Modern humans have populated Europe for more than 45,000 years. However, our knowledge of the genetic relatedness and structure of ancient hunter-gatherers is limited, owing to the scarceness and poor preservation of human remains from that period. In new research, scientists from the University of Tübingen, the Max Planck Institute for Evolutionary Anthropology and elsewhere analyzed 356 ancient hunter-gatherer genomes, including new genomic data for 116 individuals from 14 countries in western and central Eurasia, spanning between 35,000 and 5,000 years ago. They identified a genetic ancestry profile in individuals associated with the Gravettian culture from western Europe that is distinct from contemporaneous groups related to this culture in central and southern Europe, but resembles that of preceding individuals associated with the Aurignacian culture. This ancestry profile survived during the Last Glacial Maximum — the coldest phase of the latest Ice Age — in human populations from southwestern Europe associated with the Solutrean culture, and with the following Magdalenian culture that re-expanded northeastward after the Last Glacial Maximum. Conversely, they revealed a genetic turnover in southern Europe suggesting a local replacement of human groups around the time of the Last Glacial Maximum, accompanied by a north-to-south dispersal of populations associated with the Epigravettian culture. From at least 14,000 years ago, an ancestry related to this culture spread from the south across the rest of Europe, largely replacing the Magdalenian-associated gene pool. After a period of limited admixture that spanned the beginning of the Mesolithic, the authors found genetic interactions between western and eastern European hunter-gatherers, who were also characterized by marked differences in genetic variants.
Reconstruction of a hunter-gatherer associated with the Gravettian culture (32,000-24,000 years ago), inspired by the archaeological findings at the Arene Candide site, Italy. Image credit: Tom Bjoerklund.
“The data we gained from this study provides us with astonishingly detailed insights into the developments and encounters of West Eurasian hunter-gatherer groups,” said Dr. Cosimo Posth, a researcher at the University of Tübingen and the Max Planck Institute for Evolutionary Anthropology.
“Further interdisciplinary research will clarify which exact processes were responsible for the genetic replacements of entire Ice Age populations.”
Modern humans began to spread across Eurasia around 45,000 years ago but previous research showed that the first modern humans that arrived in Europe did not contribute to later populations.
In their research, Dr. Posth and colleagues focused on the people who lived between 35,000 and 5,000 years ago and that are, at least partially, the ancestors of the present-day population of Western Eurasia, including — for the first time — the genomes of people who lived during the Last Glacial Maximum, around 25,000 years ago.
Surprisingly, they found that populations from different regions associated with the Gravettian culture, which was widespread across the European continent between 32,000 and 24,000 years ago, were not closely related to each other.
They were linked by a common archaeological culture: they used similar weapons and produced similar portable art.
Genetically, however, the populations from western and southwestern Europe (today’s France and Iberia) differed from contemporaneous populations from central and southern Europe (today’s Czech Republic and Italy).
Furthermore, the gene pool of the western Gravettian populations is found continuously for at least 20,000 years: their descendants who are associated with the Solutrean and Magdalenian cultures stayed in southwestern Europe during the coldest period of the Ice Age (between 25,000 and 19,000 years ago) and later spread north-eastward to the rest of Europe.
“With these findings, we can for the first time directly support the hypothesis that during the Last Glacial Maximum people found refuge in the climatically more favourable region of southwestern Europe,” Dr. Posth said.
The Italian peninsula was previously considered to be another climatic refugium for humans during the Last Glacial Maximum.
However, the researchers found no evidence for this, on the contrary: hunter-gatherer populations associated with the Gravettian culture and living in central and southern Europe are no longer genetically detectable after the Last Glacial Maximum.
People with a new gene pool settled in these areas, instead.
“We find that individuals associated with a later culture, the Epigravettian, are genetically distinct from the area‘s previous inhabitants,” said Dr. He Yu, a reseracher at the Max Planck Institute for Evolutionary Anthropology and Peking University.
“Presumably, these people came from the Balkans, arrived first in northern Italy around the time of the glacial maximum and spread all the way south to Sicily.”
The analyzed genomes also show that the descendants of these Epigravettian inhabitants of the Italian peninsula spread across the rest of Europe about 14,000 years ago, replacing populations associated with the Magdalenian culture.
“At that time, the climate warmed up quickly and considerably and forests spread across the European continent,” said Dr. Johannes Krause, a researcher at the Max Planck Institute for Evolutionary Anthropology.
“This may have prompted people from the south to expand their habitat.”
“The previous inhabitants may have migrated to the north as their habitat, the ‘mammoth’ steppe, dwindled.”
Furthermore, the findings show that there had been no genetic exchange between contemporaneous hunter-gatherer populations in western and eastern Europe for more than 6,000 years.
Interactions between people from central and eastern Europe can only be detected again from 8,000 years ago.
“At that time, hunter-gatherers with distinct ancestries and appearances started to mix with each other. They were different in many aspects, including their skin and eye color,” Dr. Yu said.
During this time agriculture and a sedentary lifestyle spread from Anatolia to Europe.
“It is possible that the migration of early farmers into Europe triggered the retreat of hunter-gatherer populations to the northern edge of Europe,” Dr. Krause said.
At the same time, these two groups started mixing with each other, and continued to do so for around 3,000 years.
“Our study reveals that western and southwestern Europe served as climatic refugia for the persistence of human groups during the coldest phase of the latest Ice Age whereas populations in the Italian peninsula and the eastern European plain were genetically overturned, challenging the role of these regions as glacial refugia for humans,” the authors concluded.
“The incoming Villabruna ancestry later became the most widespread hunter-gatherer ancestry across Europe.”
Further paleogenomic studies on Upper Paleolithic individuals from the Balkans will be essential for understanding whether southeastern Europe represents the source of the Villabruna ancestry and a climatic refugium for human populations during the Last Glacial Maximum.”
The research is described in a paper published in the journal Nature.
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C. Posth et al. 2023. Palaeogenomics of Upper Palaeolithic to Neolithic European hunter-gatherers. Nature 615, 117-126; doi: 10.1038/s41586-023-05726-0
