As an isolated island, Isle Royale initially had neither wolves nor moose. The moose are believed to have either swum across Lake Superior from Minnesota in the early 1900s or were stocked on the island by man for the purpose of recreational hunting. In 1949 a few wolves, possibly only a single pair, crossed an ice bridge from Ontario to the island during a harsh winter. But because only one pair of wolves migrated to the island, they have suffered from severe inbreeding. According to Rolf Peterson, a professor at Michigan Technological University and the lead wolf-moose researcher, "Moose were isolated here 100 years ago. Most of the genes are still here, but they have enough population (to compensate). There are so few wolves that they have lost genetic variability. The scientific dogma suggests that they are not going to make it." In fact, all of the wolves' DNA on Isle Royale can be traced back to one ancestor. Inbreeding leads to inbreeding depression and fitness problems, often accompanied by violent social rejection by other wolves.