New research has uncovered intricate dynamics of Denisovan ancestry among Eurasians over the past 40,000 years, emphasizing a diverse history of interactions between modern humans and Denisovans.
In this groundbreaking study, scientists performed a systematic analysis of ancient DNA segments inherited from Denisovans, which have been identified in both ancient and contemporary human populations. By examining these genetic segments over millennia, the researchers were able to reconstruct the patterns of Denisovan ancestry across continental Eurasia.
The team compiled ancient genome data from various Eurasian populations and discovered that some of the earliest East Asians, including the Tianyuan individual from China, who lived approximately 40,000 years ago, exhibited the highest levels of Denisovan ancestry, exceeding 0.2 percent compared to all other ancient and modern individuals studied.
However, the patterns of shared Denisovan DNA segments among these individuals suggest that their ancestry stemmed from common interactions with Denisovans at different times. “This indicates that gene flow occurred from a source with less or no Denisovan ancestry, diluting the Denisovan ancestry of early East Asians,” said population geneticist Stéphane Peyrégne, who co-supervised the study.
The findings also demonstrate that Denisovan ancestry reached West Eurasia, albeit at a minimal level, primarily due to the migration of people from Eastern Eurasia that began before around 12,000 years ago.
Interestingly, the study highlights the ancient Jomon people of Japan and the Ryukyu/Okinawa islands, who are ancestors of modern Japanese. The Jomon exhibited the lowest Denisovan ancestry among East Asians, even though their Denisovan lineage shared the same origin as populations on the mainland. This implies that the Jomon descended from a lineage that did not encounter Denisovans directly but instead acquired their Denisovan ancestry through subsequent gene flow from Mainland East Asia.
Alternatively, this lineage might have received limited Denisovan gene flow prior to diverging from other East Asians but subsequently missed a significant influx of Denisovan genes. “This suggests that some groups took different routes during the early dispersals in East Asia, or Denisovans were so sparsely distributed that interactions with them were rare,” explained lead author Jiaqi Yang, a PhD researcher at the Max Planck Institute for Evolutionary Anthropology.
While knowledge about the origins of the Jomon and other East Asians during the Paleolithic remains limited, these findings underscore a complex and regionally varied history of interactions between modern humans and Denisovans. Future research utilizing additional ancient genomic data is expected to provide further insights into the timing and nature of these interactions.
