Celtic origins: 4,587 ancient genomes and four models

A team centred on palaeogeneticist Eske Willerslev of the Globe Institute in Copenhagen analysed genome-wide data from 4,587 ancient individuals, focusing on Bronze and Iron Age Europe. The aim was to test which models of the origin of Celtic languages fit reconstructed demographic histories, according to a paper in Nature available via doi.org doi.org. Celtic languages are today restricted to Europe's Atlantic fringes but were widely spoken across the continent during the Iron Age doi.org.

Four models of Celtic origin

The authors group existing hypotheses into four models. The Bell Beaker model links the Celtic split with the Bell Beaker Complex (roughly 4750–4500 to 4000–3800 bp) and holds that Celtic diverged largely in situ in the following millennia doi.org. The Celtic-from-the-West model places Proto-Celtic within the maritime networks of the Atlantic Bronze Age Culture (3300–2700 bp), connecting Atlantic Iberia, parts of France, Ireland and Britain, with a later eastward expansion doi.org.

The Celtic-from-the-Centre model situates Proto-Celtic in inland France and possibly northwestern Italy 4000–3000 bp, with a spread in many directions after 3000 bp doi.org. The fourth model locates its formation in eastern central Europe and ties its diversification to the Late Bronze Age Urnfield culture, the later Hallstatt culture and the La Tène horizon, or a combination of these doi.org. These scenarios imply very different population movements, so the genomic record can help exclude inconsistent ones.

Three population movements in the genomes

The analysis identified three processes relevant to the Celtic dispersal. First, Steppe-related ancestry arrived with Bell Beaker-associated groups after around 4400 bp across the region where Celtic and related languages were later spoken doi.org. Second, a movement from southwestern Europe into Britain occurred during the Bronze Age (3800–3200 bp), consistent with scenarios in which Celtic formed along the Atlantic façade doi.org.

Third, ancestry related to Late Bronze Age Knovíz–Urnfield-associated populations expanded westward from eastern central Europe (3200–2800 bp). It affected France, the British Isles, northeastern Iberia and Italy and was later associated with Iron Age Hallstatt and La Tène contexts doi.org.

All three movements have parallels with proposed models. The authors argue that the final one, from eastern central Europe, is the most parsimonious for the spread of Celtic doi.org. They note that human history does not necessarily follow a parsimonious trajectory and that language shifts need not track genetic change. In their view, the results delimit the demographic scenarios that are plausible for the emergence of Celtic in prehistoric Europe doi.org.

Study of 4,587 ancient genomes: authors favour eastern central Europe as origin of Celtic spread

Four models of Celtic origin

Three population movements in the genomes

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