Far from easily colonizing Africa, our modern human ancestors were actually wiped out multiple times before eventually settling the globe, research has surprisingly disclosed.
The latest DNA research has also provided insight into the role our Neanderthal ancestors played in our success.
Traditionally, early European humans were thought to have surpassed other human groups after migrating out of Africa. However, recent studies reveal that individuals who mated with Neanderthals managed to survive and propagate, whereas other human lineages went extinct.
In fact, genetic contributions from Neanderthals may have been essential to our success by offering us resistance to previously unknown diseases.
Research for the first time precisely dates a relatively brief period ago - 48,000 years ago - during which Homo sapiens, after departing from Africa, crossed with Neanderthals, following which they spread more widely across the globe.
The research indicates that early humans, belonging to the Homo sapiens species, had migrated from Africa prior to the period of interbreeding, but those populations did not happen to survive.
Prof. Johannes Krause of the Max Planck Institute of Evolutionary Biology in Germany told Wander ThoughtsNews that the history of modern humans will now need to be revised.
We consider contemporary humans a major story of achievement, originating from Africa around 60,000 years ago and spreading to inhabit all ecosystems, becoming the most prosperous mammal on the planet," he said. "However, we were not always so; we went extinct on multiple occasions at the beginning.
The long-standing question of how the human species evolved was originally answered by studying the fossilized remains of our ancient ancestors, which provided a glimpse of our gradual anatomical transformation over hundreds of thousands of years.
The ancient remains have been few and often severely damaged. However, the capacity to extract and decipher the genetic code from bones that are tens of thousands of years old has shed light on our enigmatic past.
The DNA in fossils reveals the story of the individuals, illustrating their familial relationships and migration patterns.
After successfully interbreeding with Neanderthals, our European population still faced certain difficulties.
The early modern humans who had interbred with Neanderthals and coexisted with them became extinct in Europe 40,000 years ago - but not before their descendants had migrated further into the world.
It was ultimately the forebears of these early globalization trailblazers who eventually went back to populate Europe.
This research provides a fresh viewpoint on why Neanderthals became extinct shortly after Homo sapiens arrived from Africa. The underlying reasons for this are still unclear, However, the new findings cast doubt on the theories that our species wiped them out or that we possessed superior physical or intellectual abilities.
Instead, Professor Krause expresses support for the notion that the cause was likely environmental in nature.
'Humans and Neanderthals both became extinct in Europe,' he said. 'If our species was wiped out in the region, it's not surprising that the Neanderthal population, which was even smaller, became extinct as well.'
The climate was incredibly unstable back then. It could rapidly shift from almost the same warmth we experience today to extremely cold temperatures, sometimes even within a single individual's lifetime, as noted by independent expert Prof Chris Stringer of the Natural History Museum in London.
"The research indicates that when Neanderthals were nearing the end of their time on Earth, their population was quite small, with a lower genetic diversity than that of modern humans with whom they coexisted, and it likely wouldn't have taken much to drive them to extinction," he said.
A different DNA study, published in the journal Science, reveals that modern humans retained certain crucial genetic features from Neanderthals which may have provided them with an evolutionary advantage.
One relates to the human immune system. When humans left Africa, they were extremely vulnerable to new diseases they had never encountered. Mixing with Neanderthals provided genetic protection for their offspring.
It's possible that inheriting Neanderthal DNA contributed to our success because it provided better adaptive qualities outside of Africa," said Prof. Stringer. "We had evolved in Africa, whereas the Neanderthals had adapted to live outside of Africa.
Our ancestors seemed to have acquired a rapid enhancement of their immune systems through interbreeding with Neanderthals.
