In a groundbreaking study that reshapes our understanding of early human migration and interaction, scientists have analyzed the genome of the oldest human fossil ever found in Mongolia. This ancient individual, a woman who lived roughly 34,000 years ago, has provided valuable insight into the movements and relationships of early populations across the vast expanse of Eurasia. Researchers discovered that she inherited about 25 percent of her DNA from western Eurasians, a clear indication that early human populations were already highly mobile and interconnected, even in prehistoric times. Even more intriguing, her genetic makeup also includes traces of DNA from the mysterious Denisovans, an archaic human species that lived in Asia long before modern humans arrived.
The story begins in 2006, when miners working in the remote Salkhit Valley, located in Norovlin county in eastern Mongolia, made a remarkable discovery. They unearthed a hominin skullcap bearing unusual features that immediately puzzled scientists. Initially dubbed Mongolanthropus, some experts believed the skull might belong to a Neandertal, or even Homo erectus, two species of archaic humans known to have lived in Eurasia tens or hundreds of thousands of years ago. However, the remains—now known as the Salkhit individual—were destined to reveal an entirely different and more complex story.
The Salkhit skullcap represents the only known Pleistocene hominin fossil ever found in Mongolia, making it a unique window into the ancient past of East Asia. Advances in ancient DNA (aDNA) extraction and analysis allowed scientists to retrieve genetic material from the fossil. When they sequenced and examined her genome, they confirmed that the skullcap belonged not to a Neandertal or Homo erectus, but to a female modern human. She lived approximately 34,000 years ago and was genetically closer to ancient and modern Asians than to Europeans. Yet her genome contained a surprising amount of western Eurasian ancestry—an estimated one quarter—likely introduced through admixture with ancient populations living in Siberia.
These findings, published in the prestigious journal Science, suggest that human populations were not isolated in different corners of the Eurasian landmass but were instead interacting and mixing with each other far earlier than previously believed. According to Diyendo Massilani, lead author of the study and a researcher at the Max Planck Institute for Evolutionary Anthropology, this genetic evidence provides direct proof that modern human communities in East Asia were already cosmopolitan more than 34,000 years ago. “Migration and interaction among populations across Eurasia were not rare occurrences,” Massilani explains. “They happened frequently, and this was already the case tens of thousands of years ago.”
To make these discoveries, researchers at the Max Planck Institute developed and employed innovative techniques capable of identifying segments of DNA inherited from now-extinct hominins. They applied these methods not only to the Salkhit woman’s genome but also to the genome of another ancient human: a 40,000-year-old man from Tianyuan Cave, located outside Beijing, China. This individual, often referred to as the Tianyuan Man, is the only other early East Asian human whose genome has been thoroughly analyzed so far.
The comparison between the Salkhit and Tianyuan genomes revealed that the two individuals shared genetic ties, though they were not part of the same population. What set them apart was the Western Eurasian ancestry found in the Salkhit woman but absent in the Tianyuan Man. This suggests that the Salkhit woman’s population had interacted with western Eurasian groups, while the Tianyuan Man’s community had not—or at least not to the same extent.
Another fascinating aspect of both genomes is their inclusion of Denisovan DNA, confirming that interbreeding between Denisovans and modern humans occurred at least 40,000 years ago. Denisovans are a close cousin species to the Neandertals, and their remains have been found primarily in Denisova Cave in Siberia. However, evidence of Denisovan ancestry in modern populations is scattered across Asia and Oceania, particularly among Melanesian and Australian Aboriginal groups. What makes the discovery in Mongolia so significant is that it demonstrates early mixing events with Denisovans occurred farther north in East Asia, not only in the southern regions closer to Oceania.
Byambaa Gunchinsuren, a researcher from the Institute of Archaeology of the Mongolian Academy of Sciences, emphasizes the importance of this finding: “This is direct evidence that Denisovans and modern humans met and mixed more than 40,000 years ago in regions we hadn’t previously associated with Denisovan-modern human contact. The fact that the Salkhit woman carried Denisovan ancestry opens up new possibilities for understanding the range and influence of this archaic species.”
Adding another layer to the story, scientists discovered that the Denisovan DNA segments in both the Salkhit and Tianyuan genomes overlap with the Denisovan genetic sequences found in present-day East Asian populations, but not with the sequences found in populations from Oceania. This observation supports a theory of multiple, separate admixture events between Denisovans and modern humans at different times and locations in prehistory. It suggests that at least two distinct waves of interbreeding took place—one in East Asia and another, entirely separate event, contributing to the Denisovan ancestry observed in the peoples of Oceania.
The presence of Neandertal DNA in the Salkhit and Tianyuan individuals further highlights the complex web of interactions between archaic and modern human populations. These ancient people did not simply replace the earlier hominins they encountered as they expanded across Eurasia; they also interbred with them, incorporating archaic DNA into their own gene pools and passing it down to present-day populations. For example, all modern non-African humans carry Neandertal DNA, typically between 1 to 2 percent, as a legacy of these ancient interbreeding events.
These new insights from Mongolia challenge long-held assumptions about the direction and pace of human migration out of Africa and across Eurasia. Scientists now recognize that ancient human populations were more mobile and interconnected than once believed. There were no strict boundaries dividing regions or populations—people moved, met, and mixed with one another, shaping the complex tapestry of human ancestry we see today.
The discovery of the Salkhit woman’s genetic makeup not only expands our knowledge of early human history in East Asia but also raises exciting new questions about the movement of ancient human groups, their interactions with archaic hominins, and the diverse genetic legacies they left behind. As Diyendo Massilani puts it, “This rare specimen from Mongolia reminds us that prehistoric Eurasia was a place of dynamic human movement, cultural exchanges, and genetic diversity. We are only beginning to uncover the full story.”
Moving forward, researchers hope to find and analyze more ancient human fossils from Mongolia and surrounding regions. Each new discovery promises to refine our understanding of the ancient world and the ancestral relationships that tie all modern human populations together. The study highlights the importance of genomic research in archaeology and anthropology, offering a new lens through which we can view the deep history of our species.
More information: D. Massilani el al., “Denisovan ancestry and population history of early East Asians,” Science (2020). science.sciencemag.org/cgi/doi … 1126/science.abc1166
D. Zhang el al., “Denisovan DNA in Late Pleistocene sediments from Baishiya Karst Cave on the Tibetan Plateau,” Science (2020). science.sciencemag.org/cgi/doi … 1126/science.abb6320