An international team of researchers led by the Max Planck Institute for the Science of Human History has analyzed two 3,800-year-old Y. pestis genomes that suggest a Bronze Age origin for bubonic plague. The strain identified by the researchers was recovered from individuals in a double burial in the Samara region of Russia, who both had the same strain of the bacterium at death. The study, published in the journal Nature Communications, shows that this strain is the oldest sequenced to date that contains the virulence factors considered characteristic of the bubonic plague, and is ancestral to the strains that caused the Justinian Plague, the Black Death and the 19th century plague epidemics in China.