W.D. Hamilton is considered by many the most important theoretical bio logist of the 20th century. He has made major discoveries in evolution ary biology, genetics, and social behavior, and his essays continue to exert tremendous influence throughout the discipline. This second vol ume of his collected papers focuses on his groundbreaking work on sex and sexual selection. It contains the 18 papers he published between 1 980 and 1991, many of them examining the role of parasites and disease in promoting genetic diversity. For each paper, Hamilton has written an accessible introduction...