A new genetic analysis reveals a surprising lack of Denisovan DNA among prehistoric people who lived in Japan’s Jomon period (roughly 16,000 to 3,000 years ago). This finding offers intriguing hints about early human movements and interactions across Eurasia. The study, published in Current Biology, explored the complex history of gene mixing between modern humans (Homo sapiens) and their mysterious cousins, the Denisovans.
Denisovans, an extinct group of hominins known only through fragmentary fossil remains and genetic traces, once populated parts of Eurasia. Their DNA lingers today in people of Oceanic, East Asian, Southeast Asian, and Indigenous American descent. Scientists use this “Denisovan fingerprint” to piece together the ancient journeys of these archaic humans.
The research team compared genetic data from 115 ancient individuals spanning multiple regions of Eurasia and dating back as far as 45,000 years ago with that of 279 modern-day individuals. The findings paint a compelling picture of Denisovan influences across different populations:
- East Asian Ancestry: Ancient mainland East Asians from China and Mongolia carried the highest concentration of Denisovan DNA among all Eurasian groups analyzed. This significant amount suggests multiple encounters with different Denisovan populations before the Last Glacial Maximum (a period of intense cold approximately 26,500 to 19,000 years ago).
- Western Eurasian Ties: In contrast, ancient people from West Eurasia (Iran and Georgia) exhibited the lowest levels of Denisovan ancestry.
The most surprising discovery? The Jomon people of prehistoric Japan, who lived around 16,000 to 3,000 years ago, had remarkably little Denisovan DNA. One individual from this period, dating back about 3,755 years, possessed only one-sixth to one-eighth the Denisovan genetic contribution seen in modern East Asians. This finding contrasts sharply with the substantial Denisovan ancestry found in later Japanese populations from the Kofun period (roughly A.D. 300 to 710), suggesting a subsequent influx of Denisovan genes possibly linked to migrations from mainland East Asia into Japan during this time.
While the reasons for this unique pattern in Jomon ancestry remain unclear, researchers offer several possibilities:
- Distinct Migration Routes: Early modern humans may have taken diverse paths as they spread across East Asia, leading some groups – like the Jomon – to avoid encountering Denisovans altogether.
- Sparse Denisovan Distribution: Denisovans may have been geographically scattered, making contact with them a relatively rare occurrence for certain populations, including the early Jomon.
Further genetic analysis from earlier periods in Japan’s prehistory (around 32,000 years ago) could shed more light on this intriguing puzzle and refine our understanding of how ancient humans interacted across Eurasia. This study underscores the power of ancient DNA to unravel complex migration patterns and illuminate the interconnected history of human evolution.
