Their long association with humans has led dogs to be uniquely attuned to human behavior, enabling an abundant cosmopolitan distribution and to be able to thrive on a starch-rich diet that would be inadequate for other canids.[from wikipedia]

The dog has been selectively bred over millennia for various behaviors, sensory capabilities and physical attributes.[from wikipedia]

This influence on human society has given them the sobriquet of "man's best friend."[from wikipedia]

Dogs are subclassified into breeds, which vary widely in shape, size and color.[from wikipedia]

The domestic dog's origin includes the dog's genetic divergence from the wolf, its domestication, and the emergence of the first dogs. Genetic studies show that all ancient and modern dogs share a common ancestry and descended from an ancient, extinct wolf population - or closely related wolf populations - which was distinct from the modern wolf lineage.[from wikipedia]