Owning pets solely for companionship began with the start of cities, and also affluence. When people lived in homes with little to no land, domesticated animals did not have vital work tasks to perform, and were kept for companionship. The peasant class could not afford to feed and maintain animals that did not “pull their weight” and provide a monetary return. Inevitably there has, and still are countless situations where loved house pets still perform work duties. In ancient times and the middle ages, cats were kept to dispose of rats, and people today have dogs to alert owners to intruders. But the significant shift between the two uses of domesticated animals can be pointed to the rise of population density, and affluence.