Sarah Blaffer Hrdy is one of the most original and influential minds in evolutionary anthropology…[Her] gracefully written, expert account of human behavior focuses on the positive, and its most important contribution is to give cooperation its rightful place in child care. Through a lifetime of pathbreaking work, she has repeatedly undermined our complacent, solipsistic, masculine notions of what women were meant ‘by nature’ to be. Here as elsewhere she urges caution and compassion toward women whose maternal role must be constantly rethought and readjusted to meet the demands of a changing world.