At a laboratory in Leipzig, Germany, a researcher is puzzling over a piece of ancient bone. Surely it can’t be true? According to DNA tests, this relic represents something that paleontologists thought they would never find: a hybrid between two of humanity’s early relatives. It’s no surprise that the expert first suspects an error has been made. But there’s no mistake here. Astonishingly, these remains come from a girl whose parents were from two entirely different species. And this breakthrough could well revolutionize what we know about our ancestors.