How Did a Volcano Turn This Roman’s Brain to Glass?

In 79 AD the Roman towns of Pompeii and Herculaneum were destroyed by an enormous volcanic eruption. The devastation caused by the eruption of Vesuvius went on for two days, burying the two towns under superheated ash and mud.

The destructive power of Vesuvius was estimated to be some 100,000 times greater than the atomic bombs dropped on Hiroshima and Nagasaki. Over 20,000 people lived in the area surrounding the volcano, and the remains of over 1,500 have been found to date in the two towns.

Typically it is not entirely fair to call these remains “bodies” as they are rather the hollows in the ash layer where the people fell as they ran for their lives. Over a thousand casts have been made of these bodies, their contorted poses of fear and desperation bringing a grim immediacy to the tragedy.

However not all the bodies were preserved in this way, and the intense heat and pressure caused by the volcanic eruption led to some unusual finds, and some that are downright inexplicable. Perhaps the most famous of these is the man whose brain was turned to glass.

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Yep, you heard that right. Found amidst the bodies in Herculaneum was a young man in his bed in the Collegium Augustalium who had been killed by the eruption. But something had happened at the end which wrought unknown chemical changes in his brain.

The result was not some perfect replica of a human brain made of glass to be sure. However the presence of glassy material inside a human skull is a fact that cannot simply be ignored, and a new study published in Nature from a team led by Guido Giordano of Roma Tre university may just have an explanation.

First, the facts. We know that glass can form naturally on Earth, under an unusual set of circumstances where liquid cools at a certain rate, is given time to relax and therefore avoids crystallization. Typically this needs to occur for specific temperatures, depending on the composition of the cooling material.

We also know that the human brain can be turned to glass artificially, if you really want to do that sort of thing. But because organic tissues contain liquid water at room temperature this can only work if the brain is cooled to well below freezing. The temperature gap between volcanic magma and freezing water is about as extreme as you can manage on our planet.

It should, therefore, be impossible for the eruption of Vesuvius to cause this change. The heat from the ash should have raised the man’s body temperature to the point where the contents of his skull would have returned to soft material, and been burned.

But in this single instance this did not occur. Instead portions of the man’s brain turned to obsidian-like glass. Detailed scans with an electron microscope reveal a network of neurons, axons and other neural structures, perfectly preserved. 

How did this happen? It should, according to our understanding of such things, be impossible; a human brain has never been found preserved in this way before.

The answer seems to be in the rate at which the body cooled. Most bodies in the eruption were encased in ash from the pyroclastic flows off the volcano, but this one was not. Instead it was exposed to the air and able to cool at a rapid rate.

The team have constructed the most likely scenario that caused this formation. The man was killed by a fast moving, very hot ash cloud which enveloped him but which did not penetrate to the core of his body. However the body was only buried in a few centimeters of ash and, as the cloud dissipated, this allowed for rapid cooling.

This is more than a historic curio. Understanding this process at such high temperatures has potential ramifications for our understanding of material science, forensic biology and volcanology.

But for now, we have an explanation for the Roman whose brain turned to glass. It was highly unlikely, it required a very specific sequence of events, but it seems that we finally understand how such a thing is even possible.

Header Image: The formation of glass inside this Roman’s brain could only come from a very specific sequence of events, but this new study has confirmed that it is, at least, possible. Source: UnexpectedToy / Public Domain.