A collection of stone artifacts unearthed at the archaeological site of Tolbor-16 in the northern Khangai Mountains of Mongolia indicate that anatomically modern Homo sapiens traveled across the Eurasian steppe 45,000 years ago, about 10,000 years earlier than previously thought.
“The site points to a new location for where modern humans may have first encountered their mysterious cousins, Denisovans,” said Dr. Nicolas Zwyns, a researcher at the University of California, Davis, and the Max-Planck Institute for Evolutionary Anthropology.
The excavations at Tolbor-16 yielded thousands of stone artifacts, with 826 stone artifacts associated with the oldest human occupation at the site.
“With long and regular blades, the tools resemble those found at other sites in Siberia and Northwest China — indicating a large-scale dispersal of humans across the region,” Dr. Zwyns said.
“These objects existed before, in Siberia, but not to such a degree of standardization.”
“The most intriguing aspect is that they are produced in a complicated yet systematic way — and that seems to be the signature of a human group that shares a common technical and cultural background.”
That technology, known in the region as the Initial Upper Paleolithic, led the researchers to rule out Neanderthals or Denisovans as the site’s occupants.
“Although we found no human remains at the site, the dates we obtained match the age of the earliest Homo sapiens found in Siberia,” Dr. Zwyns said.
“After carefully considering other options, we suggest that this change in technology illustrates movements of Homo sapiens in the region.”
The age of the Tolbor-16 site is about 10,000 years earlier than the fossil of a human skullcap from Mongolia, and roughly 15,000 years after modern humans left Africa.
Evidence of soil development — grass and other organic matter — associated with the stone tools suggests that the climate for a period became warmer and wetter, making the normally cold and dry region more hospitable to grazing animals and humans.
Dr. Zwyns and colleagues also found bone fragments large (wild cattle or bison) and medium size bovids (wild sheep, goat) and horses, which frequented the open steppe, forests and tundra during the Pleistocene.
The dates for the stone tools also match the age estimates obtained from genetic data for the earliest encounter between Homo sapiens and Denisovans.
“Although we don’t know yet where the meeting happened, it seems that Denisovans passed along genes that will later help Homo sapiens settling down in high altitude and to survive hypoxia on the Tibetan Plateau,” Dr. Zwyns said.
“From this point of view, the site of Tolbor-16 is an important archaeological link connecting Siberia with Northwest China on a route where Homo sapiens had multiple possibilities to meet local populations such as Denisovans.”
The study was published online in the journal Scientific Reports.
Nicolas Zwyns et al. 2019. The Northern Route for Human Dispersal in Central and Northeast Asia: New Evidence from the Site of Tolbor-16, Mongolia. Scientific Reports 9, article number: 11759; doi: 10.1038/s41598-019-47972-1