"Most mammals don't live long past their reproductive years, failing to serve much evolutionary purpose after they can stop passing on their genes to offspring. Only three long-lived social mammalian species are known break that mold. Killer whales (Orcinus orca), pilot whales (Globicephala macrorhynchus) and humans (as well as possibly some other great apes) all have females that generally live for decades after they cease being able to bear young. So what might we have in common with these cetaceans?" - Steven Perez from Bookmarklet