“There were various theories about the origin of the Black Death,” says Johannes Krause. The chronological and geographical origins of the plague epidemic have not yet been elucidated. One theory claimed that the cause of the disease was bacteria Yersinia pestis, originated in China due to the great genetic diversity of modern rodents. Other considerations suggested that the disease originated in Central Asia or South Asia. It is undeniable that it was a zoonosis, a disease that passed from animals to humans. According to the director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, the oldest evidence of the plague comes from the Eastern Mediterranean.
“In the Black Sea, the first historical traces can be found in Caffa, a Genoese colony besieged in 1346. And then during the siege this epidemic occurs and from there pathogens spread to Europe by ship and caused the Black Death.”
This first wave of infection was the beginning of a 500-year pandemic that would last until the early 19th century.
“What you see in the pedigree of this pathogen, and it’s very exciting, is that we have a big bang event. We have such a big bang, where great genetic diversity arises, where in a very short time there will be four divisions, where four strains will be created and which come from a common ancestor. And exactly where this common ancestor was, it was basically the research question we looked at in this project. ”
The Black Death killed 60 percent of the population
The international team proceeded systematically in the research. They were looking for skeletons from shortly before the global outbreak of the black death that transmitted the plague pathogen. There were rapid indications that the required answers could be provided by Central Asian archaeological finds from the area near Lake Issyk-Kul in present-day Kyrgyzstan.
“We are very lucky. We had access to material that had been excavated in the 1880s on a site near Bishkek, the capital of Kyrgyzstan. From this settlement was a settlement and a cemetery, which dates back to the 14th century. And graves with tombstones were found as early as the 18th century, indicating that these people had died around 1338, that a particularly large number of people had died there, and that the tombstones had also been said to have died of the plague.
The excavated bones were then transported to St. Petersburg. And there, in the Kunstkammer collection, Johannes Krause and his team rediscovered the old skeletons. The teeth of the dead were genetically examined and lucky again. Geneticists were able to identify the pathogen in three of the seven individuals and reconstruct the entire plan, the plague genome.
The root trunk of the Black Death was identified
“To our great surprise, it was a species of this big bang tribe, specifically the one that belongs to the pedigree where 80 percent of today’s tribes are born. In other words, where many different strains are formed in a very short time. It’s a bit like reconstructing Wuhan for Corona from the past, a kind of patient zero, the place where the pathogen first spread to humans or where many new strains have formed in a short time, where this strain originated, which once led to the Black Death, but and other tribes that we find today in, for example, Kazakhstan, Mongolia and China. “
Of course, it is not exactly clear that these people were actually the very first victims of the Black Death, but they were carriers of the original pathogen, the so-called tribe, and were therefore among the early infected. Then an epidemic developed rapidly, which later led to a pandemic tribe that caused mass deaths in Europe, the Middle East and North Africa. The long search came to a happy ending, says Johannes Krause. Because it is now clear when and where the Black Death originated – in 1338 in the foothills of the Tien Shan Mountains.
“And that we now have such a temporary arrangement, so to speak, you even have a tombstone that says when you died and what caused it. This is very unusual and now even for this tribe – well, you could say it’s really a lottery win. “
New data help to understand pandemics genetically, when and how pathogens spread and change. Not only does this affect the current coronavirus pandemic, but it may also provide signs of even earlier epidemics that are not yet known.
“Now we’re trying to go back in time and then maybe identify prehistoric pandemics in this data – now that we know the traces it leaves in genetics, what the pedigree of the pandemic looks like.”