Genetics study reveals Ice Age drama for humans in Europe

By Will Dunham

(Reuters) – Europe was no warm paradise during the Ice Age, with the huge glaciers covering large parts of the continent and making large areas inhospitable to humans. But our species – a new immigrant to Europe – persevered, but with great adversity.

Scientists on Wednesday unveiled an analysis of genome data from 356 hunter-gatherers who lived in the region between 35,000 and 5,000 years ago, a span that included the coldest interval of the Ice Age between 25,000 and 19,000 years ago. This enabled them to decipher the population dynamics of prehistoric Europe, including the movement of groups of people and some important physical characteristics.

While some populations hunkered down and survived in relatively warmer parts of Europe, including France, Spain and Portugal, others died out on the Italian peninsula, the study showed. It also provided insight into the emergence of traits such as fair skin and blue eyes in Europeans.

“It is the largest ancient genomic dataset of European hunter-gatherers ever produced,” said paleogeneticist Cosimo Posth of the University of Tübingen in Germany, lead author of the study published in the journal Nature.

“It refreshes our knowledge of how humans survived the Ice Age,” added paleogeneticist and study co-author He Yu of Peking University in China.

Europe had been the domain of the Neanderthals, our robust and big-browed cousins, but they died out about 40,000 years ago when our species, Homo sapiens, established a firm foothold on the continent. Homo sapiens originated approximately 300,000 years ago in Africa, then spread throughout the world, reaching Europe at least 45,000 years ago.

Various groups of hunter-gatherers roamed the European landscape, hunting large mammals including woolly mammoths, woolly rhinoceroses and reindeer, and gathering edible plants. During the coldest period of the Ice Age, known as the Last Glacial Maximum, ice sheets called continental glaciers covered half of Europe, with much of the rest under tundra conditions with frozen subsoil.

The only people who survived this harshest period in Europe were hunter-gatherers who had found refuge in parts of France and the Iberian Peninsula, the study found. The Italian peninsula, previously thought to have been a refuge for humans during this period, was just the opposite – all the inhabitants perished.

“It’s a big surprise that humans went extinct on the Italian peninsula,” said senior author Johannes Krause, director of the Max Planck Institute for Evolutionary Anthropology in Germany.

This region was repopulated around 19,000 years ago by hunter-gatherers from the Balkans, who later expanded across Europe and by around 14,500 years ago had replaced everyone who had lived there, the researchers found.

“From about 14,000 to 13,000 years ago, the climate warmed and most parts of Europe gradually became forested, similar to today,” Yu said.

The Homo sapiens individuals who entered Europe after a migration out of Africa were dark-skinned. The genome data showed a shift towards light skin among humans in Europe between 14,000 and 8,000 years ago that accelerated with the subsequent spread of farming on the continent.

Certain traits of Western European hunter-gatherers, known for blue eyes and dark skin, differed from their counterparts in Eastern Europe, who had light skin and dark eyes. These two populations began to intermingle around 8,000 years ago only after the first farmers arrived in Europe from Anatolia – modern Turkey – and pushed all hunter-gatherers northwards.

The genome data showed that populations associated with the so-called Gravettian culture dating to about 34,000 to 26,000 years ago – known for certain types of stone tools, cave paintings and small sculptures called “Venus” figures – were not actually homogeneous. Instead, there were two largely unrelated populations that shared cultural attributes.

“A big surprise to me,” Yu said, “is the fact that Gravettian populations carried two genetically distinct ancestries and that one of these disappeared from Europe.”

(Reporting by Will Dunham in Washington; Editing by Rosalba O’Brien)

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