DANIEL LIBERMAN: Treadmills are really weird. They’re a weird, modern piece of equipment that we spend a lot of money on, and we spend a lot of money to go to a gym, which makes you work really hard to stay in the same place. It is the apotheosis of exercise. Think of it a treadmill, right? We think treadmills are synonymous with exercise, but it’s a noisy and expensive machine that makes you work very, very hard for no purpose other than to keep you moving and getting nowhere. Most of us, if we’re forced to be on a treadmill, listen to a podcast or some music, watch something on our iPhones or whatever to make it tolerable. My name is Dan Lieberman. I’m a Professor of Human Evolutionary Biology at Harvard University, and I’m the author of “Exercised,” Why Something We Never Evolve To Is Healthy And Rewarding.
The first treadmills were probably invented by the Romans or even other ancient people to move wheels and the like. But the true genesis of the modern treadmill comes from Victorian prisons. They were invented by a man named William Cubitt sometime in the 19th century to keep prisoners in England, such as debtors’ prisons, from relaxing and enjoying themselves. So they made the prisoners trudge for hours a day on these big slat-like treadmills to make it unpleasant for them to be in jail. And of course, now, people still trudge on treadmills, except they do it of their own free will, but many of them still feel like it’s some kind of form of torture. I don’t know anyone who really enjoys being on a treadmill.
OLD TV SEGMENT: ‘It’s easy to work your way up to shapely hips and thighs.’
LIEBERMAN: Many modern forms of exercise are like cod liver oil: not really enjoyable.
OLD TV SEGMENT: ‘Extra sun for us in winter and spring.’
LIEBERMAN: We make them because they’re good for us.
OLD TV SEGMENT: Come on, come on, come on!
LIEBERMAN: But it’s not fun.
OLD TV SEGMENT: Make your muscles cry.
LIEBERMAN: And then it’s like taking your medicine. It is important to make a distinction between physical activity and exercise, so physical activity is just movement. You do anything: go shopping, pick up your groceries and take them to your car, that’s physical activity. When you sweep the kitchen floor, that’s physical activity. But exercise is a discretionary and voluntary physical activity for the sake of health and fitness.
The word exercise comes from the Latin ‘exercitatio’ and meant “to train”. We still do math exercises. When you were plowing a field, for example, that would be considered exercise in an early English sort of way. Or the soldiers do exercises to get in shape. On the other hand, it also means to be exercised, to be upset, to be confused, to be anxious, to be somewhat worried. You know, we work out with our math homework. In the modern world, many people are confused about exercise. They find it hard to do, they’re not quite sure how much to do, there are all kinds of myths surrounding it.
OLD TV SEGMENT: “The burn is a sign that your muscles are working harder than they should.”
LIEBERMAN: Most people don’t do it because they want to, they do it because it helps prevent death and decay. By shining the light of evolution and using a kind of anthropological perspective, my goal is really to help people be less concerned about exercise.
OLD TV SEGMENT: ‘Right, left, right, left. Walking is one of the best exercises for people of all ages.’
LIEBERMAN: If there’s any physical activity humans evolved for, it’s walking. Walking is the way humans move, get food. It’s fundamental to who we are as a species. Today, in the modern western world, with cars, escalators, elevators, Zoom, TV, and all that sort of stuff, we just don’t walk much. You know, the average hunter-gatherer will take between 10 and 15,000 steps a day. The average American, before the pandemic, was taking something like 4,700-something steps a day. So much less than our ancestors.
One of the ways we medicalize exercise in the Western world is that we think there’s a certain amount you have to do, right? We prescribe it. “You must take two aspirin, you must sleep eight hours, and you must walk 10,000 steps a day.” We like that, right? There’s nothing necessarily wrong with a goal, right? Goals can be really helpful, actually. But 10,000 steps is somewhat arbitrary. The number actually comes from when the first pedometer was invented in Japan before the 1960 Olympics. In the boardroom, they were trying to decide what to call it. It turns out that 10,000 is a very auspicious number in Japan, and they thought that sounded good, seemed kind of reasonable, so they called it a 10,000-step monitor, and that stuck with them. Surprisingly, it turns out that 10,000 steps isn’t actually a bad goal. If we look at what people in non-Western societies do, 10,000 steps isn’t that far off. So it’s a perfectly reasonable goal to aim for, but nothing special about it. If you do 8000 steps, that’s fine; if you do 15,000 steps, that’s fine. The important thing is to be physically active because some is better than nothing, and a little more tends to be better than that. But you know, everything is fine. There is no magic number. It’s not a U-shaped curve with a bottom on it, right, where it tells you where to aim. That does not exist.
I mean, all cultures get involved in sports, right? He is a human universal. Sports are important. They are used for all kinds of functions. There are many wonderful things about being on a team and, especially as a child, you learn good sportsmanship. If someone scores a goal for you, it’s not appropriate to punch them in the face, that kind of thing. You learn hierarchies, you learn camaraderie, you learn to cooperate. But some sports also have another origin. It’s no coincidence that many of the sports, for example, in the ancient Olympics, especially, were skills that were really important for warriors. You know, javelin throwing and chariot racing. Well, we don’t do car races anymore. Sprint, wrestling, boxing, right? These are all very physically demanding sports that are related to combat. Sports, I think, also evolved to help us learn not to be ‘reactively aggressive’, sort of an instant type of unplanned aggression. I mean, the extreme for me is tennis.
ANGRY TENNIS PLAYER: ‘You can’t be serious!’
LIEBERMAN: You’re not even allowed to swear when you play tennis.
ANGRY TENNIS PLAYER: ‘They’re not going to take a point away from us because this guy is an incompetent fool. You know it? That’s what he is.
LIEBERMAN: Road Rage is a perfect example of reactive aggression.
MIDNIGHT COWBOY MOVIE LINE: ‘I’m walking here, I’m walking here. Up yours, nutcase!
LIEBERMAN: But there is also ‘proactive aggression’, when you plan something, you premeditate it, you resolve it beforehand. War is an example of proactive aggression. Sports are also kind of proactive aggressions at times. It’s perfectly acceptable to be appropriately proactively aggressive, as long as you’re within the rules. And that’s what humans excel at. We are better than most species at stopping reactive aggression, though not as often, but we are capable of extraordinary proactive aggression. You know, every once in a while there’s a mass shooting and there’s kind of a standard reaction. Everyone says, “Oh my gosh, how could this person do this? I go to church with him and whatever. He’s a good person, etc.” But we are confusing reactive aggression with proactive aggression. Hitler was a vegetarian, but of course one of the most proactively aggressive human beings that ever lived.
We must not confuse these two different types of aggression. Our bodies were not designed, they were not engineered, they are not machines, they evolved. So if you want to understand why our brains work the way they do, why our feet work the way they do, why we run, why our immune systems work the way they do, the only explanation for those kinds of questions are an evolutionary matter. Question. There’s an old expression: “Nothing in biology makes sense except in the light of evolution.” I would say that nothing about human behavior makes sense except in the light of culture and anthropology, and we also need to understand the cultural component of our behaviors.
