Almost 1,950 years after Mt. Vesuvius erupted — leaving a trail of death and destruction that’s enthralled scientists and historians for centuries — fossilized human remains continue to illuminate the catastrophe’s horrific toll.
Scientists have already concluded that the fast-moving river of scalding ash, lava and gas that flowed downhill boiled victims’ blood and caused their skulls to explode. Now, Italian researchers say they’ve figured out how the overwhelming heat from the volcanic blast likely caused natural organic glass to form in one person’s brain. And they say what happened to him could have safety implications for today.
Wait, back that up. Glass formed in the human brain? Yes, say the researchers, who detail their findings in a new study published Thursday in the journal Scientific Reports. In it, they chronicle how they investigated remains, believed to be of a man who died when he was around 20, found entombed within pyroclastic flow deposits in Herculaneum, a Roman town buried by 20 feet of ash when Vesuvius erupted in 79 CE. Inside his skull, they discovered shiny dark gray and black fragments that looked a lot like the volcanic glass obsidian. The discovery stunned them, prompting further investigation.
How And Why Did The Glass Form?
As shocking and strange as the presence of glass in the man’s brain may be, the team’s research led them to an explanation that follows familiar principles. Glass forms when sand and/or rocks are heated at high temperatures, melting and losing their crystalline structure. As the mixture cools, it solidifies into a new form.
The Vesuvius researchers conclude that the victim’s body underwent a similar process when a superheated but short-lived ash cloud enveloped Herculaneum, leaving structures intact but killing residents by the thousands in the first deadly event following the eruption. One unlucky inhabitant who found himself in the wrong place at the wrong time was the man with the glass brain.
The scientists suggest that the ash cloud quickly elevated his body above 950 degrees Fahrenheit before it rapidly cooled to ambient temperatures as the cloud dissipated. The young man didn’t have sand or rock in him, but his soft, water-rich brain tissue hardened much like those materials do when converted to glass.
Brain tissue would be expected to burn in such extreme heat. However, the thick bones of this particular man’s skull and spine likely protected his brain from completely burning, the researchers say. That allowed the brain tissue, though damaged and disaggregated, to heat and then cool, forming the unique organic glass.
“The brain tissue studied here is the only known case of preserved vitrification of human tissue as a result of cooling after heating to very high temperatures,” reads the study led by Roma Tre University geologist Guido Giordano.
Soft tissue turned to glass marks a strange and striking find, all the more so because the conversion to glass, a process known as vitrification, rarely happens in nature. This man, of course, faced highly unusual and specific conditions.
To learn more about how the fragments formed and remained preserved, the researchers analyzed them using X-rays and electron microscopy, exposing them to varying temperatures to see how they behaved.
“It is amazing to see preserved the microscopic neural structures of an ancient brain,” Giordano said in an interview.
Where Was The Man’s Body Found?
The victim’s carbonized body was first discovered in the 1960s lying on a wooden bed buried beneath volcanic ash at the Collegium Augustalium, a public building dedicated to the worship of Emperor Augustus where the young man likely served as a guard. But it wasn’t until decades later, in 2020, that a team observed and described irregularly shaped pieces within his skull — the same group that recently reconstructed the sequence of events leading to the young man’s death.
Every skeleton uncovered in Herculaneum and Pompeii offers a powerful glimpse into the personal tragedies of that day, reminding us that history is made up of real people with their own aspirations, hardships and fates.
“The cataclysm was an unimaginable situation of human loss and destruction. We still want to know the human side of that story,” said University of Kentucky computer science professor Brent Seales. Seales is co-founder of the Vesuvius Challenge, an international contest that taps machine learning and computer vision to decipher the contents of scrolls burned in the eruption.
But while the man whose brain turned to glass adds to our understanding of the past, he could have lessons for today, Giordano said.
“In active volcanic areas, while it is essential to evacuate all people possibly in the way of pyroclastic flows, it is also essential to fit houses as shelters able to resist heat, such as is done for wildfires,” he said. “This way, should anyone be caught in a dilute hot ash cloud, as was the case of the unfortunate ancient Roman in Herculaneum, there could be a possibility to survive and wait for rescue.”
Nearly two millennia after Vesuvius erupted, its victims still have much to reveal.
