Four teeth found in a cave in the Tongzi county of southern China have scientists scratching their heads.

In 1972 and 1983, researchers extracted the roughly 200,000-year-old teeth from the silty sediments of the Yanhui cave floor, initially labeling them as Homo erectus, the upright-walking hominins thought to be the first to leave Africa. Later analysis suggested they didn't quite fit with Homo erectus, but that's where the story paused for nearly two decades.

Now, a study published in the Journal of Human Evolution takes a fresh look at these ancient teeth, using modern methods to examine the curious remains. The new analysis excludes the possibility that the teeth could come from Homo erectus or the more advanced Neanderthals, but