Could this ancient flea harbor ancestors of the bubonic plague?

SEPTEMBER 30, 2015

by Savanna Walker

Here's hoping no one goes Jurassic Park on this and unleashes prehistoric Black Death upon us all. Scientists from Oregon State University have found a 20 million year old flea, fossilized in amber, and surrounded by bacteria that they believe may be the ancestors of the Black Death.

George Poinar, Jr., an entomologist and expert on life forms preserved in amber, published the findings in the Journal of Medical Entomology. The fossilized flea was found in amber mines from the Dominican Republic, an area which was a tropical forest millions of years ago. Very few fleas have been found in amber, and none have had associated bacteria.

It’s not certain yet that the bacteria are Yersinia pestis, but their size, shape, and characteristics are similar to modern forms of the disease. They come in both rod and spherical shapes, and Yersinia is the only pathogenic bacteria transmitted by fleas that evidences both forms. Also, the location of the bacteria in both the rectum and proboscis of the flea is consistent with how Yersinia is transmitted today.

Uh wait, does this mean evolution is wrong?

However, modern genomic studies date the flea-plague-vertebrate cycle as evolving only 20,000 years ago, far more recent than the 20 million-year-old flea fossil. If these microbes are actually Yersinia pestis, it would mean that the disease actually predates humans and the previous dates given for its evolution are wrong.

There are several strains of Yersinia pestis, and some past outbreaks of the disease were probably caused by strains that are now extinct. Poinar believes that ancient forms of the disease could have been strictly rodent parasites.

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