Tia Ghose, LiveScience, March 3, 2016
Some of Europe’s earliest inhabitants mysteriously vanished toward the end of the last ice age and were largely replaced by others, a new genetic analysis finds.
The finds come from an analysis of dozens of ancient fossil remains collected across Europe.
The genetic turnover was likely the result of a rapidly changing climate, which the earlier inhabitants of Europe couldn’t adapt to quickly enough, said the study’s co-author, Cosimo Posth, an archaeogenetics doctoral candidate at the University of Tübingen in Germany.
But relatively little was known about human occupation of Europe between the first out-of-Africa event and the end of the last ice age, around 11,000 years ago. During some of that time, the vast Weichselian Ice Sheet covered much of northern Europe, while glaciers in the Pyrenees and the Alps blocked east-west passage across the continent.
To get a better picture of Europe’s genetic legacy during this cold snap, Posth and his colleagues analyzed mitochondrial DNA–genetic material passed on from mother to daughter–from the remains of 55 different human fossils between 35,000 and 7,000 years old, coming from across the continent, from Spain to Russia. Based on mutations, or changes in this mitochondrial DNA, geneticists have identified large genetic populations, or super-haplogroups, that share distant common ancestors.
“Basically all modern humans outside of Africa, from Europe to the tip of South America, they belong to these two super-haplogroups that are M or N,” Posth said. Nowadays, everyone of European descent has the N mitochondrial haplotype, while the M subtype is common throughout Asia and Australasia.
The team found that in ancient people, the M haplogroup predominated until about 14,500 years ago, when it mysteriously and suddenly vanished. The M haplotype carried by the ancient Europeans, which no longer exists in Europe today, shared a common ancestor with modern-day M-haplotype carriers around 50,000 years ago.
The genetic analysis also revealed that Europeans, Asians and Australasians may descend from a group of humans who emerged from Africa and rapidly dispersed throughout the continent no earlier than 55,000 years ago, the researchers reported Feb. 4 in the journal Current Biology.
For whatever reason, the already small populations belonging to the M haplogroup were not able to survive these changes in their habitat, and a new population, carrying the N subtype, replaced the M-group ice-age holdout, the researchers speculate.
Exactly where these replacements came from is still a mystery. But one possibility is that the newer generation of Europeans hailed from southern European refugia that were connected to the rest of Europe once the ice receded, Posth speculated. Emigrants from southern Europe would also have been better adapted to the warming conditions in central Europe, he added.