Ancient Vesuvius victim’s brain contains first natural organic glass ever seen

A unique organic glass discovered in the brain of a victim of the 79 AD Mount Vesuvius eruption is the first known example of high-temperature vitrification of animal tissues. Experiments suggest that the brain was heated to at least 510°C before being rapidly cooled following the catastrophic eruption that destroyed the Roman town of Herculaneum.

The transformation of liquids into a glass via rapid cooling is called vitrification. Inorganic glasses form naturally under conditions such as lightning strikes forming fulgurite or earthquakes forming pseudotachylyte. Normally, when a liquid cools, its molecules arrange into an ordered crystalline structure. But if cooling occurs very rapidly, molecular motion is stopped before crystallisation can take place and an amorphous, glassy solid forms instead. While organic tissues can undergo vitrification to form glasses when cryopreserved at temperatures far below 0°C, this vitrified brain tissue is the only example of soft tissue vitrification at high heat.

The remains of the victim, believed to be a roughly 20-year-old male, were found in the remnants of a wooden bed within the Collegium Augustalium in Herculaneum. The public building was dedicated to worshipping Emperor Augustus and the victim is believed to have been a guardian of it.

Working on fragments taken from the skull and spinal cord of the victim, researchers used tomography and x-ray and Raman spectroscopy to characterise the substance as vitrified brain tissue and analyse its physical properties. The glass is primarily made up of carbon and oxygen, with small amounts of sodium, chlorine, potassium, magnesium, aluminium and silicon. Scanning electron microscopy revealed exceptionally well-preserved neural structures, axons and neurons, something not seen in ancient brains preserved by other means.

To better understand the extreme and unique conditions under which the victim’s brain was vitrified, the scientists performed a series of differential scanning calorimetry analyses. Based on the results, they propose a scenario wherein a fast-moving extremely hot ash cloud engulfed victims as one of the first deadly events of the 79 AD eruption. Temperatures likely exceeded 510°C within the cloud, but when it dissipated within minutes, it started dropping rapidly. The extremely rapid cooling of the brain tissue was sufficient to circumvent the crystallisation process and trap the organic tissue in a glassy state.