Book excerpt: Exhaustively researched and years in the making, this innovative book documents how the many components of the head function, how they evolved since we diverged from the apes, and how they interact in diverse ways both functionally and developmentally, causing them to be highly integrated. This integration not only permits the head's many units to accommodate each other as they grow and work, but also facilitates evolutionary change. Lieberman shows how, when, and why the major transformations evident in the evolution of the human head occurred. The special way the head is integrated, Lieberman argues, made it possible for a few developmental shifts to have had widespread effects on craniofacial growth, yet still permit the head to function exquisitely. --