Dog is a member of the genus Canis (Canidae), a wolf-like canid and the most widely distributed carnivore. Dogs and the extant gray wolves are sister taxa, and modern wolves are not closely related to the wolves that were originally domesticated. Dogs were the first species to be domesticated and have been selectively bred over thousands of years for various behaviors, sensory abilities, and physical traits.
Their long association with humans makes dogs uniquely adaptable to human behavior, allowing them to thrive on starch-rich foods that are not adequate for other canines. Dogs come in a wide variety of shapes, sizes, and colors. Dogs perform many roles for humans, such as hunting, herding, pulling, protection, assisting the police and military, companionship, and more recently, aiding the disabled. This impact on human society has earned them the nickname "man's best friend."
Over thousands of years, domestic dogs have been selectively bred for various behaviors, sensory abilities, and physical characteristics. Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal . Dogs are predators and scavengers, and like many other carnivorous mammals, dogs have powerful muscles, fused carpal bones, a cardiovascular system to support sprinting and endurance, and teeth for capturing and biting.
A dog’s senses include sight, hearing, smell, taste, touch and sensitivity to the Earth’s magnetic field. Another study showed that dogs can see the Earth's magnetic field.
