The evolution of dogs and the forces that drove its amazing transformation from a fierce wild carnivore, the wolf, to the astonishing range of comparatively docile domesticated dogs that we know today. How is it that Homo sapiens formed such a special relationship with what, on the face of it, is a most unlikely ally? It is more than just a story of domestication but an astonishing example of the co-evolution of two species, man and wolf, to each others mutual benefit. This co-evolution was a vital step in helping Homo sapiens overcome competition from other human species and to expand in numbers from relative obscurity on the margins towards the overwhelming numerical superiority and influence that we enjoy today. The book draws on the rich scientific detail of the genomes, both dog and human, that has accumulated over the past two decades. In each case we see a clear pattern of the origins of both species, resolving questions that have puzzled scientists for centuries. Sykes explores the breadth of this "special relationship" between man and dog. We know that dogs descend from wolves. We know that their domesticated descendants form close bonds with ourselves and there are a multitude of theories to account for our compatible social organisations. But to a geneticist, this is nowhere near powerful enough to explain this most peculiar situation. Many theories explore what it was that propelled Homo sapiens from the position of a scarce, medium-sized primate to the position of complete domination that we enjoy today. The ability to control fire, the evolution of language and the invention of agriculture are three prominent examples. Sykes crucially adds a fourth: our transformation of the wolf into the multi-purpose helpmate that is the dog. We owe our dominance and our survival to the dog.