Gerbils Caused Europe's 14th Century Bubonic Plague, Not Rats

The arrival of the bubonic plague in Europe in the mid-14th century has been blamed on rats in history books across the world. However, a new study released this week has put a different rodent under suspicion: gerbils.

A study by the University of Oslo focused on tree-ring records in Europe to determine weather conditions for more than 7,000 black death outbreaks, the BBC reported.

For a rat-driven outbreak, said Oslo's Prof. Nils Christian Stenseth, "You would need warm summers, with not too much precipitation.  "And we have looked at the broad spectrum of climatic indices, and there is no relationship between the appearance of plague and the weather."

As detailed in a new study published in PNAS, scientists found that wind and weather conditions in Europe would not have been conducive to large rodent- and flea-spawned disease outbreaks.

The researchers 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 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.

"My bottom line is that this is a fascinating new thesis," said Schaffner, who was not involved in the study. "And I think that it likely will result in a lot of controversy among people who are disease historians."