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. The controversy surrounding the book's publication--and surrounding its central claim that human social behavior has a biological foundation--reverberates to this day. In the introduction to this twenty-fifth anniversary edition, Edward O. Wilson shows how research in human genetics and neuroscience over the past quarter of a century has strengthened the case for a biological understanding of human nature.