As far back as 250,000 years ago, the ancestors of most modern people in Europe and Asia left Africa and journeyed toward the colder northern terrain of Eurasia. There, they encountered our closest, now-extinct human relatives — the Neanderthals. Over thousands of years, these groups mated and exchanged DNA.
Today, we can still see the genetic legacy of these interbreeding events: approximately 2% of the genomes of people outside of Africa comes from Neanderthals.
