Population sizes of vertebrate species -- mammals, birds, reptiles, amphibians, and fish -- have declined by 52 percent over the last 40 years. in other words, those populations around the globe have dropped by more than half in fewer than two human generations. -- World Wildlife Fund Living Planet report 2014 This book straddles an awkward boundary between being a colorful popular work and a scientific literature review.... Profusely and beautifully illustrated with figures, maps, charts, and period reconstructions. Recommended. -- Choice A good introduction to the great puzzle that is extinction study. -- Publishers Weekly Selected by the Scientific American Book Club and now a more affordable paperback for a far-wider audience. For more than a century scientists have tried to identify and understand the precise processes responsible for species extinction. Solving the species extinction puzzle has become even more important, even urgent, as human populations and technologies rival sea-level change, volcanic eruptions and asteroid impacts as an extinction mechanism. The Great Extinctions explores the search for an understanding of Earth's five great extinction events and whether the sixth is upon us already. Leading paleontologist Norman MacLeod examines the controversies and conclusions and what they mean to the efforts to preserve Earth's biodiversity. He also reveals how, contrary to popular conception, species extinction is as natural a process as species evolution. Examining extinction over geological time, he compares ancient extinction events and uses them to predict future extinctions. Featuring the latest scientific evidence on the subject and informative illustrations and diagrams, The Great Extinctions is an easy-to-understand presentation of a complex and controversial subject.