Ancient Black Death Bacteria Discovered in a 20-Million-Year-Old Flea Frozen in Amber

A flea that's been frozen in time may possess bacteria that's the ancestor of the Black Death. Scientists have discovered a flea preserved in amber with tiny bacteria that could have eventually evolved into the dreaded strain of the bubonic plague.

The Black Death was one of the most devastating pandemics in human history. It swept across Europe, peaking during the years of 1346 to 1353. In all, it killed an estimated 75 to 200 million people during the time. Spread by a bacillus called Yersina pestis, the plague was carried by the fleas on rats, transported through trading routes and on ships.

In this case, the researchers found a bacteria similar to Yersina pestis attached to the proboscis of a 20 million-year-old flea preserved in amber. They also found the bacteria compacted in the flea's rectum.

"Aside from physical characteristics of the fossil bacteria that are similar to plague bacteria, their location in the rectum of the flea is known to occur in modern plague bacteria," said George Poinar, one of the researchers, in a news release. "And in this fossil, the presence of similar bacteria in a dried droplet on the proboscis of the flea is consistent with the method of transmission of plague bacteria by modern fleas."

With that said, it can't be determined with certainty that these bacteria are related to the same bacteria that caused the Black Death. However, it seems that they are closely related.

The findings are actually in conflict with modern genomic studies that indicate that the flea-plague-vertebrate cycle only evolved in the past 20,000 years rather than 20 million. However, today there are several strange of this plague. There's also evidence that past outbreaks of this disease were caused by still different strains, some of which are extinct today.

"If this is an ancient strain of Yersinia, it would be extraordinary," said Poinar. "It would show that plague is actually an ancient disease that no doubt was infecting and possibly causing some extinction of animals long before any humans existed. Plague may have played a larger role in the past than we imagined."

The findings are published in the Journal of Medical Entomology.

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