Dog

The dog is a domesticated form of the Gray Wolf, a member of the Canidae family of the order Carnivore. The domestic dog has been one of the most widely kept working and companion animals in human history. The dog quickly became ubiquitous across culture in all parts of the world, and was extremely valuable to early human settlements. Dogs perform many roles for people, such as hunting, herding, protection, companionship, and, more recently, assisting handicapped individuals.

Over the 15,000 year span that the dog had been domesticated, it diverged into only a handful of land races, groups of similar animals whose morphology and behavior have been shaped by environmental factors and functional roles. As the modern understanding of genetics developed, humans began to intentionally breed dogs for a wide range of specific traits. Through this process, the dog has developed into hundreds of varied dog breeds, and shows more behavioral and morphological variation than any other land mammal. For example, height measured to the withers ranges from a few inches in the Chihuahua to a few feet in the Irish Wolfhound; color varies from white through grays to black, and browns from light to dark 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 this coat, but non-shedding breeds are also popular.