For the past decade, a fossil human relative about the size of a toddler has loomed large in the story of our evolutionary history. This mysterious creature—found on the Indonesian island of Flores—has sparked a heated debate about its origins, including questions over its classification as a unique species. But now, a scattering of teeth and bone may at last unlock the mystery of the “hobbits,” also known as Homo floresiensis. The 700,000-year-old human remains are the first found outside Liang Bua cave, the site on Flores that yielded the original hobbit fossils. The much older samples show intriguing similarities...