Evolutionary biologists believe that gray wolves emerged about 800,000 years ago during the Pleistocene epoch. Modern European and North American wolves are believed to have descended from a subspecies that arose about 150,000 years ago.
The gray wolf is the ancestor of the domestic dog. It is also closely related to the eastern wolf, the red wolf, the coyote and the golden jackal and can produce fertile hybrids with any of these species. Gray wolves have the widest range of any canid species and are the only canids found in both the Old and New Worlds. They were exterminated from much of North America by the early 1960s but have been successfully reintroduced to the Great Lakes region and parts of Washington, Oregon, Idaho and Montana.