Such a genetic impact is evidence for substantially greater fitness of Old Gray compared to the other inbred wolves on the island. Scientists expected that such an introduction would create a "genetic rescue" population boom, but it did not happen. "A co-author of the study, Rolf O. Peterson, a research professor at Michigan Technological University, said that the population of Isle Royale hangs on by a thread, as it has for decades. The average reproduction after the Old Gray Guy arrived was no different from before. Yet this does not mean that he had no effect."