Fantastic! Springy legs, twiggy torsos, sweat glands, hairless skin, vertical bodies that retain less sun heat—no wonder we’re the world’s greatest marathoners. But so what? Natural selection is all about two things—eating and not getting eaten—and being able to run twenty miles ain’t worth a damn if the deer disappears in the first twenty seconds and a tiger can catch you in ten. What good is endurance on a battlefield built on speed?
