Ice Age DNA Suggests Europeans Weren’t So Isolated After All

Cave Bone Links Ice Age Europe’s West to Its East

A woman who lived about 30,000 years ago in what is now southwestern France carried DNA from two sides of Europe. Most of her ancestry matched other people from the west, as expected. A smaller share matched groups tied to central and eastern Europe, evidence that distant Ice Age populations were in contact earlier, and farther south, than DNA had previously shown.

Her genetic profile came from a bone fragment found in Isturitz Cave, in the French Basque Country. It anchors a new study in Science Advances that examined three Ice Age individuals from France, Spain, and Italy, plus DNA pulled directly from cave dirt in northern Spain.

Between roughly 34,000 and 25,000 years ago, the Gravettian culture spread across Europe, and its portable art, tools, and burial practices looked broadly alike from region to region, hinting at far-reaching social networks. DNA told a different story, with two main ancestry groups, one western and one eastern, staying largely separate. Only about 25 Gravettian individuals have yielded broad genetic data, so each new person can shift the picture.

Bone, Tooth, and Cave Dirt Yielded Rare Ice Age DNA

Researchers recovered 454,258 genetic markers from the Isturitz woman’s bone. Markers are single spots in the DNA code that differ from person to person. Her dataset is the oldest broad genetic record yet recovered from a modern human in southwestern Europe. A tooth from a woman who lived around 27,000 years ago in Chufín Cave, in Cantabria, Spain, fared worse. It was heavily degraded and carried some modern DNA contamination, leaving only 19,895 markers, too few for a detailed look at her ancestry.

A male fetus from Ostuni Cave in southern Italy, called Ostuni1b, was the third individual, dating to between about 27,800 and 27,400 years ago. His 467,368 markers showed he was most likely the son of Ostuni1, a woman studied earlier, with no sign his father came from a different population. Genetic predictions for the newly studied individuals pointed to dark skin, dark hair, and brown eyes, traits typical of Europeans from that era.

Skeletons from the coldest stretch of the Ice Age, about 26,500 to 19,000 years ago, are “extremely rare,” in the authors’ words. So the team tested a layer of sediment from El Mirón Cave, dated to about 22,000 years ago. After repeated rounds of sequencing, they recovered close to 14,000 usable human markers, enough to link that layer to a specific ancestry without a single bone. Dirt can hold DNA from several people, so the result reflects a group, not an individual.

Ice Age Europeans in France Carried Eastern Ancestry

Earlier DNA studies had found two main ancestry groups in Gravettian Europe, one western and one eastern, the latter best known from skeletons in the Czech Republic. The clearest earlier example of a blend of the two came from Belgium, in people who lived around 27,000 years ago.

Statistical tests detected the eastern share in the Isturitz woman’s ancestry, and a best-fit model traced it to a population related to the ancestors of the Czech skeletons. Ormesson, a site in France’s Paris Basin, showed a similar signal when its previously published DNA was reexamined. To date the blend, the team used a method that reads how inherited DNA from two groups gets shuffled apart over generations. Assuming a single event, its estimate put the blend between about 32,500 and 31,500 years ago.

Two explanations fit the evidence. People from the east may have met western groups during the early Gravettian, or an older eastern-related ancestry may already have been in the west. The authors consider the first better supported, since the signal is missing from earlier Belgian samples and vanishes from every sampled southwestern European individual after 30,000 years ago, including the Chufín woman. Isturitz makes a plausible meeting spot. Archaeologists have long viewed the cave as a gathering place where groups came together to hunt, trade goods and information, socialize, and find mates. Its artifacts, among the richest collections of portable art in southern Europe, resemble items found across the Pyrenees and Cantabria.

Which eastern group was involved, and what route it took, remains unknown. Comparisons with several groups from the eastern cluster found no clear candidate.

Cave Dirt Shows Western Ancestry Persisted Through the Freeze

DNA from the El Mirón dirt carried the same western ancestry seen in older skeletons from the region. Combined with earlier data, that points to the western line holding on in southwestern Europe until about 21,000 years ago, through the coldest stretch. Earlier work had proposed that southwestern Europe carried only western ancestry around 30,000 years ago, and the Isturitz woman contradicts that. The genetic data argue against a major population replacement there around 28,000 years ago, a turnover that earlier researchers had inferred from fossil teeth.

Ice Age Europe was more connected than its genes once suggested. Matching art and tools hinted at that, and DNA from a single bone in a French cave now backs it up, at least in part.

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