Dog
Dogs are the domesticated descendant of an ancient, now exstinct, species of Wolf. Dogs are characterized within the Canis family by an upturning tail. The dog is believed to be the first species domesticated by humans, approximately 15,000 years ago.
Due to their long association with humans, dogs' behaviour has become uniquely adapted to humans, and they have even gained the ability to thrive on a starch-rich diet that would be inadequate for other canids. In addition, humans have selectively bred dogs for various behaviours and physical attributes, resulting in a high degree of variation between the many breeds.