Medieval social landscape through the genetic history of Cambridgeshire before and after the Black Death

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 Death.

Insufficient evidence for natural selection associated with the Black Death

“…These include a scan based on time series of ancient DNA (rs2549794 empirical P = 0.18) [10], the singleton density score based on high coverage sequence data (rs2549794 Z=1.33, P = 0.09) [18] and a scan based on estimated coalescent times in UK Biobank (minimum P value within 1Mb 0.40) [19]. The locus also failed to replicate in two independent studies of ancient genomes from before and after the Black Death in Britain and Norway [9, 20].…”

Pathways to the medieval hospital: collective osteobiographies of poverty and charity

“…Ancient DNA analysis demonstrates that, genetically, the hospital's population was indistinguishable from other people living in Cambridge at the time. However, unlike in the parish cemeteries, no kinship links have been found among the hospital inmates (Hui et al 2023), which suggests that they were admitted according to individual need, not place of residence or family ties. Moreover, unlike in parish cemeteries, young children under seven ('infants' in medieval terminology) are absent from the hospital cemetery and only 16 per cent of the burials are of individuals aged 7-16 years old at death; the vast majority are adults.…”

“…One is the probable scholar discussed above. The other two are PSN332/Burial 901, a young female (18-25 years) with strontium isotope values suggestive of a childhood in south-western or north-western England, Wales, Scotland, Norway, Brittany, central France or further afield, and genetic affinities with Dutch and Scandinavian populations (Hui et al 2023); and PSN66/Burial 276, a young male (18-25 years) whose strontium isotope values indicate that he either came from overseas or from western Wales, Cumbria and the Scottish highlands where such values are found in small, thinly populated areas.…”

Reply to Barton et al: signatures of natural selection during the Black Death

“…Another variant (rs2548527) in strong LD with rs2549794 (r 2 = 0.79 in 1000Genomes' GBR population) exhibits qualitatively similar changes in allele frequency between pre-and post-Black Death samples, indicating that our results for ERAP2 are not due to potential DNA damage (Figure 2B). Notably, in a recent study on ancient DNA samples from Cambridgeshire, England, the putatively protective allele of ERAP2 also increased in frequency from 52% pre-Black Death to 60% post-Black Death 7 . While Barton et al highlight that Hui et al 7 do not replicate this SNP as an FST outlier, we note that this analysis only focused on only n=50 samples (approximately a third of our sample size for London only).…”

“…Notably, in a recent study on ancient DNA samples from Cambridgeshire, England, the putatively protective allele of ERAP2 also increased in frequency from 52% pre-Black Death to 60% post-Black Death 7 . While Barton et al highlight that Hui et al 7 do not replicate this SNP as an FST outlier, we note that this analysis only focused on only n=50 samples (approximately a third of our sample size for London only).…”