It's no wonder these pups are man's best friends!
Greenlandic sled dogs, also known as Qimmit, play while resting. Markus Trienke via Wikimedia Commons under CC-BY-SA-2.0 Man’s best friend has been our faithful companion for thousands of years.
The role for which a dog was bred—say retrieving birds—is reflected in their brain structure, according to a study of 33 breeds.