Fossils are the fragments from which, piece by laborious piece, the great mosaic of the history of life has been constructed. Here and there, we can supplement these scraps by the use of biochemical markers or geochemical signatures that add useful information, but, even with such additional help, our reconstructions and our models of descent are often tentative. This book explores the origin and evolution of living things, the changing environments in which they have developed, and the challenges we now face on an increasingly crowded and polluted planet. The book argues that the future well-being of our burgeoning population depends in no small part on our understanding of life's past, its long and slow development, and its intricate interdependencies. The book's accessible and extensively illustrated treatment of the origins narrative describes the nature of the search for prehistoric life, the significance of geologic time, the origin of life, the emergence and spread of flora and fauna, the evolution of primates, and the emergence of modern humans.