Neanderthals, once the dominant human species across Europe, are believed to have disappeared around 39,000 to 41,000 years ago. Despite their extinction, they continue to leave a genetic legacy in present-day populations, particularly in those of Eurasian descent. Modern humans in these regions carry between 1 to 3% Neanderthal DNA, a testament to the ancient interactions between the two species. However, despite the widespread distribution of Neanderthals in Europe and theories suggesting significant cultural exchanges with modern humans, there had been little evidence, until recently, that Neanderthal genes were passed down to the current population in any significant way. This led to some confusion and debate among scientists about the exact nature of human-Neanderthal interactions in Europe.
However, a groundbreaking discovery has provided new insight into this issue. Dr. Fu Qiaomei and a team of scientists from Germany, the USA, Romania, and Canada unearthed evidence that a 37,000 to 42,000-year-old modern human found at the Peştera cu Oase cave in Romania—known as Oase 1—contained a remarkable percentage of Neanderthal ancestry. The research, published on June 22 in Nature, shows that approximately 6–9% of the genome of this individual is derived from Neanderthals, far more than any other modern human sequenced to date. This finding significantly shifts the understanding of Neanderthal interaction with early humans, suggesting that these genetic exchanges weren’t confined to the first waves of humans leaving Africa or even to regions like the Near East but likely occurred within Europe as well. The implications of this discovery paint a new picture of how modern humans and Neanderthals may have coexisted and intermixed in Europe.
The Oase 1 specimen was found in 2002 in the Peştera cu Oase cave, located in the southern Carpathian Mountains of Romania. A mandible belonging to this individual provided crucial insights into the early population of modern humans in Europe. The direct radiocarbon dating of the specimen suggested an age of approximately 37,000 to 42,000 years, making Oase 1 one of the earliest known modern humans to have inhabited Europe. Morphologically, Oase 1 displayed mostly modern human features, but some aspects of its structure showed evidence of Neanderthal traits, hinting at possible interbreeding.
Researchers faced the challenge of extracting usable DNA from this ancient specimen, as the bone contained relatively small amounts of human DNA. To overcome this, the team employed an innovative enrichment strategy that focused on isolating DNA sequences particularly informative about Neanderthal ancestry. By carefully analyzing these DNA fragments, the team was able to determine that around 6–9% of the genome of Oase 1 was of Neanderthal origin, which is a higher proportion than any other modern human genome sequenced to date.
The Neanderthal ancestry was concentrated in three significant chromosomal segments, each more than 50 centimorgans in size. This suggests that the individual had a Neanderthal ancestor as recently as four to six generations prior to their life, which places the interbreeding event to less than 200 years before the time Oase 1 lived. Such a close genetic connection indicates that Neanderthals and modern humans in Europe were interbreeding well after the initial migration of Homo sapiens from Africa, offering evidence that these interbreeding events were more complex and enduring than previously thought.
Despite this significant amount of Neanderthal ancestry, the Oase 1 individual’s genetic makeup did not show a stronger connection to later European populations than to East Asians. This suggests that while there was interbreeding, the Oase population, represented by Oase 1, did not contribute substantially to the genetic makeup of later Europeans. In other words, although the Oase 1 individual possessed significant Neanderthal ancestry, his population may not have been a major contributor to the broader genetic pool of Europe. As explained by Dr. Fu Qiaomei, the lead author of the study, “the Oase individual does not share more alleles with later Europeans than with East Asians, suggesting that the Oase population did not contribute substantially to later humans in Europe.”
The discovery challenges earlier assumptions about the patterns of Neanderthal interbreeding and raises intriguing questions about the dynamics between early modern humans and Neanderthals. As Dr. Mateja Hajdinjak, another key researcher in the study, pointed out, the close relationship between Oase 1 and a Neanderthal ancestor suggests that the mixture between the two species occurred much later than previously believed. The individual’s Neanderthal ancestry, removed by only a few generations, implies that Neanderthal admixture did not just occur in the distant past but continued much later into human history, potentially overlapping with the lives of early modern humans in Europe.
Importantly, the research also suggests that the genetic legacy of Neanderthals may have been uneven across different populations. While Oase 1 shows significant Neanderthal ancestry, the absence of a clear genetic link to later populations of Europeans hints that his group may have been one of many early modern human populations in Europe that interbred with Neanderthals, but did not leave a lasting genetic imprint on subsequent generations. Dr. Hajdinjak emphasized the need for further study of other specimens like Oase 1 to better understand the complex interactions between early humans and Neanderthals. Specimens with morphological features suggestive of Neanderthal admixture could hold the key to unraveling the story of early human migration, evolution, and the nature of their interactions with Neanderthals.
The findings of this study add to a growing body of evidence that suggests that Neanderthals were more deeply integrated into the human story than once thought. For many years, the interaction between Neanderthals and modern humans was assumed to be relatively short-lived and limited, confined mainly to the initial periods of human migration into Europe and Asia. However, with discoveries like the Oase 1 genome, it is becoming increasingly clear that the relationship between Neanderthals and early modern humans was far more complex and enduring. Far from being a brief, isolated event, the mixing of Neanderthal and Homo sapiens genomes appears to have been a continuous process, especially in regions like Europe where both species coexisted for thousands of years.
Moreover, this discovery also has profound implications for understanding the nature of human evolution. The genetic material passed down from Neanderthals continues to influence the health and traits of modern humans, contributing to various aspects of human biology. Some studies have suggested that Neanderthal DNA could be linked to immune response, skin pigmentation, and even certain medical conditions, offering a window into how our ancient ancestors may have adapted to their environments and how those adaptations were passed down through generations.
This research also highlights the importance of studying ancient populations from a variety of archaeological sites. While the genome of Oase 1 sheds new light on the past, it is just one piece of a larger puzzle. Further analysis of other specimens, particularly those with mixed Neanderthal features, will undoubtedly yield even more valuable insights into the complex web of human history. As genetic technology continues to advance, it is likely that more evidence will come to light, revealing an even more intricate picture of our shared ancestry with Neanderthals.
More information: “An early modern human from Romania with a recent Neanderthal ancestor.” Nature (2015) DOI: 10.1038/nature14558