Book excerpt: A remarkable look at dolphin and whale intelligence, communication, and culture, with stunning photographs: “A wonderful read.” —Biologist Dolphins, whales, and porpoises are often considered to be the smartest nonhuman 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? In Deep 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 Thinkers reveals 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 Thinkers is 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. “Everything you always wanted to know about cetaceans and their intelligence captured here in a single beautiful volume by some of the world’s greatest experts.” —Frans de Waal, New York Times–bestselling author of Are We Smart Enough to Know How Smart Animals Are? “Teeming with cool stuff.” —NPR’s 13.7: Cosmos & Culture