As dogs cross the finish line in the grueling 1,150-mile (1,850-kilometer) Iditarod this week, they’ll probably be feted with extra treats. But we owe sled dogs a really great tummy scratch, too, for their role in human history. Ancient dog bones uncovered in the Arctic are showing that humans have had a close and complex relationship with dogs for thousands of years, from eating them to burying them lovingly with ornaments—and, of course, using them to haul things around. (Discover 5 surprising facts about the Iditarod.)

"Dogs have been critical to human habitation in the Far North," says Robert Losey of the University of Alberta, who specializes in the archaeology of human-animal relationships. Losey has excavated canine