When this classic work was first published in 1975, it created a new discipline and started a tumultuous round in the age-old nature versus nurture debate. This book is widely known as the object of bitter attacks by social scientists and other scholars who opposed its claim that human social behaviour, indeed human nature, has a biological foundation. The controversy surrounding the publication of the book reverberates to the present day. In the introduction to this 25th anniversary edition, the author shows how research in human genetics and neuroscience has strengthened the case for a biological understanding of human nature. Human socio-biology, now often called evolutionary psychology, has in the last quarter of a century emerged as its own field of study, drawing on theory and data from both biology and the social sciences. From its illustrated descriptions of animal societies, and as a crucial step forward in the understanding of human beings, this volume should be of interest to a new generation of students and scholars in all branches of learning.