Humans may not have survived without Neanderthals

Far from triumphantly breezing out of Africa, modern humans went extinct many times before going on to populate the world, new studies have revealed.

The new DNA research has also shed new light on the role our Neanderthal cousins played in our success.

While these early European humans were long seen as a species which we successfully dominated after leaving Africa, new studies show that only humans who interbred with Neanderthals went on to thrive, while other bloodlines died out.

In fact, Neanderthal genes may have been crucial to our success by protecting us from new diseases we hadn’t previously encountered.

The research for the first time pinpoints a short period 48,000 years ago when Homo sapiens interbred with Neanderthals after leaving Africa, after which they went on to expand into the wider world.

Homo sapiens had crossed over from the African continent before this, but the new research shows these populations before the interbreeding period did not survive.

Prof Johannes Krause of the Max Planck Institute of Evolutionary Biology, in Germany, told BBC News that the history of modern humans will now have to be rewritten.

“We see modern humans as a big story of success, coming out of Africa 60,000 years ago and expanding into all ecosystems to become the most successful mammal on the planet,” he said. “But early on we were not, we went extinct multiple times.”

For a long time, deciphering how the only surviving species of humans evolved was based on looking at the shapes of fossilized remains of our ancestors living hundreds of thousands of years ago and observing how their anatomy subtly changed over time.

The ancient remains have been sparse and often damaged. But the ability to extract and read the genetic code from bones that are many thousands of years old has lifted a veil on our mysterious past.

The DNA in the fossils tell the story of the individuals, how they are related to each other and their migration patterns.

Even after our successful interbreeding with Neanderthals, our population of Europe wasn’t without hitches.

Those first modern humans that had interbred with Neanderthals and lived alongside them died out completely in Europe 40,000 years ago – but not before their offspring had spread further out into the world.

It was the ancestors of these early international pioneers who eventually returned to Europe to populate it.