The Genomic Legacy of the Norman Conquest in Rural England

[Graham]

What's your view on the provenance of most of the French IA ancestry? I'm still torn for a number of reasons.

Central Southern English Counties had higher Northern French like IA from Late Bronze. It could have still spread from within England later.

[J. Ketch]

Central Southern English Counties had higher Northern French like IA from Late Bronze. It could have still spread from within England later.

I haven't seen those maps before. What are they from?

The Atrebates were a Belgic tribe in Southern England, who had a namesake across the channel they obviously came from.

[Graham]

Article
Open access
Published: 15 January 2025
Continental influx and pervasive matrilocality in Iron Age Britain

https://www.nature.com/articles/s41586-024-08409-6

[J. Ketch]

Article
Open access
Published: 15 January 2025
Continental influx and pervasive matrilocality in Iron Age Britain

https://www.nature.com/articles/s41586-024-08409-6

Aha, finally some genetic evidence of the Belgae settlement of Southern England.

An increase in continental ancestry components has been described for Iron Age genomes from the south of Britain (England and Wales)17 and has been interpreted as the result of large-scale movements into the island during and before the Late Bronze Age (around 1000 to 875 bc). This is detectable as a rise in Early European Farmer (EEF) ancestry (Supplementary Note 6.2). When we incorporate our data, we find a previously undetectable significant (Welch’s t-test, two-tailed, P = 0.0005) increase in EEF ancestry between the Early and Late Iron Age (from 39.7% ± 0.2% to 41.8% ± 0.5%), driven by genomes from southern regions along the central and eastern English Channel coast, including those from the Durotrigian territory (Fig. 3d and Supplementary Table 25). These regions emerged archaeologically as a core of unprecedented continental influence during the Middle Bronze Age, with cross-channel communities exhibiting parallel developments in disposal of the dead, settlement architecture and material culture over centuries, suggestive of high levels of population mobility3. Close cross-channel relations persisted throughout the Iron Age, when much of Britain seems to have developed a more regional and distinctively insular cultural footprint.

The impact of continental gene flow specific to the channel core zone is visible in principal-components analysis (PCA) of modern and ancient western Europeans (Extended Data Fig. 2), as well as patterns of haplotype copying from continental populations, characterized using ChromoPainter36 (Fig. 3b). We used SOURCEFIND37 to decompose the ancestry of Iron Age genomes into contributions from Early Bronze Age British and continental groups and further validated our results using an alternative approach of non-negative least squares38 (NNLS) with a different panel of surrogates (Methods and Supplementary Note 6.3). Overall, we estimate an average contribution of 73% (estimated by SOURCEFIND; NNLS estimate: 75%) from the British Early Bronze Age (2500 to 1500 cal bc) to the English and Welsh Iron Age population (800 bc to ad 50). Although this value is larger than the estimate of a previous study17, which inferred a 50% long-term replacement rate for the gene pool, it is in agreement with the reported dilution of British- and Irish-specific R1b-L21 haplogroup Y chromosomes by one quarter17.

A sharp dip in Bronze Age continuity is seen along the channel coast (Fig. 3b and Extended Data Fig. 8). This is centred on Hampshire (SOURCEFIND estimate of 60%), a region traditionally associated with Belgic tribes that Caesar mentioned as having migrated from Gaul3. Both Hampshire and the neighbouring Durotrigian zone show independent and significant increases in EEF ancestry between the Early and Late Iron Age (Extended Data Fig. 7). Notably, the Durotrigian territory was home to a major port at Hengistbury Head, one of the focal points of intensifying cross-channel networks as Roman influence spread across Gaul39. With fewer samples for analysis, haplotypic data provide less resolution on fine-grained temporal trends but identify numerous genetic outliers in the Middle to Late Iron Age, all from the channel core region, which are not discernible when EEF ancestry alone is considered (Extended Data Fig. 3; see Supplementary Note 6.3 for further discussion of genetic outliers). These outliers include one of the most elaborate warrior burials known for Iron Age England (North Bersted on the channel coast; around 50 cal bc), which has been proposed, on the basis of isotopic signature and burial rite, to belong to a stream of cross-channel migrants, fuelled by Caesar’s conquest of Gaul40.

I have a feeling this local increase of Gaulish ancestry was missed in previous ancestral estimates, which might need revising.

[Opie]

I haven't seen those maps before. What are they from?

The Atrebates were a Belgic tribe in Southern England, who had a namesake across the channel they obviously came from.

I remember reading about a Belgic tribe coming to settle to Britain after Caesar's invasion. In the Middle Ages, both Henry I and Henry II brought Flemish settlers to Britain. Maybe there were a few times when people from Benelux came to settle, but in the grand scheme of things, I believe their role in increasing continental Celtic genes in Britain rather small. The biggest event that transformed the British Isles genetics, language and culture was Anglo-Saxon invasion. Normans and Vikings had their impact too but much smaller compared to Anglo-Saxons.

[Birchy]

Excellent, been waiting for a study on this for years, ever since the Gretzinger Anglo-Saxon paper left us with the mystery of how so much Gaulish ancestry ended up in Medieval England.

It's one cemetery in Surrey but more evidence that the Norman conquest had a modest genetic impact. I increasingly believe that the long-term Anglo-Saxon invasions were largely Germanic people who were already heavily Celtic mixed, and Frankish influence is understated.

It may also have come from Anglo Saxon invasions into France after the initial invasion in which they took French wives back with them. The study mentions this as well, which suggests French like admixture was female-mediated to a considerable extent.

[J. Ketch]

I remember reading about a Belgic tribe coming to settle to Britain after Caesar's invasion. In the Middle Ages, both Henry I and Henry II brought Flemish settlers to Britain. Maybe there were a few times when people from Benelux came to settle, but in the grand scheme of things, I believe their role in increasing continental Celtic genes in Britain rather small. The biggest event that transformed the British Isles genetics, language and culture was Anglo-Saxon invasion. Normans and Vikings had their impact too but much smaller compared to Anglo-Saxons.

Yes, the Flemish/Walloon influence is undoubtedly very small on England overall, but I have wondered if it had an appreciable influence on East Anglia, given that it strangely has more French IA/CWE ancestry than any other region today and is genetically the closest to continentals (you would expect that to be SE England).

[J. Ketch]

It may also have come from Anglo Saxon invasions into France after the initial invasion in which they took French wives back with them. The study mentions this as well, which suggests French like admixture was female-mediated to a considerable extent.

Was that the Gretzinger paper? I may have forgotten that, but important if true.

[Birchy]

Was that the Gretzinger paper? I may have forgotten that, but important if true.

I believe it was a seperate UCL study actually, will have to find it.