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Photo pixabay
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Scientists have identified the first known victim of the plague – a hunter-gatherer who lived 5,000 years ago in what is now Latvia and was a carrier of the bacterium that causes the disease, AFP reported, quoted by BTA.
The plague has been a scourge on humanity for millennia, killing almost half of Europe’s population during a devastating epidemic in the 14th century known as the Black Death. However, its origins and evolution have long puzzled scientists. The man who is the subject of this study by experts from the University of Kiel, Germany, is called “RV 2039”. The hunter-gatherer had turned 20 years old. Its skeleton was discovered along with the remains of three other people in the late 19th century, then disappeared before “reappearing” in 2011.
The researchers sequenced the DNA from the bones and teeth of the four and tested them for viruses and bacteria. They were surprised to find that the hunter-gatherer was infected with an ancient strain of plague caused by the bacterium Yersinia pestis. “Analyzes of the strain we identified show that the bacterium Y. pestis evolved earlier than we thought,” said Ben Krause-Chiora of the research team.
According to scientists, the strain identified was from a line that originated about 7,000 years ago at a time when agricultural development began in Central Europe. The researchers believe that the bacterium periodically jumped from animals to humans without causing large outbreaks of infection. Over time, it adapted to infect humans, eventually evolving into a form known as bubonic plague, which spread from fleas and devastated medieval Europe.
“It was really surprising to come across this bacterium,” says Krause-Kiora. Scientists initially looked for a possible relationship between the hunter-gatherer and the other three when they made the discovery. The bacterium Yersinia pestis probably killed the man, although the researchers said the disease was slow. According to them, at the time of the hunter-gatherer’s death, there were high levels of the bacterium in his blood, which in rodent studies has been linked to less aggressive infections.
The individuals around the man were not infected, indicating that he was not infected with pneumonic plague, a highly contagious form of the disease. According to the researchers, the individual “RV 2039” became infected after being bitten by a rodent. The bacterium is missing key genes, such as the one that allows fleas to transmit the infection. This means that the ancient version in question was less contagious and deadly than the medieval one.
The more recent flea-borne strain dates back about 3,800 years ago, when the first “megacities” with more than 10,000 inhabitants began to form in the Middle East and the Mediterranean. The density of the growing population probably provoked the evolution of the bacterium.
Knowing the history of Yersinia pestis can reveal how man evolved to protect himself. “We are intrigued by future research on how these ancient infectious diseases have affected our current immune system,” says Ben Krause.
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