According to National Geographic, for some time researchers have suspected that two ancient human species, Neanderthals and Denisovans, interbred. It wasn’t until paleogeneticist Viviane Slon, of the Max Planck Institute, received the results from a 90,000-year-old flake of bone she had tested (and five other sample tests from the same “child”) that this was confirmed. Slon has published her findings in the scientific journal Nature and it’s groundbreaking as nobody has ever before identified a first-generation hybrid. Denisovas were a “sister group of the Neanderthals, splitting from a common ancestor some 390,000 years ago” and so far pinned only to one area of Siberia. Read more about them—and Slon’s discoveries—at NatGeo.