Scientists Decode Genome of the Bacteria that Caused the Justinian Plague

The Justinian Plague lasted from 541 to 750 CE. This was the first plague pandemic and public health crisis which wiped out close to 100 million people in Asia, Africa and Europe in just 5 years. The culprit: yersinia pestis – the bacteria responsible for this pandemic and all plague pandemics since.

An international team of researchers led by the Max Planck Institute for the Science of Human History analyzed the remains of 21 victims from burials across Austria, Britain, France, Germany and Spain, and reconstructed eight plague genomes to find out the bacteria evolved, and the impact it had on Early Middle Age Europe, IFLScience.com reported. Reconstructing the genomes of eight separate strains allowed them to compare their structure to those of previously published ancient and modern strains of the bacteria.

They found that there were many more strains of this bacteria than previously realized, and many “were closely intertwined genetically-speaking and some of which may have co-existed in the same places at the same times.” They were also able to confirm the plague’s presence in Anglo-Saxon England for the very first time.

The researchers also detected signs of convergent evolution between the different strains, with those appearing later in the pandemic exhibiting missing aspects of genetic code that were also missing in the plague genomes from the later stages of the Black Death.

“These Y. pestis strains independently evolved similar characteristics. Such changes may reflect an adaptation to a distinct ecological niche in Western Eurasia where the plague was circulating both pandemics,” co-author Maria Spyrou said in a statement. “The fact that all genomes belong to the same lineage is indicative of a persistence of plague in Europe or the Mediterranean basic over this time period, instead of multiple reintroductions.