Yersinia pestis, the early variant of bacteria that caused the Black Death plague in the 14th century wiped out many populations.
Finding evidence of extinct bacteria like Y. pestis is a rare find for scientists concerning the progress of pandemics and plagues from ancient times to the modern day. This opens the opportunity to study the evolution of such variants.
Archaic skeleton has surprises
The Y.pestis bacteria was present in the remains of a 5,000-year-old skeleton of a hunter-gather male specimen called RV 2039, reported the Daily Mail.
When analysis of the remnant DNA was done, researchers were surprised that it was not deadly contagious. In the Middle Ages, the variant was more virulent killing more people during the Black Death.
For the RV 2029 specimen, this older version of the bacteria in 3,000 BC was less virulent and did not spread as fast, compared to the Middle Age plague.
From 3,000 BC to the next 4,300 years, Y.pestis was mutating it descendants into more lethal pathogens to infect humans severely. The evidence of the mutation killed populations in the form of dooms day "Black Death" in Europe and Africa, noted What's New 2Day.
This plague caused death by the thousands from 1346 to 1353, though not sure an estimate of 50% of Europe were sent to rotting mass graves.
What about RV 2039?
Genetic analysis was done by Ben Krause-Kyora, who is from the University of Kiel in Germany, his discipline as biochemist and archeologist figured out the puzzle. He says this early variant of bacteria caused Black Death plague in the Middle Ages.
He suggested that Y.pestis is an ancient bacteria that existed more than expected. An extra 2,000 years old could be added to its estimated age.
The estimation of RV 2039 will be at 20 to 30 years when the plague killed him. There were two found in the late 1800s in Rinnukalns. But after the discovery in that year, they had disappeared in 2011. These specimens were in the collection of Rudolph Virchow, a German anthropologist when they resurfaced.
Two more specimens from the same area where the first two were seen now has four skeletons from the same hunter-gather group.
Taking samples from the teeth and bone from all four remain to sequence the genes, and later test bacterial and viruses for contrast. It was only RV 2039 who has Y.pestis, not the other three.
All the data was used to reform the bacteria's genomic sequence and contrast it to other ancient viruses. What they found was very old.
It arose from a strain originating about 7,000 years ago with estimates of several hundred years when Y.pestis evolved from Yersinia pseudotuberculosis, its ascendant bacteria. Krause-Kyora added that even minor changes can affect the virulence of pathogens.
One way that Y.pestis can infect is by the Oriental rat flea that is carried by rodents that enabled the spread of the Black Plague, cited by Science Direct. Rats would indirectly spread the sickness via fleas with the genes that infected people.
It was that gene that allows the bacteria to infect humans, causing the pus-filled skin bubble on humans. Subject RV 2039 was bitten by a rat then which is why the three weren't infected.
This early variant of bacteria caused Black Death plague but took time to evolve over 7,000 years.