Unique in the world The mystery of the glassy brain has been solved
A spectacular find from near Pompeii provides researchers with new insights into the deadly violence of the eruption of Vesuvius in 79 AD.
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- In 2020, researchers discovered the world's only known vitrified brain in the skull of a Vesuvius victim.
- Exceptional circumstances preserved the brain since the volcanic eruption in 79 AD.
- A new study shows: The deadly heat that led to the vitrification did not come from the ash avalanche, but from an extremely hot gas cloud that had hit the city shortly before.
- The sudden drop in temperature caused the brain to vitrify without crystallizing: a natural phenomenon called "vitrification".
- The findings not only help archaeology. They can also save lives because they expand our knowledge of volcanic hazards.
Back in the 1960s, the body of a 20-year-old man was discovered during excavations in Herculaneum - lying on his bed, buried under volcanic material. He was probably a guardian of the Collegium Augustalium, a building dedicated to the worship of Emperor Augustus in the center of the city.
The find went unnoticed for decades - until its spectacular discovery in 2020, when researchers discovered that the man's skull contained a shiny black, hard substance. It was completely vitrified brain material and dated back to 79 AD.
"Nothing like this has ever been found in any of the skeletons of the victims of the Vesuvius eruption," explains forensic archaeologist Pier Paolo Petrone from the University of Naples Federico II. Of the approximately 2,000 Vesuvius victims that have been excavated so far, this is the only case in which a vitrified brain has been found. This shows how exceptional the circumstances must have been in the Collegium Augustalium.
Vitrification due to a heat wave
So what happened back then, almost 2000 years ago? A German-Italian research team has now deciphered exactly how this unique phenomenon could have occurred. As the new study in Scientific Reports shows, pyroclastic flows - those dreaded avalanches of ash, gas and rock - were not responsible for the vitrification.
Although they reach temperatures of up to 465 °C, they cool too slowly to vitrify a brain. This would have simply destroyed the tissue.
The cause was apparently an extremely hot gas cloud that preceded the actual ash avalanche and swept over the city at lethal speed. This cloud brought with it temperatures of over 510 °C.
This was enough to heat the brain tissue instantly and then cool it down again just as quickly due to its rapid retreat. The result: vitrification, a process in which biological material turns into a glass-like substance.
Lessons for the future
Microscopic examinations showed that the finest neuronal structures were still recognizable in the glass material. The victim's thick skull bone may have played a decisive role. It insulated the tissue just long enough to survive the extreme heat wave - until the rapid cooling set in.
"These gas clouds are treacherous," says study leader Guido Giordano from the University of Rome III. They leave hardly any traces on buildings, but they kill immediately. A dangerous effect that is often underestimated in the risk analysis of volcanic events.
The researchers see their work not only as an archaeological breakthrough, but also as a contribution to modern disaster prevention in volcanically active regions. In other words, what a glass brain can tell us about ancient life can ensure our survival.
