Modern plague bacteria on the spines of an Oriental rat flea.

Modern plague bacteria (Yersinia pestis, yellow) on the spines of an Oriental rat flea, Xenopsylla cheopis. Credit: NIH/SPL

Infection

Newcomers from the east brought deadly microbe to Europe

Ancient DNA points to Eurasian steppe as infamous bacterium’s birthplace.

Ancient people of the Eurasian steppe who trekked west may have carried plague to Europe.

To determine when plague first reached Europe, a team led by Alexander Herbig and Johannes Krause at the Max Planck Institute for the Science of Human History in Jena, Germany, screened hundreds of ancient tooth and bone samples from eastern and central Europe for the DNA of the plague bacterium, Yersinia pestis. The team recovered six prehistoric plague genomes, dating from 3,700 to 4,800 years ago.

All six are members of a now-extinct lineage of Y. pestis that is distinct from those responsible for Europe’s documented historical plagues, such as the fourteenth-century Black Death. One of the strains was ancestral to the other five, as was a strain previously isolated by another team. The ancestral strains were Russian, but the five later strains were found further west, suggesting that the pathogen had moved west over time.

Both of the ancestral strains were 4,600 to 4,800 years old — dating from roughly the same period that people from the steppe of present-day Russia and Ukraine were pushing west into Europe. This migration may have established Y. pestis in Europe, with later human migrations carrying it back to central Eurasia, the authors say.