An international team has recovered Yersinia pestis DNA from a ~4,000‑year‑old domesticated sheep in Russia’s Southern Ural Mountains, the first such genome from a nonhuman Bronze Age specimen. The result suggests that prolonged circulation of the Bronze Age plague lineage—lasting about 2,000 years—may have depended on close interactions among people, livestock and wild animals on the Eurasian steppes. The study, published in Cell, highlights how ecological and social networks can sustain ancient pathogens and offers a cautionary lesson about disturbing natural systems.
Ancient Sheep DNA Reveals How a Bronze Age Plague Traveled Across Eurasia
Close-up of a sheep. Credit: Pixabay.
New genetic evidence suggests a surprising animal link to a long‑running Bronze Age plague. Researchers have recovered Yersinia pestis DNA from the bones of a domesticated sheep dated to about 4,000 years ago, offering a fresh clue about how an ancient lineage of the plague circulated across Eurasia for roughly two millennia.
The discovery, reported in Cell, comes from livestock remains excavated in Russia’s Southern Ural Mountains during the 1980s and 1990s and associated with the Sintashta culture—an early Bronze Age people known for horse riding, bronze weaponry, and fortified settlements. Because animal bones from this period are often fragmentary or cooked, intact pathogen genomes from nonhuman specimens are extremely rare.
What the Sheep DNA Tells Us
Previous studies showed that the medieval Black Death strain spread in part via fleas, but the mechanisms that sustained the Bronze Age lineage (c. 2900–500 B.C.) were unclear. That early strain likely lacked the fully evolved flea‑transmission machinery seen later, leaving open questions about hosts and reservoirs that kept it active for centuries.
Finding Y. pestis in a domesticated sheep does not mean sheep were efficient transmitters among themselves. Instead, the result supports a scenario in which intensified contact among humans, their herds, and wild animals on the steppes created opportunities for cross‑species exposure. Rodents—today’s primary plague reservoir—along with other wild fauna, may have played a central role in maintaining and dispersing the bacterium while people and livestock acted as bridges across regions.
“It was alarm bells for my team,” said archaeologist Taylor Hermes of the University of Arkansas, a co‑author of the study. “This was the first time we recovered a Yersinia pestis genome from a nonhuman Bronze Age sample.”
Broader Implications
The finding sheds light on how social and ecological networks on the Bronze Age steppe—herding routes, trade and cultural contacts between communities like the Sintashta and their neighbors—could have enabled long‑range spread of disease. It also underscores a modern lesson: human alteration of ecosystems and closer contact with animals can create conditions that sustain and amplify infectious agents.
While this single sheep genome does not answer every question about Bronze Age plague dynamics, it adds an important data point to efforts to reconstruct ancient disease ecologies and highlights the value of reexamining old archaeological collections with modern DNA techniques.
Study: International team; published in Cell. Lead archaeologist quoted: Taylor Hermes, University of Arkansas.
