The dog is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from an ancient, extinct wolf, and the modern wolf is the dog's nearest living relative. The dog was the first species to be domesticated, by hunter-gatherers over 15,000 years ago, before the development of agriculture.
They perform many roles for humans, such as hunting, herding, pulling loads, protection, assisting police and the military, companionship, therapy, and aiding disabled people. Over the millennia, dogs became uniquely adapted to human behavior, and the human-canine bond has been a topic of frequent study. This influence on human society has given them the sobriquet of "man's best friend".
