Animals, too, varied in their usefulness. Zebras were too ornery to be tamed. Lions and tigers were too dangerous and not particularly tasty. But herd animals such as goats, cattle, and horses were easier to control, particularly if humans could stand in for the leader of the herd. If the animals were grass-eaters, they could turn grass into meat, milk, fibers, and power, enabling humans to exploit the world’s vast grasslands. And their meat was usually tasty and nutritious.
