Double burial of the two plague victims in the Samara region, Russia
[Credit: V.V. Kondrashin and V.A. Tsybin; Spyrou et al.
Nature Communications, 2018]
The plague, caused by the bacterium Yersinia pestis, was the cause of some of the world's deadliest pandemics, including the Justinian Plague, the Black Death, and the major epidemics that swept through China in the late 1800s. The disease continues to affect populations around the world today. Despite its historical and modern significance, the origin and age of the disease are not well understood. In particular, exactly when and where Y. pestis acquired the virulence profile that allows it to colonize and transmit through the flea vector has been unclear.
Recent studies of ancient Y. pestis genomes identified its earliest known variants, dating to the Late Neolithic and Early Bronze Age, but these genomes did not show the genetic signatures thought to make the plague particularly efficient - namely, adaptation to survival in fleas, which act as the main vectors that transmit the disease to mammals. This study aimed to look at more Bronze Age Y. pestis genomes, in order to investigate when and where these important adaptations occurred.
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