Researchers finally found the cause of the Black Death
[May 16, 2023: Staff Writer, The Brighter Side of News]
Reconstruction of plague victim from All Saints, Cambridge. (CREDIT: Mark Gridley)
In 1347, the Black Death first made its way into the Mediterranean through trade ships that carried goods from the territories of the Golden Horde in the Black Sea. The outbreak then spread across Europe, the Middle East, and northern Africa, leading to the loss of up to 60 percent of the population. This initial wave of the plague gave rise to a 500-year-long pandemic, known as the Second Plague Pandemic, which persisted until the early 19th century.
The source of the Second Plague Pandemic has been a topic of much discussion for years. While one of the most widely accepted theories suggests that it originated in East Asia, particularly in China, the only archaeological evidence available at present comes from Central Asia, near Lake Issyk Kul, in what is currently Kyrgyzstan.
According to the findings, a local trading community was ravaged by an epidemic during the years 1338 and 1339. Nearly 140 years ago, excavations uncovered tombstones indicating that people died during that time due to an unknown epidemic or "pestilence."
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. (CREDIT: Lyazzat Musralina)
Since their initial discovery, scholars have debated the significance of the tombstones, which are inscribed in Syriac language, in relation to the Black Death in Europe.
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An international team of researchers conducted an analysis of ancient DNA from human remains and historical and archaeological data from two sites that contained "pestilence" inscriptions. The aim of the study was to determine the cause of the epidemic that was mentioned in the inscriptions.
Excavation of the Kara-Djigach site, in the Chu-Valley of Kyrgyzstan within the foothills of the Tian Shan mountains. This excavation was carried out between the years 1885 and 1892. (CREDIT: A.S. Leybin, August 1886)
The initial results of the study were promising. The team was able to identify DNA from the plague bacterium, Yersinia pestis, in individuals whose tombstones were inscribed with the year 1338. Phil Slavin, a senior author of the study and historian at the University of Sterling, UK, stated that the study finally provided evidence that the epidemic mentioned on the tombstones was indeed caused by the plague.
Researchers found the Black Death’s source strain
Researchers have previously linked the initiation of the Black Death with a significant increase in the number of plague strains, referred to as the Big Bang event of plague diversity. However, the exact date of this occurrence had remained imprecise and was estimated to have taken place sometime between the 10th and 14th centuries. Could this event be the source of the Black Death?
Plague inscription from the Chu-Valley region in Kyrgyzstan. The inscription is translated as follows: “In the Year 1649 [= 1338 CE], and it was the Year of the tiger, in Turkic [language] "Bars". This is the tomb of the believer Sanmaq. [He] died of pestilence”. (CREDIT: A.S. Leybin, August 1886)
By reconstructing the entire genomes of ancient plague strains from sites in Kyrgyzstan, the team investigated their possible association with the Big Bang event. Their findings showed that the ancient strains from Kyrgyzstan were positioned precisely at the node of this extensive diversification event. "We have identified the Black Death's source strain and even know its exact date, which is 1338," says Maria Spyrou, lead author and researcher at the University of Tübingen.
A disease then disseminated across Europe, the Middle East and northern Africa claiming up to 60 percent of the population in a large-scale outbreak known as the Black Death. (CREDIT: Getty Images)
In summary, the Black Death's origin has been linked to the Big Bang event of plague diversity, which previously could not be accurately dated. However, through the reconstruction of ancient plague genomes from Kyrgyzstan, the team identified the precise source strain of the Black Death and its date, which was in the year 1338.
The origin of the strain that caused the Black Death remains a mystery. Scientists are unsure whether it evolved locally or spread to the region from another location. Plague is not exclusive to humans, as the bacterium survives in wild rodent populations around the world, in areas known as plague reservoirs. Therefore, the ancient Central Asian strain responsible for the 1338-1339 epidemic near Lake Issyk Kul likely originated from one of these reservoirs.
Lake Issyk Kul is an endorheic lake (i.e., without outflow) in the Northern Tian Shan mountains in Eastern Kyrgyzstan. (CREDIT: Wikimedia)
According to Johannes Krause, director at the Max Planck Institute for Evolutionary Anthropology and senior author of the study, modern strains closely related to the ancient strain can be found in plague reservoirs around the Tian Shan mountains. This finding indicates that the ancestor of the Black Death likely originated in Central Asia, in close proximity to where the ancient strain was discovered.
With unparalleled precision, the research illustrates how scrutinizing well-defined archaeological contexts and fostering close partnerships among historians, archaeologists, and geneticists can unravel major enigmas of our history, such as the origins of the notorious Black Death.
For more science news stories check out our New Discoveries section at The Brighter Side of News.
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