A group of researchers from Sweden, Denmark and France analyzed skeletons from a tomb outside Falköping and found DNA traces of yersinia petis, the bacteria that cause plague.
The remains belonged to farmers who lived in the area around 4900 years ago.
All strains of the plague discovered in later periods – of which the most well-known being the Black Death which killed more than 50 million in the 14th century – are variants of this one, the researchers said.
"Discovering such an early variant (of plague) in Falköping was completely unexpected, as earlier findings have pointed to it originating in Asia. This will now have to be reevaluated, so it is a significant discovery," said Gothenburg University archaeologist Karl-Göran Sjögren in a statement.
Some of the remains examined. Photo: Gothenburg University
The researchers' hypothesis is that the plague started in the Cucuteni-Trypillia culture north of the Black Sea a few hundred years before it reached Falköping, and then spread west and east.
"This may have been facilitated by better communications, thanks to among other things ox-carts which was starting to come into use," said Sjögren.
The researchers' findings so far were published in science magazine Cell on Thursday.