with the exception of the Siberian husky, a more ancient dog breed that's closely related to the wolf. This muscle, which runs along the eye’s outer edge, exposes more of the white of the eye ...

The blue eye of a white Siberian husky dog, Canis lupus familiars. Photograph by David Liittschwager, Nat Geo Image Collection “With 6,000 people getting DNA samples from their dogs and mailing ...