Wolves come in gray, white and, in North America, black. Where did those unusual black coats originate? Scientists from Stanford University and elsewhere compared the DNA of wolves from the Canadian Arctic and Yellowstone National Park with the DNA of coyotes and dogs. The black coat gene, the researchers found, appears to have come from dogs. Some North American wolves likely interbred with domesticated dogs, now extinct, that accompanied people who crossed the Bering Strait from Asia more than 10,000 years ago.