Cats began their relationship with humans with the Egyptians, who had rodents raiding their grain storage and ships. As efficient rat catchers that didn't require care, they went on to earn their keep for thousands of years. But at some point, humans decided that cats could come inside. There were mice in the house, after all, and furry cats made great footwarmers on a cold night. Cats became permanent fixtures in homes around the world and over time new breeds emerged or were purposely bred.