Dogs were one of the earliest animals domesticated by humans starting around 9,000 BC to aid with hunting and protection. In ancient civilizations like Mesopotamia, Egypt, Greece, and Rome, common pets included dogs, cats, monkeys, and birds. Dogs and cats in particular were favored as they provided companionship and guarded homes. Exotic animals also became status symbols for wealthy rulers starting in the modern age, though farm animals lived alongside people in poorer households despite hygiene issues.