How scientists were able to uncover the secret of the Black Death?

It is no exaggeration to say that the explanation of the origin date of the Black Death - the most deadly epidemic ever in humans - was until recently the most mysterious medical mystery in human history.

The Black Death, which lasted from 1346 to 1353 AD, was the first wave of a long-term pandemic that lasted from the 14th to the 19th century, killing between 50 and 60% of the population in Europe, the Middle East and North Africa, and an unknown number of the population. In Central Asia.

many imaginations

Many researchers and scientists over the centuries have put forward many interpretations, perceptions and theories, and the researcher Philip Slavin, professor of history at the University of Stirling in Scotland, mentioned some of them in his article published in The Conversation website.

Among these perceptions, scholars who witnessed the plague in Europe and the Islamic world said that the Black Death plague originated in the East, specifically in the regions where Central Asia, Mongolia and China intersect.

The French scientist Joseph de Jane also put forward an academic theory in 1758 indicating that the plague originated in China, and epidemiologists mentioned that Central Asia in general and the Tian Shan region (a mountainous region on the border between China and Kyrgyzstan) is the cradle of the Black Death plague.

Tombstones that wrote the cause of death were the key to solving a mystery that puzzled scientists 8 centuries (websites)

Some scholars mentioned that the source of the plague was other regions such as northern Iraq, the Caucasus, the Volga region in Russia, the western Ural Mountains, western Siberia, the Gobi desert and India. Indeed, one of the historians mentioned that the beginnings of the Black Plague are linked to a meteorite that struck the Earth in that period.

In a study published in 2013, a team of microbial scientists identified a major evolutionary mutation in which the main strain of the pandemic (Faction Zero) mutated and split into 4 new strains, namely, families 1 to 4. The researchers called this mutation metaphorically the “Big Bang.” The strain (or family 1) is the one associated with the Black Death plague.

The study, based on computer probabilities, dates this mutation to the period between 1142 and 1339.

The researchers concluded that the plague bacteria may have originated in the Qinghai (Tibet) Plateau in Asia.

Based on this study, researchers believed that the pandemic spread widely in the 13th century due to the expansion of the rising Mughal Empire.

strange tombs

The turning point in the search for the origins of the Black Plague was when Philip Slavin found records describing the "Kara-Gigach" tombs, discovered by Russian archaeologist Nikolai Bantusov in 1885 and 1886 and analyzed by Russian scientist Daniel Choulson.

Map showing the location of the Kara Zegach tombs and the Tian Shan Mountains region (websites)

Out of a total of 467 graves covering the period from 1248-1345, there are 118 graves dating back to the year 1338, which is a suspiciously large number of deaths.

The tombstones did not contain great details about the graves that are remembered except for the names and dates of death, but 10 of them had words explaining the cause of death, and one of these messages on the tombstones was saying: Here lies the believer Sanmaq.

He died of the plague."

This aroused the curiosity and surprise of Philip Slavin greatly;

It was not only referring to the "epidemic", but all of them had in common that it dates back to the years 1338 and 1339, that is, about 7 or 8 years before the arrival of the Black Plague epidemic in the Crimea and its subsequent spread in Europe and North Africa.

Philip surmised with a strong feeling that this connection was not accidental and that it needed extensive scientific study.

Philip Slavin joined a multidisciplinary team of 13 researchers and scientists to unravel this mystery. Scientists examined the genetic code of DNA extracted from the remains of Black Plague victims whose graves share the same date, 1338 and 1339;

And they obtained conclusive results from the teeth of 7 of them.

The team published the results of the study in the journal "Nature" on June 15.

Unprecedented important discoveries

Genetic analysis revealed the presence of plague bacteria in 3 samples, which confirms that it is the cause of the plague.

The scientists noted that the strain (in the zero family) seemed to precede the genetic mutation, from which the Black Death strain appeared shortly after;

Therefore, the study indicated that the Black Plague began shortly after (or perhaps during) the outbreak of this pandemic between 1338 and 1339.

The common rodents in Tian Shan that transmitted the plague bacteria are badgers (Shutterstock)

Of course, there is no indication that the Karajigac cemetery was the exact source of the plague, but scholars believe that the disaster began somewhere in the vast Tian Shan, most likely not far from this site.

It is worth noting that the plague bacteria (Y. pestis) lives among wild rodents, and the common perception was that mice were the source of the plague, but the common rodents in the Tian Shan area that transmitted the plague bacteria are badgers, and therefore their colonies are likely to be the first source of the plague outbreak Between 1338 and 1339.

The other important discovery is that the ancient plague strains found today in badger colonies in the Tian Shan plague reservoirs are much earlier in evolution and even older than the strain of bacteria found in the "Kara Jigach" cemetery.

That is why scientists are certain that the strain of bacteria discovered in the victims of the Kara Zegach cemetery evolved internally in the colonies of local badgers in the vast Tian Shan region, and did not move there from another distant habitat.

At some point later, the bacteria then spread to the human population of the area.

The common perception was that rats were the source of the plague (Shutterstock)

The importance of this study

This study resolved the centuries-old controversy about the origin and location of the Black Plague, which is considered the most deadly epidemic in humans.

Otherwise, this study has provided a model for scientists and researchers to benefit from in the emergence of epidemics and other pandemics.

To understand the new pandemics - and the Corona pandemic is far from us - it is necessary to understand the full picture of the evolution of bacteria or viruses, to know the different stages of development, and to avoid treating different strains as isolated phenomena from each other. Placing the epidemic in the environmental and social contexts is necessary to understand how these diseases develop and spread.

The study also provides a model that embodies the need for fruitful cooperation between colleagues and researchers from various fields, specializations, skills, approaches and experiences, and that this combination of skills and experiences is the future of historical research based on genetic code analysis and genetic engineering.