[[link removed]]
SUNDAY SCIENCE: A DEADLY OUTBREAK OF PLAGUE, NEARLY 5,000 YEARS
BEFORE THE BLACK DEATH
[[link removed]]
Carl Zimmer
June 17, 2026
The New York Times
[[link removed]]
*
[[link removed]]
*
*
[[link removed]]
_ The oldest known cases, discovered among hunter-gatherers in
Siberian graves, contradict the theory that the disease once was mild.
_
The skull of an adult woman plague victim., Angela Lieverse
In ancient Siberian graves, scientists have discovered the oldest
traces of one of humanity’s greatest enemies. Examining skeletons of
hunter-gatherers who lived 5,500 years ago, the researchers have
isolated DNA from the bacteria that cause the plague.
The findings suggest that the plague, which would later devastate
Europe in the “Black Death
[[link removed]],” was
already a lethal threat early in human history. That would be a big
change from the earlier view of scientists: that these bacteria were
originally relatively mild, and only later produced deadly outbreaks.
“It doesn’t fit the model,” said Eske Willerslev, a geneticist
at the University of Copenhagen and an author of the study
[[link removed]] published on
Wednesday. “But we have to accept the data.”
The bacteria that cause the plague, called Yersinia pestis, mostly
live today in rodents. Fleas take up the bacteria in their bites and
pass them along to other animals. If those fleas happen to bite
people, the victims develop swellings in their lymph nodes, called
buboes, and risk about a 50 percent chance of death in a matter of
days.
Across the world today, a few hundred people contract the plague each
year. But historians have chronicled enormous epidemics from the Roman
Empire onward. The disease seemed to be intimately tied to the rise of
farming and cities.
Rats were drawn to stores of grain and other foods, bringing them into
close contact with people. Fleas jumping from the rats could pass the
bacteria to people. And then fleas on people could spread the disease
further, starting an epidemic.
About 30 years ago, geneticists began adding fresh evidence to this
history. As it turned out, when people die of plague, their bodies may
contain so much bacteria that some travel into teeth and bone.
There, the DNA can survive for thousands of years. In 2015
[[link removed]],
Dr. Willerslev and his colleagues set a new record for ancient
Yersinia DNA, finding it in 5,000-year-old teeth. It was a surprising
discovery in many ways.
For starters, the people who had this early form of the plague were
not city dwellers or even farmers. They were nomadic pastoralists who
herded cattle and sheep on horseback across the steppes in what is now
Russia and Ukraine.
Moreover, these early Yersinia lacked crucial genetic adaptations
found in more recent strains, mutations that account for the
bacteria’s deadliness today. Stranger yet, they did not carry a gene
that today’s Yersinia need to survive in fleas.
Dr. Willerslev and his colleagues came up with new hypotheses to
explain what they had found: Maybe plague first spilled over to humans
not on farms or in cities, but in the grasslands of Central Asia, as
herders and livestock came into contact with wild infected rodents.
But if that were true, humans at the time could not have been infected
by fleas. And it appeared that this early form of Yersinia was mild.
The evidence suggested that over 1,000 years passed before the
bacteria evolved into an epidemic-causing, flea-driven threat.
More recently, Dr. Willerslev and his colleagues examined the bones of
hunter-gatherers interred in cemeteries near Lake Baikal. The
researchers obtained DNA from the teeth of 46 skeletons at three
sites, discovering Yersinia DNA in 18 individuals. The oldest dated
back 5,500 years, a new record.
But the great age of these bacteria was just one remarkable finding.
The victims here were not herders or farmers, but nomads who moved in
small groups across the Siberian landscape, catching fish, hunting
game and collecting plants for food.
The deadliness of the bacteria was unexpected. The researchers found
plague DNA in 39 percent of the hunter-gatherers they studied, which
is about the same detection rate in studies of the remains of people
who died in the Black Death.
The results hint at a devastating die-off among ancient Siberians.
“To the best of my knowledge, it’s the first evidence that these
early strains of plague were in fact deadly,” Dr. Willerslev said.
“This actually was a dangerous thing.”
He and his colleague also found some telling clues about the
plague’s victims. A striking number were children. Many of the dead
belonged to the same families or were close relatives.
Comparing the ages of the cemeteries, Dr. Willerslev and his
colleagues concluded that plague hit the region, disappeared and
returned in another outbreak a few centuries later.
But that’s not to say the plague was limited to that region. The DNA
of the Lake Baikal Yersinia is most similar to that in a sample
isolated in 2021 about 3,000 miles to the west, from the teeth of a
5,000-year-old hunter-gatherer in what’s now Latvia.
“Higher population density and animal domestication were not an
essential condition for severe outbreaks,” said Alexander Herbig, a
computational biologist at the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, who was not involved in the study.
Dr. Willerslev said that he and his colleagues did not have any
obvious explanations for how a lethal plague could have struck
hunter-gatherers who were spread over thousands of miles for centuries
— without the help of fleas.
They suggested that rodents across Asia and Europe had harbored the
bacteria, which somehow jumped directly to people.
Other experts disagreed. “That’s a big leap with no evidence,”
said David Wagner, a microbial geneticist at Northern Arizona
University who was not involved in the study.
Not only does Yersinia today need fleas to cross from rodents to
people, he observed, but the pathogen also depends on them to jump
from one rodent to another
Dr. Wagner favors another possibility: The plague originally spread
directly between people. It’s a form of transmission that happens
today from time to time, known as pneumonic plague.
People dying of the plague build up so much bacteria that it gets into
their lungs, and they cough the germs into the air. Bystanders may
inhale the Yersinia-laced respiratory droplets and become infected.
“If you don’t get treated, it’s a death sentence,” Dr. Wagner
said.
_CARL ZIMMER_ [[link removed]]_ covers news
about science for The Times and writes the __Origins column_
[[link removed]]_._
_Subscribe to the NEW YORK TIMES_ [[link removed]]
DARTMOUTH’S AI SUMMER AND WHAT CAME NEXT
[[link removed]]KATE
CRAWFORDSCIENCEThe 70th anniversary of the first AI workshop invites
reflection on the technology’s wider legaciesJune 25, 2026
* Science
[[link removed]]
* archeology
[[link removed]]
* Medicine
[[link removed]]
* The Plague
[[link removed]]
* DNA
[[link removed]]
* genetics
[[link removed]]
* bacteria
[[link removed]]
*
[[link removed]]
*
*
[[link removed]]
INTERPRET THE WORLD AND CHANGE IT
Submit via web
[[link removed]]
Submit via email
Frequently asked questions
[[link removed]]
Manage subscription
[[link removed]]
Visit xxxxxx.org
[[link removed]]
Bluesky [[link removed]]
Facebook [[link removed]]
[link removed]
To unsubscribe, click the following link:
[link removed]
