"Scientists have reconstructed the genetic code of a deadly strain of bacteria that caused one of the most deadly pandemics in history nearly 1,500 years ago."

"They did it by finding the skeletons of people killed by the plague and extracting DNA from traces of blood inside their teeth."

"This plague struck in the year 541, under the reign of the Roman emperor Justinian, so it's usually called the Justinian plague. The emperor actually got sick himself, but recovered. He was one of the lucky ones."

"'Some of the estimates are that up to 50 million people died,' says evolutionary biologist David Wagner at Northern Arizona University. 'It's thought that the Justinian plague actually led partially to the downfall of the Roman Empire.'"