This is Scientific American ― 60-Second Science, I'm Susanne Bard.The Black Death.Also known as the Great Plague, it spread across Europe between 1346 and 1353and brought a swift but very painful demise to up to 60 percent of the population―perhaps 200 million people in all.A bacterium called Yersinia pestis causes the plague. It's transmitted to humans by fleas.The insects hitched rides on the black rats that flourished along trade routes, aiding the spread of the plague."The Black Death was part of a larger pandemic that occurred in Europe and in the nearby regions between the 14th and 18th centuries.And it is, by many, considered to have been the most deadly of the three pandemics of plague that have occurred throughout our history."Paleogeneticist Maria Spyrou of the Max Planck Institute for the Science of Human History."By analyzing ancient DNA from past pandemics and coupling that together with archeological and also historical evidence,we can really begin to build the history of those pandemics in great detail."Spyrou and her team of disease detectives teamed up with archaeologists,looking for clues to the plague's arrival in Europe and its subsequent pattern of dispersal.Visiting old cemeteries across the continent,they sampled DNA from people who had likely succumbed to the plague―specifically, from their teeth.