George C. Williams is professor emeritus of biological sciences at the State University of New York at Stony Brook. He is the author of Adaptation and Natural Selection and has contributed numerous articles to scholarly publications on the behavior and ecology of fish and has published several technical articles on evolutionary mechanisms, especially in relation to social behavior, strategies of reproduction, and adaptive features of life cycles. He is a member of the National Academy of Sciences and was awarded its Elliot Medal.

• Introduction; I: Altruistic Behavior and Social Organization; 1: On the Effects of Selection on Social Insects; 2: The Genetical Evolution of Social Behavior. I.; 3: The Genetical Evolution of Social Behavior. II.; II: Adaptive Regulation of Population Density; 4: Intergroup Selection in the Evolution of Social Systems; Group Selection and Kin Selection: A Rejoinder; A Reply to Maynard Smith’s Rejoinder; Survival of Young Swifts in Relation to Brood-Size; A Rejoinder to Perrins; III: Higher Levels of Organization; 5: The Evolution of Stability in Marine Environments: Natural Selection at the Level of the Ecosystem; IV: Sex Ratio; 6: Natural Selection and the Sex Ratio; 7: Evolutionary Origin of Sexual Differentiation and the Sex Ratio; 8: Comments on the Two Preceding Papers; V: Sex; 9: The Origin and Maintenance of Sex; 10: Evolution in Sexual and Asexual Populations; 11: Evolution in Sexual and Asexual Populations; 12: Evolution in Sexual and Asexual Populations

George C. Williams is professor emeritus of biological sciences at the State University of New York at Stony Brook. He is the author of Adaptation and Natural Selection and has contributed numerous articles to scholarly publications on the behavior and ecology of fish and has published several technical articles on evolutionary mechanisms, especially in relation to social behavior, strategies of reproduction, and adaptive features of life cycles. He is a member of the National Academy of Sciences and was awarded its Elliot Medal.

• Introduction; I: Altruistic Behavior and Social Organization; 1: On the Effects of Selection on Social Insects; 2: The Genetical Evolution of Social Behavior. I.; 3: The Genetical Evolution of Social Behavior. II.; II: Adaptive Regulation of Population Density; 4: Intergroup Selection in the Evolution of Social Systems; Group Selection and Kin Selection: A Rejoinder; A Reply to Maynard Smith’s Rejoinder; Survival of Young Swifts in Relation to Brood-Size; A Rejoinder to Perrins; III: Higher Levels of Organization; 5: The Evolution of Stability in Marine Environments: Natural Selection at the Level of the Ecosystem; IV: Sex Ratio; 6: Natural Selection and the Sex Ratio; 7: Evolutionary Origin of Sexual Differentiation and the Sex Ratio; 8: Comments on the Two Preceding Papers; V: Sex; 9: The Origin and Maintenance of Sex; 10: Evolution in Sexual and Asexual Populations; 11: Evolution in Sexual and Asexual Populations; 12: Evolution in Sexual and Asexual Populations

George C. Williams is professor emeritus of biological sciences at the State University of New York at Stony Brook. He is the author of Adaptation and Natural Selection and has contributed numerous articles to scholarly publications on the behavior and ecology of fish and has published several technical articles on evolutionary mechanisms, especially in relation to social behavior, strategies of reproduction, and adaptive features of life cycles. He is a member of the National Academy of Sciences and was awarded its Elliot Medal.

• Introduction; I: Altruistic Behavior and Social Organization; 1: On the Effects of Selection on Social Insects; 2: The Genetical Evolution of Social Behavior. I.; 3: The Genetical Evolution of Social Behavior. II.; II: Adaptive Regulation of Population Density; 4: Intergroup Selection in the Evolution of Social Systems; Group Selection and Kin Selection: A Rejoinder; A Reply to Maynard Smith’s Rejoinder; Survival of Young Swifts in Relation to Brood-Size; A Rejoinder to Perrins; III: Higher Levels of Organization; 5: The Evolution of Stability in Marine Environments: Natural Selection at the Level of the Ecosystem; IV: Sex Ratio; 6: Natural Selection and the Sex Ratio; 7: Evolutionary Origin of Sexual Differentiation and the Sex Ratio; 8: Comments on the Two Preceding Papers; V: Sex; 9: The Origin and Maintenance of Sex; 10: Evolution in Sexual and Asexual Populations; 11: Evolution in Sexual and Asexual Populations; 12: Evolution in Sexual and Asexual Populations