Dog, mammal generally considered to be the first domesticated animal. This trusted work partner and beloved pet learned to live with humans more than 14,000 years ago. A direct descendant of the wolves that once roamed Europe, Asia, and North America, the domestic dog belongs to the dog family, which includes wolves, coyotes, foxes, and jackals. Dog ancestry has been traced to small, civet-like mammals, called miacis, which had short legs and a long body and lived approximately 40 million years ago.
The evolving relationship between the domestic dog and humans has been documented in fossil evidence, artifacts, and records left by earlier civilizations. Prehistoric dog skeletal remains, excavated from sites in Denmark, England, Germany, Japan, and China, indicate the early coexistence of dogs with people. An ancient Persian cemetery, dating to the 5th century bc, contained thousands of dog skeletons. Their formal burial and the positioning of the dog remains reveal the esteem in which the ancient Persians held their dogs. The relationship shared by dogs and humans also is evident in cave drawings, early pottery, and Asian ivory carvings that depict dogs. A statue of Anubis, the half dog, half jackal Egyptian god, was discovered inside King Tutankhamen’s tomb, constructed in about 1330 bc.
Literary references to the dog include those found in the Bible and in the Greek classic the Odyssey by Homer. In 1576 an English physician and dog fancier, John Caius, wrote a detailed text on dog breeds, Of English Dogges. Dogs are featured in tapestries that were created in the Middle Ages (5th century to 15th century), and in the work of many artists, including 17th- and 18th-century European painters Peter Paul Rubens and Thomas Gainsborough.
Although it is not known how humans and dogs first learned to coexist, people soon discovered the many ways dogs could enrich their lives. Dogs have been used to hunt for food, herd animals, guard livestock and property, destroy rats and other vermin, pull carts and sleds, perform rescues, and apprehend lawbreakers. They have been used during wartime as sentinels and message carriers. Today trained dogs are used to alert deaf people to common household sounds, such as the ringing telephone or doorbell; guide the blind; or retrieve objects for quadriplegics. Perhaps the most common of the many roles served by the domestic dog, however, is that of companion. As animals with strong social tendencies, dogs typically crave close contact with their owners. And people tend to form loving bonds with dogs. This companionship often helps to ease the pain and isolation of the elderly or people whose physical or mental health requires long-term convalescence or institutionalization.