman is a biologist, anthropologist, professor and avid runner. His fieldwork has taken him to Kenya and Mexico, where he studied the evolution of physical activity and its widespread implications. Lieberman’s published works uncover important connections between human evolution and contemporary health, challenging our long-standing notions about exercise and encouraging us to move.

Resources Mentioned:

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Read Transcript

DAN LIEBERMAN: The mantra of the book is that we evolved to be physically active for two reasons and two reasons only. One is when it’s necessary, and the other is when it’s rewarding. The more we can make it necessary and rewarding, the likelier we are to enjoy it and not feel guilty or stressed.

CHARLES MIZRAHI: My guest today is Dan Lieberman. Dan is a professor of biological sciences and human evolutionary biology at Harvard University. His focus is on the evolution of human physical activity. Dan’s latest book is: Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding.

CHARLES MIZRAHI: In addition to busting myths about exercise, he asks: “Is sitting really the new smoking? If we are born to walk and run, why do most of us take it easy whenever possible? Does running ruin your knees?”

CHARLES MIZRAHI: Using his own research and experiences throughout the world, Dan recounts in simple-to-understand English how and why humans evolved to walk, run, dig and do other necessary and rewarding physical activities while avoiding needless exertion.

CHARLES MIZRAHI: I recently sat down with professor Lieberman to tell the story of how we never evolved to exercise or do voluntary physical activity for the sake of health — and why we shouldn’t feel so stressed about it.

CHARLES MIZRAHI: Professor Dan Lieberman, thank you so much for being on the show. I greatly, greatly appreciate it.

DAN LIEBERMAN: It’s my pleasure. Thanks for inviting me!

CHARLES MIZRAHI: I’ve read a lot of books on health and exercise. There’s something about your book that — when I started to read it and go on YouTube to listen to your lectures — just resonated with me.

CHARLES MIZRAHI: So, before we begin, your book is called: Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding.

CHARLES MIZRAHI: What I found so interesting was the places on this planet that you went to in order to observe how indigenous people lived — and then you took that forward. Where was the wackiest place in the world you’d ever been to?

DAN LIEBERMAN: I don’t know. Of all the things I did for this book, I think the strangest was going to a mixed martial arts event in Plymouth, Massachusetts.

DAN LIEBERMAN: I’ve been working in Africa since 1987. I’ve [also] been working in Mexico and have traveled all over the world.

DAN LIEBERMAN: But the place that I felt the most at sea — the most alien — was when I went hunting with some Inuit hunters in Greenland. I realized that if I fell off the sled and they lost me, I would die soon. That was a hostile, dangerous environment. It was amazing that humans could live there.

CHARLES MIZRAHI: Why did you go there?

DAN LIEBERMAN: I was invited by a colleague who I’m collaborating with, from Danish researchers, to study diabetes and the effects of physical activity on diabetes. They were doing a documentary on diabetes in Denmark, and Denmark has a long association with Greenland. So, they decided to go to Greenland, where diabetes rates are going up, and explore what’s going on. I got invited to go on this trip and I couldn’t say no because it was such an interesting opportunity.

CHARLES MIZRAHI: What did you learn while you were on this trip? You had a great account in the book. I don’t want to spill the beans, but there were some really super things that you learned from that insane trip and how cold it was there.

DAN LIEBERMAN: I think the most important thing you can learn is just how incredibly powerful cultural adaptation is. Humans have figured out how to solve so many problems. If you can learn to live in 74 degrees north in the winter without modern technology —

CHARLES MIZRAHI: Negative [74 degrees]?

DAN LIEBERMAN: So, that’s the latitude. When I was there, it was minus 30 to minus 40. It doesn’t matter whether it’s Celsius or Fahrenheit — it’s the same thing. But remember: people have lived there since before the Industrial Revolution, electricity and all those incredible inventions. If we can learn to do that, there’s nothing we can’t solve. I think that’s what really impressed me.

DAN LIEBERMAN: Also, what impressed me was just how challenging that life was. It was physically challenging, and I described that in the book. One of the challenges I never expected was sitting on a sled for hours. To get from the coast to the central plateau, we had dogs pull us on a sled. And it wasn’t like a car, which was designed for your comfort. It was an ancient, old fashioned Inuit sled.

DAN LIEBERMAN: I was in agony on that sled because I wasn’t used to sitting without back support for hours and hours — for days, actually. It was just one of many eye-opening experiences.

CHARLES MIZRAHI: First of all, what I really enjoy about your approach is that you go into godforsaken places where there are still indigenous people who have lived the same way for tens of thousands of years, more or less. I know they’re becoming fewer and fewer.

CHARLES MIZRAHI: You observe them in terms of their activity — at rest and during work — and come to amazing conclusions based on those observations. [You] take a lot of what we consider facts and turn them into stories — nothing more than myths.

DAN LIEBERMAN: It’s normal to think your life is normal, right? We think it’s normal to sit in chairs all day, drive around in cars, get on airplanes, eat breakfast cereal that comes in a box and all the other things that are part of our world. And this is normal to us. There’s nothing wrong with that. But I’m an evolutionary biologist and anthropologist, and my job is to try to think about how our world differs from the way humans have lived for generations — thousands of generations.

DAN LIEBERMAN: Even the way you and I live today — compared to [how] our great grandparents lived — is astoundingly different. And yet, we don’t often think about how that affects our bodies. We know that at a sort of general level. There’s a lot to learn. There are so many things about the modern world that we’ve gotten right. Life expectancy is extraordinary today. Infant mortality is incredibly, incredibly small.

DAN LIEBERMAN: Just think of how fast we were able to come up with vaccines for the for the coronavirus. It’s impressive! It’s incredible! It’s amazing! Yet, we also have higher rates of cancer, heart disease, diabetes and all kinds of other diseases that used to be rare — to the point of nonexistence.

DAN LIEBERMAN: So, I think we can have our cake and eat it too. I think we can enjoy all the wonderful benefits of the modern world but do much better by learning about how our bodies work, the environments we’ve created and how we can have the best of both worlds.

CHARLES MIZRAHI: Give me one example. I know you give tons of examples in the book — like the way our grandparents lived in terms of the sewing machine. Just expand on that.

DAN LIEBERMAN: My grandmother had one of those old-fashioned Singer sewing machines, which she pedaled with her foot. I can’t remember the exact number of calories, but [you burn] 15 to 20 more calories an hour to pedal that sewing machine.

DAN LIEBERMAN: Imagine you’re working in a factory and you’ve got an electric sewing machine versus a pedal sewing machine. You’re just pedaling that sewing machine for several hours a day, five days a week and 50 weeks a year. That’s a lot of calories! That’s a lot of physical activity. And then you add to that to the elevators, escalators, shopping carts etc…

DAN LIEBERMAN: We have decreased, over the last two generations, the number of calories we spend just doing stuff. Forget exercise. We’ve decreased the calories we spend in normal life by 200 to 300 calories per day. That’s an enormous amount when you add that up over weeks, months and years. And that’s just one example.

CHARLES MIZRAHI: When they rebuilt Yankee Stadium in the 70s, a friend of mine bought one of the old seats they had. And the seats at Yankee Stadium — from the house that Ruth built — were much narrower. They lost so many seats when expanding the stadium because our butts are much bigger now than they were 70 years ago.

DAN LIEBERMAN: Yeah. We’ve changed. Just in my lifetime, the percentage of Americans who are obese has doubled. That’s insane.

DAN LIEBERMAN: With that comes a lot of trouble. But the reason I wrote this book is that we are often in the blame game. We’re often trying to make people feel bad about their physical inactivity. We make people feel bad about being overweight. The one thing I’ve learned is that there’s nothing special about people who aren’t overweight versus overweight. For most people who are overweight, it’s not their fault. For most people who are physically inactive, it’s not their fault. What we do, though, is make people feel bad. We make them feel exercised. That’s why I titled the book [how I did]. We make them feel anxious, confused, nervous, blamed and shamed.

CHARLES MIZRAHI: Hang on a second. Why isn’t it their fault? Let me just build a case.

CHARLES MIZRAHI: I was overweight most of my life. Growing up, my mother would tell me I snacked too much, didn’t go out enough, didn’t play enough sports — or whatever it was. It was my responsibility. The reason that I was a big kid was because everything was on me. And you’re telling me that’s not so?

DAN LIEBERMAN: Well, we all have basic instincts. We’ve had millions and millions of generations for us to eat whatever food is available and be as inactive as possible. All of the sudden, we’ve created this environment with all the snack foods you could possibly have — and escalators, elevators, shopping carts and cars. Then, we’re asking people to do something intrinsically unnatural, which is to say, “No, I’m not going to have that piece of chocolate cake,” or “No, I’m not going to take that escalator.”

DAN LIEBERMAN: Think about the treadmill. [It’s a] noisy, expensive and nasty machine that nobody really likes. Let’s be honest. You trudge on for hours and hours a week because it’s like cod liver oil. There’s a reason most people hate it, right? But we’re told that if we don’t do it, we’re lazy.

DAN LIEBERMAN: But we never evolved to do anything like that. Yes, there is some personal choice and responsibility. All of us have to make choices. But we’re asking people to make choices that are really hard to make. More importantly, we’re asking kids to make them. Children don’t have the wherewithal to understand this sort of stuff.

DAN LIEBERMAN: By the time you’re overweight — if you’re a kid — you just do what your parents and environment tell you to do. It’s really hard to turn that around. You can, but it’s really, really hard.

CHARLES MIZRAHI: So, 70 or 80 years ago, escalators weren’t so ubiquitous. In many buildings, elevators were nonexistent. You had to walk up six flights of stairs. Or, like your grandmother, you had to use the pedal on the sewing machine. Or, you had to carry a big lump of ice or coal into your apartment.

CHARLES MIZRAHI: You were burning off calories and doing what evolution taught you to do by moving and consuming whatever calories you needed because there wasn’t fast food and all sorts of junk — dense, calorie-packed things — that we have today. Is that, more or less, accurate?

DAN LIEBERMAN: Basically, yeah. And it’s not just about calories. It’s also about turning on all the cellular machinery that your body activates when you’re active. When you’re active, your cells produce antioxidants and molecules that help repair DNA.

DAN LIEBERMAN: There are cells that produce more of the molecules that help you fight viral infections like COVID. These are all things that our bodies have evolved to do when we we’re physically active.

DAN LIEBERMAN: Now, we’ve created a world where physical activity is optional. Now, we have to choose to do it. That’s exercise. Exercise is physical activity that’s discretionary — that’s voluntary — which we do for the sake of health and fitness. That’s great. I exercise. I really promote exercise. But let’s be honest and recognize that exercise is a really weird, modern thing that nobody used to do.

DAN LIEBERMAN: So, in the populations where I go and do fieldwork — Greenland, Africa or Mexico — nobody exercises. I’m the only guy who gets up in the morning and goes for a six-mile run. They think I’m hilarious!

CHARLES MIZRAHI: It’s a jog to nowhere.

DAN LIEBERMAN: Yeah, to nowhere! “What’s this [guy] doing?” It’s crazy.

DAN LIEBERMAN: And sometimes the kids run along and shout at me — and that’s fine. But they don’t need to because they’re working hard. They’re in the fields growing corn or milking the cows. In Kenya — in the community where I’ve been doing fieldwork for over 12 years now — the average kid has to go about 10 kilometers every day to get to school on foot. How many American kids have to walk six miles to get to school?

CHARLES MIZRAHI: How many kids walk six miles?

DAN LIEBERMAN: Yeah, and that’s the average! Some are doing more. They have no choice because they have to get to school. So, a lot of them run because… They’re late. They run to school barefoot, by the way. They don’t choose to do it. They don’t get up in the morning and think: “I think I’m going to run to school.” They don’t do that. They do it because they have to. But it turns out it’s really good for us.

CHARLES MIZRAHI: What happened? What switch is still flipped on for us that put our bodies, which are wonders of nature, in today’s society where those things are still not flipped off?

CHARLES MIZRAHI: For example, we’re still trained or programed to conserve calories and not burn them. So, if we see stairs or an escalator, why is it that — I think you wrote 5% of people take the stairs — our brains immediately flip and say, “Take the escalator”?

DAN LIEBERMAN: First of all, nobody knows the gene or genes behind that. Those are undiscovered. But it’s clearly an instinct, right? It’s an instinct to save calories. And the reason for that is — and it makes sense from an evolutionary perspective — if you think about evolution and life, it’s a really simple equation. The equation of life is calories in babies out.

DAN LIEBERMAN: We eat so we have energy to do stuff — and ultimately, to have babies. It’s really kind of depressing, but that’s actually all natural selection cares about. Those of us who have more babies — who survive — pass on our genes to the next generation. That’s very sad. Until recently, almost everybody on the planet struggled to get enough calories. There were just enough calories to do that. So, the people who had more calories had more babies.

DAN LIEBERMAN: There’s two ways of having more calories. One is to spend them spend less, and the other is to get more in. So, we have deep-seated instincts, all of us, to eat calorie-rich foods — foods with lots of sugar and fat.

DAN LIEBERMAN: We also have deep-seated instincts to not expend calories when it isn’t useful for us. Play is useful. Working in the fields is useful. Going out hunting or gathering is useful. Certain kinds of social interactions like dancing, finding a mate and being sexy are useful. But getting on a treadmill for an hour is not useful. Those are those deep instincts.

DAN LIEBERMAN: Although there were never escalators in the Stone Age, that little voice all of us have… When I go to my office, there’s an elevator to the fifth floor of my building. Every single time I go into the building — no exceptions — I have to fight with that little voice that wants me to take that elevator. The only reason I usually take the stairs is because I write about this stuff. If anybody catches me in the elevator, they’ll know I’m a hypocrite.

DAN LIEBERMAN: So, I have serious motivation. But I struggle with that all the time. Everybody does! It’s hard. It’s really hard to overcome that.

DAN LIEBERMAN: Now, imagine I am super stressed. I have two jobs, screaming kids and various other things I have to do. I’m not going to take the stairs! Of course, I’m going to take the elevator.

CHARLES MIZRAHI: I always find that I start to rationalize. I have to get there quicker or I’m going to miss the plane. I need to take that walkway. I always fight with that by trying to be logical and saying, “I’m going to sit on a plane for three to six hours. Let me get moving now.” So, I usually take the stairs. It’s just unbelievable to me that people wait in line to take an escalator, but in 10 to 20 steps, I’m up at the top already. I guess it’s that little voice that tries to tell us to save calories.

DAN LIEBERMAN: Yeah, of course. And then the other phenomenon, which I’m sure you know very well, is hyperbolic discounting. We value the short term more than the long term. A bird in the hand is worth two in the bush. So, I think to myself, “If I just take the elevator this time… It’s only once, right? Tomorrow I’ll take the stairs.” I’ll take that teaspoon of sugar in my coffee today. Tomorrow, I won’t. It’s just one teaspoon. We all know that if we keep doing that, those little doses will add up over hours, days, weeks and years. They turn out to be rather meaningful.

DAN LIEBERMAN: If you’re one of those folks who’s trying to cut down on your sugar, just do a little simple calculation about how much sugar you should take. You can consume less if you don’t put sugar in your coffee, for example. I’ll make a bet. It’s quite a bit.

CHARLES MIZRAHI: You got me thinking, when I was reading your book, about your grandmother and the sewing machine peddle. I think you wrote somewhere it’s the equivalent of one or two marathons a year in terms of calorie expenditure.


CHARLES MIZRAHI: Right there is five or six pounds that you could easily gain per year. In five years, that’s 25 to 30 pounds overweight — just that she kept in check, or anyone could keep in check.

DAN LIEBERMAN: Yeah, it’s true. I mean these little things add up. It’s astounding. But it’s very hard to kind of think about that in the here and now.

DAN LIEBERMAN: You’ve probably read about behavioral economists and the slow brain and fast brain. Our fast brain is our instincts, basically. We have the capability of overriding our fast brain with our slow brain, but it’s work. It’s effort. It takes training. It also takes some wherewithal.

DAN LIEBERMAN: It used to be that people who were wealthy, the elites, could afford to be inactive, hang around on couches all day and be served. Everybody else was thin and active.

DAN LIEBERMAN: For the first time in history, that’s been reversed. It’s now the people who are wealthy — who have the time, money and ability to go and exercise — whereas everybody else commutes and works jobs that prevent them from being physically active. They’re the ones who are struggling more.

DAN LIEBERMAN: Somebody told me, and I’m not sure this is true, that Runner’s World has the second highest per-capita income of any magazine. I don’t know if it’s No. 2, but it’s certainly up there. If you go to Ironman or marathons, you see a lot of people who are well-to-do, well-off, middle-aged or successful. You can’t be a marathoner if you’ve got a hard, serious, or difficult day job with a long commute.

CHARLES MIZRAHI: Or, you have two jobs or a night job. Or, you’re a single parent. It’s very difficult how much spare time you need to devote to exercise.

DAN LIEBERMAN: Right! Yeah, exactly.

CHARLES MIZRAHI: So, you go to these places on planet Earth where you see indigenous people living as they’ve lived for many, many generations. You monitor what they do, and more importantly, the myths that we’ve developed about what they do — which they don’t do.

CHARLES MIZRAHI: For example, they are always moving. They don’t rest. They don’t slouch. They don’t do anything. You just turn that completely around.

DAN LIEBERMAN: I mostly work in farming villages. I’m really interested in subsistence farmers. If you walk into a farming village in Mexico or Africa, people are working hard in the fields a lot of the day. But when they’re not, they’re plopped down under a tree. They’re sitting and resting.

DAN LIEBERMAN: I’ve had the good fortune to go to a few hunter-gatherer camps and meet some hunter-gatherers. You walk into camp, and everybody’s sitting. People have put sensors on folks in these communities. It turns out they sit as much as we do. The Hadza, a very famous group of hunter-gatherers in Tanzania, are famous because they’re one of the few. People have been studying them a lot.

DAN LIEBERMAN: One of my former students, Dave Raichlen and company, actually put sensors on the Hadza. That’s not work I did. That’s work they did. They found that the Hadza people sat an average of 10 hours a day, which was pretty much the average amount of time a middle-aged American spent sitting.

DAN LIEBERMAN: So, the idea that we sit more than hunter-gatherers is just completely made up. It’s just not true.

CHARLES MIZRAHI: I love all the not true things because if you tell people, they look at you cross-eyed. Slouching in a chair… That’s another thing you’ve observed these people do?

DAN LIEBERMAN: Everybody slouches! There’s a reason we slouch. When you slouch, you spend less energy sitting.

DAN LIEBERMAN: There was a German orthopedist named Stoffel in the 1800s who decided that… This was when the chair first became commercialized.

DAN LIEBERMAN: Until the 1850s, almost nobody could afford a chair with a back because they weren’t mass-manufactured. People sat on stools and benches. It wasn’t until the Industrial Revolution got going that chairs with backs became common and that average, everyday people could buy them. This horrified Stoffel and other German orthopedists. They decided that was going to be really bad and that and that people, when they sat, should sit the same way they stand. That was where the idea about posture came in.

DAN LIEBERMAN: Ever since then, people have been scolding people, like me, for slouching. Yet, if you go to an African village, everybody is slouching when they’re sitting down. If their back is against a tree, they’ll slouch. Most of time they can’t because they’re sitting on the ground. Or, they lay down. I was kind of interested by this, so I started delving into the literature.

DAN LIEBERMAN: There’s a lot of research on the relationship between posture when you’re sitting and your likelihood of back pain. It turns out we’ve confused cause and effect. People who slouch aren’t more likely to have back pain than people who don’t slouch — even though we’re told that all the time. What is the case is that people who have weak backs are more likely to have back pain. People who have weak backs are more likely to slouch. So, that’s the relationship.

DAN LIEBERMAN: But it’s not the slouching itself that causes the back pain. It’s [caused by] having a weak back, which is caused by sitting all the time on a chair like I’m sitting on right now — with a back rest. That enables me to never have to use my back muscles. So, go ahead and slouch. Don’t worry about the slouching because the slouching itself is not causing problems. But if you can’t sit up straight, it probably means you have weak back. That’s what you should worry about.

CHARLES MIZRAHI: So, we’re confused about causation and correlation.

DAN LIEBERMAN: Absolutely. We do that all the time.

CHARLES MIZRAHI: It’s one of those things where we like to come up with a quick answer without thinking it through.


CHARLES MIZRAHI: When I started rowing… I bought a rower.

CHARLES MIZRAHI: I look at it and feel guilty if I don’t use it. So, I’m totally exercised with that.

CHARLES MIZRAHI: I’ve noticed that people from Third World countries are able to get into a squat position with much more flexibility than modern folk today. That’s usually the way they eat. I think you had experience with that as well, correct?

DAN LIEBERMAN: Yeah, I’m a terrible squatter. I’m stiff. I’m a runner, and runners are often pretty stiff. I’m trying to be less stiff and stretch more.

CHARLES MIZRAHI: I hate stretching. That’s another thing. Could you tell me if that’s because of something in my genes? I hate to stretch.

DAN LIEBERMAN: The funny thing is that I never see anybody stretching in these communities. They’re just naturally more flexible because they don’t sit in chairs for long periods of time.

DAN LIEBERMAN: So, I was at this campfire watching women roast a tortoise. It’s a complicated story. I was trying to be ho hum about it and just watch the scene. I was sitting in between two women, and my legs were on fire because I’m really bad at squatting. I was in agony, but I was stuck. I described this in the book, but I actually fell into the lap of one of those ladies. I just lost it. I just tumbled into her lap. They all thought that was really funny.

CHARLES MIZRAHI: And they are able to squat well into their older years, where most older people in America can’t even get out of a chair. These people are able to squat.

DAN LIEBERMAN: They’re strong and they flexible. I think the chapter I’m most proud of in the book is the one about aging. We [live in] a world in which we think that it’s normal to be less physically active as you get older. We have a concept of retirement. We also have weekends. We have all these wonderful things that make life easier and more comfortable. And we like them because it’s nice to have comfort. But the problem is that it enables us to atrophy.

DAN LIEBERMAN: What we’ve found is that in hunter-gatherer populations, subsistence farmer populations or pre-industrial populations, people stay pretty strong as they age. They do lose some strength because they’re not working as vigorously, but they don’t lose it at the same rate as Americans tend to.

DAN LIEBERMAN: The result is that they’re less likely to become frail. One of the big problems with aging is muscle wasting. The technical term for it is called sarcopenia. “Sarco” is the Greek word for flesh, and “penia” is the word for loss. It’s flesh loss, and kind of a graphic term.

DAN LIEBERMAN: But we all know sarcopenia. As you get older, you become frail, you can’t get out of a chair, it’s harder to get off the toilet, and you walk more slowly. When that happens, you get into a vicious cycle. That’s because as you become frailer, doing other tasks becomes harder, and then you do them less and less. That’s a problem. When you’re physically active, you turn on all kinds of repair and maintenance mechanisms that help keep you young and keep you from senescing.

DAN LIEBERMAN: We can’t stop aging. We all go. All of us will, hopefully, get old. But senescence is when things break down as you age. The reason physical activity is so important is that it turns on all these mechanisms — and there are so many that we don’t even know them all — that slow the rate at which we senesce. So, continuing to use your body as you get older is unquestionably really, really important. The older we get, the more important exercise is — not less.

CHARLES MIZRAHI: I’ve noticed this in the past couple of years, as I often fly down to Florida on business. Checked baggage is about 35 dollars — or whatever it is — so most people take a carry-on.

CHARLES MIZRAHI: I can’t tell you how many times I’ve gotten on a plane with elderly people and they couldn’t take a 20-pound bag, lift it over their heads and place it in the overhead compartment. I help them and say to myself: “My gosh, I’ve just got to keep exercising and doing strength training because I never want to be in that situation.” I’m also thinking: “When was the last time they lifted anything that was 20 to 30 pounds over their heads?” It was probably decades.

DAN LIEBERMAN: The only problem is when they get on a plane, someone like you helps them. Why would you have to in the world today? We have machines that do everything for us.

DAN LIEBERMAN: Just think about this: Until recently, if you wanted dinner, you had to carry it. If you wanted water, you had to go into the bathroom and turn on a pipe.

DAN LIEBERMAN: We just think that’s normal, right? You turn on the faucet, and out comes water. You have hot water too. It’s a miracle. But until recently, everybody had to carry every little bit of water that was used — and firewood! Humans carry stuff. That’s one of the reasons why bipedalism is so cool. It enables us to carry stuff. Now, nobody has to carry anything, and we’re paying the price for it.

CHARLES MIZRAHI: I remember seeing — I forgot in which country — a whole bunch of strong men who do all these crazy feats like the farmer’s carry, which is holding heavy weights in both hands and walking.

CHARLES MIZRAHI: Usually, these guys carried their body weight in each hand and walked 20, 30, 40 or 50 feet. So, they went to this place and saw old ladies in a field carrying pumpkins and gourds — doing the farmer’s carry that they were struggling with. And they were doing it with ease! It was absolutely amazing.

CHARLES MIZRAHI: I don’t think it was a set-up, but these old ladies were used to doing this. That was what they did. That was their position in their tribe or social structure: carrying heavy objects. So, we invented these farmers’ carries, and they did that and got stronger.

DAN LIEBERMAN: Exactly. We have to invent new ways to be physically active because we don’t have to do it anymore. One of the really cool things that has recently been discovered is when older people lift weights — we now recommend that as you get older — they should try [to do so] twice per week.

DAN LIEBERMAN: It turns out you don’t have to have the no pain, no gain stuff. If you want to look like Arnold Schwarzenegger, go ahead. But if you just want to keep your strength, you don’t need to be in pain to get the benefits of strength training.

DAN LIEBERMAN: What we found is that, even down to the genetic level, you don’t lose the ability to respond to those loads. So, if you’re in your 70s and you’re weak, go to the gym. You can get that back. It’s never too late. That’s another important thing. You don’t have to be super strong. You don’t have to be super ripped. You don’t have to do crazy workouts that [cause] you pain. You can just do moderate levels of physical activity and get enormous benefits.

CHARLES MIZRAHI: There is one strength trainer in Chicago who specializes in elderly people — with squats, dead-lifts, presses and bench presses. He has 95-year-old people deadlifting their body weight. It’s just a lot of practice. People who couldn’t get out of a chair are now able to squat.

DAN LIEBERMAN: Yeah! And there’s abundant evidence that this is how our bodies have evolved. We never turn off those mechanisms. That’s the good news. It doesn’t take a lot, and everybody can do it. People who have disabilities are often most aware of how important this is because they don’t take things for granted. There are lots of ways that all of us can get the benefits from physical activity.

CHARLES MIZRAHI: OK. I want to ask you this. I walk my dog, on average, three to 3.5 miles per day. [We have] two different walks every day. Then, I make sure to always take the stairs when there’s an elevator … In some places, you can’t even take the stairwell because the doors don’t open. I’ll always try to take the stairs at the airport. I usually do. I always bypass the walkway. I try to find things to do that replace exercises I would usually do. My wife sends me to the supermarket, and I carry [things] home — ten blocks — instead of taking the car.

CHARLES MIZRAHI: Then why, when I look at my rowing machine, do I feel so guilty that I’m not using it? What’s going on in my brain that’s making me feel that way? Why am I feeling exercised?

DAN LIEBERMAN: I don’t know. But one reason is that, when you’re in an airport, you still need to get to the top of the stairs. You need to get up there because the gate or lounge is there. You’re getting something out of it. It’s may be not the most economical way to get there, but there’s a benefit to you. There’s an obvious, immediate benefit.

DAN LIEBERMAN: Also, I’ve noticed that it’s just faster to take stairs in an airport.

CHARLES MIZRAHI: It’s a single line up the escalator, and you have to wobble your carry-on. I’m always scared someone’s going to drop one on me. It’s one of those crazy fears I have.

DAN LIEBERMAN: I think you’re getting some benefit out of it. Whereas, if you go to the gym and get on a treadmill, rowing machine, StairMaster or whichever torture device you’ve got down there, you know that there’s a benefit, but you’re not getting anything out of it immediately. You might get a little dopamine hit afterwards and feel better for the rest of the day…

DAN LIEBERMAN: The mantra of the book is that we evolved to be physically active for two reasons and two reasons only. One is when it’s necessary, and the other is when it’s rewarding. The more we can make it necessary and rewarding, the likelier we are to enjoy it and not feel guilty or stressed.

CHARLES MIZRAHI: I think you’re spot-on because, for my whole life, I’ve hated treadmills. I would rather go for a walk outside and get fresh air — or take my bike somewhere — instead of going on a treadmill for 40 minutes. It has never made sense to me. It bores me.

CHARLES MIZRAHI: People use TVs and music, but why don’t they just walk 10 blocks?

DAN LIEBERMAN: Yeah. Look, I’m not opposed. If you can stand a treadmill, and you like watching a movie on it, all power to you. I find that the only way I can tolerate a treadmill is by diverting my —

CHARLES MIZRAHI: It’s totally misdirection.


CHARLES MIZRAHI: And now we have the Peloton, where people are going on bikes for $2,000 and paying a monthly subscription service to be in a race with other people to motivate them to ride the Peloton.

DAN LIEBERMAN: Yeah, right. If that works for you, that’s fine. I’m not judgmental about it. But we know that it’s not working for most people.

DAN LIEBERMAN: First of all, most people can’t afford a Peloton. Secondly, not everybody likes that kind of thing. According to our government’s efforts to measure those sorts of stats — [from] the CDC and various other studies — only about 20% of Americans have managed to get 150 minutes of physical activity per week. So, 80% of us aren’t even getting an average of 21 minutes per day of physical activity.

DAN LIEBERMAN: Despite our efforts to commercialize, prescribe and medicalize it…

CHARLES MIZRAHI: It’s not working.

DAN LIEBERMAN: It’s working for some, but it’s not working for everybody.

CHARLES MIZRAHI: You’re telling me 80% of Americans are not getting — let’s say 10 minutes, twice a day — [enough] physical activity?

DAN LIEBERMAN: The U.S. government, World Health Organization, American Heart Association, American College of Sports Medicine — and every major organization in the world — more or less agrees that 150 minutes per week of physical activity is baseline.

DAN LIEBERMAN: So, that’s 21 minutes per day. According to most studies, on average, only about 20% of Americans are getting that. That means 80% of us aren’t managing to get a total of 21 minutes per day of moderate-to-vigorous physical activity.

CHARLES MIZRAHI: Give me an example of moderate-to-vigorous activity.

DAN LIEBERMAN: We define that as getting your heart rate up above 50%. That would be like a brisk walk. A brisk walk is moderate physical activity. So, you don’t even have to be running. Climbing the stairs [is] moderate physical activity. Running is vigorous physical activity. Playing a game of soccer or swimming is vigorous physical activity. We’re just not getting our heart rates up very much.

CHARLES MIZRAHI: So, 17 or 18% of our GDP — or three to $3.5 trillion — is spent on health care. And that’s just increasing as years go on because the population is now aging.

CHARLES MIZRAHI: It seems to be such a low level of activity that is very gettable by anybody with a pair of sneakers… Just move. Do something. What’s the barrier to entry? Why is that taking place?

DAN LIEBERMAN: You’re right. We spend almost 20% of our GDP on health care, and about 75% of most medical care is for preventable diseases. Diet and exercise are the two major forms of prevention. So, diet is also important.

DAN LIEBERMAN: And yet, we spend, by any estimate, less than 5% on prevention. There’s a number of reasons. One is that our medical system is not designed to prevent disease. You go see a doctor after you’re sick, not before. Our medical system is really designed around treatment — not prevention.

DAN LIEBERMAN: And we don’t really have a society that’s devoted to prevention. Schools of public health are into that game. But there aren’t that many schools of public health, and they don’t have a lot of power.

DAN LIEBERMAN: The other [reason] is that we’ve created a world where nobody’s making money off of prevention. Certainly, health clubs are, and that’s all good. There are companies that are producing healthy foods. That’s good. But there are also plenty of other companies that are making money off our instincts. Comfortable shoes and escalators — all the things that make our lives more comfortable and easier. And we buy them because we want them. It’s nice! Comfort is nice!

DAN LIEBERMAN: So, we need a society to figure out ways to help each other. Simply scolding each other or making people feel bad is not functioning. I really like the “nudge” philosophy of libertarian paternalism.

DAN LIEBERMAN: We can’t force people to exercise. That’s not going to happen — just like we can’t prevent them from smoking. If somebody wants to smoke, that’s their right. If somebody doesn’t want to exercise, that’s their right.

DAN LIEBERMAN: But most of the people who don’t exercise want to exercise. If you ask them [why they don’t], it’s because they don’t have time, don’t like it, or a whole bunch of [other] reasons. I don’t think that we are doing a very good job of helping those folks.

DAN LIEBERMAN: Part of that is because we haven’t really looked at this phenomenon with the right lens. I think this evolutionary anthropological lens can help us rethink exercise. I know I sound like a broken record, but I think the key central message is: We’re telling people to do something that is fundamentally and intrinsically abnormal.

DAN LIEBERMAN: Once you know that, I think it’s empowering. It’s like when you’re at the escalator, and that little voice says, “Let’s take the escalator. Take the escalator!” We all have that voice. If you know that, you [can] override it.

DAN LIEBERMAN: Just that little bit of knowledge is very empowering. Think about time. If you knew that 21 minutes per day could lower your risk of dying by 50%… You lower the death rate by 50% just by being physically active 21 minutes per day.

DAN LIEBERMAN: You don’t have to run a marathon. You don’t have work out like a madman at the gym. You don’t have to do crazy amounts of stuff. You can just do a moderate amount of physical activity and see enormous benefits. I think that’s also empowering.

DAN LIEBERMAN: The final thing is that, if you hate being on a treadmill, you’re normal. We need to help people find ways to make physical activity necessary and rewarding. To me, I think the solution is to make it social. There are tons of ways that we could, as communities, help each other promote social forms of physical activity — like dancing.

DAN LIEBERMAN: One of the places where I work is in Chihuahua. In the city of Chihuahua, on many evenings, in front of the church, people dance. There are little groups that come, and somebody plays some music. Anybody who wants to can dance. It’s delightful. It’s charming. Why don’t we do that?

DAN LIEBERMAN: How much would it cost to have a little oom-pah, jazz or rock band in various town squares so people can dance? Everybody loves dancing.

CHARLES MIZRAHI: I think one thing I do — when you say turn off the switch — is that any time I have to go less than a mile from my house, I always think: “Why am I taking the car?”

CHARLES MIZRAHI: I know I walk pretty quickly, so it’ll take me around 14 to 15 minutes to walk there at my pace. If I take the car, then I get aggravated because there’s no parking in Brooklyn. It’s not worth it. I’m cognizant, and I really try to stop myself. But, as you say, your brain just says, “If you jump in the car, it’ll much easier.” It’s that fight.

CHARLES MIZRAHI: My question to you is — and you’ve been studying this for so many years and seen these people — how do we show [Americans] that, in their daily lives, all you need is X or to do X. Garden, dance or walk to the corner store. How do we get them to think that way when marketing has been so brilliant? “If you work out on this machine for 10 minutes per day, you’ll have a body like this.” Or, do this or that…

DAN LIEBERMAN: I’m not sure I have a magic wand and know exactly what that magic wand is because it’s going to be really challenging. I think there are several things.

DAN LIEBERMAN: The first is: I would focus more on schools and kids. We are really doing a terrible job with physical education in schools. It’s not just in elementary, middle and high school. It’s also in college. There are a lot of studies that show that the habits you develop when you’re young [stay with] you as you age. College seems to be really important for that.

DAN LIEBERMAN: It used to be that 100% of universities and colleges in America required physical education of some sort. Starting in the 1960s and 70s, that diminished. Now, very few schools have physical education requirements, and they’re kind of pitiful. But those are important years for helping develop lifelong habits. I think the first place to start is with our kids.

CHARLES MIZRAHI: I just want to interrupt you for a second. When I was a kid, and the class was bad, our punishment was that we weren’t allowed to go outside for recess. Here you have kids that you just want to get some fresh air… And we’re talking about movement and doing things.

CHARLES MIZRAHI: We had to sit in a classroom for 3.5 hours or so, [have] lunch and then sit in class for another 3.5 hours. How were we supposed to be moving? Forget about gym. Gym was only twice a week. It wasn’t daily. We had to sit straight. And I was always a kid who fidgeted around. I used to get sent to the principal’s office because I wasn’t sitting still.

DAN LIEBERMAN: This is the problem, right? And it’s something that we can and should address. It’s not like we don’t know what we need to know to solve this.

DAN LIEBERMAN: There have been plenty of studies in which school administrators worry that if [students] have more recess and playtime, they will learn less. Actually, that’s been disproven. We know that that’s actually not true because you get back better concentration, memory and mood. It’s not a trade-off in the slightest.

DAN LIEBERMAN: So, that’s one thing. It’s a no-brainer, right? But it’s going to have to take concerted social action. It’s a political issue. It’s a parent issue. I think parents have to rise up against school committees and boards and demand what’s sensible and normal. I think most people understand that. I don’t think it’s a big lift. Everybody and their grandmothers know that. This is not contrary to common sense.

DAN LIEBERMAN: I think the larger issue for older folks — for the rest of us middle-aged and older folks — is much more challenging. I think it’s going to require us taking a broader view of physical activity. Again, we tend to think of physical activity as an optional kind of chore-like… [It’s] like taking cod liver oil. It’s no fun! And the various ways we have to promote physical activity aren’t very enjoyable for most people. Some are — like Zumba classes. It’s amazing. I know friends who, during this pandemic, are now exercising with each other on Zoom — which is so cool!

DAN LIEBERMAN: That’s wonderful, right? They’re looking at each other across time and space and doing jumping jacks. And that’s great. We need to come up with more ways to do that and just make it fun. I don’t know if a big government program will succeed, but there’s certainly going to have to be a social shift in terms of getting the word out and encouraging it. Maybe this is where a small amount of money and public service announcements… I’m not sure. That’s not my job. I’m an evolutionary biologist, not a psychologist.

CHARLES MIZRAHI: You find the problem and leave it to others to figure out how to make it work.

DAN LIEBERMAN: I would love to figure it out. But unfortunately, that’s not a skillset I have. It’s a psychological issue. We need to get people involved whose job it is to help change behaviors. I think we need to get them thinking like anthropologists. If you think only about what Americans do, you’ll miss a large portion of the picture. I think we need to take a broader view.

DAN LIEBERMAN: It’s funny, but when I say, “Exercise is abnormal,” people in the exercise world look at me like I’m from Mars. They’re like, “What are you talking about?” I explain it, and they’re like, “Oh, yeah!” We haven’t gotten this first basic insight down. Once we get that, we can use it to do a lot of other things.

CHARLES MIZRAHI: What is the minimum amount of physical activity that one would need living in America today? How would they get that?

DAN LIEBERMAN: We like to prescribe a dose. Everyone wants to know how much to take — how many pills and whatever. So, we want to know how much exercise to do.

DAN LIEBERMAN: If you look at the data, the important thing to recognize is there is no one dose. Anything more than none is good. And it’s true! If you only exercise an hour a week… It doesn’t have to be super vigorous — just moderate exercise. You can lower your relative rate of dying by about 40%. Double that to 250 minutes per week, and you can go further down. The curve eventually flattens out.

DAN LIEBERMAN: So, you don’t need to run marathons to get health benefits from physical activity. If you’re struggling to exercise, whatever you do is good. You don’t need to do a ton. That’s the first thing.

DAN LIEBERMAN: Secondly, the more we learn about physical activity, the more we realize that cardio is still the base. You want to get your heart rate up and get blood pumping around your body. That’s good for hypertension, Alzheimer’s, heart disease and all kinds of other things.

DAN LIEBERMAN: But it’s also important to mix it up, occasionally. You’ll want to do some strength training — lift stuff and carry things. Sometimes it’s really good to really pump it up and do something vigorous. If you’re frail, make sure to see a doctor beforehand. Mixing it up is kind of obvious.

DAN LIEBERMAN: The bedrock is walking. We evolved to walk. You walk your dog every day for several miles… That’s fundamental. That’s basic. The average hunter-gatherer walks six to nine miles per year. That’s like [walking] from L.A. to New York City every year.

CHARLES MIZRAHI: That’s six to nine miles a day?

DAN LIEBERMAN: Per day. Everyday.

CHARLES MIZRAHI: So, over a year, that becomes…

DAN LIEBERMAN: You cross the country.

DAN LIEBERMAN: You think walking from L.A. to D.C. [means going] an insane distance, but that’s actually what we’re built for. If you walk five miles per day, that’s basically what you’re doing. Again, the little bits add up over 365 days. That’s a lot.

DAN LIEBERMAN: We can just walk a lot, climb the stairs or lift stuff. If you can go to the gym, that’s great. Or, do push-ups! I do push-ups every morning when my coffee is in the French press. It [takes] four minutes. I do push-ups while the coffee is sitting there. I’ve developed a habit. So, if I don’t do that, there’s something wrong with the coffee.

DAN LIEBERMAN: But that’s it! It doesn’t have to be very complicated. A little bit will go a long way. Mix it up! Have fun! If it’s not fun, you won’t do it. So, make it fun. Find out what you enjoy. [Whether] that’s walking with a friend, dancing, watching a movie on a treadmill or whatever it is…

CHARLES MIZRAHI: Just get moving.

DAN LIEBERMAN: Find a way that’s fun.

DAN LIEBERMAN: Also, I think we should treat exercise like education. Education is also abnormal. Nobody went to school in the Paleolithic. Nobody learned to read in the Paleolithic. Nobody learned algebra, fractions or any of that kind of stuff.

DAN LIEBERMAN: How do we make education work? We make it necessary and fun. You have to go to school. It’s required. But we also make school fun — usually. Not always, but usually, right? You see your friends. There’s music, art and whatever.

DAN LIEBERMAN: I think we should treat exercise in just the same way — make it necessary and fun. And there are lots of ways to do that.

CHARLES MIZRAHI: Before I let you go, Dan, in these cultures that you’ve observed, the activity they’re doing is in a social context, right? They’re usually doing it in communities — hunting and running together.

DAN LIEBERMAN: Absolutely. When people go hunting, they often go together. They gossip. They talk about what’s going on back at camp and who’s doing what to whom. They dance and work together.

DAN LIEBERMAN: I’ve gone out while the Hadza women are digging tubers, and they’ll gossip for hours! Or, the guys in the field, in Kenya, talk to each other while hoeing and plowing. It’s social. We’re social creatures. It’s not coincidental.

DAN LIEBERMAN: When I exercise, I often exercise with friends because it’s fun. Otherwise, I wouldn’t do it!

CHARLES MIZRAHI: Right. Beautiful. Dan Lieberman. The book is: Exercised. Fantastic. I love it. You’ve made me feel so much better. I have a different relationship now. After I read your book, I looked at my rower and didn’t feel so guilty.

CHARLES MIZRAHI: I say, “I’m basically programed to hate you,” and I live with that. I always try to find reasons to move.

CHARLES MIZRAHI: The book is really great. You’ve done a tremendous, tremendous service. I think the biggest thing is you’ve taken [away] a lot of stress. For those who read your book, a lot of the stress that one puts on oneself from not exercising… You’ve basically shown that’s ridiculous. I just think about the detriment, stress levels, anxiety, procrastination and work. You have to work to avoid using that machine. It is energy wasted.

DAN LIEBERMAN: Yeah, it’s counterproductive. That’s why I entitled the book: Exercised. I think we’re exercised about exercise. So, let’s all be more compassionate.

CHARLES MIZRAHI: I love it. Dan, thank you so much for being on the show. I greatly appreciate it.

DAN LIEBERMAN: My pleasure. Thanks for asking me!

CHARLES MIZRAHI: Thanks for listening to this episode of The Charles Mizrahi Show. If you’re a new listener, welcome! If you’ve been listening for a while, we’re glad to have you back. Either way, we’d love to know what you think of the show. Please leave a review if you listen on Apple Podcasts. Reviews make it easier for others to find the show. You can also see a video of the interview on The Charles Mizrahi Show channel on YouTube.

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