Studies of kin recognition have progressed rapidly during the past decade. One of the most exciting aspects of this research is that the ability to recognize kin has been found, in some form or other, throughout the animal kingdom, from single-celled organisms to man. The increase in studies reporting kin recognition has led to a widespread acceptance of the role of kinship in behaviour. There is, of course, good theoretical reasons, provided by kin selection theory and mate choice theory, why this should be so, however, the importance of kinship for behaviour has often been unquestioned. One of the reasons for compiling this volume was to critically assess the role of kinship in behavioural interactions: is kin recognition responsible for the many observed differential interactions between kin and non-kin? Whilst many species have been demonstrated to recognize their kin, little attention has been given to determining how this is achieved and consequently the mechanisms underlying this ability are poorly understood. A second goal of this book was to present research which has investigated how individuals recognize their kin.

Rather than provide a taxonomic discussion of kin recognition, I have aimed to provide a book which deals with particular themes. Leading researchers in these areas were asked to discuss these issues with respect to their own expertise and species or group studied. The book may be broadly divided into two sections – that dealing with function and that dealing with mechanisms.