Description

The domestic dog (Canis lupus familiaris), isa subspecies of the gray wolf (Canis lupus), a member of theCanidae family of the mammalian order Carnivora. The term "domesticdog" is generally used for both domesticated and feral varieties.The dog may have been the first animal to be domesticated, and hasbeen the most widely kept working, hunting, and pet in humanhistory. The word "dog" may also mean the male of a canine species,as opposed to the word "bitch" for the female of the species.

The present lineage of dogs was domesticated from gray wolves about15,000 years ago. Though remains of domesticated dogs have beenfound in Siberia and Belgium from about 33,000 years ago, none ofthose lineages seem to have survived the Last Glacial Maximum.Although mDNA testing suggests an evolutionary split between dogsand wolves around 100,000 years ago, no specimens prior to 33,000years ago are clearly morphologically domesticated dog.

Dogs' value to early human hunter-gatherers led to them quicklybecoming ubiquitous across world cultures. Dogs perform many rolesfor people, such as hunting, herding, pulling loads, protection,assisting police and military, companionship, and, more recently,aiding handicapped individuals. This impact on human society hasgiven them the nickname "Man's Best Friend" in the Western world.In some cultures, dogs are also a source of meat.In 2001, therewere estimated to be 400 million dogs in the world.

Most breeds of dogs are at most a few hundred years old, havingbeen artificially selected for particular morphologies andbehaviors by people for specific functional roles. Through thisselective breeding, the dog has developed into hundreds of variedbreeds, and shows more behavioral and morphological variation thanany other land mammal. For example, height measured to the withersranges from 6 inches (150 mm) in the Chihuahua to about 2.5 feet(0.76 m) in the Irish Wolfhound; color varies from white throughgrays (usually called "blue") to black, and browns from light (tan)to dark ("red" or "chocolate") in a wide variation of patterns;coats can be short or long, coarse-haired to wool-like, straight,curly, or smooth. It is common for most breeds to shed thiscoat.