Scientists have long-known that our human ancestors got down and dirty with Neanderthals. But when exactly did this interbreeding first occur? A study from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany offers a new answer. For the study, researchers sequenced the genome of a 45,000-year-old modern human male, using a femur bone that was unearthed in 2008 near the small village of Ust’-Ishim in western Siberia.