Paleontology is the scientific study of fossils. It can help us understand human evolution. A jawbone fossil from the mountains of Tibet helped scientists understand a mystery. Tibetans and Han Chinese living at high altitudes commonly have a gene called EPAS1. Researchers wondered where the gene originates from. Scientists believe this jawbone, which belonged to a Denisovan from at least 160,000 years ago, holds the key to understanding where the gene comes from.