It took us 650 years to figure out that gerbils, not rats, caused the 'Black Death' plague!

Gerbil with evil villain mustache
Public Domain Wikimedia

Cute but deadly

The Black Death plague was without question one of the most devastating pandemics in human history. It peaked in Europe between the years 1346-1353, and it's estimated to have caused between 75 to 200 million deaths, with many successive outbreaks over the next four centuries. That's at a time when total world population was around 450 million!

Oops, sorry about ruining your reputation, rats

The plague originated in Asia and was brought to Europe via trade on the silk road that linked the continents at the time. Until recently, the main hypothesis blamed the spread of the epidemic to Europe on rats, which carried infected fleas. But researchers at the University of California, Berkeley, might have found a new culprit.

By studying weather patterns at the time, the scientists concluded that it was unlikely that the conditions necessary for the outbreak to be caused by rats were present. But conditions were good for another kind of animal:

"We show that wherever there were good conditions for gerbils and fleas in central Asia, some years later the bacteria shows up in harbour cities in Europe and then spreads across the continent," Prof Nils Christian Stenseth, from the University of Oslo, said.

He said that a wet spring followed by a warm summer would cause gerbil numbers to boom.

"Such conditions are good for gerbils. It means a high gerbil population across huge areas and that is good for the plague," he added.

The fleas, which also do well in these conditions, would then jump to domestic animals or to humans.

This discovery came as a surprise, and if the new thesis stands up to scrutiny, European history might have to be rewritten.

"Suddenly we could sort out a problem. Why did we have these waves of plagues in Europe?

"We originally thought it was due to rats and climatic changes in Europe, but now we know it goes back to Central Asia."(source)

The next step to test the hypothesis is to analyze plague bacteria DNA found on ancient skeletons from that period in Europe. "If the genetic material shows a large amount of variation, it would suggest the team's theory is correct. Different waves of the plague coming from Asia would show more differences than a strain that emerged from a rat reservoir."

In the meantime, let's keep an eye on gerbils, just in case...

GerbilWikimedia/CC BY-SA 2.0

Staring deep into your soul.

Via PNAS, WaPo, BBC

Tags: Animals | Health

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