Neanderthal DNA Theory Explains Major Mystery
A new analysis of ancient genomes has shed light on the mystery of Neanderthal DNA carried by human populations in Europe and Asia. Published in the journal Science Advances (via CNN), the study presents a more precise understanding of Neanderthal genetic contributions, made possible by a wealth of invaluable data.
In East Asia, where Neanderthals were never believed to have lived, people have higher percentages of Neanderthal DNA than Europe likely because of genome dilution.
The story of Neanderthal interbreeding with early Homo sapiens has fascinated scientists for years. Most humans today carry a tiny percentage of Neanderthal DNA due to prehistoric liaisons between our ancestors and these now-extinct hominins. These interactions occurred before the Neanderthals’ extinction around 40,000 years ago.
However, Neanderthal DNA is slightly more prevalent in the genomes of East Asian populations despite Neanderthal remains being discovered in Europe and the Middle East. Mathias Currat, a senior lecturer of genetics and evolution at the University of Geneva and co-author of the study, addressed the situation, saying, “So what’s puzzling is that in an area where we’ve never found any Neanderthal remains, there’s more Neanderthal DNA.”
On average, Neanderthal DNA constitutes about 2 percent of the genetic makeup of people in Eurasia. However, this proportion can be as high as 4 percent in East Asia. To solve this mystery, researchers at the University of Geneva conducted a meticulous analysis of the distribution of Neanderthal DNA in human genomes over the past 40,000 years.
“We are beginning to have enough data to describe more and more precisely the percentage of DNA of Neanderthal origin in the genome of Sapiens at certain periods of prehistory,” Currat explained. Interestingly, the findings revealed that the distribution of Neanderthal DNA didn’t always appear as it does today.
The research team used a database containing more than 4,000 ancient genomes from Europe and Asia to uncover the missing piece of the puzzle. The analysis demonstrated that Stone Age Homo sapiens in Europe, who lived as hunter-gatherers after the Neanderthals’ extinction, carried a slightly higher proportion of Neanderthal DNA than their counterparts in Asia for samples older than 20,000 years.
Most humans today carry a tiny percentage of Neanderthal DNA due to prehistoric liaisons between our ancestors and these now-extinct hominins.
This led the researchers to conclude that the current pattern of higher Neanderthal ancestry in Asian populations compared to European populations likely developed later, particularly during the Neolithic transition, when farming began to replace hunting and gathering as the predominant way of life approximately 10,000 to 5,000 years ago.
During this period, the first farmers from Anatolia, modern-day western Turkey, and the Aegean region mixed with hunter-gatherer populations in Western and Northern Europe. This intermingling resulted in a lower proportion of Neanderthal DNA observed in European genomes, effectively diluting the Neanderthal ancestry.
“The thing was that they had less Neanderthal ancestry, so they diluted the (Neanderthal ancestry) in European populations,” Currat continued. However, the transition in Asia remains less clear due to a relative lack of information, as the study included 1,517 samples from Europe compared to 1,108 from Asia, an area more than four times larger.
Neanderthal DNA is slightly more prevalent in the genomes of East Asian populations despite Neanderthal remains being discovered in Europe and the Middle East.
Tony Capra, an associate professor at the University of California, San Francisco, not affiliated with the research, described the study as “an exciting and promising strategy for integrating analysis of ancient human and Neanderthal DNA from different geographic locations with modern genomes to connect the dots of evolution through time and space.”
The research also emphasizes the potential medical relevance of Neanderthal DNA in modern humans. For instance, previous studies have suggested that some genetic traces left by Neanderthals could influence modern humans’ health, potentially playing a role in conditions like Covid-19.
Neanderthal DNA offers a unique perspective on our complex genetic heritage, tracing the footsteps of our ancient ancestors and revealing how they continue to influence our genetic makeup and health in the present day.
