A team of international researchers has uncovered the recovery of plague DNA from a 4,000-year-old sheep at an ancient Bronze Age settlement in Russia. The study, published in the journal Cell, sheds new light on how the early form of Yersinia pestis spread across Eurasia.
The investigation involved analyzing bones and teeth from cattle, sheep, and goats buried at the Sintashta-Petrovka settlement. Scientists discovered Yersinia pestis bacteria in a sheep molar, which formed a nearly complete genome matching the Late Neolithic Bronze Age lineage known to have infected people around the same time.
The discovery suggests that domesticated livestock served as intermediary hosts, bringing humans into contact with the pathogen as herders moved across the steppe. Genetic comparisons indicate that an unknown wild reservoir repeatedly spilled the bacterium into both sheep and humans, leading to isolated spillovers into ancient human populations.
Researchers found nearly identical genomes of the Late Neolithic Bronze Age strain up to 6,000 kilometers apart, defying explanation by slow human or herd movement alone. The team also observed repeated mutations in the same genes, pointing to unusual evolutionary pressures.
The study highlights the value of analyzing animal remains, which can provide insights that no human sample can. According to researchers, the extensive herding practices of the Sintashta-Petrovka culture created opportunities for their livestock to come into contact with wild animals infected by Yersinia pestis, ultimately leading to human infection.
Source: https://www.jpost.com/archaeology/article-863997