Molecular systematics indicate that the domestic dog is descended from a wolf-like ancestor. As reflected in the nomenclature, dogs are a subspecies of wolf and are thus still able to interbreed.

The relationship between man and canine is a long-standing tradition. Wolf remains have been found in association with hominid remains dating from 400,000 years ago. Dogs were, and are, valued for their aid in hunting. Dog burials at the Mesolithic cemetery of Svaerdborg in Denmark indicate that in ancient Europe dogs were valued companions. The molecular genetic data suggests that the domestic lineage separated from modern wolves around 150,000 years ago (Vilà et al, 1997). Conservative estimates propose that the domestication of the dog probably occurred at least 14,000 years ago. There is archaeological evidence of dog remains that are morphologically different from wolves from that time frame. However, in the early 2000s some research indicated that domestication in fact had already begun to occur as early as 100,000 years ago.