The 31,000-year-old skeleton of a young adult found in a cave in Indonesia that is missing its left foot and part of its left leg reveal the oldest known evidence of an amputation, according to a new study. Scientists say the amputation was performed when the person was a child – and that the “patient” went on to live for years as an amputee. The prehistoric surgery could show that humans were making medical advances much earlier than previously thought, according to thestudy published Wednesday in the journal Nature. Researchers were exploring a cave in Borneo, in a rainforest region known for having some of the earliest rock art in the world, when they came across the grave, said Tim Maloney, an archaeologist at Griffith University in Australia and the study’s lead researcher. Though much of the skeleton was intact, it was missing its left foot and the lower part of its left leg, he explained. After examining the remains, the researchers concluded the foot bones weren’t missing from the grave, or lost in an accident – they were carefully removed. The remaining leg bone showed a clean, slanted cut that healed over, Maloney said. There were no signs of infection, which would be expected if the child had gotten its leg bitten off by a creature like a crocodile. And there were also no signs of a crushing fracture, which would have been expected if the leg had snapped off in an accident.