A research group that grew out of a collaboration between Germany and Scotland claims to have found the spot where the “Black Plague” began, the 14th-century plague epidemic that claimed the lives of tens of millions of people worldwide caused. according to the most shared estimates. The study explains that traces of Yersinia pestis, the bacterium that causes the disease, were identified in some teeth found near the Issyk-Kul salt lake in Kyrgyzstan. According to the research team, the Black Plague began to be present in the area between 1338 and 1339 and later spread to Europe, Asia and the rest of the world.
Plague is an infectious disease caused by the bacterium Yersinia pestis, which comes into contact with humans directly through the bite of rat fleas or indirectly through the bite of a rat or other infested rodent. Fleas and lice, although in minor forms, can in turn lead to inter-individual infections in humans.
The symptoms of plague are highly dependent on the areas where the bacterial colonies are concentrated in the body. The plague can be pulmonary, bubonic, and septicemic, causing severe infection of the blood cells leading to necrosis of the tissues, which then turn black and become non-viable. Today it can be easily treated with antibiotics, but in the past it was highly fatal in the absence of adequate medication.
The plague devastated European and Asian populations for centuries. The so-called “Justinian plague” was a pandemic that spread between 541 and 542, mainly in Constantinople and in various port cities of the Mediterranean: it is estimated that it killed between 25 and 50 million people in total in the different waves of the disease in the following two centuries.
The black plague in Eurasia (which peaked in Europe in the first half of the 14th century) had even more devastating effects, killing between 75 and 200 million people overall. Historians estimate that this resulted in the deaths of 30 to 60 percent of all Europeans and reduced the world population from 450 million people to around 360 in the 14th century (it took almost three centuries for the world population to return to pre-plague levels). .
Reconstructing the path of the Black Death has always been very difficult because the disease is rapid and leaves virtually no traces in the bones, often the only organic remains that can be analyzed by people who lived in the past. Thanks to the evidence of the 14th century, historians were nevertheless able to reconstruct a probable route of infection: from China via the western Chinese border to Europe and later to North Africa and the Middle East. However, there were not enough elements to say with certainty that the pandemic was caused by Yersinia pestis, precisely because of the difficulty in gathering direct evidence from the bones.
Spread of the Black Death in Europe (Wikimedia)
A decade ago, the same research team now curating the new study claimed they could track down the DNA of the bacteria that causes plague in teeth, and specifically in the remains of the pulp, the soft tissue that lives inside them. The analytical technique had been put into practice for a study involving some of those who had died from the plague in London, where the authorities of the 14 Other. These later recovered and preserved corpses were ideal for conducting studies of the plague as they had been cataloged with precise details of the time and circumstances of death.
After the research group had demonstrated the effectiveness of the analysis method on teeth, the research group analyzed the genomes of other people who died from the Black Death around the world in order to gradually track the occurrence of variants of the bacterium and, incidentally, to be able to reconstruct a kind of Yersinia family tree -Pestis infections. After a long period of essentially one branch, a time was identified when four more branches began to form.
Evolution of the Black Death bacterium, Yersinia pestis (nature)
However, it was not easy to reconstruct the details of that moment, just as it was not easy to date it. Historians believed that this may have happened between the 10th and 14th centuries, but the dating was rather general and of little use for a more in-depth study of the Black Death.
The research team had long suspected the outbreak began on the western border with China and identified two Christian cemeteries in Kyrgyzstan with well-preserved graves and headstones, in some cases listing the cause of death of the buried person. with the word “plague”. Studying the data had also made it clear that the number of deaths in the area had increased significantly by the late 1430s, indicating the probable presence of a highly contagious and deadly disease.
The peak of deaths was recorded in 1338, just under a decade before the Black Death appeared in Europe. So it was decided to analyze the teeth of three bodies buried in these cemeteries and discover DNA traces of the bacterium that causes the plague.
The study, recently published in Nature, reports that the bacterial strain identified in Kyrgyzstan is placed in the black plague family tree roughly where the new branching occurred. The research team believes this is the starting point of the pandemic, which occurred primarily through trade routes and not due to the movement of armies and military activity in earlier centuries, as suggested by other historians. The bacterium was originally spread by some marmots that still have fleas carrying strains of Yersinia pestis whose origins can be traced back to those of the black plague.
The new research has attracted a lot of interest, particularly for the techniques used to detect traces of the bacterium in teeth, but not everyone is yet convinced of its conclusions. However, the research team is planning new analysis and fieldwork that could lead to even more compelling evidence to support their theory.