Book excerpt: In Cornwall, hiking around the half-buried ruins of an old tin mine, Melanie Challenger started to think about the things that have disappeared from our world. When the gigantic bones of mammoths were first excavated from the Siberian permafrost in the eighteenth century, scientists were forced to consider a terrifying possibility: many species that had once flourished on the Earth no longer existed. For the first time, humans had to contemplate the idea of extinction. Challenger became fascinated by this idea, and started to consider how we think about the things we have lost, and, indeed, how we come to lose them. From our destruction of the natural world to the human cultures that are rapidly dying out, On Extinction is a passionate exploration of these disappearances and why they should concern us. Challenger asks questions about how we've become destructive to our environment, our emotional responses to extinctions, and how these responses might shape our future relationship with nature. She travels to the abandoned whaling stations of South Georgia, the melting icescape of Antarctica and the Inuit camps of the Arctic, where she traces the links between human activities and environmental collapse. On Extinction is an account of Challenger's journey that brings together ideas about cultural, biological and industrial extinction in a beautiful, thought-provoking and ultimately hopeful book.