Ashkenazi-associated hereditary diseases predate 12th century

Human remains recovered from a disused well in Norwich have been suggested as the victims of a medieval antisemitic pogrom, according to radiocarbon dating and genetic analysis.

The results, published in the journal Current Biology and arising from a collaboration between institutions including University College London (UCL) and the Natural History Museum, show that the remains date back to the 12th century, and that the individuals displayed genetic variants associated with hereditary diseases found in modern Ashkenazi Jewish populations, before they were understood to have arisen.

Dr Selina Brace, co-lead author of the study based at the Natural History Museum, said 'I'm delighted and relieved that twelve years after we first started analysing the remains of these individuals, technology has caught up and helped us to understand this historical cold case of who these people were and why we think they were murdered'.

The remains, which have been named the 'Chapelfield individuals', were found in Norwich in 2004 during the construction of a shopping centre. They consist of at least seventeen individuals, eleven of whom were children and there was a lack of clarity over the cause of death.

Radiocarbon dating of the remains indicated that the incident occurred between 1161 and 1216. This encompasses a historically documented antisemitic pogrom which occurred in Norwich in 1190, as chronicled by the medieval cleric Ralph de Diceto. The remains have since been buried in a Jewish cemetery.

Genetic analysis of six Chapelfield individuals was also conducted. While considerable genetic research has taken place surrounding the Ashkenazi Jewish population, these are the oldest sequenced genomes of Jewish remains, as disturbance of Jewish burial sites for scientific purposes is strictly prohibited.

All six individuals were found to have significant genetic similarity to modern Ashkenazi Jews who are descended from communities formed in Northern and Eastern Europe, including identification of genetic variants known to exist in the modern Ashkenazi Jewish population, including one linked to the disorder primary ciliary dyskinesia.

The frequencies of these variants amongst modern Ashkenazi Jews likely arose due to a bottleneck event, which describes when a significant decrease in population size leads to increasing prevalence of rare genetic mutations amongst the resulting population.

This bottleneck event was estimated to have occurred between 500 and 800 years ago. However, the appearance of these variants amongst the Chapelfield individuals indicates that the event must have occurred prior to the pogrom in Norwich.

'It was quite surprising that the initially unidentified remains filled the historical gap about when certain Jewish communities first formed, and the origins of some genetic disorders' said Professor Mark Thomas, co-lead author of the study and professor of evolutionary genetics at UCL.