Researchers have identified plague DNA in 5,500-year-old human remains near Lake Baikal in Siberia, pushing back the earliest known plague outbreak by roughly 2,000 years. The discovery challenges the conventional understanding that plague only emerged as a threat after the rise of agriculture and densely populated settlements.

The team analyzed genetic material from ancient graves in the region and detected Yersinia pestis, the bacterium responsible for plague. The infected individuals belonged to hunter-gatherer communities that inhabited the area during the early Neolithic period. These populations lived in small, mobile groups rather than the large settlements typically associated with plague transmission.

This finding complicates long-held assumptions about plague's origins. Historians and epidemiologists previously believed plague became a major human pathogen only after farming communities created conditions favoring rodent populations and close human contact. The Siberian evidence indicates the disease circulated among pre-agricultural societies thousands of years earlier than documented elsewhere.

Researchers remain uncertain how plague spread among scattered hunter-gatherer bands or why it did not cause the massive epidemics observed in later centuries. The genetic analysis suggests the pathogen may have had a longer co-evolutionary relationship with human populations than previously recognized. Plague likely jumped from rodent reservoirs in the region to infect these early groups, though the exact mechanism remains unclear.

The study contributes to a growing body of ancient DNA research revealing that infectious diseases shaped human history far deeper in time than traditional historical records show. Other work has identified tuberculosis and measles in ancient populations, indicating that major pathogens were not recent inventions of civilization.

Scientists stress that ancient plague DNA does not mean the disease was widespread or deadly in those early communities. Population size, mobility, and other ecological factors may have limited its impact compared to later outbreaks. The Lake Baikal discovery opens questions about plague's natural history and