Ancient Migrations May Explain How Germanic And Celtic Languages Spread

Europe’s Language Map Was Redrawn by Migrations, Ancient DNA Suggests

English and Irish seem to have little in common, but two new studies in Nature suggest the roots of both languages may trace back to ancient migrations. Using DNA from 4,587 ancient Europeans, researchers found a Baltic-linked population entering Sweden about 4,000 years ago, a likely carrier of early Germanic, and a separate wave out of eastern central Europe that best fits the spread of Celtic.

Each answer comes with a catch. “DNA sequences do not tell us directly which language people spoke,” said senior author Eske Willerslev of the University of Copenhagen in a university release. That makes these best-fit explanations, not proof.

Read together, the studies describe a language map redrawn over thousands of years. Ancestry linked to Celtic’s spread moved west, and much later, Germanic-linked ancestry moved south into regions presumed to speak Celtic, including present-day Germany, Poland and the Netherlands.

Ancient DNA From 4,587 People Traced Germanic and Celtic Languages

An international team led by the University of Copenhagen and Leiden University published both studies together. Researchers sequenced 712 ancient individuals and added 4,009 genomes that other teams had already published. After removing close relatives and low-quality samples, the main dataset held 578 new individuals plus the 4,009 published ones, 4,587 in all, spanning roughly 5,000 years from the late Stone Age through the Viking Age. The Celtic study reused that dataset.

Long shared stretches of DNA, inherited from common ancestors, did the sorting. People who share many such stretches fall into clusters, which let researchers tell closely related populations apart and watch ancestry shift across the map through time.

Germanic Languages Likely Arrived With a Baltic-Linked Population

Before about 2,800 years ago, Scandinavia held three genetic groups. One, labeled Eastern Scandinavian, carried extra ancestry from hunter-gatherers whose closest match was in Latvia and Lithuania, and it likely formed somewhere between Finland and northeast Sweden. It shows up in Sweden by about 4,000 years ago and was widespread across Scandinavia by about 3,500 years ago, alongside new burial customs and the first lasting bronze trade networks.

Word borrowing with Celtic and with early Finnish- and Sami-related languages indicates early Germanic was spoken between northern Germany and the eastern Baltic by the Late Bronze Age. By then, the other two Scandinavian groups had shrunk. That makes the Baltic-linked group the simplest carrier, and it places Germanic’s arrival in Scandinavia some 800 years later than traditionally assumed.

Later migrations went in several directions. Anglo-Saxons in England carried ancestry that best matched northern Germany. Then, as Old Norse took shape between roughly 1,575 and 1,200 years ago, northern German and southern Jutland ancestry moved into Denmark and southern Sweden, and on the Danish islands local ancestry had essentially vanished by about 1,250 years ago.

A Westward Migration Best Fits Celtic Languages

Celtic once stretched from Spain to the Balkans, yet scholars disagree on where it started. Four theories compete: Bell Beaker groups of western and central Europe, Atlantic sea traders, inland France, and eastern central Europe. Each was scored on direction, territory and timing, and the best theory needs the fewest extra assumptions.

Two earlier migrations fit less well. Around 4,400 years ago, ancestry from the grasslands of eastern Europe spread through Bell Beaker groups across the region where Celtic was later spoken. Between 3,800 and 3,200 years ago, people from southwestern Europe moved into Britain, a fit for the sea-trade theory. Both came before most estimates for when Proto-Celtic, Celtic’s unwritten shared ancestor, formed, which cluster between 3,600 and 2,800 years ago.

A third migration fits best. Ancestry tied to the Urnfield culture of eastern central Europe spread west from about 3,200 to 2,800 years ago, reaching France, the British Isles, northeastern Spain and Italy, and it lands in the peak window for Proto-Celtic’s formation, about 3,200 to 3,000 years ago. Cremation means few genomes survive from that period, so the dates lean on the few burials that exist plus later samples.

One complication remains. In Iron Age England, the largest share of ancestry tended to trace to older Bell Beaker groups, so Celtic would have had to spread with a small genetic footprint in Britain.

Migration Alone Does Not Explain Germanic and Celtic Languages

Both studies end on the same caution. Norway kept a largely continuous population yet still ended up speaking Old Norse, so the authors credit a mix of population movement and cultural change. Goths show it too: burials in Poland matched Scandinavian ancestry, but later Goths in Ukraine and Spain mostly carried local ancestry, which fits locals adopting Gothic language and identity. For Celtic, “language shifts need not track genetic change.” If related dialects were already spoken across the region, newcomers and locals in Britain may have understood each other, letting Celtic words and grammar spread by borrowing instead of replacement.

Europe’s language map was drawn partly by people on the move and partly by neighbors borrowing from neighbors. Until more genomes fill the gaps, a Baltic-linked arrival for Germanic and an eastern central European one for Celtic remain the leading explanations, not settled ones.

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