Humanity’s upright gait may have roots in trees

A new analysis of apes’ wrist bones suggests that a two-legged stride evolved from tree climbing, not ground-based knuckle-walking

Chimpanzees don’t knuckle under like gorillas, and that may explain how people ended up walking on two legs, a new study suggests.

WRIST SPLIT Gorillas’ wrist bones, shown at right, form a column, illustrated in center drawing, that supports a distinctive mode of knuckle-walking, a new study suggests.