According to a new study, migrating farmers from prehistoric Middle East could be why several modern Europeans have lesser Neanderthal DNA compared to East Asians of today.
Modern European's Lesser Neanderthal DNA Compared to East Asians
Every human who has ancestral traces outside of Africa has Neanderthal DNA. On average, this Neanderthal DNA takes up roughly 2% of the genome.
However, for those with East Asian ancestry, the numbers have a higher range. East Asians have 8% to 24% more Neanderthal DNA compared to those who have European ancestry.
This finding comes as a surprise, especially since fossil evidence shows that Neanderthals used to dwell in Europe. The question now lies in why East Asians carry more of these genes compared to their modern European counterparts.
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Migration Could Be The Reason
A new study shed light on this mysterious matter. The study noted that a wave of Homo sapiens migrating roughly 10,000 years ago may have diluted Neanderthal DNA across Europe. This migration involved the movement of farmers who had minimal ancestry from Neanderthals. These farmers moved from the present-day Middle East and southwestern Asia all the way to Europe.
These farmers were also accompanied by some local hunter-gatherers. This led to a more diverse genome to enter the region.
Homo Sapiens who lived in Easy Aria around 60,000 to 70,000 years ago did not experience any dilutions from these ancient individuals.
Claudio Quilodrán, the lead author of the study and a postdoctoral researcher in evolution and ecology in the University of Oxford, explains that they propose an explanation that is simple: migration.
According to paleoanthropologist John Hawks from the University of Wisconsin-Madison, who did not participate in the study, since the first sequencing of the Neanderthal genome that took place 13 years ago, there have been questions raised regarding the mix of Neanderthal and modern human genes. Research posits that the inclusion of Neanderthal genes did not result in any significant survival disadvantages or advantages for humans. Given this, Hawks explains that natural selection could be the reason why there are some populations with great genetic amounts compared to others.
Others have also suggested that East Asians could have met and mixed with Neanderthals in some unknown areas, though this notion remains to be a speculation.
To examine the historical link between Neanderthals and humans, Quilodrán and the team examined 4,464 genomes of ancient to modern H. sapiens that were sequenced before. These genomes date from 40,000 years ago up until today. They examined Neanderthal DNA proportion relative to region, time, longitude, and latitude.
The researchers discovered that Neanderthal DNA proportions were anatomically higher among modern humans in Europe than in Asia during earlier times. This matches with what could have happened if early H. sapiens left Africa to meet cousins in Europe and Near East. The Neanderthal DNA reduction in Europeans came later.
Notable differences were observed between Neolithic farmers and European hunter-gatherers. The former came to settle in Europe roughly 10,000 years ago. The hunter-gatherers had higher Neanderthal gene proportions compared to Neolithic farmers, which suggests that the newcomers could have genomically diluted the ancestry of Neanderthals across Europe.
This was not observed in East Asia, which means that the dilutions did not occur in the same way.
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