Around 60,000 years ago, humans migrated out of Africa, but we were not alone. Humans encountered Neanderthals and inbred, which is why Neanderthals play an important role in the story of human evolution. On today's Please Explain, we learn why, with Shara Bailey Associate Professor, Center for the Study of Human Origins at NYU, and Jamie Shreeve, Executive Editor for Science at National Geographic Magazine.