'Jay Schulkin is able to stand back from the mass of detail that sometimes overwhelms the rest of us, and offers us the enjoyment and excitement of a true synthesis. In this book he discusses the fundamental ability that is an absolute requirement for biological success: adaptation. The essence of his argument is that this involves not only physical adaptation to a harsh and competitive world, but social adaptation … Relating this to internal events in the body, particularly those that have evolved to deal with stress and its aftermath, makes this a synthesis that will intrigue and fascinate us all. Those who study social behaviour often seem separated by a chasm of incomprehension from those working on the neural and hormonal aspects of adaptation … Schulkin has attempted to build not one, but several bridges across this chasm. To walk across them is a pleasure.' Joe Herbert, University of Cambridge