Ancestor of Bubonic Plague Bacteria Found in 3,800 Year-Old Teeth

In the teeth of 3,800 year-old human skeletons, scientists have found a historically important bacteria. The pulp of these teeth was home to the ancestor of the bacteria that would one day cause the bubonic plague.

A study published in the journal Nature Communications describes the genome of Yersinia pestis, a bacterium from the bronze age of Eurasia. According to the study, this bacteria had not yet adapted to life on fleas. Y. pestis would later evolve into a bacteria that could hitch rides on fleas and go rapidly from person to person. (Recent studies suggest that rodents had little or nothing to do with the spread of the disease, despite the popular belief that rats were at fault.)

Fleas carried and spread the bacteria, which would start a pandemic in the year 500, and then the devastating Black Death in 14th Century Europe. The disease killed more than 20 million people. Because of the devastation the plague caused, it's important for scientists to understand the outbreak and its patterns in case we need to prevent another in the future.

That's where the study of bacteria found in teeth comes in. A few years ago, archaeologists discovered skeletons east of the Volga river in what is now Russia. Someone pulled teeth from the skeleton and sent them to the Max Planck Institute, where paleogeneticist Maria Spyrou studied the pulp extracted from the teeth and performed genetic tests on it to find the plague-bacteria ancestor.

This discovery is significant because it means this deadly bacteria existed 1,000 years earlier than scientists believed. It also gives context to the evolution of the bubonic plague, and can help scientists understand its origin.

According to STAT, it also raises the question: How many other diseases are living close to us that are just waiting to become pandemics?