Evidence suggests that modern humans did not emerge from Africa with an unbroken lineage, but rather experienced multiple extinction events on the way to their global dominance, according to recent studies.
Recent DNA research has shed fresh insights into the role our Neanderthal ancestors played in our own evolutionary success.
While this initial perception viewed early European humans as a species that eventually gained dominance after departing from Africa, current research indicates that only those human populations that interbred with Neanderthals were able to endure and thrive, whereas other lineages became extinct.
It is indeed possible that Neanderthal genes played a crucial role in our success in protecting us from new diseases we have never encountered before.
Researchers have found that around 48,000 years ago, shortly after leaving Africa, Homo sapiens interbred with Neanderthals for a brief period, paving the way for their eventual spread across the globe.
Humans had migrated from the African continent before this, but the new research indicates that those populations did not endure before the period of interbreeding.
Professor Johannes Krause of the Max Planck Institute of Evolutionary Biology, Germany, stated to News that the history of present humans will now require to be revised.
We perceive modern humans as a compelling tale of triumph, emerging from Africa approximately 60,000 years ago and subsequently colonizing diverse ecosystems to become the most dominant mammal on the planet," he said. "However, our early history was marked by multiple instances of extinction.
For a long time, understanding how the only remaining human species evolved was based on analyzing the shapes of fossilized remains of our ancestors that lived hundreds of thousands of years ago and examining how their anatomy gradually changed over time.
Ancient remnants have been scarce and frequently vandalized. However, the capacity to extract and decipher the genetic code from bones aged tens of thousands of years has shed light on our enigmatic past.
The DNA in fossil remains reveals the history of the individuals, their family connections, and the paths they took for migration.
Even after our successful interbreeding with Neanderthals, our population in Europe still faced significant challenges.
The first modern humans that had interbred with Neanderthals and lived alongside them became extinct in Europe 40,000 years ago - but not before their descendants had expanded into other parts of the world.
It was their ancestors who eventually returned to Europe to repopulate it.
The study offers a fresh perspective on what led to the demise of Neanderthals shortly after the arrival of modern humans from Africa. The exact reason behind their extinction remains unclear, but these findings prompt us to reconsider speculations that our species drove them to extinction or were inherently more advanced in physical or intellectual terms.
According to Prof. Krause, it aligns with the idea that the issue was caused by environmental factors instead.
We see that humans and Neanderthals experienced extinction in Europe at the same period," he said. "If a species with more resources, like ours, struggled and eventually went extinct in the area, it's hard to be shocked when a species with fewer numbers and limited means, such as Neanderthals, also faced extinction.
The climate was extremely unpredictable during that era. It could suddenly shift from temperatures close to what we have today to extremely frigid conditions, sometimes even changing within a person's lifetime, as stated by Prof Chris Stringer of the Natural History Museum in London, who is not involved with the new research.
"The study highlights that nearly at the end of their presence on the planet, Neanderthals were very scarce in numbers, less genetically diverse than their contemporaneous human counterparts, and it could have not taken much to drive them to extinction," he said.
A separate DNA analysis published in the journal Science reveals that modern humans retained certain vital genetic characteristics from Neanderthals that could have granted them an evolutionary advantage.
As humans left Africa, they became highly susceptible to new diseases they had never faced. This vulnerability benefited from the intermingling of their genetic material with that of Neanderthals, conferring their offspring with protection.
Might the inclusion of Neanderthal DNA have been crucial to our evolutionary success due to the improved adaptability it provided outside of Africa," said Prof Stringer. "As we evolved in Africa, the Neanderthals had undergone their evolution elsewhere in the world.
We obtained a temporary boost to our immune systems through interbreeding with the Neanderthals.
