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Thursday, December 23, 2021

When did Celtic languages arrive in Britain?

A new paper at Nature by Patterson et al. argues that Celtic languages spread into Britain during the Bronze Age rather than the Iron Age [LINK]. This argument is based on the observation that there was a large-scale shift in deep ancestry proportions in Britain during the Bronze Age.

In particular, the ratio of Early European Farmer (EEF) ancestry increased significantly in what is now England during the Late Bronze Age (LBA). On the other hand, the English Iron Age was a much more stable period in this context.

I don't have any strong opinions about the spread of Celtic languages into Britain, and Patterson et al. might well be correct, but their argument is potentially flawed because:

- significant population shifts need not result in any noticeable changes in ancient ancestry proportions

- ancient ancestry proportions can shift without significant migrations from afar due to cryptic population substructures

- large-scale population shifts need not result in langage shifts, especially if they're gradual

- small-scale population shifts can result in language shifts, especially if they're sudden.

Indeed, when I plot some of the key ancient samples from the paper in my ultra fine scale Principal Component Analyses (PCA) of Northern and Western Europe, it appears that it's only the Early Iron Age (EIA) population from England that overlaps significantly with a roughly contemporaneous group from nearby Celtic-speaking continental Europe. The relevant PCA data are available here and here, respectively.

See also...

Celtic vs Germanic Europe

Avalon vs Valhalla revisited

R1a vs R1b in third millennium BCE central Europe