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How we solved the centuries-old mystery of its origins

Black Death: How We Solved the Ancient Mystery of Its Origin

Tombstones examined in new research, most from 1338. Credit: P.-G. Borbone/nature, author provided

It’s no exaggeration to say that the question of where and when the Black Death, the deadliest pandemic ever, originated is one of the greatest mysteries in human history. After all, the Black Death was the first wave of the second plague pandemic from the 14th to the early 19th century. It killed some 50-60% of the population in Europe, the Middle East and North Africa and an inexplicable number of people in Central Asia.

Several proposals have been made, based on competing theories. But in 2017 I came across some records describing an intriguing medieval cemetery in Kara-Djigach, Chüy Valley, northern Kyrgyzstan, which I suspected could be the key. As part of a multidisciplinary team led by Maria Spyrou at the University of Tübingen, we have now examined several specimens of individuals buried at that site – and come up with an answer

The idea that the Black Death originated in the East — areas roughly overlapping Central Asia, Mongolia and China — dates back to the pandemic’s contemporaries in Europe and the Islamic world. Modern academic Chinese origin theory dates back to at least 1756-1758 and a publication on the history of Central Asia by the French scholar Joseph de Guignes.

Other plague historians view Central Asia in general and the Tian-Shan region, a mountainous region on the border between China and Kyrgyzstan, as the cradle of the Black Death. But some scholars have argued for: alternative regions as diverse as Northern Iraq, the Caucasus, the Russian Volga, the Western Urals or Western Siberia, the Gobi Desert, and India. One historian even suggested that the beginning of the Black Death was associated with: an unknown cosmic event

Likewise, the chronological origin of the pandemic has also been disputed. In a 2013 studya team of microbiologists identified a key evolutionary event in which the main plague lineage (branch 0) mutated and split into four new plague lines: branches 1-4. The researchers, also called the “Great Polytomy” or “Big Bang”, found that this event created the tension (on Branch 1) associated with the Black Death. The study, which was based on probability, dated this event to a period between 1142 and 1339. They also concluded that Y. pestis—pest bacteria—may have originated in the Tibetan Qinghai Plateau in Asia.

Based on this work, it has been suggested that the pandemic spread widely in the 13th century, thanks to the expansion of the nascent Mongol Empire.

Black Death: How We Solved the Ancient Mystery of Its Origin

Tian Shan region. Credit: Lyazzat Musralina, , author provided

Genetics to the rescue

Without securely dated ancient DNA from Central Asia, the question would ultimately remain unsolved.

This changed when I came across records of the Kara-Djigach Cemetery – excavated by Russian archaeologist Nikolai Pantusov in 1885 and 1886 and analyzed by Russian scholar Daniel Chwolson (1819-1911). Of the total of 467 stones, which cover the period 1248-1345, 118 date from 1338 – a suspiciously high number of dead. Most of the stones have few details about the person they commemorate, only with the names and dates of death, but there are ten longer inscriptions from those years, stating “pestilence” (mawtānā in Syriac, the language of ancient Syria) as cause of death.

It was intriguing. Not only that “plague” was mentioned, but the accompanying tombstones were all dated to 1338-1339 – just seven to eight years before the arrival of the Black Death in Crimea, and its subsequent spread across western Eurasia and North Africa . I had a strong gut feeling about the likely connection.

So we decided to genetically sequence the remains of several specimens from these plague year burials, and we managed to get results from the teeth of seven different individuals. Our analysis detected the presence of Y. pestis in three copies, confirming that the plague was indeed caused by this bacterium. We also noticed that the species (on Branch 0) appeared to just predate the Great Polytomy, from which the Black Death species evolved shortly after. The study therefore indicates that the Black Death began shortly after (or possibly even during) this 1338–1339 outbreak.

Of course, there is no indication that Kara-Jigach was the specific source of the pandemic. Rather, we think the disaster started somewhere in the wider Tian Shan area, perhaps not too far from that spot. It is important to keep in mind that: Y. pestis is a bacterium that lives among wild rodent populations. We often associate plague with rats. But in Tian Shan, marmots are the most common carriers of the plague by rodents. It is therefore likely that it was their colonies that were the ultimate source of the 1338-1339 outbreak.

Importantly, ancient plague strains found today in marmot colonies in the Tian Shan plague reservoirs are evolutionarily older even than the Kara-Djigach strain. Therefore, we conclude that the Kara-Jigach tribe must have evolved locally in marmot colonies in the extensive Tian Shan area, rather than being introduced into the Kara-Jigach community from a distant origin. At one point, the bacteria simply crossed over to human inhabitants of the region.

The publication in question has brought an end to the age-old debate about the spatio-temporal origin of the Black Death. But what else do we get out of it? To understand the phenomenon of emerging epidemic diseases, it is essential to have a large evolutionary picture. It is important to see how these diseases develop evolutionarily and historically, and to avoid treating different strains as isolated phenomena. To understand how the diseases develop and are transmitted, it is also crucial to consider the ecological and socio-economic context.

We also hope that our study will set an example for other historians and scientists who hope to answer such big questions – demonstrating that a collaborative approach involving colleagues from different fields and bringing together different skills, methods, experiences and talents is the future. of historical and paleogenetic research.

Ancient Plague Genomes Reveal the Origin of the Black Death

Provided by The Conversation

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