The genetic history of the dog is a sensational example of the co-evolution of two species, man and wolf, to each other's mutual benefit. But how did this ancient partnership begin? To answer this question, Professor Bryan Sykes identifies tantalising clues in the recently mapped genetic makeup of both species. Sykes paints a vivid picture of the dog as an ancient and essential ally. While undoubtedly it was the mastery of fire, language and agriculture that propelled Homo sapiens from a scarce, medium-sized primate to the position we enjoy today, Sykes crucially credits a fourth element for this success: the transformation of the wolf into the multi-purpose helpmate that is the dog. Drawing upon archaeology, history and genetics, Sykes shows how humans evolved to become the dominant species on Earth, but only with the help of our canine companions.