The plague has not been eradicated, and recent research offers a clue regarding the origins of this civilization-killing pathogen—the bacterium *Yersinia pestis*. Capable of defeating armies, toppling empires, collapsing civilizations, and ushering in dark eras like the Middle Ages, it altered the course of history; without it, human evolution would surely have been much more rapid—and, of course, there would be more of us (in terms of sheer numbers, not necessarily human compassion).

What has been discovered in Siberia—specifically on the southwestern shores of Lake Baikal—reveals a true story. Researchers found ancient burial sites there belonging to Stone Age settlements dating back 5,500 years.

Piecing together the clues much like a criminal investigation, researchers have reconstructed the narrative of what happened there—near Lake Baikal—some 5,500 years ago; to put that in perspective, this was a full millennium before the Great Pyramid of Egypt was built. We are in Siberia, Russia—specifically on the banks of the Angara River, very close to the southern end of Lake Baikal. A hunter was likely returning to his camp with his catch: a marmot. It was not a massive prize, but it provided a valuable pelt and between two and seven kilograms of meat to feed the family. It was probably raining that day; the wood was wet, making it difficult to light a fire—and this is not merely a poetic flourish of mine, but a conclusion reached by researchers. Because of this, the hunter and his kin likely had to eat the marmot—a type of rodent—raw or barely cooked. That was the crucial factor, and that was the terrible mistake.

The night passed quietly, and everyone slept with full stomachs. The following day was routine for that family of hunter-gatherers; their clan, too, went about its normal activities—for this was a small settlement, not just a single family. But by the third day, the youngest girl in the family developed a soaring fever. A few hours later, her sister—or perhaps her cousin—was also burning up and drenched in sweat; both were racked with intense chills and suffered from extreme weakness, headaches, muscle pain, vomiting, and diarrhea. The youngest girl did not live to see the next dawn, and perhaps that was for the best; in the days that followed, her siblings, parents, other close relatives, and clan members in general began to fall ill with the same symptoms and die.

Clan members who had not eaten the marmot tried to help their relatives and friends however they could; yet, by caring for the sick and sharing the same cramped quarters in their huts, they breathed the same air, became infected, and ultimately met the same fate. Within little more than a week, most had died—it was the plague, the oldest epidemic outbreak detected to date.

It was the same disease that would eventually become one of humanity's greatest scourges, capable of defeating armies, killing kings, and toppling entire civilizations. This account is pieced together from clues discovered by an international team of researchers and was published on June 17, 2026, in the scientific journal Nature under the title "Deadly plague outbreaks among Lake Baikal hunter-gatherers 5,500 years ago."