Which mammal has the longest lifespan?

Scientists used to think bowhead whales only lived for about 50 to 70 years, but the Alaskan Iñupiat Inuit have been saying for generations that bowhead whales "live two human lifetimes." They were proven right in 2007 when hunters in Alaska caught a 49-foot bowhead with a fragment of an explosive harpoon manufactured between 1879 and 1885. The whale had been swimming around with a Victorian-era weapon stuck in its body for over a century (and you complain when you sleep wrong for one night). That discovery pushed researchers to take a closer look, and they found one specimen that was at least 211 years old. That would make some of those bowhead whales older than "Moby-Dick," which was published in 1851! Their secret might be the cold Arctic waters they call home, combined with DNA repair proteins at levels 100 times higher than other mammals.