Humans may not have survived without Neanderthals

Contrary to popular assumption, modern humans did not enjoy a smooth exit from Africa, but instead faced extinction several times before successfully colonizing the globe, according to recent findings.

Investigations into the genetic code have also shed new insights into the role our Neanderthal ancestors played in our accomplishments.

While these early European humans were previously considered a species we had successfully displaced after leaving Africa, new studies demonstrate that only the humans who interbred with Neanderthals were able to thrive, whereas other lineages eventually became extinct.

In fact, Neanderthal genetic traits may have played a vital role in ensuring our survival by safeguarding us from new illnesses we had not faced before.

For the first time, research identifies a brief period 48,000 years ago, during which humans interbred with Neanderthals following their departure from Africa, and then went on to expand into the wider world.

They had previous migrations from the African continent, but research now suggests that the populations that came before the interbreeding did not sustain themselves.

Professor Johannes Krause of the Max Planck Institute of Evolutionary Biology, located in Germany, stated to News that the history of contemporary humans will have to be revised.

We view humans as a considerable success story, emerging from Africa 60,000 years ago and extending into all ecosystems to become the most successful mammalian species," he said. "However, early on we were not successful, we underwent multiple extinctions.

The long-standing understanding of human evolution was largely based on studying the shapes of ancient human fossils and tracking the gradual changes in their anatomy over hundreds of thousands of years.

Archaeological discoveries have been limited and frequently fragmented, but advances in recovering and deciphering ancient genetic information from fossils that date back many millennia have opened up new avenues for understanding bygone eras.

The DNA found in the fossils provides information about the individuals, their family relationships, and the paths they followed during migrations.

Even after our successful interbreeding with Neanderthals, our population in Europe still faced certain difficulties.

Those initial modern humans, who had intermingled with Neanderthals and coexisted with them, disappeared entirely in Europe 40,000 years ago - but only after their descendants had dispersed more widely into the world.

It was these early adventurers' predecessors who ultimately returned to their European homeland to repopulate it.

New evidence challenges conventional theories about the demise of Neanderthals following the arrival of modern humans from Africa. The exact reasons for this event remain unclear; however, the research refutes the notion that our species eradicated them or possessed physical or intellectual advantages.

It confirms the theory that environmental factors were the primary cause.

It's not surprising that both humans and Neanderthals became extinct at this time in Europe," he noted. "If we, a thriving species, were to disappear in the area, it's only logical to assume that Neanderthals, who had an even smaller population, would face the same fate.

The climate was extremely unpredictable at that time.

"The research suggests that towards the end of their time on the planet, Neanderthals were scarce in numbers, less genetically diverse than modern humans they cohabited with, and it may not have required much to push them into extinction," he said.

Research featured in the journal Science reveals that modern humans retained certain genetic characteristics from Neanderthals which could have granted them a distinct survival benefit.

One aspect refers to their immune system. Upon leaving Africa, humans were extremely vulnerable to new diseases, which they had never exposed themselves to before. Through interbreeding with Neanderthals, their offspring inherited some protection, providing them with immunity to certain diseases.

Maybe obtaining Neanderthal DNA contributed to our success because it granted us superior adaptability outside of Africa," said Prof Stringer. "We developed in Africa, whereas the Neanderthals established themselves beyond Africa.

When humans crossed with Neanderthals, their immune systems received an instant upgrade.

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