Ancient DNA Reveals History of Hunter-Gatherers in Europe

"Looking at DNA gleaned from ancient remains, researchers identified at least eight previously unknown populations of early Europeans.

In the 1800s, archaeologists began reconstructing the deep history of Europe from the bones of ancient hunter-gatherers and the iconic art they left behind, like cave paintings, fertility figurines and “lion-man” statues.

Over the past decade, geneticists have added a new dimension to that history by extracting DNA from teeth and bones.

And now, in a pair of studies published on Wednesday, researchers have produced the most robust analysis yet of the genetic record of prehistoric Europe.

Looking at DNA gleaned from the remains of 357 ancient Europeans, researchers discovered that several waves of hunter-gatherers migrated into Europe. The studies identified at least eight populations, some more genetically distinct from each other than modern-day Europeans and Asians. They coexisted in Europe for thousands of years, apparently trading tools and sharing cultures. Some groups survived the Ice Age, while others vanished, perhaps wiped out by other groups.

“We are finally understanding the dynamics of European hunter-gatherers,” said Vanessa Villalba-Mouco, a paleogeneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and an author of both studies.

The new genetic analysis suggests that when farmers arrived in Europe about 8,000 years ago, they encountered the descendants of this long history, with light-skinned, dark-eyed people to the east, and possibly dark-skinned and blue-eyed people to the west.

Dr. Villalba-Mouco and her colleagues have given these peoples a list of new names that can be as hard to memorize as the kingdoms of Westeros: the Fournol, the Vestonice, the GoyetQ2, the Villabruna, the Obserkassel and the Sidelkino, among others.

But the scientists are only just beginning to understand how so many different groups emerged 45,000 to 5,000 years ago.

“I didn’t expect these amounts of replacements and changes in ancestry,” said Carles Lalueza-Fox, the director of the Natural Sciences Museum in Barcelona and an author of one of the new papers. “We lack still an understanding of why these movements were triggered. What happened here, why it happened — it’s strange.”

Modern humans arose in Africa and expanded to other continents about 60,000 years ago. Last year, archaeologists reported what might be the oldest evidence of those humans reaching Europe: a set of 54,000-year-old teeth in a French cave.

When these groups arrived in Europe, Neanderthals had already been living across the continent for more than 100,000 years. The Neanderthals disappeared about 40,000 years ago, perhaps because modern humans outcompeted them with superior tools.

But the oldest DNA of modern humans in Europe, dating back 45,000 years, undermines such a simple story. It comes from people who belonged to a lost branch of the human family tree. Their ancestors were part of the expansion out of Africa, but they split off on their own before the ancestors of living Europeans and Asians split apart.

These early Europeans have almost no genetic link to younger remains of hunter-gatherers. It appears that the first modern humans in Europe may have disappeared along with the Neanderthals, said Cosimo Posth, a paleogeneticist at the University of Tübingen in Germany and an author on the two papers published Wednesday.

“It’s actually quite interesting that the very first modern humans also had a very hard time to actually survive,” Dr. Posth said.

Before the advent of ancient DNA analysis, archaeologists would give names to cultures based on the styles of the things they made. The oldest modern human culture in Europe is known as the Aurignacians, named for the continent’s oldest figurative cave paintings and sculptures.

About 33,000 years ago, as the climate turned cold, a new culture called the Gravettian arose across Europe. Gravettian hunters made spears to kill woolly mammoths and other big game. They also made so-called Venus figurines that might have represented fertility.

Dr. Posth and his colleagues found DNA in Gravettian remains scattered across Europe. The scientists had expected all of the individuals to have come from the same genetic population, but instead found two distinct groups: one in France and Spain, and another in Italy, the Czech Republic and Germany.

“They were very distinct, and this was a very big surprise to us because they practiced the same archaeological culture,” Dr. Posth said.

Dr. Posth and his colleagues named the western population the Fournol people, and found a genetic link between this group and 35,000-year-old Aurignacian remains in Belgium.

They called the eastern group Vestonice, and discovered that they share an ancestry with 34,000-year-old hunter-gatherers who lived in Russia.

That genetic gulf led Dr. Posth and his colleagues to argue that the Fournol and Vestonice belonged to two waves that migrated into Europe separately. After they arrived, they lived for several thousand years sharing the Gravettian culture but remaining genetically distinct.

“This result is, in my opinion, groundbreaking,” said Anaïs Luiza Vignoles, an archaeologist at the University of Paris who was not involved in the study.

Dr. Vingoles said that archaeologists could now investigate the kind of cultural contacts these two populations had. It’s clear from the new study that they were not isolated entirely from each other. In Belgium, the scientists found 30,000-year-old remains with a mix of Fournol and Vestonice ancestry.

Jüergen Richter, an archaeologist at the University of Cologne who was not involved in the new studies, suggested that in these sporadic contacts between the two peoples, they might have shared cultural ideas and artifacts like fertility figuring. “I’m absolutely not surprised,” he said of the new findings.

About 26,000 years ago, the two groups faced a new threat to their survival: an advancing wall of glaciers. During the Ice Age, from 26,000 to 19,000 years ago, European hunter-gatherers were shut out of much of the continent, surviving only in southern refuges.

Dr. Villalba-Mouco and her colleagues shed light on the refuge of the Iberian Peninsula, the region now occupied by Spain and Portugal, by studying DNA in the teeth of a 23,000-year-old man found in a cave in southern Spain. His DNA revealed that he belonged to the Fournol people who lived in Iberia before the Ice Age. The researchers also found genetic markers linking him to a 45,000-year-old skeleton discovered in Bulgaria.

When the glaciers retreated, some descendants of the Fournol continued living in Iberia. But others expanded north as a new population, which Dr. Posth and his colleagues called GoyetQ2. “It really seems like a peopling of Europe after the last glacial maximum,” he said.

The Vestonice, by contrast, did not survive the Ice Age. When the glaciers were at their most expansive, the Vestonice may have endured for a time in Italy. But Dr. Posth and his colleagues found no Vestonice ancestry in Europeans after the Ice Age. Instead, they discovered a population of hunter-gatherers that appeared to have expanded from the Balkans, known as the Villabruna. They moved into Italy and replaced the Vestonice.

For several thousand years, the Villabruna were limited to southern Europe. Then, 14,000 years ago, they crossed the Alps and encountered the GoyetQ2 people to the north. A new population emerged, its ancestry three parts Villabruna to one part GoyetQ2.

This new people, which Dr. Posth and his colleagues called Oberkassel, expanded across much of Europe, replacing the old GoyetQ2 population.

Dr. Posth speculated that another climate shift could explain this new wave. About 14,000 years ago, a pulse of strong warming produced forests across much of Europe. The Oberkassel people may have been better at hunting in forests, whereas the GoyetQ2 retreated with the shrinking steppes.

To the east, the Oberkassel ran into a new group of hunter-gatherers, who probably arrived from Russia. The scientists named this group’s descendants, who lived in Ukraine and surrounding regions, the Sidelkino.

But in Iberia, there were no great sweeps of newcomers replacing older peoples. The Iberians after the Ice Age still carried a great deal of ancestry from the Fournol people who had arrived there thousands of years before the glaciers advanced. The Villabruna people moved into northern Spain, but added their DNA to the mix rather than replacing those who were there before.

When the first farmers arrived in Europe from Turkey about 8,000 years ago, three large groups of hunter-gatherers thrived across Europe: the Iberians, the Oberkassel and the Sidelkino. Living Europeans carry some of their genes, which allowed Dr. Posth and his colleagues to make some educated guesses about the physical appearances of the ancient populations.

The Sidelkino people in the east had genes associated with dark eyes and light skin. The Oberkassel in the west, in contrast, probably had blue eyes and may have had dark skin, although it’s harder to be sure of their appearance than the Sidelkino.

These three groups of hunter-gatherers remained isolated from each other for about 6,000 years, until the farmers from Turkey arrived. After this advent of agriculture, the three groups began mixing, the scientists found. It’s possible that the spread of farmland forced them to move to the margins of Europe to survive. But over time, they were absorbed into the agricultural communities that surrounded them.

Ludovic Orlando, a molecular archaeologist at Paul Sabatier University in France who was not involved in the new research, said that it was a milestone in the study of early humans. “I was really blown away,” he said.

Dr. Orlando said that every continent will likely have its own history of hunter-gatherer migrations. Researchers were able to plumb Europe’s history in such great detail because they could take advantage of 150 years’ worth of remains that have been stored in museums there.

But he predicted that scientists won’t have to dig up a lot of new skeletons on other continents to reconstruct their genetic histories. That’s because it is now possible to extract human DNA from cave sediments rather than searching for bones and teeth.

“We cannot develop a Eurocentric vision of the past,” Dr. Orlando said."