Some 900 years ago, a Peruvian healer used a hand drill to make dozens of small holes in a patient's skull. (Photo Credit: Danielle Kurin)

Several trepanation holes were drilled over an area of mottled, inflamed bone. The surgery may have been done to alleviate the pain caused by serious infection. (Photo Credit: Danielle Kurin)

Ancient practitioners used various tools to create trepanations of distinct sizes and shapes. (Photo Credit: Danielle Kurin)