Hunter-gatherers in Siberia died of a plague outbreak 5,500 years ago - Ars Technica

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Plague swept through groups of hunter-gatherers in southeastern Siberia 5,500 years ago, leaving dozens dead in its wake—with DNA from Yersinia pestis bacteria still trapped inside their teeth.

University of Oxford ancient DNA researcher Ruairidh Macleod and his colleagues recently sequenced the telltale bacterial DNA in teeth from plague victims at four ancient cemeteries in the area around Russia’s Lake Baikal. The tragedy that befell these communities is now the earliest known plague outbreak, courtesy of the oldest strain of Y. pestis ever sequenced.

Unearthing a new backstory for the plague

Until recently, scientists who study the evolution of diseases have held two fairly solid ideas about the origins of plague, the disease caused by Yersinia pestis bacteria. It’s a scourge so awful that it has gone down in history as not just a plague but the plague. The first idea is that the earliest strains didn’t have the right genetic traits to be really lethal. And the second is that the plague first began menacing humans when the first farmers settled in densely packed towns alongside rats and domestic animals.

But the dead of Ust’-Ida I cemetery, near Lake Baikal, tell a very different story.

“Our findings demonstrate that the earliest known outbreaks of plague occurred in prehistoric hunter-gatherers centuries before infections are observed in Neolithic farmers,” wrote Macleod and his colleagues in their recent paper.

That challenges our previous assumption that plague spillover was a side effect of people taking up farming and settling in permanent villages and towns, living closer to each other and to an assortment of animals (and their fleas).

“Much of the accepted theory around epidemiology of disease in the past is that this kind of thing shouldn’t occur in hunter-gatherers because hunter-gatherers are constantly moving around the landscape because they’re in such small groups all the time,” said Macleod in a press conference. “The theory, at least, is that infectious disease can’t really take hold and devastate entire communities in this way.”

So much for that theory.

Welcome to the world’s first plague cemetery

The Angara River flows from the depths of Lake Baikal. The people who lived along it thousands of years ago survived by hunting, foraging, and fishing. They would have lived in relatively small groups, but they seem to have stayed connected across hundreds of kilometers through marriage and family ties. Although their lifestyle would have been one of constant movement, they buried their dead in cemeteries such as Ust’-Ida, interring them with offerings of clay pots, stone tools, and bone and antler points.

This map shows the location of Ust’-Ida I and Shumilikha cemeteries near Lake Baikal and the Angara River

Credit:<br>By Tara Young, taray@ualberta.ca and NASA https://wist.echo.nasa.gov/api/ – NASA’s freely offered GDEM https://wist.echo.nasa.gov/api/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=21156871

This map shows the location of Ust’-Ida I and Shumilikha cemeteries near Lake Baikal and the Angara River

Credit:

By Tara Young, taray@ualberta.ca and NASA https://wist.echo.nasa.gov/api/ – NASA's freely offered GDEM https://wist.echo.nasa.gov/api/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=21156871

At Ust’-Ida, archaeologists with the Baikal Archaeology Project unearthed a grim mystery: an unusually high number of dead children, a cluster of radiocarbon dates suggesting that many of the cemetery’s occupants died at around the same time, and no evidence of violence. Something tragic happened to this ancient hunter-gatherer community, but what? Archaeologists thought ancient DNA might shed some light on the mystery.

Macleod and his colleagues started with shotgun sequencing, a technique used to identify the DNA sequences in a sample when scientists don’t know exactly which organisms they’re looking for. They used samples from the roots of 46 ancient people’s teeth from four different cemeteries along the Angara River.

And to their complete surprise, they found plague.

Fun fact: Because dental roots are fed by lots of blood vessels, anything in your bloodstream is likely to pass through your teeth at some point, which means if you die with the plague, it may leave its DNA behind in your teeth. “This is really cool evidence that the plague was in the bloodstream, which is lethal,” said co-author Frederik Seersholm, a...