Dogs have been around a considerable while now, being in existence as far back as 10,000 B.C., according to Ian Zaczek in the book "Dog Facts, Figures & Fun." While nobody has yet determined their exact evolutionary process, one thing is for certain: dogs and man have a unique partnership that is nearly as old as civilization itself.
Dogs belong to the canidae family of living things -- the family that includes the jackal, the fox and the wolf. Some naturalists believe dogs to have descended directly from wolves, owing to the numerous similarities between the two species, including the shape of their skulls, the structure of their jaws and their pack mentality. Ludwig Rutimeyer, a Swiss naturalist, named the first domesticated dog canis familiaris palustris, or the Peat Dog.
The Romans were the first to formally classify dogs into categories such as sporting dogs, shepherd dogs, housedogs and war dogs. As of June 2011, the American Kennel Club officially recognizes more than 150 dog breeds, adding three new breeds in January 2011. The AKC divides dog breeds into seven groups, namely terriers, working, hound, sporting, toy, herding and nonsporting. Individual species within each breed vary in general characteristics and personalities. However, all dogs are identical anatomically.
Dogs have a highly specialized sense of smell and are renowned for their hearing. According to the Natural History Museum, dogs have 25 times more olfactory cells than humans and can detect odors a 100 million times lower than odors detected by humans. They can hear sounds between 16 Hz to 60,000 Hz, as compares to human beings who can detect sounds that range between 20 Hz and 20,000 Hz. Adult dogs have 42 permanent teeth while puppies typically have 28. Teeth include molars, premolars, canines and incisors.
Dogs are extremely territorial and the male species marks its territory by spraying strategic points with urine. They are social animals and exhibit pack mentality even in the homes, considering their human owners as an extension of their canine packs. Dogs dislike being left alone and can howl for hours when they feel abandoned.
Dogs have distinct personalities that the Canine Personality Profile, developed by Jack and Wendy Volhard, can accurately determine. Some are nervous, while others are sociable and aggressive. According to Immanuel Birmelin in the book "Know Your Dog," dogs exhibit a range of emotions including scorn, happiness, joy, curiosity, disappointment, hope and disgust.
According to B.A. Hoena in the book "Dogs ABC," at least 33.3 percent of all American dog owners leave messages on their answering machines for their dogs. The author claims most dogs to understand between 35 and 45 spoken words from their owners' vocabulary. Stanley Coren in the book "How to Speak Dog," claims it possible to teach a dog up to 140 words.
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