The dog (Canis lupus familiaris) is a domesticated subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. The term encompasses both feral and pet varieties and is also sometimes used to describe wild canids of other subspecies or species. The domestic dog has been (and continues to be) one of the most widely-kept working and companion animals in human history, as well as being a food source in some cultures. There are estimated to be 400 million dogs in the world.
The dog has developed into hundreds of varied breeds. Height measured to the withers ranges from a few inches in the Chihuahua to a few feet in the Great Dane; color varies from white through grays(usually called blue) to black, and browns from light (tan) to dark ("red" or "chocolate") in a wide variation of patterns; and, coats can be very short to many centimeters long, from coarse hair to something akin to wool, straight or curly, or smooth.Dog Origin and Evolution
Based on DNA evidence, the wolf ancestors of modern dogs diverged from other wolves about 100,000 years ago, and dogs were domesticated from those wolf ancestors about 15,000 years ago. This date would make dogs the first species to be domesticated by humans. Evidence suggests that dogs were first domesticated in East Asia possibly China and some of the peoples who entered North America took dogs with them from Asia.Ancestry and History of Dog Domestication
Molecular systematics indicate that the domestic dog (Canis lupus familiaris) descends from one or more populations of wild wolves (Canis lupis).
The relationship with humans and canines has deep roots. Converging archaeology and genetic evidence indicates a time of domestication between 17,000 and 14,000 years ago. Fossil bones and genetic analysis of current and ancient dogs and wolf populations have not yet been able to conclusively determine whether all dogs descended from a single domestication event or whether dogs where domesticated independently in more than one location.