Rats have been blamed for a plague wave that killed millions in Europe beginning in the 14th Century.
Now suspicion has fallen on a rodent that is much more cuddlier: the gerbil.
Scientists from Norway and Switzerland have challenged the widespread belief that flea-carrying diseases were spread by rats to communities in Europe for centuries.
Researchers say in an article published in the Proceedings of the National Academy of Sciences this week that they believe the plague bacteria may have originated from populations of the Great Gerbil and other rodents in Central Asia.
'If we are right, we will have to rewrite this part of history', Professor Nils Christian Steenseth of University of Oslo and one of the study's authors, told BBC.
Scientists investigated Europe's Second Plague Pandemic. It began in 1347 with the Black Death and lasted for over four centuries.
What is carried along the trade routes?
It's not logical to blame rats alone.
The plague outbreaks did not coincide with climate conditions that would have allowed the fleas to spread the disease quickly.
By analyzing tree rings to determine climate, the researchers found that plague outbreaks in Central Asia were likely carried into Europe.
Stenseth, a BBC reporter, said: 'We have shown that where there were favorable conditions for fleas and gerbils in Central Asia, the bacteria appeared in harbor cities across Europe a few years later and spread to the rest of the continent.
Scientists believe that the plague may have been reintroduced by trading networks from the time.
The disease could have been spread to Europe by caravans of traders with their camels who traveled through areas infested in Central Asia.
Pet gerbils not a risk
Researchers plan to test their hypothesis by analyzing ancient plague DNA from victims.
If rats think that the scientists' hypothesis will let them off the hook completely, they need to reconsider. According to the study, they may have still played a role in the spread by ships of plague.
There's nothing to worry about if you suddenly become worried about your pet gerbil.
Ken Gage, an expert on plague at the Centers for Disease Control and Prevention told NPR that if you buy your gerbil from a pet shop, you shouldn't worry.