Today many scientists believe some whales and dolphins, like humans, have distinct cultures. Researchers see signs in sperm whales in the Galápagos and the Caribbean, in humpbacks across the South Pacific, in Arctic belugas, and in the Pacific Northwest’s killer whales. The possibility is prompting new thinking about how some marine species evolve. Cultural traditions may help drive genetic shifts, altering what it means to be a whale. But this idea is also reshaping our view of what separates us from these aquatic beasts. Whale culture, it seems, is rattling timeworn conceptions of ourselves.