From ABC News in Science, 23 October 2015:
The microbe responsible for the Black Death plagues was infecting Bronze Age humans more than 3,000 years earlier than the pandemics it is most notorious for.
Early forms of the bacteria, Yersinia pestis, have been found in Bronze Age human teeth up to 5,000 years old, according to a report today in the journal Cell.
Plague is maybe the most traumatic event that has ever been recorded in human written times of the past [but] the earliest physical evidence [to date] is from the first pandemic in 540 AD
Associate Professor Simon Rasmussen
The research has also shown how and when the pathogen evolved into the deadly strain — known as the bubonic plague — spread by fleas, which killed between 30 and 50 per cent of the European population over several centuries.
Researcher Associate Professor Simon Rasmussen said the discovery of the ancient plague bacteria was actually a side effect of research into how Bronze Age migrants from the Russian steppes replaced Europe’s Stone Age populations.
“We see that there is a decline of the Stone Age farmers around the time that these Bronze Age people arrive to northern Europe,” said Dr Rasmussen, from the department of systems biology at the Technical University of Denmark
While the Bronze Age migrants could have deliberately killed the locals, they could also have wiped them out by bringing an epidemic with them, the researchers thought.
They decided to look for evidence of this in a collection of Bronze Age teeth, 2,800 to 5,000 years old, from settlers across Europe and Asia.
By chance, the first microbe they looked for — Yersinia pestis — turned up across their sample collection.
“Plague is maybe the most traumatic event that has ever been recorded in human written times of the past, [but] the earliest physical evidence [to date] is from the first pandemic in 540 AD,” said Dr Rasmussen. Read more.
Bianca Nogrady 