Ice sheets spread across much of northern Europe around 25,000 to 19,000 years ago, rendering a huge expanse of land uninhabitable. This difficult event sparked a previously unrecognized story of two human populations that took place on opposite ends of the continent.
Western European hunter-gatherers have survived the ice blast in the past. The Orientals were replaced by migrations of newcomers.
It is the implication of the largest study to date of the DNA of ancient Europeanscovering a period before, during and after what is called the last glacial maximum, paleogeneticist Cosimo Posth and his colleagues report on March 1 at Nature.
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As researchers have long thought, southwestern Europe provided refuge from the severe cold of the last Ice Age for hunter-gatherers based in and near this region, scientists say. But it turns out that southeastern Europe, where Italy is now, did not offer lasting respite from the cold for nearby groups, as previously assumed.
Instead, these people were replaced by genetically distinct hunter-gatherers who had presumably lived just east along the Balkan Peninsula. These people, who had ancestors from parts of southwestern Asia, began their trek in what is now northern Italy around 17,000 years ago, as the Ice Age began. to decline.
“So local [Ice Age] populations from Italy did not survive and were replaced by groups from the Balkans, this completely changes our interpretation of the archaeological record,” says Posth, from the University of Tübingen in Germany.
Posth and his colleagues’ findings are based on DNA analyzes of 356 ancient hunter-gatherers, including new molecular evidence for 116 individuals from 14 countries in Europe and Asia. Excavated human remains that yielded DNA dated between about 45,000 and 5000 years ago (SN: 07/04/21).
Comparisons of sets of genetic variants inherited by these hunter-gatherers from common ancestors have allowed researchers to piece together the population movements and replacements that shaped the genetic makeup of ancient Europeans. For the first time, ancient DNA evidence included individuals from the so-called Gravettian culture, which dates to around 33,000 to 26,000 years ago in central and southern Europe, and the southern Solutrean culture. -western Europe, which dates from around 24,000 to 19,000 years ago. .
Contrary to expectations, Gravettian toolmakers belonged to two genetically distinct groups that populated Western and Eastern Europe for about 10,000 years before the Ice Age reached its peak, Posth says. Scholars have traditionally viewed Gravettian tools as the products of a biologically uniform population that occupied much of Europe.
“What we previously thought was one genetic ancestry in Europe turned out to be two,” says paleogeneticist Mateja Hajdinjak of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who was not involved in the news. study. And “it seems that western and southwestern Europe served as [refuge from glaciation] more than South Eastern Europe and Italy.
The descendants of the Western Gravettian population, which are associated with Solutrean artifacts and remnants of another ancient culture in Western Europe that occurred around 19,000 to 14,000 years ago, survived the Ice Age before spreading northeast across Europe, researchers say.
Further support for southwestern Europe as an Ice Age refuge comes from DNA extracted from a pair of fossil teeth that once belonged to an individual linked to the Solutrean culture in southern Spain. . This adult of about 23,000 years was genetically similar to Western European hunter-gatherers who lived before and after the Last Glacial Maximum, Max Planck paleogeneticist Vanessa Villalba-Mouco and her colleagues, including Posth, report on March 1 to Nature ecology and evolution.
During this time, genetic evidence suggests that the hunter-gatherers of what is now Italy were replaced by people further east, likely based in the Balkan region. These newcomers must have brought with them a distinctive brand of stone artifacts, previously excavated at Italian sites and elsewhere in Eastern Europe, known as Epigravettian tools, Posth explains. Many archaeologists have suspected that the Epigravettian artefacts were the products of hunter-gatherers who clustered in Italy during the peak freeze of the Ice Age.
But, says Hajdinjak, DNA analyzes from fossils of Ice Age Balkan peoples are needed to clarify which groups passed through Italy and when those migrations took place.
Ultimately, descendants of Ice Age migrants to Italy reached southern Italy and then western Europe around 14,000 years ago, according to Posth and his colleagues. Ancient DNA evidence indicates that during these journeys they left a major genetic mark on hunter-gatherers across Europe.