Over the millennia admission of certain wolves into human camps and exclusion of larger, more threatening ones led to development of people-friendly breeds distinguishable from wolves by size, shape, coat, ears, and markings. Dogs were generally smaller than wolves, their snouts proportionally reduced. They would assist in the hunt, clean up camp by eating rubbish, warn of danger, keep humans warm, and even serve as food. By the fourth millennium b.c. Egyptian rock and pottery drawings show hounds hunting with men, driving game into nets. In ancient Greece, 350 years before Christ, Aristotle described three types of domesticated dogs, and Three hundred years later Roman warriors trained large dogs for battle. The brutes could knock an armed man from his horse and dismember him.