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Precursor of Black Death Detected in 4,000-Year-Old Sheep Excavated in Russia: Study

Researchers excavated a 4,000-year-old sheep tooth from Russia and found that it was infected by the Late Neolithic Bronze Age plague lineage of 'Yersinia pestis.'

BY SOMDATTA MAITY

PUBLISHED 10 HOURS AGO

Plague bacteria, Yersinia pestis, illustration. (Representative Cover Image Source: Getty Images/ Photo by Dr_Microbe)

A prehistoric form of Black Death seems to have run through Eurasia during the Bronze Age. The cause behind this Black Death precursor was identified as the Late Neolithic Bronze Age (LNBA) plague lineage of "Yersinia pestis" by experts. The specific lineage was recently detected in a 4,000-year-old domesticated sheep from present-day Russia. After analysis of these remains, researchers suggested a possible transmission method of this pathogen during the Bronze Age. Their speculation was explained in detail within the journal Cell.

Yersinia pestis (Representative Image Source: Wikimedia Commons | Photo by Ras67 )

First Bronze Age Animal with this Pathogen

The prehistoric pathogen lineage was identified through ancient human DNA samples by researchers in the past, according to Popular Science. The samples showcase that the infection triggered by LNBA ran rampant around 5,000 years ago. Evidence could be found across 3,700 miles, from Europe to Mongolia. For 2,000 years, the pathogen lineage remained an entity in several DNA samples, but after that, it completely vanished from the archaeological records. For the first time, it has been detected in an animal. It proves that the precursor plague reached both animals and humans. As it was identified in a sheep, it could be speculated that the sheep spread the pathogen to humans.

Shallow Focus Photography of White Sheep on Green Grass (Representative Image source: Pexels | Photo by Kat Smith)

Why did Researchers Excavate the Sheep?

Past studies have showcased that many modern human diseases have developed during the last 10,000 years, according to CNN. It coincides with the timing of animal domestication by human society, making researchers speculate that, along with fleas, livestock and pets could also be spreading pathogens to humans. To prove this theory, they needed to find evidence of ancient bacterial genomes from animal hosts.

It made them explore an archaeological site in Russia known as Arkaim. It was once inhabited by people from a culture called Sintashta-Petrovka, who worked a lot with livestock. Here, they excavated the tooth of a 4,000-year-old sheep, which was determined to have been infected by LNBA. The same lineage was then detected in nearby human remains from the Bronze Age.

The infection was found to be zoonotic, which originated in wild animals. It made researchers claim that the infection could have spread from wild animals to livestock, and finally to humans. "We're sort of unveiling this in real time and trying to get a sense for how Bronze Age nomadic herders out in the Eurasian Steppe were setting the stage for disease transmission that potentially led to impacts elsewhere," Dr. Taylor Hermes, a study coauthor and an assistant professor of anthropology at the University of Arkansas shared, "not only in later in time, but also in a much more distant, distant landscape."

The infection had a massive impact, as 20% of the human bodies buried in Eurasian steppes carry the LNBA strain. It implies that they were either infected or killed by the disease. The identification of sheep as a host showcases one way how the disease could have been transmitted, but the condition becoming so widespread still remains a mystery.

Connection with Black Death

The Black Death, which put the entire world into havoc during the 14th century, was caused by the plague bacterium "Yersinia pestis." The same bacterium caused the aforementioned infections in the Bronze Age. However, unlike the Black Death, it could not spread through fleas because the bacterium in the 14th century had a specific genetic toolkit that allowed its later strains to propagate through fleas. The lineage that attacked living beings in the Bronze Age, the LNBA, was not accompanied by this genetic toolkit in "Yersinia pestis." So, this strain was spread by some other means, which, after discovery in Russia, is speculated to be sheep.

The findings have allowed researchers to understand the ecology and transmission of this infection, as well as the role livestock could have played in the propagation of such diseases. Researchers believe that learning more about these pathogens could also help in dealing with upcoming infections. "Evolution can sometimes be 'lazy,' finding the same type of solution independently for a similar problem — the genetic tools that worked for pestis to thrive for over 2000 years across Eurasia might be reused again," lead author Ian Light-Maka, a doctoral researcher at the Max Planck Institute for Infection Biology in Berlin, shared.