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. Courtesy of Esther Gokhale and Ian Mackenzie/Nomads of the Dawn hide caption

itoggle caption Courtesy of Esther Gokhale and Ian Mackenzie/Nomads of the Dawn

Generic hydrocodone plus acetaminophen pills seen in a pharmacy in Montpelier, Vt., in 2013. Toby Talbot/AP hide caption

itoggle caption Toby Talbot/AP