The evolution of new species - speciation - is a central theme in evolution. How does one species split into another? Why? How long does it take for a new species to be born? And what is a species anyway? Such is the importance of the problem that Charles Darwin himself dubbed it "the Mystery of Mysteries". These questions, the focus of intense debate in biology and critical for any assessment of biodiversity, are all tackled in the book. Schilthuizen, reputed scientist and journalist, launches into the debate with tremendous energy and wit. Using the sometimes vicious academic debates and vivid personalities of the scientists as background, he explores the meandering path of speciation research and sets it out in the clearest possible terms. The whole subject leaps to life and its significance for understanding biodiversity comes clear. This is a fascinating, galloping read that will appeal equally to the lay reader and to students getting to grips with the fundamentals of a complex subject.