Black rats may not have been to blame for numerous outbreaks of the bubonic plague across Europe, a study suggests.
Scientists believe repeat epidemics of the Black Death, which arrived in Europe in the mid-14th Century, instead trace back to gerbils from Asia.
Prof Nils Christian Stenseth, from the University of Oslo, said: "If we're right, we'll have to rewrite that part of history."
The study is in the Proceedings of the National Academy of Sciences.
The Black Death, which originated in Asia, arrived in Europe in 1347 and caused one of the deadliest outbreaks in human history.
Over the next 400 years, epidemics broke out again and again, killing millions of people.
It had been thought that black rats were responsible for allowing the plague to establish in Europe, with new outbreaks occurring when fleas jumped from infected rodents to humans.
However, Prof Stenseth and his colleagues do not think a rat reservoir was to blame.
They compared tree-ring records from Europe with 7,711 historical plague outbreaks to see if the weather conditions would have been optimum for a rat-driven outbreak.
He said: "For this, you would need warm summers, with not too much precipitation. Dry but not too dry.
"And we have looked at the broad spectrum of climatic indices, and there is no relationship between the appearance of plague and the weather."
The team now plans to analyse plague bacteria DNA taken from ancient skeletons across Europe.
If the genetic material shows a large amount of variation, it would suggest the team's theory is correct.
This is why I love the current way to broadcast news by modern new agencies.
A lot more than basic grammar it seems. It's a new theory based on analysis of figures, like most science, it needs further checking. I just thought it might interest people.
Btw, a vile Holocaust denier has no place arguing the historical veracity of anything. Go back under your rock.
Modern bubonic plague typically needs to reach a high frequency in the rat population before it spills over into the human community via the flea vector. Historically, epidemics of bubonic plague have been associated with enormous die-offs of rats.
“There are no reports of dead rats in the streets in the 1300s of the sort common in more recent epidemics when we know bubonic plague was the causative agent,” says Wood.
Instead of being spread by animals and insect vectors, the researchers believe that the Black Death was transmitted through person-to-person contact, as are measles and smallpox. The geographic pattern of the disease seems to bear this out, since the disease spread rapidly along roadways and navigable rivers and was not slowed down by the kinds of geographical barrier that would restrict the movement of rodents.
This theory was bolstered somewhat by the discovery of anthrax spores in a plague pit (burial site for plague victims) in Scotland as well as the discovery of recorded symptoms during the Black Death not indicative of Y. pestis.