Prehistoric plague jumped from unknown species to sheep-and then humans

A new study discovered old plague DNA in 4,000 -year -old bones, shedding light on how the pathogen has infected thousands of people around the world.

The bacteria Yersinia pestis it was a Bubonic plague initial form which circulated during the late neolithic periods and bronze age about 5,000 to 2,000 years ago.

This pathogen is a genetically unique and prehistoric From the plague that infected humans throughout Eurasia – before it presumably is extinguished.

A new one, presented in an article published on Monday in the magazine Cellhas now discovered DNA of this old plague in 4,000 -year -old sheep bones.

“We have more than 200 genomes from Y. Pestis of ancient humans, but humans are not a natural plague host, ”he says Ian Light-Makaresearcher at the Max Planck Institute, in Germany, and the main author of the study, quoted by.

Most human pathogenslike the plague, are zoonotic origin. This means that the plague went through a process known as spillover, the transmission of a pathogen between species, where in this specific case the pathogen jumped from animals to humans.

“One of the first steps to understand how a disease spreads and evolves is find out where you hidebut we haven’t done that in the old DNA field yet, ”says Light-Maka.

The Max Planck Institute’s team of investigators at Harvard University, University of Arkansas and the University of Seoul investigated bronze age bones and teeth at Arkaim’s archaeological site in Russia, to track this spillover.

Then conducted a genetic analysis that revealed that humans and sheep were infected by Fesirpes of fish Y. Pestis almost identical.

“If we didn’t know it was a sheepeveryone would have assumed that it was another human infection – it is almost indistinguishable, ”he says Christina WarinnerProfessor of Scientific Archeology at Harvard University in the USA and Coauthor of the study.

With animal infections for humans increasing – due to changes caused by man in the climate, land use, population density and connectivity – the study demonstrates the impact that animal domestication It has in the propagation and emergency of zoonotic diseases.

The team formulates the hypothesis that the plague would have been in this case transmitted through of an unknown wild animal for sheep and then for humans.

The pathogen in question has a distinct evolution that lacked the genetic machinery needed to pass through fleas. This suggests that the spillover em It didn’t happen from fleas to sheep.

“Arkaim was part of the Cultural Complex Sintashta and offered us a great place to look for plague clues, ”he says Taylor Hermesresearcher at the University of Arkansas and also co -author of the study.

“They were Ancient pastoral societies without the type of grain storage that would attract rats and their fleas, and previous syntashta individuals were found with infections of Y. Pestis. Could your cattle be a missing link?“Asks Hermes.

Researchers suggest that the findings fall into the historical context of the Bronze Age, as there was a Increased cattle breeding which may have taken the greatest contact between humans and sheep.

“The Sintashta-Petrovka culture is famous for its extensive pasture About vast pastures aided by innovative horsepower technologies, this has provided many opportunities for their cattle to contact wild animals infected with Y. Pestis“Says Warinner.

Although remain questions About how pathogens spread so far in a short time, researchers expect this study to be just the beginning. “There will be more and more interest in analyzing these collections,” says Key, “they give us perspectives that no human samples can.”