By Angus Dalton
Parts of a human brain solidified into black glass when the eruption of Mount Vesuvius blasted a young man’s bedroom with a scorching ash cloud, researchers have concluded in a new analysis.
The obsidian-like “organic glass” formed in a freak reaction that required extraordinary heat, rapid cooling and the partial shielding of the brain by the skull and spine before the bones exploded into blackened char.
The remains of an individual – suspected to be a young man – who died in his bed in Herculaneum.Credit: Guido Giordano et al./Scientific Reports
The finding potentially rewrites our understanding of what happened in Herculaneum, which was devastated by the eruption alongside Pompeii in AD 79, because it suggests a superheated ash cloud was the first deadly event to rip through the town before it was buried by volcanic debris.
The black brain fragments are the only documented example of glass preservation in animal or human tissue, researchers from Roma Tre University in Italy wrote in a Scientific Reports paper released on Friday.
The brain probably belonged to a man in his 20s who served as a guardian in the cult of Emperor Augustus, researchers previously wrote. He died face-down in his bed within a college building dedicated to the emperor.
Italian forensic anthropologist Dr Pier Paolo Petrone re-examined the remains recently and spotted something shining within the victim’s head.
A sample of the organic glass, which resembles obsidian.Credit: Guido Giordano et al./Scientific Reports
Scientists scrutinised these shards and discovered perfectly preserved neurons and traces of neurotransmitter proteins. The new analysis of the glass used X-rays and electron microscopy to uncover the exact conditions required for this act of volcanic alchemy.
The glass couldn’t have formed when the volcano’s pyroclastic flow hit the city. This meld of rock, ash and lava would have burnt and destroyed soft tissue but wasn’t hot enough to trigger the brain to “vitrify” or become glass. It also wouldn’t have allowed the rapid cooling needed for the brain to solidify.
The only way the black brain glass could have formed is if the town was hit first by an ash cloud hotter than 510 degrees that rapidly dissipated, allowing the brain to return quickly to ambient temperature, the authors of the new research argue.
Then the pyroclastic flow came, they write, burying the guardian and his glittering brain.
Nerve cells preserved within the organic glass.Credit: P. Petrone et al/PLOS One
“There’s not a lot of studies that show how intense the blast was,” Dr Renaud Joannes-Boyau, an archaeological scientist at Southern Cross University who wasn’t involved in the study, said.
“It’s just extraordinary that we’re able to find these kinds of remains almost 2000 years later. This is absolutely mind-blowing.”
Dr Estelle Lazer, an internationally renowned expert on the victims of Vesuvius at the University of Sydney, noted there is no consensus on how the victims of Herculaneum died. Other scholars claim the heat was considerably lower than estimated in the new research.
Further analysis of the glass could tell more about the people killed in the eruption.
“Romans were using lead pipes to bring water into their houses and cities … a lot of people had malformation and heavy metal poisoning,” Joannes-Boyau said. “Microanalysis of the brain could let us look at that.”
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