Plague infected humans thousands of years earlier than previously believed, a new study suggests.
Researchers analyzed DNA from the teeth of Bronze Age human remains in Europe and Asia and found signs of plague infections about 4,800 years ago. That is 3,300 years earlier than prior evidence.
But it was at least another thousand years before the plague-causing Yersinia pestis bacterium went through genetic changes that enabled it to spread via fleas and to avoid the host immune system, the new study contends.
The study was published Oct. 22 in the journal Cell.
“We found that the Y. pestis lineage originated and was widespread much earlier than previously thought, and we narrowed the time window as to when it developed,” senior author Eske Willerslev of the Center for GeoGenetics at the University of Copenhagen, Denmark, said in a journal news release.
“This study changes our view of when and how plaque influenced human populations and opens new avenues for studying the evolution of diseases,” Willerslev added.
The researchers plan to search for evidence of plague in other regions and time periods to learn more about the disease, which has caused devastating outbreaks throughout human history.
The investigators will also seek ancient DNA remains of other blood-borne bacteria and viruses.
“Our findings reveal that one can find ancient pathogenic microbes in ancient human material showing no obvious morphological signs of disease,” Willerslev said. “So plague is just one disease to look at, and one could explore all kinds of diseases like this in the future.”
The U.S. Centers for Disease Control and Prevention has more about plague.