Final answer:
A dog described with a double thick coat, square body, and independent nature is likely part of the Spitz breed group, which is known for such features and historically used for sled-pulling and herding.
Step-by-step explanation:
A dog with a double thick coat, a square body, and an independent nature is likely a descendant of the Spitz breed group. Spitz-type dogs are known for these physical characteristics and behaviors. Historically, they have been used in various roles, such as pulling sleds in cold climates and herding. The thick coat is particularly adapted to cold environments, providing insulation against harsh weather, and the square body shape often seen in these breeds contributes to their strength and endurance. Independence is a trait that has been encouraged in breeds that are expected to work with minimal supervision, such as in roles like sled-pulling or livestock guarding.