PUMP

By definition, the heart is an organ that receives fluid containing oxygen and nutrients from the body and then pumps it back out. Tiny, one-celled organisms—and some not so tiny (flatworms, corals, jellyfish)—don’t need one; they acquire these necessities by simple diffusion from the outside. More than 500 million years ago, writes Schutt, who is also a research associate in residence at the American Museum of Natural History, muscles evolved, forming the earliest circulatory system that moved fluids around. Hearts evolved later. The heart allows animals to grow large and move fast, but it isn’t essential. Insects don’t have one, but they don’t grow large. Although most readers give priority to their own heart, the author waits until the book’s halfway point to take it up. Nonetheless, few will object to his detours, including the especially enjoyable sections on the horseshoe crab and the blue whale. Ten chapters on the human heart deliver a scattershot but satisfying mixture of history, biology, and high-tech medicine. We are aware of our heart, perhaps more than other organs, so common sense convinced people throughout history that it was the seat of consciousness and personality. The rise of scientific research led to more accurate information, but it was a bumpy process, as revealed by Schutt’s informative and gruesome history of transfusions and transplantation. This is not a self-help book, but readers will learn details of common heart diseases and their treatments. Schutt peppers his text with jokes, asides, and cute footnotes, but tolerant readers will learn a great deal. Wynne’s clean, black-and-white line drawings, especially the diagrams of complex biological systems, provide a helpful visual accompaniment to the text.