Victims of Ancient Vesuvius Eruption Were Baked, Not Vaporised, According to New Research

By George Dvorsky on at

A novel analysis of the skeletal remains of Vesuvius victims who sought shelter during the catastrophic eruption 2,000 years ago suggests they endured a slower death than is typically appreciated.

Like the nearby settlements of Pompeii, Stabiae, and Oplontis, the ancient Roman city of Herculaneum was devastated when Mount Vesuvius erupted in 79 CE. The ash and pumice that settled onto the city resulted in its remarkable preservation, making it an important site for archaeologists.

In the early 1980s, archaeologists stumbled upon a gruesome scene while excavating the city’s beach and nearby boat chambers, known as fornici. During the eruption, hundreds of people fled to the beach in a desperate attempt to escape the volcano’s wrath, some of whom managed to cram inside the vaulted stone fornici. Over the years, archaeologists have uncovered the charred skeletal remains of 340 individuals, all of whom perished on the beach or inside one of the dozen boat chambers.

The Herculaneum boat chambers. Image: R. Martyn et al., 2020/Antiquity

A conventional theory said that the residents who sought shelter in the boat chambers died an instant death. The tremendous heat generated by the volcano’s pyroclastic flow – a fast-moving wave of hot gas and volcanic materials – caused the soft tissue in their bodies to instantly vaporise, according to a theory promulgated by Pierpaolo Petrone from the University Federico II in Naples, Italy. In 2018, Petrone co-authored a PLOS One paper, in which he argued that intense heat from the eruption caused skulls to explode and skin to turn directly into ash. Petrone and his colleagues estimated that the heat inside the chambers got as high as 500 degrees Celsius (932 degrees Fahrenheit).

New research published today in the science journal Antiquity offers a different interpretation of events. Biological anthropologist Tim Thompson from Teesside University and his colleagues argue that the bodies inside the chambers were not subject to instant vaporisation, as evidenced by the residual collagen found within their bones. Rather, the bodies of the victims were baked from the outside, while the interior portions of their bodies, including their bones, were less affected.

The authors speculate that the pyroclastic flow was not as hot as is typically believed and that the temperatures inside the boat houses got no higher than 400 degrees C (752 degrees F). So instead of an instant death, the victims inside the fornici lived long enough to suffocate from the volcano’s toxic fumes. It was only after they died that their bodies burned, according to the new research.

Prior to the new study, Thompson and his colleagues analysed preserved structures and collagen found inside the bones of recently cremated individuals (collagen is a binding protein and exists in large quantities inside of bone). Residual traces of collagen in the cremated remains could be correlated to the way in which the bones were exposed to heat. A similar thing was found for crystalline structures inside the bones. These findings led the researchers to develop a technique that allowed them to determine how much heat a body was exposed to as it burned.

“We were really keen to apply our newly developed methods on this incredible context to see if we could glean additional understanding of the people who lived and died at Herculaneum,” Thompson told Gizmodo. “We’ve used these methods before, both experimentally and on archaeological remains, but never at Herculaneum and never on victims of a volcanic eruption.”

Skeletal remains still in their original position inside the stone chambers. Image: R. Martyn et al., 2020/Antiquity

For the study, the researchers applied their technique to the ribs of 152 people from six different boat house chambers at Herculaneum. Their results did not match what would be expected from exposure to extreme heat, namely temperatures between 300 and 500 degrees C (572-932 degrees F).

“Overall, good collagen preservation and crystallinity values falling within the range indicative of no-to-low intensity burning events suggest that the Herculaneum victims within the fornici were not exposed to significantly high temperatures at the time of death,” wrote the authors in the study. “This means either that previous estimates for the flow temperature are too high, or that other mechanisms buffered the victims’ skeletons from exposure to the full thermal energy of the pyroclastic surge.”

Or a combination of the two. Indeed, the new research suggests the pyroclastic flow was not as hot as previously believed and was likely lower than 400 degrees C (752 degrees F) and possibly as low as 240 degrees C (464 degrees F). What’s more, the boat chambers may have offered some protection from the heat. Thus, the Herculaneum inhabitants who sought shelter in the fornici were not instantly vaporised, living long enough to die from exposure to toxic fumes produced by the volcanic eruption, the authors speculate. This was perhaps not as merciful a death as instant vaporisation, but certainly better than being cooked alive.

The new research “gives us a better understanding of what happened and how the people responded to the oncoming disaster,” Thompson told Gizmodo. “We can see men on the beach, presumably dragging the boats out. We can see the women and children sheltering in the boat houses. But unfortunately they were not fast enough, and so they ended up being trapped in the fornici and suffocating in the increasing heat.”

Petrone – the aforementioned advocate of the instant vaporisation theory – wasn’t thrilled with the new research. In an email to Gizmodo, Petrone said the authors failed to study the skeletons in their original archaeological context (i.e. in situ), which he said is “essential to understanding how these people died and the effects they suffered by the hot ash surge.”

By (apparently) sheer coincidence, Petrone published a brief paper in the New England Journal of Medicine yesterday, in which he, along with Piero Pucci from the Center of Genetic Engineering & Advanced Biotechnology and their colleagues, describe their analysis of a vitrified (turned to glass-like substance) brain that belonged to a victim of the Vesuvius eruption, also from Herculaneum. This individual was not in the boat chambers but was instead lying at home in a wooden bed when the pyroclastic flow struck. Analysis of this individual’s glass-like brain remnant suggests the heat had to have reached 510 degrees C (950 degrees F) for vitrification to have occurred – evidence which Petrone says is further validation of the instant vaporisation hypothesis.

“If someone wants to rewrite the history of how the inhabitants of Herculaneum died in 79 AD – a history widely documented by publications in prestigious scientific journals by those who personally dug and studied those skeletons – in my opinion [the authors have] to show more convincing evidence,” Petrone told Gizmodo.

In response to Petrone’s criticisms, Thompson said his research is novel insofar as it’s the first time such a method was used to study remains from Herculaneum. He said the paper’s conclusions were considered before, “but no one sat down to prove it.” As for the claim that the authors didn’t study the skeletons in their archaeological context, Thompson said at least one co-author had, but that it wasn’t a fundamental requirement of the research. Seeing the bones in situ wouldn’t “change the outcome of the results,” he said, adding that the two new papers don’t contradict the other, as they’re speaking to two very different conditions at Herculaneum during the eruption.

That said, Thompson was careful to point out that he doesn’t buy into the rapid vaporisation hypothesis. He said he’s “never seen a context in which tissue is rapidly vaporised” and that he’s “done experiments that involve temperatures hotter than a volcano, and the soft tissue is destroyed, but not rapidly vaporised in the way described.”

Looking ahead, Thompson would like to apply the new methods to the victims on the beach, to see if they get similar readings in response to the eruption. His personal feeling “is that we won’t and that we will see different results,” he said.

We eagerly await the results of this future research, as the debate rages on as to how these unfortunate individuals met their untimely demise.

Featured image: Norbert Nagel (Wikimedia)