Humans aside, dolphins, whales, and porpoises are often considered to be the smartest creatures on Earth. Science and nature buffs are drawn to stories of their use of tools, their self-recognition, their beautiful and complex songs, and their intricate societies. But how do we know what we know, and what does it mean? InDeep Thinkers, renowned cetacean biologist Janet Mann gathers a gam of the world’s leading whale and dolphin researchers—including Luke Rendell, Hal Whitehead, and many more—to illuminate these vital questions, exploring the astounding capacities of cetacean brains.Diving into our current understanding of and dynamic research on dolphin and whale cognition, communication, and culture,Deep Thinkersreveals how incredibly sophisticated these mammals are—and how much we can learn about other animal minds by studying cetacean behavior. Through a combination of fascinating text and more than 150 beautiful and informative illustrations, chapters compare the intelligence markers of cetaceans with those of birds, bats, and primates, asking how we might properly define intelligence in nonhumans. As all-encompassing and profound as the seas in which these deep cetacean cultures have evolved,Deep Thinkersis an awesome and inspiring journey into the fathoms—a reminder of what we gain through their close study, and of what we lose when the great minds of the sea disappear.