Humans escaped Europe’s deep freeze

Where were the missing ancient DNA ancestors in European hunter-gatherers living in the coldest periods of the ice age?

To find out, Posth and his colleagues analysed hundreds of genome data from hunter-gatherers who lived in Europe and western Asia between 35,000 and 5,000 years ago.

Adding one data point is very important because the ancient genomes from this time period are hard to come by.

A landmark 2016 study identified a genetic signature in 35,000-year-old remains from the Goyet cave system in Belgium, which persisted in hunter-gatherer populations that lived tens of thousands of years later. The Goyet remains were associated with Aurignacian artefacts, a Europe-wide material culture known for its elaborate cave-wall art and ‘Venus’ figurines.

But the 2016 study raised a mystery. The Goyet ancestry was missing for a period of 20,000 years from the time before the ice age until it reappeared in hunter-gatherers in western Europe. “Where were these people hiding for 20,000 years?” asks Cosimo Posth, a palaeogeneticist at the University of Tübingen in Germany.

The researchers traced this ancestry to 21,000- and 23,000-year-old individuals from sites in northern Spain and southwestern France, respectively. The sites are connected to the culture of the Solutrean.

Posth says they descend from people who experienced the very low temperatures in southeastern Europe. There’s currently no ancient DNA from this time period to confirm that hunch, leaving a big empty spot on the map.

The work of an archaeologist at the University of Colorado Colorado Springs suggests that ice-age Italy was less friendly to humans than it was to Iberia4. He says that it makes sense that the eastern hunter-gatherers moved in because Italy was once connected to Croatia.

The studies paint a dynamic picture of European hunter-gatherer populations, which don’t always line up with cultural shifts, says Natasha Reynolds, a palaeolithic archaeologist at the University of Bordeaux, France. They also show that, for parts of Europe at least, the coldest period of the ice age wasn’t as inhospitable as it’s often made out to be. “People weren’t just huddling in caves waiting for the glaciers to retreat,” she says.

Fu says that the people were definitely East Asian and also northern East Asian. The genomes reveal fresh influxes of genes that suggest lowland East Asian immigrants arrived on the plateau more than once. Before 4,700 years ago, trade with millet farmers from the upper Yellow River region of what is now northeastern China was probably responsible for interactions between existing Tibetan settlers and newcomers. During the past 700 years, there has been a further influx of genes from the east.

When people established a long-term foothold on the area and where they came from, it has been a question of debate, according to a study by an evolutionary geneticist.

The historical records are only 2,500 years old. The central plateau might have been the home of people for as long as 7,400 years ago.

Computational genomics researcher Vagheesh Narasimhan at the University of Texas Austin says it’s very exciting that we are getting ancient DNA.

“There’s a continuity,” says Irene Gallego Romero, a genomics researcher at the University of Melbourne in Australia, “but there is also consistent movement of influences in and out of the region.”

Fu says that pottery and other artifacts show how populations are exchanging more than their culture and knowledge.

The high-altitude EPAS1 variant re-visited: When did it first come into existence, and how far back did it go?

It is unclear when the high-altitude EPAS1 variant first appeared. “It would be really interesting to know how far back that goes,” says Gallego Romero. Fu is keen to answer this question by sequencing genomes of older remains, if they are discovered on the plateau.