In this lively, unexpected look at the hearts of animals-from fish to bats to humans-American Museum of Natural History zoologist Bill Schutt tells an incredible story of evolution and scientific progress. We join Schutt on a tour from the origins of circulation, still evident in microorganisms today, to the tiny hardworking pumps of worms, to the golf-cart-size hearts of blue whales. We visit beaches where horseshoe crabs are being harvested for their blood, which has properties that can protect humans from deadly illnesses. We learn that when temperatures plummet, some frog hearts can freeze solid for weeks, resuming their beat only after a spring thaw. And we journey with Schutt through human history, too, as philosophers and scientists hypothesize, often wrongly, about what makes our ticker tick. Schutt traces humanity's cardiac fascination from the ancient Greeks and Egyptians, who believed that the heart contains the soul, all the way up to modern-day laboratories, where scientists use animal hearts and even plants as the basis for many of today's cutting-edge therapies. Written with verve and authority, weaving evolutionary perspectives with cultural history, Pump shows us this mysterious organ in a completely new light.