Pre-Neolithic DNA Suggests Major Late Glacial Population Turnover in Europe
DNA evidence lifted from the bones and teeth of hunter-gatherers who lived in Europe from 35,000 years ago (Late Pleistocene) to 7,000 years ago (early Holocene) shows a major shift in the population around 14,500 years ago during the Late Glacial, a period of climatic instability at the end of the Pleistocene.
“We uncovered a completely unknown chapter of human history: a major population turnover in Europe at the end of the last Ice Age,” said Dr. Johannes Krause, a researcher at the Max Planck Institute for the Science of Human History, Germany, and senior author on a study published this week in the journal Current Biology.
Dr. Krause and co-authors analyzed 55 complete human mitochondrial genomes (mtDNAs) of hunter-gatherers who lived in Italy, Germany, Belgium, France, the Czech Republic, and Romania from 35,000 to 7,000 years ago.
“There has been a real lack of genetic data from this time period, so consequently we knew very little about the population structure or dynamics of the first modern humans in Europe,” Dr. Krause said.
The analysis of these ancient mtDNAs unexpectedly revealed that three individuals from before the coldest period in the last Ice Age (Last Glacial Maximum) that were excavated in present-day Belgium and France belong to a type of mtDNA called haplogroup M.
“This lineage is absent in contemporary Europeans, although it is found at high frequency in modern Asians, Australasians, and Native Americans,” Dr. Krause and his colleagues explained.
“I couldn’t believe it,” said Dr. Cosimo Posth from the University of Tübingen, lead author on the study. “The first time I got this result I thought it must be a mistake, because in contemporary Europeans haplogroup M is effectively absent, but is found at high frequency in modern Asians, Australians and Native American populations.”
The absence of the M haplogroup and its presence in other parts of the world had previously led to the argument that non-African people dispersed on multiple occasions to spread across Eurasia and Australasia.
“The discovery of this maternal lineage in Europe in the ancient past now suggests instead that all non-Africans dispersed rapidly from a single population, at a time they place around 50,000 years ago. Then, at some later stage, the M haplogroup was apparently lost from Europe,” the scientist said.
“When the Last Glacial Maximum began around 25,000 years ago, hunter-gatherer populations retreated south to a number of putative refugia, and the consequent genetic bottleneck probably resulted in the loss of this haplogroup,” Dr. Posth said.
The biggest surprise, however, was evidence of a major turnover of the population in Europe around 14,500 years ago, as the climate began to warm.
“Our model suggests that during this period of climatic upheaval, the descendants of the hunter-gatherers who survived through the Last Glacial Maximum were largely replaced by a population from another source,” said co-author Dr. Adam Powell, of the Max Planck Institute for the Science of Human History.