Over the past half billion years, there have been five major mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists around the world are currently monitoring the sixth extinction, predicted to be the most devastating extinction event since the asteroid impact that wiped out the dinosaurs. In prose that is at once frank, entertaining and deeply informed, Elizabeth Kolbert provides an account of the disappearances occurring all around us and traces the evolution of humanity's understanding of extinction from its first articulation by Georges Cuvier in revolutionary Paris up through Lyell and Darwin and on to the present day. Kolbert shows that the sixth extinction is likely to be mankind's most lasting legacy, compelling us to rethink the fundamental question of what it means to be human.