More than a third of Europe's population in 14th century was killed due to Black Death plague. A microbe called Yersinia pestis is responsible for the plague epidermis. The origin of the plague has always been a mystery. Now, a new research has found that the microbe was infecting people as long as 5,000 years ago.

The research work started from the previous study. In the earlier study, the researchers have extracted DNA from 101 human bones found in Europe and Asia aged between 3,000 and 5,000 years old. The researchers noted abrupt changes in the genetic profile of people.

Eske Willerslev, director of the Center for GeoGenetics at the University of Copenhagen, said that they thought the change from one population to another genetic population might be due to an ancient epidemic.

The researchers then thoroughly studied their DNA samples to find out if they belong to pathogens from the era. There was no evidence with researchers that pathogens were present at that time period. But the researchers decided to include them in their study.

Their idea worked as the researchers found the presence of the microbe in seven of 101 individuals coming from places that are now Poland and Siberia. The researchers have even carried out comparative analysis of the ancient sample and recent strains of the plague.