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The dog is a canine mammal of the Order Carnivora. Dogs were first domesticated from wolves at least 12,000 years ago[1] but perhaps as long as 150,000 years ago based on recent genetic fossil evidence and DNA evidence[2]. In this time, the dog has developed into hundreds of breeds with a great degree of variation. For example, heights at the withers range from just a few inches (such as the Chihuahua) to roughly 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 tremendous variation of patterns.Dogs, like humans, are highly social animals and pack hunters; this similarity in their overall behavioral pattern accounts for their trainability, playfulness, and ability to fit into human households and social situations. Dogs fill a variety 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 common and perhaps most important role of dogs is as companions. Dogs have lived with and worked with humans in so many roles that their loyalty has earned them the sobriquet "man's best friend." Conversely, some cultures consider dogs to be unclean. In other cultures, some dogs are used as food.更多内容：http://en.wikipedia.org/wiki/Dog需要设置代理访问145.97.39.136:80目录如下Contents [hide]1 Terminology 2 Physical characteristics 3 Intelligence 4 Diet 4.1 Treats 4.2 Dangerous substances 5 Reproduction 5.1 Fertility 5.2 Menarche 5.3 Pregnancy and litters 6 Spaying and neutering 7 Attributes 7.1 Sight 7.2 Hearing 7.3 Scenting 7.4 Direction and spatial sense 7.5 Weather detection 8 Dog health 8.1 Diseases 8.2 Parasites 8.3 Common physical disorders 9 Behavior 9.1 Interactions between Dogs and Humans 9.2 Dogs as working partners 9.3 Dogs as hunting and sporting partners 9.4 Dogs as pets 9.5 Attacks on humans and livestock 9.6 Abandoned dogs 10 Ancestry and history of domestication 10.1 Wolf ancestors 10.2 Speed of domestication 10.3 Dogs as food 11 Dog breeds 11.1 Neoteny in the rapid evolution of diverse dog breeds 12 See also 13 References and further reading 14 External links |
