In 79 A.D, Mt. Vesuvius erupted, killing thousands of people in the Roman cities of Pompeii and Herculaneum. Currents of hot gas and volcanic matter, ash and gases, as well as subsequent earthquakes caused brutal, widespread devastation. Archaeological evidence even reveals the brain of one young man who died lying in his bed became the only known example of a person’s brain vitrifying—i.e., turning to glass. 

Finding brain tissue in an archaeological dig is already fairly rare. When archaeologists do discover ancient brains, they’ve often turned to soap. Researchers believe this victim’s brain turned to glass due to quick changes in temperature as the natural disaster unfolded.

Hot Ash Cloud and Quick Cooling Turned Brain to Glass

The man whose brain turned to glass died in Herculaneum, an ancient Roman city that was closer to Mt. Vesuvius than Pompeii, and therefore experienced the volcano’s destruction first. He died while lying in a bed at the Collegium Augustalium, a building dedicated to Emperor Augustus. The man was around 20 years old, and may have been a guardian at the Collegium.

Modern archaeologists discovered his remains in the 1960s, but it wasn’t until 2018 that archeologist Pierpaolo Petrone spied the glass in the young man’s skull. In 2020, he and his colleagues published a letter in The New England Journal of Medicine and an article in PLOS One about their preliminary research. They found that the glass in the skeleton contained elements found in the human brain and spinal cord. It appeared that parts of this man’s brain and spinal cord had turned to glass—but how?