What led to the fall of the Eastern Roman Empire? A devastating epidemic which broke out during the reign of Emperor Justinian 541 AD, killed a quarter of the population of North Africa, Europe, Central and South Asia and Arabia. Total estimated historians Plague of Justinian claimed the lives of 30 to 50 million people. However, the origin of the infection has long remained a mystery to scientists.
Now, in the course of decoding DNA samples taken from two ancient skeletons buried in the VI century on the territory of the German Bavarian scientists received the complete genome of Yersinia pestis Yersinia pestis - the bacteria, which is also considered the cause of the Black Death pandemic that struck Europe in 1346. The discovery suggests that the Yersinia pestis can deliver crushing blows to humanity repeatedly. By the way, this is the most ancient pathogen genome studied to date.
A study led by Hendrik Poinar (Hendrik Poinar), an evolutionary geneticist at McMaster University in Canada. He examined not only the results of DNA sequencing of ancient plague victims Bavarian, but DNA inhabitants of London, the Black Death killed. According to him, the information obtained is not unambiguous evidence that Yersinia pestis was the sole cause of both diseases, but increases the likelihood that the Y. pestis - a significant part of the big stories.
"The study proved fascinating, but also caused a lot of new questions to be explored - for example, why the pandemic, which killed about 50-100 million people died out and did not recur?" - Says Poinar.
The team had to analyze the 12 skeletons buried in a large cemetery Aschheim Bavaria. DNA ten of them showed fairly low levels of Y. pestis, but the teeth of the other two was enough to allow the team to recover the entire DNA sequence of the bacteria.
On the remains of beads, buried next to one of the victims of the pandemic in the cemetery, the scientists determined that the burial can be dated to 525-550 years BC (ie the time of the first wave of Justinian plague). Bavaria was not part of the Byzantine Empire, but judging by the stories, the disease has spread almost all over Europe and even reached out to Persia.
In the future, scientists had expected another startling discovery. It turned out that the "Bavarian" E. coli is a branch to interrupt the disease, while its "cousin", identified in the DNA of skeletons exhumed from a mass grave of victims of the London plague of 1348, turned the ancestor of almost all modern human infections spread around the world. Even now, bubonic plague can be transmitted from its natural vectors such as rats or woodchucks. Doctors warn that the plague may well once again (fortunately now mankind has antibiotics that can effectively deal with the deadly disease).
The analysis identified genetic sequences never helped scientists figure out why once became the cause of Y. pestis pandemics, and today is not even half of such devastating consequences.
And the Plague of Justinian and the Black Death race around Europe, is rapidly transferred from person to person. But the so-called third pandemic, which originated in Hong Kong at the turn of the XIX and XX centuries, spread much more slowly, and people are more likely to get it from the vectors (rats and fleas). This knowledge prompted Poinar the idea that Y. pestis was not the only cause of two devastating disasters, and was only a "last straw" that killed the weakened another, more widespread infection of people. For example, bacterial pneumonia often "to seek" the body after suffering flu.
A team of researchers has developed a method of screening thousands of human pathogens at once. This will thoroughly search the ancient bones to identify the causes of the true causes of the pandemic.
Note that there are hypotheses that explain the current weakness of Yersinia pestis that mankind simply evolved and become less sensitive to Y. pestis, or climatic conditions now are less suitable for the survival of the bacteria in the wild.
Scientific article Poinar and his colleagues was published in the Lancet Infectious Diseases.
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