Plague struck humans 5,500 years ago, oldest known evidence reveals

Researchers have found oldest-known evidence of a plague outbreak in 5,500-year-old human remains from Siberia's Lake Baikal region. Ancient DNA from teeth showed Yersinia pestis infected several hunter-gatherers, suggesting disease was already deadly in prehistoric communities. The findings push plague's history back about 200 years, with pneumonic disease likely spreading from marmots to humans.