A photo provided by the National Museum of Denmark showing a 1939 photograph of excavations of the Neolithic burial site Stroby in Denmark. — ©2024 The New York Times Company
AROUND 5,300 years ago, a mysterious collapse swept through Scandinavia and northwest Europe.
Populations plummeted, farming communities vanished, and megalithic projects like Stonehenge ground to a halt.
“Settlements were abandoned. Everyone vanished,” says Frederik Seersholm, a geneticist at the University of Copenhagen.
This demographic crash, known as the Neolithic decline, allowed nomadic Yamnaya herders to migrate west, altering Europe’s genetic makeup.
The cause has long been debated, with wars and agricultural crises as prime suspects.
Now, a groundbreaking genomic study published in Nature introduces a chilling possibility: an ancient plague pandemic.
Yersinia pestis – the bacterium behind the infamous Black Death – may have played a central role.
Previously, scientists doubted whether early strains of the plague could trigger widespread epidemics.
“That hypothesis no longer holds,” Seersholm, the study’s lead author, asserts.
The study suggests that the plague could have originated in small farming villages and spread along trade routes.
“We can’t prove this was exactly how it happened, not yet anyway,” Seersholm admits. “But it’s significant that we can show it could have happened.”
Yersinia pestis typically spreads through fleas and rats in its bubonic and septicemic forms, but the deadlier pneumonic strain transmits via airborne droplets.
This form is highly contagious among humans and animals alike.
In her book Plague, Wendy Orent, an anthropologist in Atlanta, speculates that the first account of bubonic plague was the Old Testament story of the Philistines who stole the Ark of the Covenant from the Israelites and were afflicted with “swellings”.
Since antiquity, Yersinia pestis has driven three catastrophic pandemics.
The first, the Plague of Justinian (AD541-750), devastated Europe, Africa, and Asia, claiming up to 50 million lives.
It struck during the reign of Byzantine Emperor Justinian, who survived his own bout with the disease and deepened the social and economic collapse of western Europe.
The next major outbreak of the plague has been pinned on a variant of Yersinia pestis that most likely jumped from wild marmots to humans in what is now northern Kyrgyzstan.
The first recorded emergence occurred in the 14th century during the siege of Kaffa, a Genoese trading port in Crimea, where the Mongols reportedly catapulted disease-ridden corpses over the walls.
From 1346-53, the Black Death – a grim reference to the gangrenous blackening and death of tissue, mostly on the extremities – wiped out perhaps half of Europe’s population.
It proved to be the initial wave of a nearly 500-year contagion that included the Great Plague of London in 1665-66, as a witness observed, “The warning cry ‘bring out your dead’ and the rumble of the ‘dead-carts’ disturbed the stillness of the night.”
A descendant of that strain is blamed for the third pandemic, known as the Modern Plague, which originated in 1855 in China and traversed the globe over the next several decades, resulting in the deaths of about 12 million people in India alone.
Although it still smolders in small pockets worldwide the Modern Plague is now treatable with antibiotics if caught early.
In 2001, scientists decoded the Yersinia pestis genome after tracing a fatal case to a Colorado veterinarian infected by a sneezing cat.
A decade later, researchers identified plague bacteria in 5,000-year-old Eurasian teeth.
More recently, evidence emerged from a Latvian man’s Stone Age skull, and in 2023, British scientists detected the bacterium in 4,000-year-old remains.
The latest study sequenced the genomes of 108 individuals buried between 3300BC and 2900BC across nine sites in Sweden and Denmark. Yersinia pestis was the most prevalent pathogen, found in about 17% of the bodies.
“One in six people had active infections at the time of death,” Seersholm notes, adding that the actual infection rate was likely higher.
A family burial spanning six generations revealed a sobering pattern: 12 of 38 family members had the plague.
“It was almost certainly pneumonic,” Seersholm explains. Unlike the bubonic form, this strain didn’t require fleas or rats. “No rats were required.”
The team identified three distinct plague waves during the period. The first two appeared relatively mild, but the third was more virulent and may have precipitated the Neolithic collapse.
Despite the compelling findings, some experts remain cautious.
Pooja Swali, a geneticist at University College London, acknowledges the study’s significance but urges restraint.
“Yersinia pestis may have played a role or dealt some final blows, but many factors likely contributed,” she says. Famine, other diseases, or societal stresses might have compounded the crisis.
Historian Kyle Harper, author of Plagues Upon the Earth, emphasises the gaps in our knowledge.
Unlike the well-documented Justinian Plague or Black Death, the Stone Age pandemic is still shrouded in mystery.
“How did it spread? How did it affect people? These are still huge unknowns,” Harper concludes.
While questions remain, the study underscores an unsettling possibility: the plague’s deadly legacy may stretch back far earlier than previously thought, its shadows reaching all the way to the end of the Stone Age. — ©2024 The New York Times Company
