On their journey westward, Lewis and Clark demonstrated an amazing ability to identify the new plants and animals they encountered, and their observations enriched science's understanding of the trans-Mississippi West. Others have written about their discoveries and have faithfully cataloged their findings; now a twenty-first-century biologist reexamines some of those discoveries in the light of modern science to show for the first time their lasting biological significance. The Natural World of Lewis and Clark interprets the expedition's findings from a modern perspective to show how advances such as DNA research, modern understanding of proteins, and the latest laboratory methods shed new light on them. David Dalton recounts the expedition's observations and, in clear, readily accessible terms, relates them to principles of ecology, genetics, physiology, and even animal behavior. Writing in informal language with a bit of wry humor, Dalton invites readers to imagine the West that Lewis and Clark found, revealing the dynamic features of nature and the dramatic changes that earlier peoples brought about. He explains surprising facts, ranging from why Indians used cottonwood bark as winter feed for horses to why the explores experienced gastric distress with some foods, and even why the Expedition's dog would have been well-advised to avoid a diet of salmon. Dalton introduces the tools and techniques of today's science in a way that won't intimidate nonspecialist readers. Throughout the book he expertly balances botanical and zoological information, with coverage ranging from the extinction of large animals in North America a few thousand years ago to the expected effects of invasivespecies and climate change in the coming centuries. Enhanced with unusual and informative illustrations--not only nature photography but also historical images--this book will fascinate any reader with an interest in the natural history of the American West as well as broader issues in conservation and ecology. The Natural World of Lewis and Clark tells the story behind the story of this remarkable expedition and shows that its legacy extended not only across a continent but also into our own time.