Researchers from Stockholm University revealed that many populations in Northeast Asia were destroyed by the plague bacteria somehow reaching Siberia.
Experts believe that the "death event" subsequently changed the genetic makeup of people living in the area, who also began climbing to today’s North American region some 5,500 years ago.
To come up with this information, the team of evolutionary geneticists led by Gũlsah Merve Kilinc and Anders Gotherstrom extracted DNA from the remains of 40 human skeletons unearthed in eastern Siberia.
The DNA of Yersinia pestis, the bacteria that caused the plague, was found in two of the ancient Siberians. One of the victims of the plague lived about 4,400 years ago, while the other dates back to about 3,800 years ago.
It is still unclear how the plague reached Siberia and how far it spreads, Professor Gotherstrom said. He and his colleagues found that genetic diversity in ancient human DNA samples dropped drastically from about 4,700 to 4,400 years ago. This could be the result of the population decline at that time.
This theory is consistent with evidence of the plague discovered in the DNA of other ancient Siberians last year. However, evolutionary geneticist Hendrik Poinar of McMaster University, Canada, who was not involved in the study, argued that it is possible that ancient humans were not too dangerous to have been infected with a plague. The bacteria did not kill enough victims to alter the genetic makeup of the Siberians.
Explaining his point, Professor Poinar said that genetic data from just two individuals provided too little evidence to confirm that they possessed a strain of Yersinia pestis.
In fact, scientists believe there has been a series of population shifts in northeast Asia from around the peak of the last Ice Age (16,900 years ago) to about 550 years ago. Researchers who analyzed the genetic material of ancient Siberians and compared it with today’s human genetic material show that despite the harsh Siberian climate, the groups are close to Lake Baikal and other regions. has reproduced with other populations inside and outside Siberia from the Late Stone Age to the Middle Ages.
Meanwhile, the two Siberians carrying the plague analyzed in the new study came from regions that have experienced a large population change during most of the time being sampled. This may be partly due to people with the plague migrating to and around the area, resulting in different genetic groups.
