Dog breeding has led to a wide variation in the sizes and shapes of the many dog breeds we see today, from the tiniest Chihuahua to the biggest Great Dane, but what about your dog’s coat?

A new study of canine genetics reveals that nature, not human intervention, created the main dog coat colors and patterns in our four-legged friends.

Researchers studied a gene called ASIP (agouti signaling protein), which controls the distribution of yellow and black pigments in mammals, including dogs.

In dogs, ASIP is responsible for the familiar markings of such breeds as the Collie, German Shepherd, and Newfoundland.  It controls five color patterns:  dominant yellow, shaded yellow, agouti, black saddle, and black back.

The researchers found that when it comes to modern dogs, the history of this gene not only predates human intervention, but it also predates our dogs’ wolf ancestors.

Analysis shows that modern canine coat patterns originated from an extinct canid species that diverged from the grey wolf more than two million years ago.

The researchers also believe that genetic selection for lighter coat color came about during the Pleistocene era, in canids that lived in cold, high-altitude environments.

A similar lightening in coat color is also seen in other mammals like polar bears and arctic hares and foxes.  A lighter coat color in a snowy environment can be an advantage for both predators and prey.

You can read the full text of the article describing this fascinating study HERE.