The Black Death is regarded as the deadliest plague in human history. But despite years of research, its geographic and chronological origin has largely remained a mystery.
Now, a new study of ancient DNA from bubonic plague victims claims to have cracked the conundrum by tracing the disease back to 1338 in what is present day Kyrgyzstan.
Researchers retrieved ancient DNA traces of the Yersinia pestis plague bacterium from the teeth of three women buried in a medieval Nestorian Christian community in the Chu Valley near Lake Issyk Kul who perished in 1338-1339.
The earliest deaths documented elsewhere in the pandemic were in 1346.
Reconstructing the pathogen’s genome showed that this strain not only gave rise to the one that caused the Black Death that mauled Europe, Asia, the Middle East and North Africa but also to most plague strains existing today.
Researchers say the bubonic plague spread across the Mediterranean via the old Silk Road trade route before sparking a near 500-year-long wave of killer diseases, termed the Second Plague Pandemic.
Up to 200 million people were killed when the Black Death swept through the Middle East and Europe between 1346 and 1353, with half of all Londoners and up to 60 per cent of Europeans wiped out.
Researchers believe the Black Death first originated in Kyrgyzstan in the late 1330s. They analysed ancient DNA taken from the teeth of skeletons discovered in cemeteries. Pictured is a headstone inscription from the Chu-Valley region in Kyrgyzstan. The inscription is translated as follows: ‘This is the tomb of the believer Sanmaq. [He] died of pestilence [bubonic plague]’
Pictured is an excavation of the KaraDjigach site, in the Chu-Valley of Kyrgyzstan within the foothills of the Tian Shan mountains. This was carried out between the years 1885 and 1892
TIMELINE OF HOW THE BLACK DEATH SPREAD
A new study by an international team of researchers claims to have established the origins of the Black Death, which is regarded as the deadliest plague in human history.
This is the timeline of how experts believe it then spread:
1338 – The disease originates in what is present day Kyrgyzstan
1347 – It later spreads across the Mediterranean via trading ships to ports including Sicily
1348 – The plague reaches North Africa, mainland Italy, Spain, France and the UK
1349 – People in Austria, Hungary, Switzerland and Germany become infected, too
1350 – The Black Death arrives in Scandinavia and the Baltic countries
The Silk Road was an overland route for caravans carrying a panoply of goods back and forth from China through the sumptuous cities of Central Asia to points including the Byzantine capital Constantinople and Persia.
It also may have served as a conduit of death if the pathogen hitched a ride on the caravans.
‘There have been a number of different hypotheses suggesting that the pandemic may have originated in East Asia, specifically China, in Central Asia, in India, or even close to where the first outbreaks were documented in 1346 in the Black Sea and Caspian Sea regions,’ said archaeogeneticist and study lead author Maria Spyrou of the University of Tübingen in Germany.
‘We know that trade was likely a determining factor to the dispersal of plague into Europe during the beginning of the Black Death. It is reasonable to hypothesise that similar processes determined the spread of the disease from Central Asia to the Black Sea between 1338 and 1346.’
The Black Death is believed to have arrived in the UK in 1348 on a ship landing on the Dorset coast from Gascony in France, before quickly spreading throughout the country.
The research team behind the new study were from Scotland’s University of Stirling and Germany’s Max Planck Institute and University of Tubingen.
They analysed ancient DNA (aDNA) taken from the teeth of skeletons discovered in cemeteries near Lake Issyk Kul in the Tian Shan region of Kyrgyzstan.
The scientists were drawn to these sites after identifying a huge spike in the number of burials there in 1338 and 1339, according to University of Stirling historian Dr Philip Slavin, who helped make the discovery.
They found the cemeteries, at Kara-Djigach and Burana, had already been excavated in the late 1880s, with about 30 skeletons taken from the graves, but were able to trace them and analyse DNA taken from the teeth of seven individuals.
The sequencing, which determines the DNA structure, showed three individuals carried Yersinia pestis, a bacterium which is linked to the beginning of the Black Death outbreak before it arrived in Europe.
‘Our study puts to rest one of the biggest and most fascinating questions in history and determines when and where the single most notorious and infamous killer of humans began,’ Dr Slavin said.
Pictured, a depiction of plague victims being buried during the Black Death. The devastating bubonic plague pandemic ravaged Europe from 1346 to 1353
Researchers analysed ancient DNA (aDNA) taken from the teeth of skeletons discovered in cemeteries near Lake Issyk Kul in the Tian Shan region of Kyrgyzstan (shown)
A view of the Tian Shan mountains. Studying ancient plague genomes, researchers traced the origins of the Black Death to Central Asia, close to Lake Issyk Kul, in what is now Kyrgyzstan
WHAT IS THE SILK ROAD?
The Silk Road was an ancient network of trade routes that runs across the Asian continent, connecting countries as far east as Japan to Europe.
It derives its name from the lucrative trade in silk that occured across continents from at around 200BC.
The road was once strewn with bustling cities, desert oases and market towns, but little is known about how the roads originally formed.
Archaeologists at the Max Planck Institute and the Russian Academy of Sciences have found people were moving domestic animals such as cattle, sheep, and goat across the high mountain corridors as long as 4,000 years ago.
Part of his work involved studying the historic diaries of the original excavations in order to match the individual skeletons to their headstones, carefully translating the inscriptions, which were written in the Syriac language.
Dr Maria Spyrou, of the University of Tubingen, and the first author of the study, said: ‘Despite the risk of environmental contamination and no guarantee that the bacteria would have been able to be preserved, we were able to sequence aDNA taken from seven individuals unearthed from two of these cemeteries.
‘Most excitingly, we found aDNA of the plague bacterium in three individuals.’
Researchers have previously associated the Black Death’s initiation with a massive diversification of plague strains, a so-called ‘Big Bang’ of plague diversity.
But the exact date of this event could not be precisely estimated, and was thought to have happened sometime between the 10th and 14th centuries.
The research team have now pieced together a complete ancient plague genome from the Kyrgyzstan sites and investigated how they might relate with the ‘Big Bang’ event.
Dr Spyrou said: ‘We found that the ancient strains from Kyrgyzstan are positioned exactly at the node of this massive diversification event.
‘In other words, we found the Black Death’s source strain and we even know its exact date.’
She explained that plague is not a disease of humans; the bacterium survives within wild rodent populations around the world, in so-called plague reservoirs.
The ancient Central Asian strain that caused the 1338-1339 epidemic around Lake Issyk Kul must have come from one such reservoir, say the researchers.
Co-senior author Professor Johannes Krause, of the Max Planck Institute, said: ‘We found that modern strains most closely related to the ancient strain are today found in plague reservoirs around the Tian Shan mountains, so very close to where the ancient strain was found.’
He added: ‘This points to an origin of Black Death’s ancestor in Central Asia.’
The findings were published in the journal Nature.
The silk road is a complex system of trade routes linking East and West Eurasia through its arid continental interior. It derives its name from the lucrative trade in silk that occurred across continents from at around 200BC
WHAT WAS THE CAUSE OF EUROPE’S BUBONIC PLAGUES?
The plague, caused by the bacterium Yersinia pestis, was the cause of some of the world’s deadliest pandemics, including the Justinian Plague, the Black Death, and the major epidemics that swept through China in the late 1800s.
The disease continues to affect populations around the world today.
The Black Death of 1348 famously killed half of the people in London within 18 months, with bodies piled five-deep in mass graves.
When the Great Plague of 1665 hit, a fifth of people in London died, with victims shut in their homes and a red cross painted on the door with the words ‘Lord have mercy upon us’.
The pandemic spread from Europe through the 14th and 19th centuries – thought to come from fleas which fed on infected rats before biting humans and passing the bacteria to them.
But modern experts challenge the dominant view that rats caused the incurable disease.
Experts point out that rats were not that common in northern Europe, which was hit equally hard by plague as the rest of Europe, and that the plague spread faster than humans might have been exposed to their fleas.
Most people would have had their own fleas and lice, when the plague arrived in Europe in 1346, because they bathed much less often.