The Genetic History of Cambridgeshire before and after the Black Death

[Creoda]

We of English blood have been spoiled for genetic studies lately, marvellous.

https://www.biorxiv.org/content/10.1....531048v1.full

Abstract
The extent of the devastation of the Black Death pandemic (1346-53) on European populations is known from documentary sources and its bacterial source illuminated by studies of ancient pathogen DNA. What has remained less understood is the effect of the pandemic on human mobility and genetic diversity at local scale in the context of the social stratification of medieval communities. Here we study 275 newly reported ancient genomes from later medieval and post-medieval Cambridgeshire, from individuals buried before, during, and after the Black Death. The majority of individuals examined had local genetic ancestries. Consistent with the function of the institutions, we found a lack of close relatives among the friars and the inmates of the hospital in contrast to their abundance in general urban and rural parish communities. Accounting for the genetic component for height accentuates the disparities between social groups in stature estimated from long bones, as a proxy for health and the quality of life. While we detect long-term shifts in local genetic ancestry in Cambridgeshire that either pre- or postdate the Black Death, we find no evidence of major changes in genetic ancestry nor, in contrast to recent claims, higher differentiation of immune loci between cohorts living before and after the Black Dea

In contrast to genomes of individuals whose remains date to the Roman or Early Saxon periods (Martiniano et al., 2016;
Schiffels et al., 2016), most later medieval genomes cluster with those from the modern English
individuals from the UK Biobank data (Figure 1C). Individual outliers who, similarly to the
majority of Early Saxon period individuals, are placed among modern Dutch and Danish
populations, include a few from Cherry Hinton (Figure S2) and the Hospital of St John (Figure
S5). Two of them (PSN332 from the Hospital and PSN930 from Cherry Hinton) are also outliers
in terms of dental enamel 87Sr/86Sr values (PSN332 = 0.7122, PSN930 = 0.7108), in comparison
to the rest of the Cambridgeshire population sampled (Rose & O’Connell, forthcoming). These
values, particularly for PSN332, are higher than the estimated biosphere 87Sr/86Sr values for the
East of England (Evans et al., 2018), indicating that they did not spend their childhoods in the
area local to where they were buried (Rose & O’Connell, forthcoming). Although some areas in
Britain, particularly Wales and Scotland as well as Cornwall and smaller areas across England,
do have estimated biosphere 87Sr/86Sr values which could produce the values in these individuals,
combined with the genetic information, PSN332 is more likely to be first-generation migrant
from the Scandinavian peninsula. This is consistent with an influx of continental northern
European ancestry after the Roman period, followed by increased affinity to present-day
Scandinavian populations since the Viking Age (Gretzinger et al., 2022). For instance, in this
period there was an active North Sea trade network linking eastern England, Norway and
northern Germany and this would be a plausible origin for PSN332. On the other hand, three
individuals from Cherry Hinton, seven from All Saints, two from the Hospital, one from the
Friary, and a post-medieval Midsummer Common burial clustered closely with modern French
samples from the UK Biobank in the PCA result

Similarly to PCA results, we find that the majority of historical genomes from Cambridgeshire cluster by their connectedness
with modern UK Biobank genomes from East England (Figure 1D, Table S2) whereas a small
fraction of later medieval and Roman period genomes, which display low connectivity (Figure
1E), cluster with the UK Biobank donors born in France who display low connectivity among
themselves. The Early Saxon period genomes show higher connectivity with Scandinavian
genomes, which is also reflected in individual PCA outliers from Cherry Hinton. Overall we
observe regional shifts in individual connectedness over time (Figure 1F). There is increasing
Danish connectivity in the transition from Roman to Early Saxon period; later, during and after
the later medieval period, there is an increase of connectivity with both modern Dutch genomes
(mirroring documentary evidence showing the Dutch as the most common late medieval
immigrants locally (Ormrod et al., 2019, 2020)), and genomes from a broader zone of England.
Finally, we observe a major shift in modern East England towards higher connectivity with
Wales and Scotland, clearly reflecting the political and economic integration of recent Britain.
Our analyses of individual connectedness in the People of the British Isles (POBI) (Leslie et al.,
2015) data suggest that all later medieval genomes from Cambridgeshire likely draw most of
their genetic ancestry from the same sources as present-day central/eastern England population
(Figure 2).

Cambridgeshire/East Anglia appears to be entirely continental in the late Middle Ages, with practically no native Brittonic ancestry.