Despite tremendous advances in civil rights, we live in a world where the sexes remain sharply segregated from birth to death: in names, clothing, social groupings, and possessions; in occupations, civic association, and domestic roles. Gender separatism, so pervasive as to be almost invisible, permeates the fabric of our daily social routines. Preferring a notion of gender that is fluid and contextual, and denying that separatism is inevitable, Nancy Levit dismantles the myths of gender essentialism. Drawing on a wealth of interdisciplinary data regarding the biological and cultural origins...