Nearly 2,000 years ago, a young man lay in his bed in Herculaneum, unaware that he was about to become part of history in one of the most shocking ways. When Mount Vesuvius erupted in 79 AD, a blistering hot cloud of ash swept through the town, killing thousands. But something unique happened to this man—his brain turned to glass.
Italian scientists say this is the only known case of human brain tissue naturally transforming into glass. Their discovery not only changes what we know about one of history’s most famous disasters but could also help protect people from similar volcanic events in the future.
In the 1960s, archaeologists unearthed the charred remains of a young man, around 20 years old, in Herculaneum. He was found lying on a wooden bed inside a building dedicated to worshiping Emperor Augustus.
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For decades, the skeleton remained just another tragic relic of the eruption. But in 2018, Italian anthropologist Pier Paolo Petrone noticed something shiny inside the man’s skull. When scientists examined the fragments, they found that his brain had turned into black, glass-like pieces—a transformation never before seen in humans.
Turning organic matter into glass is extremely rare. It requires extreme heat followed by rapid cooling—conditions usually created by meteorite impacts, lightning, or lava. Scientists determined that for this man’s brain to undergo such a transformation, it must have been exposed to temperatures above 510°C (950°F)—hotter than the pyroclastic flow that buried the city.
Researchers suggest that an early blast of ash and heat from the volcano struck Herculaneum before the main pyroclastic flow arrived. This explains why the man’s brain was preserved in glass while other victims’ remains did not undergo the same process.
This discovery rewrites the history of Mount Vesuvius’ eruption. Scientists had long believed that the pyroclastic flow—a fast-moving wave of hot rock, ash, and gas—was what killed the people of Herculaneum. However, the thin layer of ash found before the flow arrived suggests that a superheated ash cloud struck first, instantly killing those in its path.
Such ash clouds are poorly understood because they leave very little trace. However, they remain a serious threat in modern volcanic eruptions. In 2018, some of the 215 people who died during Guatemala’s Fuego volcano eruption were likely killed by a similar phenomenon. Even famous French volcanologists Katia and Maurice Krafft, featured in the documentary Fire of Love, lost their lives to an ash cloud.
Credit: Canva
Scientists hope this research will lead to better protection for people living near volcanoes, including designing buildings to withstand extreme heat. While most of Herculaneum’s residents fled toward the sea, this man stayed behind in the heart of the city. He is believed to have been the guardian of the Collegium building, and his decision to remain cost him his life.
But why didn’t he try to escape? Perhaps he was asleep. Maybe he was injured. The truth is, we may never know. What we do know is that his fate was extraordinary. His brain—transformed into glass by one of history’s most famous eruptions—remains one of the most unique scientific discoveries ever made.
