An early wave of modern human ancestors interbred with Neanderthals between 470,000 and 220,000 years ago, a new DNA discovery from an ancient Neanderthal thigh bone suggests. That’s much earlier than experts had thought, and it could help explain why human DNA seems to be appearing in Neanderthal genomes much earlier than it should.
There are conflicting answers in ancient DNA
It’s not entirely clear when humans and Neanderthals split — and there are conflicting answers in ancient DNA. The 124,000-year-old leg bone offers scientists a peek at the DNA animals get primarily from their mothers, tucked away in the cells’ energy generators. It looked a lot more human-like than it should, according to scientists led by Cosimo Posth at the Max Planck Institute for the Science of Human History.
We knew already that human ancestors interbred with Neanderthals. Even today, we can see signs of the inter-species hookups in the genomes of people with European ancestry. We also know that genes flowed in the opposite direction: DNA from a 130,000-year-old Siberian Neanderthal included chunks that looked human.
But that’s weird: humans didn’t engage in mass migration from Africa, their home turf, to Europe, Neanderthal territory, until 75,000 years ago. Early human-like DNA suggests that a female ancestor of modern humans gave birth to a Neanderthal several hundred thousand years before humans and Neanderthals were first thought to meet. Does that mean a small group of archaic humans left Africa early, and interbred before the big migration? Today’s findings, in the journal Nature Communications, suggest that it could.