My oldest son, now 18 years old, has a serious genetic disorder; From an early age, he was cared for by a team of clinicians at Columbia University Medical Center in Manhattan. His geneticist, one of the most formidable intellectuals I have ever encountered, worked on the Human Genome Project in the 1990s to sequence the LEP gene, which contains leptin, a hormone that helps inhibit hunger pangs. She longs to distill her research on a eureka pill for those of us who are prone to midnight fridge attacks, that extra slice of chocolate cake – a holy grail of treatments. Eventually, however, she and her colleagues shot too short. “It’s all about diet and exercise,” she once told me, “just like your mother begged you when you were a child.”
‘Exercise’, a comprehensive, powerful new work by Daniel Lieberman, Edwin M. Lerner II Professor of Biological Sciences at Harvard, explores how and why exercise is as good for us as we as a species have evolved as loafers to to save calories. for the lean seasons. Lieberman opens the book with a pun: the title refers not only to physical exertion in the pursuit of good health, but also to the adjective, ‘to be anxious, anxious, worried, afflicted’. As he knows, most of us feel at odds with exercise; the thought of 30 minutes on a NordicTrack elliptical or deadlift at the gym can raise our blood pressure.
But is there an evolutionary underpinning to our collective fear? Lieberman argues that even our ancestors were sluggish with a thin track. When we analyze a variety of cultures around the world or even our immediate family members, such as chimpanzees, we see a clear pattern: our species is proficient in spending much of our time just saving calories. Throughout the book, Lieberman refers to the Hadza, a nourishing people grouped in Tanzania; the general biology is not so different, despite the profound differences between the routines and those of us, between the diets and those of us. They put about the same prices in camp as those of us who work in the desk.
He considers the act of sitting down and whether it is as bad for us as smoking cigarettes (it is not)[HC1] [k2]. And he contemplates the commercialization of fitness. ‘The apotheosis of the good and bad of today’s exercise is for me the treadmill. Treadmills are incredibly useful, but they are also hard, expensive and sometimes treacherous. . . The only way I can endure the boredom and discomfort of a treadmill exercise is by listening to music or a podcast. What would my distant hunter-gatherers have thought about paying a lot of money to suffer through unnecessary physical activity on an annoying machine that brings us nowhere and accomplishes nothing? ‘
There is a dry, didactic characteristic of ‘practiced’; Lieberman is a scientific and leading author, but the book does not have the style spark of a Robert Sapolsky or David Eagleman. And yet Lieberman’s clarity never falters. Should I focus on cardio rather than dumbbells when moving the book to prescription sections? Are workouts in the gym still beneficial as we get older? – he readily admits that the data is more suggestive than certain. (As a runner, he tends to the heart as the preferred exercise.) He is particularly good at detecting myths and organizing chapters around making assumptions about fitness and health. Eight hours of sleep may not be the most effective way to rest. On the contrary, Charles Atlas, we have developed, as one title in a chapter describes it, ‘from brown to slender’, and we use more graceful forms over, for example, most Neanderthals. His answers to physiological questions: “Is it bad for your knees?” “Does my 90-year-old grandmother have to bankroll every week?” – get lost lazy platitudes.
They inspire too. He emphasizes his case on preventative care, which is often dismissed by Americans as a violation of their freedom to be bankers. ‘I’m aware that people like me often sound like broken records. . . . Please do not react this way to cancer, as the cancer-fighting potential of exercise is underestimated and ineffective. . . . Just as natural selection favors people who get as many calories as possible to reproduce and then spend, the choice that drives cancer favors malignant cells that get as many calories as possible and then use them to create more copies of themselves. He highlights the leading culprits – reproductive hormones, sugar, inflammation and antioxidants – and highlights why exercise can be our strongest weapon to ward off the emperor from all diseases.
To turn back to the point of the Columbia geneticist: If ‘practiced’ occasionally reads with the tone of your stern voice, swings her finger and begs you to eat your vegetables and jog around the block, that’s all well. Lieberman accomplished his mission. But the science among its arguments is revealing, with exciting implications for evolutionary biology. Written in fast-paced prose, with ample graphs, ‘Exercise’ is an excellent collection on the broad medical benefits of exercise and a roadmap from our pandemic for better health.
Hamilton Cain is the author of ‘This Boy’s Faith: Notes from a Southern Baptist Upbringing’ and a member of the National Book Critics Circle. He lives with his family in Brooklyn, NY
Exercise: Why something we never developed is healthy and rewarding
Daniel Lieberman
Pantheon, 464 pages, $ 29.95