European Humans Underwent Hefty Shuffle at the End of Last Ice Age

Human bone fragments from the Goyet caves (Belgium), between 27,000 en 35,000 years old and belonging to haplogroups M or N. (Photo: Eric Dewamme, RBINS)
04/02/2016
European Humans Underwent Hefty Shuffle at the End of Last Ice Age
post by
Reinout Verbeke

European populations changed dramatically at the end of the last Ice Age. This is what scientists have revealed as a result of DNA analysis of more than thirty fossils from six countries. Moreover, the genetic material of Belgian fossils indicates that the modern humans have migrated from Africa straight to Europe without making a detour through Asia, which was originally thought.

An international team of scientists has analysed the DNA of 35 hunter-gatherers between 35,000 and 7,000 years old who lived in Italy, Germany, France, Czech Republic, Romania and Belgium. This has provided them with new information on how Europe’s population changed during the last Ice Age. The examined Belgian remains of eight individuals have been found in the caves of Goyet, near the city of Namur, and have been dated from 35,000 to 15,000 years old. The fossils belong to the collections of the Royal Belgian Institute of Natural Sciences (RBINS).

Out of Africa, into Belgium

The scientists of the Max Planck Institute in Jena and the University of Tübingen (Germany) unravelled the complete mitochondrial DNA (mtDNA) of 35 prehistoric individuals and added 20 existing mitochondrial genomes to their analysis as well. Only inherited from the maternal side, the mtDNA is the genetic material residing in the biological power plants of the cell. The result was definitely surprising as two individuals from the Goyet caves (respectively 35,000 and 34,000 years old) and one from La Rochette (southwestern France; 28,000 years old) were attributed to the so-called haplogroup M. This is a genetic pattern that has been absent from today’s European populations, although it is very common in present-day Asian, Australian and American indigenous populations.

“This first evidence of haplogroup M in our regions indicates that modern humans, in this African exodus, not only migrated to Asia but also found their way to Europe”, says palaeontologist Mietje Germonpré (RBINS), who has co-authored the study. From the speed at which the mtDNA mutated in both haplogroup M and haplogroup N – which was also found – the scientists were able to infer that the crossing from Africa to Eurasia took place between 50,000 and 60,000 years ago.

Bottleneck

The 55 genetic profiles also offer a better understanding of the changes within European populations. The Last Glacial Maximum (LGM) – the coldest period in the last Ice Age – turned out to be a bottleneck. When this frosty period in time occurred some 25,000 to 19,500 years ago, groups of hunter-gatherers retreated to a number of refuges in southern Europe. No trace has been found of humans during that same period in the North. Haplogroup M must have gone extinct in those southern hideouts when groups there were not able to survive in large numbers. As soon as the climate warmed up and the ice caps receded, populations started to disperse once again over Europe, although without the M group. 

Genetic analysis brought forward another piece of information: About 14,500 years ago, the European hunter-gatherers were replaced by a population with other maternal origins during a time period when climate warming was followed by a short ice age. Who this other population was, will soon be clarified after the study of the nuclear DNA of additional prehistoric fossils.

Goyet

About eighty fragments of human bone from the Goyet cave were excavated in the 1860s by geologist Edouard Dupont. However, they have only been re-discovered recently at the time when the Goyet collection of the Royal Belgian Institute of Natural Sciences was once more inspected. “Researchers of various scientific disciplines had to filter the human bones out of thousands animal remains”, says Patrick Semal, palaeanthropologist, co-author of the study and head conservator of the RBINS. “Through isotope analysis, carbon dating and DNA analysis, we are sure that we are dealing with modern humans so we could situate them in time. All these efforts are resulting, thanks to the human remains of Goyet, in a better understanding of how our ancestors systematically populated the European continent. And Goyet is the only site in Europe that has provided us with fossils from different populations.

The study has been published in Current Biology.

 

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