Humans and Neanderthals met often, but only one event matters

In 2010 researchers at the Max Planck Institute for Evolutionary Anthropology (EVA), in Leipzig, published the genome of Homo neanderthalensis, a species known in less progressive days as Neanderthal man. This contained stretches of DNA also found in Homo sapiens genomes—specifically, non-African ones. That suggested past interbreeding between the two, but only outside Africa. This is not surprising. Homo sapiens began in Africa but Neanderthals were Eurasian. Any miscegenation would have happened after sapiens left its homeland to embark on its conquest of the world. But the details were unclear.