Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding

by Daniel E. Lieberman

Among the many studies of the Hadza, one asked forty-six Hadza adults to wear lightweight heart rate monitors for several days.14 According to these sensors, the average adult Hadza spends a grand total of three hours and forty minutes a day doing light activities and two hours and fourteen minutes a day doing moderate or vigorous activities. Although these few hours of hustling and bustling per day make them about twelve times more active than the average American or European, by no stretch of the imagination could one characterize their workloads as backbreaking. On average, the women walk five miles a day and dig for several hours, whereas the men walk between seven and ten miles a day.15 And when they aren’t being very active, they typically rest or do light work.