The domestic dog is a member of genus Canis that forms part of the wolf-like canids, and is the most widely abundant carnivore. The dog and the extant gray wolf are sister taxa, with modern wolves not closely related to the wolves that were first domesticated, the dog was the first domesticated species and has been selectively bred over millennia for various behaviors, sensory capabilities, and physical attributes. Their long association with humans has led dogs to be attuned to human behavior. Dogs vary widely in shape, size and colours, dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship and, more recently, aiding handicapped individuals. This influence on society has given them the sobriquet mans best friend. The term domestic dog is used for both domesticated and feral varieties. The English word dog comes from Middle English dogge, from Old English docga, the term may possibly derive from Proto-Germanic *dukkōn, represented in Old English finger-docce. The word also shows the familiar petname diminutive -ga also seen in frogga frog, picga pig, stagga stag, wicga beetle, worm, the term dog may ultimately derive from the earliest layer of Proto-Indo-European vocabulary. In 14th-century England, hound was the word for all domestic canines, and dog referred to a subtype of hound. It is believed this dog type was so common, it became the prototype of the category hound. By the 16th century, dog had become the general word, the word hound is ultimately derived from the Proto-Indo-European word *kwon-, dog. This semantic shift may be compared with in German, where the corresponding words Dogge, a male canine is referred to as a dog, while a female is called a bitch. The father of a litter is called the sire, and the mother is called the dam, the process of birth is whelping, from the Old English word hwelp, the modern English word whelp is an alternate term for puppy. A litter refers to the offspring at one birth which are called puppies or pups from the French poupée, doll. The term dog typically is applied both to the species as a whole, and any male member of the same. An adult female is a bitch, in some countries, especially in North America, dog is used instead due to the vulgar connotation of bitch. An adult male capable of reproduction is a stud, an adult female capable of reproduction is a brood bitch, or brood mother. Immature males or females are pups or puppies, a group of pups from the same gestation period is a litter
Image: Collage of Nine Dogs
Lateral view of skeleton.
"Five different types of dogs," c. 1547.
A mixed-breed terrier. Mixed-breed dogs have been found to run faster and live longer than their pure-bred parents (See heterosis)