The domestication of animals has made a remarkable contribution to the evolution of human societies. Over the years animals have served as a means of transportation and communication, and a convenient source of food, but also as loyal and loving companions. Proof of our domestication of dogs dates back 100,000 years. Dogs as we know them today are the ancestors of wolves. For centuries, packs of wolves would follow bands of human nomads to feed off the animal carcasses the hunters left behind. The more sociable wolves were adopted and thus began their progressive genetic transformation.