If you ask a biologist to explain the evolution of the elaborate morning song of a great tit, the subtle food preferences of a domestic mouse, or the efficient hunting techniques of a pack of wolves, what sort of explanation will you get? The chances are you will be told that this type of behaviour can readily be explained by the conventional theory of natural selection acting on genetic differences between individuals. Ever since Darwin, the theory of natural selection has been applied to all sorts of biological problems, from the origin of life to the origin of language, and for most of this century it has been assumed that genetic differences between individuals underlie the variation on which natural selection acts. It is not surprising, therefore, that behavioural evolution is also seen as the outcome of the selection of genetic variations. But is this view correct? In this book we are going to argue that when applied to the behaviour of higher animals, conventional evolutionary theory is rarely adequate and is often misleading. Natural selection acting on genetic differences between individuals is not a sufficient explanation for the evolution of the behaviour of the great tit, the mouse or the wolf.

To understand why we are not satisfied with the current application of Darwin's theory to behaviour, we need to go back to basics. Darwin's theory depends on some fundamental properties of biological entities: on their ability to reproduce, on the differences between individuals and on the heritable nature of some of these differences.