Europe’s Population Dramatically Changed at the End of the Last Ice Age
Genetic analyses shed new light on early European population dynamics
Up to now, the dispersal of modern humans outside of Africa is a highly debated topic both in terms of the number of major expansions and their timing. An international team of researchers retrieved DNA from 35 ancient hunter-gatherers spanning almost 30,000 years of European pre-history. They obtained unexpected insights into early modern human population dynamics, finding a single and rapid dispersal of all non-Africans around 50,000 years ago, not only across Asia but also into Europe. They furthermore uncovered a previously unknown population turnover at the end of the last Ice Age, a time of severe climatic instability around 14,500 years ago.
Genetic information about early modern humans, who lived for 35-40,000 years as hunter-gatherers in Europe, is scarce and their population structure and dynamics are almost unknown. Using molecular and bioinformatic techniques researchers from the Max Planck Institute (MPI) for the Science of Human History in Jena and Tuebingen University in Germany, together with an international team of collaborators,were able to reconstruct complete maternally inherited mitochondrial DNA (mtDNA) genomes of 35 hunter-gatherers who lived in Italy, Germany, Belgium, France, Czech Republic and Romania between 35,000 and 7,000 years ago.
Analysis of these ancient mtDNAs unexpectedly revealed that three individuals from before the Last Glacial Maximum (LGM) - the coldest period in the last Ice Age – that were excavated in present-day Belgium and France belong to a type of mtDNA called haplogroup M. “I couldn’t believe it. 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.” reports Cosimo Posth of Tübingen University, the lead author of the study. When the LGM began around 25,000 years ago, hunter-gatherer populations retreated to a number of proposed refugia in the south of Europe. The researchers suggest that haplogroup M may have been lost due to the reduction in population size, which later re-expanded across Europe when the climatic conditions turned more favorable for humans.