How Did a Man’s Brain Turn to Glass 2000 Years Ago?

01Almost 2,000 years ago, a young man was lying in his bed near Mount Vesuvius.

02Suddenly, an extremely hot cloud of ash came down from the erupting volcano.

03The heat was so intense that it turned part of his brain to glass.

04That is the theory Italian scientists have proposed to explain the strange case of an ancient Roman's brain.

05They said it is the only human tissue ever known to have naturally turned to glass.

06This rare brain could rewrite the story of one of history's most famous natural disasters.

07Mount Vesuvius is near the modern-day Italian city of Naples.

08The volcano erupted in the year 79 AD, covering the cities of Pompeii and Herculaneum with a fast-moving layer of rock and ash called a pyroclastic flow.

09Thousands of bodies have been discovered in the two places.

10They are frozen in time, showing people today the daily life of ancient Rome.

11In the 1960s, the burnt remains of a man, about 20 years old, were found on a wooden bed in a building in Herculaneum, used for the worship of the Roman Emperor Augustus.

12Italian anthropologist, a co-author of a new study, noticed something strange in 2018.

13What was left of the man's brain had been changed into pieces of shiny black glass.

14Guido Giordano is the lead writer of the study, published in Scientific Reports in February.

15He told the French news agency, AFP, that these pieces are up to a centimeter wide.

16When the scientists studied the glass using an electron microscope, they discovered an amazing, truly unexpected thing, he said.

17Complex networks of nerve cells and other identifiable parts of the man's brain and spinal cord were preserved in the glass, according to the study.

18How this happened is something of a mystery.

19Glass only forms in nature when extremely high temperatures cool very rapidly, leaving no time for crystallization.

20It is usually caused by meteorites, lightning, or lava.

21This is even more unlikely to happen to human tissues, because they are mostly made out of water.

22The Roman's brain being preserved in glass is the only such occurrence on Earth ever documented for human or animal tissue, the study said.

23The scientists said that the brain must have been exposed to temperatures above 510 degrees Celsius.

24That is hotter than the pyroclastic flow that buried the city.

25Then the brain needed to rapidly cool down.

26All this had to happen before the flow arrived.

27The scientists think this only could have happened if the ash cloud from Vesuvius sent out a very hot blast before the pyroclastic flow arrived.

28This theory is supported by evidence of a thin layer of ash that settled in the city shortly before it was covered by thick layers of rock and ash.

29This would mean the people of Herculaneum were actually killed by the ash cloud, not the pyroclastic flow, as had long been thought.

30Giordano hoped the research would bring more attention to the threat of these hot ash clouds.

31They remain very poorly studied because they leave little evidence behind.

32French volcanologists Katia and Maurice Kraft were the subjects of the 2022 documentary film Fire of Love.

33They were killed by such an ash cloud, Giordano said.

34And some of the 215 people killed during the 2018 eruption of Guatemala's Fuego Volcano were also victims of an ash cloud, he added.

35There is a window of survivability for these hot blasts, he said, adding that building houses which can resist high heat near volcanoes could help.

36But why did the man with the glass brain alone suffer this fate?

37The other citizens of Herculaneum had some time to run away from the eruption.

38All the other bodies discovered there were clearly trying to flee.

39But the man, who was thought to have been the guardian of the collegium building, stayed in bed in the middle of town, so he was the first hit.

40Giordano said that we will likely never know the whole truth of what happened that day.

41I'm Jill Robbins.