The aim of this book is to bring the concepts and methods of current evolutionary theory to bear on the agenda of comparative sociology – that is, on the study of the underlying process by which the human cultures and societies documented in the historical, ethnographic, and archaeological record come to be of the different kinds that they are. Its principal contention is that collective human behaviour-patterns should be analysed as the outwardly observable expression of information affecting phenotype transmitted at three separate but interacting levels of heritable variation and competitive selection – biological, cultural, and social. A neo-Darwinian approach of this kind is by now commonplace in many areas of the more specialized behavioural sciences. But its potential contribution to sociology has hardly begun to be realized.

Since a preliminary formulation of a recognizably selectionist sociology already underlay the trilogy on social theory which I published between 1983 and 1997, this volume might be thought to be no more than a postscript to views which I have already put into print. But my Treatise on Social Theory was, as I now recognize, little more than an introductory exposition of its theme. Since it was published, I have not only become increasingly aware of its deficiencies and increasingly indebted to the many other authors on whose contributions to selectionist theory it is now possible to draw, but increasingly conscious of how much still remains to be done before sociology can be said to have moved decisively beyond the agenda set for it by Herbert Spencer, Karl Marx, Max Weber, and Emile Durkheim.