Primal posture: Ubong tribesmen in Borneo (right) display the perfect J-shaped spines. A woman in Burkina Faso (left) holds her baby so that his spine stays straight. The center image shows the S-shaped spine drawn in a modern anatomy book (Fig. I) and the J-shaped spine (Fig. II) drawn in the 1897 anatomy book Traite d'Anatomie Humaine.