Exercised: The Science of Physical Activity, Rest and Health

by Daniel E. Lieberman

we never evolved to exercise. What do I mean by that? Well, exercise today is most commonly defined as voluntary physical activity undertaken for the sake of health and fitness. But as such it is a recent phenomenon. Our not-too-distant ancestors who were hunter-gatherers and farmers had to be physically active for hours each day to get enough food, and while they sometimes played or danced for fun or social reasons, no one ever ran or walked several miles just for health. Even the salubrious meaning of the word “exercise” is recent. Adapted from the Latin verb exerceo (to work, train, or practice), the English word “exercise” was first used in the Middle Ages to connote arduous labor like plowing a field.1 While the word has long been used to denote practicing or training to improve skills or health, to be “exercised” also means to be harassed, vexed, or worried about something.