The Walking

Scientists tell us that, generally speaking, walking upright has had no lasting advantage among mammals (other than humans). It's too slow. Imagine strolling along and suddenly you had to outrun a lion.

Having two free hands has advantages in gathering food and holding a spear, but what made it work in the beginning was a social network. To survive in the wilderness, you needed a family, a tribe. With 20 spears you could hunt lions. To survive and prosper, you needed to be--like wolves--part of a cooperating family. Without cooperation, walking on two feet would have made you easy prey. We survived by cooperating.