The origin of the medieval Black Death pandemic has been debated by historians for centuries. Caused by the bacterium Yersinia pestis, the plague left a dark shadow over the Middle Ages, wiping out large swathes of the European population.
Actually, there have been three great world plague pandemics recorded – in 541, 1347, and 1894 CE, each time causing devastating mortality of people and animals across nations and continents.
But the second plague pandemic that raged around the world from AD 1346 to 1353 has been a topic of continuous investigation because of the pandemic’s extensive demographic impact and is estimated to have killed half of Europe’s population in the space of seven years.
It was the initial wave of a nearly 500-year-long pandemic, or the Black Death, as it is best known, and is one of the largest infectious disease catastrophes in human history.
Now, a group of researchers reports that they may have found the answer in the pulp of teeth from people buried in a graveyard during the 14th century, in what’s now Kyrgyzstan, according to CTV News Canada.
The investigation was led by Wolfgang Haak and Johannes Krause of the Max Planck Institutes for Evolutionary Anthropology and the Science of Human History in Germany as well as Philip Slavin of the University of Stirling in Scotland, who described their findings Wednesday in Nature.
The Black Plague – The world’s greatest detective story
The search for the plague’s origin “is like a detective story,” said Dr. Mary Fissell, who was not involved in the new study. “Now they have really good evidence of the scene of the crime.”
The hunt goes back to a study published in 2011 when the group that led the latest study stunned archaeologists with their report that they could find plague bacteria DNA in the teeth of skeletons. That study involved plague victims in London.
But this was important from an epidemiological focus because not only were these victims from a plague graveyard but the date of their death was known.
But since that London study, the researchers looked even further afield, including the graveyard near Issyk-Kul, a lake in a mountainous area just west of China in what is now Kyrgyzstan.
Researchers first excavated the burial sites in the 1880s. The tombstone inscriptions, written in the Syriac language, were painstakingly reexamined in 2017 by historian Phil Slavin, an associate professor at the University of Stirling in Scotland.
Of the 467 burials that were precisely dated, a disproportionate number – 118 – were from just two years: 1338 and 1339. It’s a revelation he described as “astonishing.”
“When you have one or two years with excess mortality, it means that something was going on. But another thing that really caught my attention is the fact that it wasn’t any year — because it was just seven or eight years before the (plague) actually came to Europe,” Slavin told a news briefing.
“I’ve always been fascinated with the Black Death. And one of my dreams was to actually be able to solve this riddle of its origins,” he added.
The remains of 30 of the individuals buried in the Kyrgyzstan grave sites had been taken to the Peter the Great Museum of Anthropology and Ethnography in St. Petersburg, Russia. The research team was able to get permission to attempt to extract DNA from the skeletons to understand how they had died.
The researchers were able to extract DNA from the teeth of seven individuals. They found DNA of Y. pestis in three individuals, who all had the death year 1338 inscribed on their tombstones.
This confirmed that the pestilence mentioned on the tombstones was indeed the plague, which is spread from rodents to humans via fleas.
DNA family tree of the plague
This latest study adds a wealth of information as scientists build a family tree of the plague bacterium. The sequencing of the genetic material from ancient pathogens allows us to “read” the genetic imprint in human DNA.
Researchers have been building a DNA family tree of the plague bacteria variants, and it is most interesting. The tree as reported by researchers and others, had the typical tree trunk – and then, all at once, seemed to explode into four branches of Y. pestis strains whose descendants are found today in rodents.
Scientists called the event the Big Bang and began a quest to find when and where it occurred.
In conclusion, the study authors believe the area surrounding the two cemeteries near Lake Issyk-Kul in Kyrgyzstan must have been the origin of the plague strain that caused the Black Death because two ancient plague genomes the team pieced together from the teeth revealed a single plague strain that’s the most recent direct ancestor of this big bang event.
Not only that, but the researchers report that the rodents that spread the bacteria to those victims were marmots. Marmots in that area today have fleas that carry a type of Y. pestis that appears to be derived directly from the ancestral strain.
And last, but not least, the researchers report that the strain in Kyrgyzstan is from the trunk that exploded into four strains. It is the start of the Big Bang, the group proposes.
A believable theory or not so believable, the study does put the graveyard in Kyrgyzstan on the map, and adds to a great detective story.
