The most widespread form of interspecies bounding occurs between humans and dogs, and the keeping of dogs as companions. Dog populations grew significantly after World War II. In the 1950s and 1960, dogs were kept outside acting as guard, children's playmate, or walking companion.
Characteristics
The frequency range of dog hearing is approximately 40 Hz to 60,000 Hz, which means that dogs can detect sounds far beyond the upper limit of the human auditory spectrum. Dogs have ear mobility which allows them to rapidly pinpoint the exact location of the sound. Dogs can smell odors at concentrations nearly 100 million times lower than humans can.
The coats of domestic dogs are of two varieties, "double" being common with dogs originating from cold climates, made up of coarse guard hair and soft down hair, or "single" with the topcoat only.
