Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures

One of the year's most fascinating works of popular science is also its most disgusting. From tapeworms to isopods to ichneumon wasps, ""parasites are complex, highly adapted creatures that are at the heart of the story of life."" Zimmer (At the Water's Edge) devotes his second book to the enormous variety of one- and many-celled organisms that live on and inside other animals and plants. The gruesome trypanosomes that cause sleeping sickness had nearly been routed from Sudan when the country's civil war began: now they're back. Costa Rican researcher Daniel Brooks has discovered dozens of parasites, including flies that lay eggs in deer noses: ""snot bots."" And those are only the creatures from the prologue. Zimmer discusses how the study of parasites began, with 19th-century discoveries about their odd life cycles. (Many take on several forms in several generations, so that a mother worm may resemble her granddaughter, but not her daughter.) He looks at how parasites pass from host to host, and how they defeat immune systems and vice versa. Many parasites alter their hosts' behavior: Toxoplasma makes infected rats fearless, thus more likely to be eaten by cats, who will then pick up the microbe. Quantifiable ""laws of virulence"" lead parasites to become nasty enough to spread, yet not so nasty as to wipe out all their hosts. And eons of coevolution can affect both partners: howler monkeys may avoid violent fights because screwworms can render the least scratch fatal. Two final chapters address parasites in human medicine and agriculture. Not only are parasites not all bad, Zimmer concludes in this exemplary work of popular science, but we may be parasites, tooDand we have a lot to learn from them about how to manage earth, the host we share. Illus. (Sept.)