exercise

For most of human history, people didn’t have to worry about burning too few calories. They had to worry about burning too many and dying from exhaustion or starvation.

In fact, exercise — as we now define it — was sometimes a punishment. “For more than a century, English convicts (among them Oscar Wilde) were condemned to trudge for hours a day on enormous and steplike treadmills,” Daniel Lieberman, an evolutionary biologist at Harvard, writes in his new book, “Exercised,” which is well-timed for new year’s resolutions.

As Lieberman explains, exercising for the sake of doing so is unnatural, from an evolutionary perspective. But the sedentary nature of modern life forces many people to choose between unhealthy habits and unnatural ones.

As Lieberman takes readers through the history and anthropology of physical exertion, he also encourages people not to be too hard on themselves. You don’t actually need a standing desk, for example. You just need to avoid sitting still for extended periods. “Take a break. Get up. Or at least ‘squirm shamelessly,’” John Hawks, a University of Wisconsin anthropologist, writes, in his Wall Street Journal review of “Exercised.”

“What works?” Jen Miller, The Times’s running columnist, writes in her review. “It’s not especially complicated, and Lieberman outlines the science behind his prescription of a mix of moderate-intensity aerobic exercise, strength training and high-intensity interval training.”

Related: The Times’s Tara Parker-Pope makes the case for short bursts of physical activity she describes as “exercise snacks.”