Scientists have come to believe that the dog was the first species to be domesticated by humans. 

Fossil remains of dogs dating back to the Mesolithic period, 12,000 years ago, have been found in Israel and Iraq.  In this country, canine fossils estimated to be 10,000 years old have been uncovered at an archaeological site called Jaguar Cavin in Idaho.

No one really knows why dogs were domesticated, but scientists have some ideas.  When domestication occurred, humans were gradually giving up their wandering, nomadic lifestyles and settling down into permanent communities.  Some scientsts thnk that wild dogs strated to spend time near these stettlements looking for food, and were at first tolerated  and finally accepted by humans.

Other people think htat humans deliberately tamed dogs to serve as guards or to help with hunting.  One of the most popular theories, though, is that people domesticated dogs simply because they liked them and wanted their companionship.  Their useful qualities, such as being good watch dogs, may have been discovered only after they had already become pets.