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Most studies agree that domestication was not a single discrete event. It was a process that unfolded over thousands of years—likely involving dog populations that appeared in different parts of Eurasia at different times, with dogs and wild wolves continuing to interbreed with one another and with early dog populations being replaced by later ones. Some genetic studies have documented evidence of early domestication events in specific regions. One study contends that wolves were domesticated 16,300 years ago to serve as livestock in , whereas another reports that early dogs dating from about 12,000 to 14,000 years ago came from a small strain of that inhabited . Genetic evidence also reveals that dogs did not accompany the first humans to the New World more than 15,000 years ago, suggesting instead that dogs came to the Americas only some 10,000 years ago. One study even suggested that some dogs have descended not from the but rather from the . These dogs, found in , might have given rise to some of the present native African breeds. No matter what their origins, all canids have certain common characteristics. They are mammals that live young. The females have mammary glands, and they suckle their offspring. The early breeds had erect ears and pointed or wedge-shaped muzzles, similar to the northern breeds common today. Most of the carnivores have similar dental structures, which is one way paleontologists have been able to identify them. They develop two sets of teeth, deciduous (“baby”) teeth and permanent teeth., dog, (Canis lupus familiaris), domestic mammal of the family Canidae (order Carnivora). It is a subspecies of the gray wolf (Canis lupus) and is related to foxes and jackals. The dog is one of the two most ubiquitous and most popular domestic animals in the world (the cat is the other)., Dog - Breeds, Behavior, Training: Dogs have distinctive breed-typical personalities developed through generations of selection for traits. In modern society most dogs are owned as pets, not for the work they were bred to do..

Dog - Companion, Hunting, Protection: Dogs have played an important role in human history and were among the first domesticated animals. They have served as hunting allies, bodyguards, herders and guardians of livestock, been employed as guides for the blind and disabled and for police work., Dog - Breeds, Temperament, History: There are about 400 breeds of purebred dogs worldwide. A purebred dog has a genealogy that can be traced for three generations within the same breed. Sporting dogs are hunting dogs that scent and either point, flush, or retrieve birds on land and in water., Each of a dog’s four legs ends in a foot, or paw, with five toes. Each toe has a soft pad and a claw. A coat of hair keeps the dog warm. It cools off by panting and hanging its tongue out of its mouth. Apart from these common features, dogs come in many different sizes, shapes, and colors., A dog is a domesticated mammal of the family Canidae and the order Carnivora. Its scientific name is Canis lupus familiaris. Dogs are a subspecies of the gray wolf, and they are also related to foxes and jackals. Dogs are one of the two most ubiquitous and most popular domestic animals in the world. (Cats are the other.), Dog - Reproduction, Heat Cycle, Breeding: The heat cycle of the female lasts from 18 to 21 days. The gestation period is usually 63 days, and most bitches whelp normally. Both males and females are fertile well into their advanced age. Dogs are social, territorial, pack animals. They have a repertoire of barks, growls, and howls; some can yodel., Bull Terrier, breed of dog developed in 19th-century England from the Bulldog, the White English Terrier (a breed now extinct), and the Dalmatian; other breeds including the Spanish pointer, foxhound, and Greyhound may also have been incorporated..

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