Neanderthals may have been eradicated from tropical diseases borne by homo sapiens when they migrated from Africa more than 130,000 years ago, a new study has revealed.
Archaeological evidence suggests that Eurasian Neanderthals first came in contact with our human ancestors in an area known as the Levant in the Eastern Mediterranean.
The two species together survived tens of thousands of years before the Neanderthals began to disappear and modern humans expanded beyond the Levant.
In a new report, researchers from Stanford University suggest that Homo sapiens and Neanderthals spend tens of thousands of years in a & # 39; stalemate & # 39; were locked up.
Neanderthals and homo sapiens existed side by side in the Levant for tens of thousands of years, but a failure in an invisible disease barrier may have led modern people to overwhelm Neanderthals and then spread
The Levant includes a number of modern countries, including Cyprus, Israel, Jordan, Syria, Egypt and Iraq.
Gilli Greenbaum of the Stanford team said: “Our research suggests that diseases may have played a more important role in the extinction of Neanderthals than previously thought.
& # 39; They may even be the main reason why modern humans are now the only human group on the planet. & # 39;
The team used mathematical models of modern disease transmission to show how the unique diseases of Neanderthals and modern people create an & # 39; invisible disease barrier & # 39; could have created between the two species.
This would have discouraged homo sapiens from entering enemy territory for fear of contracting a disease for which they had no immunity.
Researchers believe that the mutual fear of contracting diseases among both Neanderthals and Homo sapiens is behind their ability to coexist for tens of thousands of years
The researchers claim that this & # 39; uncomfortable balance & # 39; was eventually broken due to crossing between the two species.
The hybrid people born of these trade unions may carry immune-related genes of both species that would have spread slowly through modern human and Neanderthal populations.
As these protective genes spread, the burden of disease or the effects of infection within the two groups gradually decreased.
Eventually a turning point was reached when modern people acquired sufficient immunity to venture beyond the Levant and deeper into the Neanderthal area with few health consequences.
At this point, other benefits that modern people may have had over Neanderthals – such as more deadly weapons or more sophisticated social structures – could have gained greater importance.
It is believed that their inefficient stone tools (recreation depicted) saw the Neanderthals perish 40,000 years ago, while the homo sapien community took a big flight to become the origin of modern man
The reason modern humans have replaced the Neanderthals, not the other way around, has to do with the severity of the diseases of both species, the researchers say.
& # 39; The hypothesis is that the disease burden of the tropics was greater than the disease burden in temperate regions & # 39; s & # 39 ;, said co-author Noah Rosenberg.
& # 39; An asymmetry of disease burden in the contact zone could have favored modern man who arrived there from the tropics. & # 39;
He said the modeling discovered that even small differences in disease burden between the two groups would have grown over time in the beginning, giving homo sapiens a head start.
Dr. Greenbaum said: “It may be that by the time modern man was almost completely freed from the extra burden of Neanderthal diseases, Neanderthals were still very vulnerable to modern human diseases.
After the disease barrier no longer affected modern humans, they could have overwhelmed the Neanderthals with their superior tools and weapons
& In addition, while modern humans grew deeper in Eurasia, they would have encountered Neanderthal populations that did not receive protective immune genes through hybridization. & # 39;
The way the Neanderthals succumbed to homo sapiens is similar to what happened when Europeans came to America in the 15th and 16th centuries and decimated the indigenous population with their more powerful diseases.
If this new theory about the demise of the Neanderthals is correct, supporting evidence can be found in the archaeological file.
& # 39; For example, we predict that the Neanderthal and modern human population densities in the Levant will be lower compared to what they were before and compared to other regions & # 39; s, & # 39; said Greenbaum.
The full findings of the study were published in the journal Nature communication.
WHO WERE THE NEANDERTHALEN?
The Neanderthals were a close-knit human ancestor who died mysteriously about 50,000 years ago.
The species lived in Africa with early humans for hundreds of millennia before moving to Europe 500,000 years ago.
They were later accompanied by people who made the same journey in the last 100,000 years.
The Neanderthals were a sort of human cousin, but not a direct ancestor – the two species separated from a common ancestor – who died about 50,000 years ago. Pictured is an exhibition of the Neanderthal museum
These were the original & # 39; cavemen & # 39 ;, traditionally thought to be stupid and cheeky compared to modern people.
However, in recent years, and especially in the last decade, it has become increasingly clear that we are selling Neanderthals briefly.
A growing number of clues indicate a more advanced and multi-talented species & # 39; caveman & # 39; than someone thought possible.
It now seems likely that Neanderthals have buried their dead with the concept of an afterlife in mind.
Moreover, their diets and behavior were surprisingly flexible.
They used body art such as pigments and beads, and they were the very first artists, with Neanderthal cave art (and symbolism) in Spain apparently before the first 20,000 years old for the earliest modern human art.
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