The mandible, unearthed by paleontologists in China's Zhiren Cave in 2007, sports a distinctly modern feature: a prominent chin. But the bone is undeniably 60,000 years older than the next oldest Homo sapiens remains in China, scientists say.

In fact, at about a hundred thousand years old, the Chinese fossil is "the oldest modern human outside of Africa," said study co-author Erik Trinkaus, an anthropologist at Washington University in St. Louis.

(Also see "Oldest Skeleton of Human Ancestor Found.")

Popular theory states that Homo sapiens migrated out of Africa about 60,000 years ago, at which point modern humans quickly replaced early human