Harvard Biology Prof: Humans were never meant to exercise


I love to be flattered, especially when the compliment is both unexpected and enabling. And Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding, a new book from Daniel Lieberman, a human evolutionary biology professor at Harvard University, is 440 pages of assuring affirmations about our impulses to laze around. It turns out, our desire to drape ourselves over a soft surface is an incredibly evolved, very wise, strategic behavior.

This is because, as Lieberman writes, “all animals should be as lazy as possible.” Until very recently, from an evolutionary standpoint, energy was hard won for most people. And there were constant, necessary ways that the energy needed to be spent: building a fire, finding your food. So if humans struggle with not wanting to do any physical activity at all, it’s because we’ve evolved to avoid it. It’s the most normal thing to avoid exertion that isn’t absolutely required of us, Lieberman reassuringly argues. Normal, ingrained, clever, practical.

But, as Lieberman notes, he’s currently studying a population of humans with a big surplus of energy to expend. A sedentary day has become not only possible, but unavoidable. We’ve accidentally created a great contradiction regarding our bodily needs: We don’t need to move a great distance to fetch water for our survival, yet we do need to move our bodies or else we will atrophy and worse.

So people had to invent exercise, even though it’s very weird to do. In certain corners of the world, modern humans now regularly hand over their wealth for someone to tell them to run or carry a heavy burden. As Lieberman puts it: “Exercise — despite its manifold benefits — requires overriding deep, natural instincts.” Now that we no longer need to lift a great weight over our heads or swim to shore to ensure our survival, we have to pretend we needto lift great weights and swim to shore. We move as if these efforts will ensure our immediate survival, which they won’t, but in a larger way, they will. Exercise is an absurd delusion, but nonetheless, it is an essential one.

Exercised is full of quirky facts on the history of working out, which I’m sure I’ll retain in some inane perversion for future repetition. On some road trip, I can see myself trying to tell a friend about the terrifying effect of total inactivity on the body, which Lieberman describes by using NASA as an example: “Astronauts in the gravity-free environment of space can lose 20 percent of their muscle mass in just a week or two.” Also fascinating is Lieberman’s description of the regular fidgeter: He cites a study that found that the most wriggly people have a 30 percent lower rate of all-cause mortality, even after adjusted for other forms of physical activity, diet, and other factors. Our chairs might be our body’s enemy, but just shifting around, standing up, and squirming are our best defenses against them.

The book also gives us so many things to blame for why moving sucks (our stubby bipedal legs! commodification of an inherently free activity of moving our bodies!). Taking a longview perhaps unique to a paleoanthropologist, Lieberman affirms over and over that humans are extremely wise to avoid unnecessary expenditures of their precious energy. It’s judicious for humans to be lazy. It’s affirming, relieving, and soothing for an acclaimed scientist to tell us: Your gravitational pull to inaction, it is logical, it is protective, it is wise.

But the magic is that humans are also illogical at times. Following the precepts of an evolutionist: We’ve “evolved” not to do a lot of things — unless! As Lieberman writes, human history is filled with exceptions to his argument that we are evolved for protective inertia. There are countless instances of us moving around when we didn’t need to: for social reasons, for fun, for war games, for rituals, for showing off. Lieberman writes about cultural traditions of running as a spiritual, social practice and dancing: “A cultural universal even more popular than running, and it may be nearly as ancient and important to being human.” It’s true that we’ve always moved around unnecessarily and perhaps loved doing it.

But Lieberman removes these examples from history. Because they are social, fun, spiritual, playful, they don’t fit into his definition of exercise. To argue that exercise is uniquely human, Lieberman separates it from the phenomenon of “play,” which is something all sorts of animals do.

“My opinion is that while many animals are driven by deep instincts to move, sometimes causing pleasure, exercise as we define it — discretionary, planned physical activity for the sake of physical improvement — is a uniquely human behavior.” But our animal desire for play and random joy is readily visible in our fitness practices. It propels us to jump and dance and scurry up mountains. In his passages about the problem of “fun” in exercise, Lieberman concludes that exercise is never really fun, it’s just the camaraderie or the music or the feeling after that is fun. But it can actually be fun! There are a million ways to wiggle. We’ve invented so many ways to move because we are creative and weird and easily bored and playful. If exercise is different from play, I want no part of it; but actually, there’s no reason why it needs to be so. Our instinct for play — that it feels amazing to mess around and move around — is one of our greatest assets. It may not have been smart, at one point in human history, to be so frivolous with our energy, but now our most illogical impulses will be the ones that save us.