PERU: A new study of dozens of skulls from the south-central Andes examined the practice of trepanation, or the surgical removal of a portion of the skull. Researchers theorize that the practice arose following the collapse of the Wari Empire around A.D. 1000, which may have brought increased violence and health problems that required new, and sometimes radical, treatments. The study shows that primarily adult men were eligible, that scraping offered better outcomes than drilling, and that some skulls were used for practice after death. —Samir S. Patel