FAYETTEVILLE, ARKANSAS—Researchers from an international team have identified a potential Bronze Age host of the plague bacterium, Yersinia pestis. The plague affected populations across Eurasia for roughly 2,000 years starting around 5,000 years ago, but its pathways of spread remained unclear.

DNA from Y. pestis has now been detected in 4,000-year-old domesticated sheep from Arkaim, a fortified settlement in the Southern Ural Mountains linked to the Sintashta culture, known for herding, horse riding, and bronze weaponry.

“Our plague sheep gave us a breakthrough,” said Taylor Hermes of the University of Arkansas. “We now understand transmission as an interaction between people, livestock, and an as-yet unidentified ‘natural reservoir,’ which could have been steppe rodents or migratory birds.”

Hermes and colleagues plan to investigate which animals may have served as this natural reservoir for Y. pestis during the Bronze Age.