The dog is a mammal in the categorize Carnivora. Dogs were domesticated from wolves as newly as 15,000 years ago, or perhaps as early as 100,000 years ago based upon recent genetic fossil and DNA evidence. Other research suggests that dogs have only been domesticated for a much shorter amount of time. New evidence suggests that dogs were first disciplined in East Asia, possibly China, and the first peoples to enter North America took dogs with them from Asia. Genetic research has recognized 14 ancient dog breeds, with the oldest being the Chow Chow, Shar Pei, Akita Inu, Shiba Inu and Basenji. Because numerous of the 14 breeds are associated with China and Japan, the theory that the dog originated in Asia seems to be likely. Over time, the dog has developed into hundreds of breeds with a huge degree of variation. For example, heights at the withers range from just a few inches (such as the Chihuahua) to approximately three feet (such as the Irish Wolfhound), and colors range from white to black, with reds, grays (usually called blue), and browns occurring in a marvelous variation of patterns.
Dogs, like humans, are highly social animals and this parallel in their overall behavioral pattern accounts for their trainability, playfulness, and aptitude to fit into human households and social situations. This similarity has earned dogs a sole position in the realm of interspecies relationships. The loyalty and devotion that dogs demonstrate as part of their usual instincts as pack animals closely mimics the human idea of love and friendship, leading many dog owners to view their pets as full-fledged family members. Conversely, dogs seem to observation their human companions as members of their pack, and make few, if any, distinctions between their owners and fellow dogs. Dogs fill a selection of roles in human society and are often trained as working dogs. For dogs that do not have traditional jobs, a wide range of dog sports provide the opportunity to exhibit their natural skills. In many countries, the most ordinary and perhaps most important role of dogs are as companions. Dogs have lived with and worked with humans in so many roles that their loyalty has earned them the unique sobriquet "man's best friend". Conversely, several cultures consider dogs to be unclean. In some parts of the world, dogs are raised as livestock to produce dog meat for human consumption. In many places, consumption of dog meat is disheartened by social convention or cultural taboo.
Among dog lovers, dogs are usually valued for their intelligence, and both anecdotal evidence and scientific study suggest that dogs have a reasonably high intelligence. This intelligence is expressed differently with dissimilar breeds and individuals, however. For example, Border Collies are noted for their aptitude to learn commands, while other breeds may not be so motivated towards compliance, but instead show their cleverness in devising ways to steal food or escape from a yard. Dogs are descended from wolves, and are also packing animals, making them easier than other animals to train because dogs' instincts are to obey. But most dogs rarely have to deal with complex tasks and are unlikely to learn relatively difficult activities (such as opening doors) unaided. Some dogs (such as guide dogs for the visually impaired) are particularly trained to recognize and avoid dangerous situations.
