Plaster casts of Pompeii given first CAT scans

CAT scans on 30 of the recently restored plaster casts of people killed in the eruption of Vesuvius in 79 A.D. have found that Pompeiians had far better teeth than their modern counterparts. The scans showed the victims’ teeth were in excellent condition (the orthodontist who analyzed the scans called their teeth “perfect”) without a single cavity among them. There was some evidence of wear, but no tooth decay whatsoever.

The sample is too small to draw broad conclusions about the dental health of the overall population of the city, but that they ate healthy high-fiber foods low in fat and sugar is in keeping with what we know of their diet from previous poop studies. There’s another reason for their fine teeth: samples of Pompeii’s water and air found high levels of fluoride. Volcanic rocks and hot springs are high in fluorine which dissolves into water as fluoride, the same thing 25 countries deliberately add to their tap water for public dental health purposes.

While the casts have been X-rayed before, this is the first time any of them have been CAT scanned. One of the reasons for that is that the density of the plaster varies — the oldest of it dates to the 19th century, plus layers from subsequent restorations — but it can be as dense as bone. People with our squishy outsides are comparatively easy to scan, but add a thick plaster exoskeleton and it gets tricky. The archaeological team was able to borrow a 16-layer scanner from Philips SpA Healthcare that allowed them to see through the plaster to the bones in great detail. The scanner is superfast, taking only 100 seconds for a full body scan, and is able to block distortions to the images caused by metal elements. It was designed for people with prosthetics or implanted devices. The dead of Pompeii don’t have titanium hips and pacemakers, but metal pieces were added to some of the casts to reinforce the plaster structure.

The aperture of the scanner is just 70 cm (28 inches), so they had to select smaller casts that would fit all the way through, or limit the scan to the head and chest. The 30 casts of men, women and one child, plus two more casts of animals (a dog and a pig or wild boar) were CAT scanned. The mother holding her child discovered under the staircase in the House of the Golden Bracelet, for example, could not be scanned, but a slighter older child, probably a boy, found a few yards away from the mother was small enough to be fully scanned. The cast of the child contained a full skeleton. The length of femur established that the child was between two and three years old at time of death. A bump on the sternum previously thought to be a knot has now been identified as a fibula, probably gold, a baby version of the heavy gold bracelet found on his mother’s wrist which gave the house its name.

The scans also found fractured cranial bones, indicating that some of the deaths believed to have been caused by asphyxia from volcanic gases were in fact the result of victims being struck hard on the head by falling roof tiles or rocks.

Another fascinating find was actually the lack of a find. The cast of a woman thought from her silhouette to have been pregnant at the time of her death is empty. The CAT scan found no fetal bones and no adult bones. This is an artifact from the 19th century when some of the early casts were done after the skeletal remains were removed, possibly for ethical or religious reasons. One of the most iconic casts, the dog writhing on its back from the House of Orpheus, is also completely devoid of bones and it’s unlikely they would have been removed out of respect for the dead.

The analysis of the scans is still in the beginning stages so we’ll hear more about this project as it progresses. They have collected sufficient data to create 3D virtual models that will not only provide invaluable information about the lives and deaths of the people of Pompeii, but also about the plaster itself which will be of great aid in future conservation decisions. The team is planning to create a database of the 3D models so scholars around the world have access to them.

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21 Comments »

Comment by JD
2015-10-01 08:00:12

So you mean that the dog of the House of Orpheus is actually a fake ? OMG :eek: !

Comment by livius drusus
2015-10-01 13:07:32

Naw, the cavity the poor pup’s body left behind in the hardened volcanic ash is as real as it can be. It’s just that the bones were either removed before plaster was poured into it or they were destroyed over time, most likely the former.

 
 
Comment by rita Roberts
2015-10-01 08:41:37

Fantastic work.

 
Comment by Jeff Wood
2015-10-01 10:59:07

One has to wonder where the missing bones are; or could they be still in the ground?.

The first time I visited Pompeii, there was a little dog on display, though I cannot recall whether it was the Orpheus dog. Women came to look, their faces collapsing in grief before a handkerchief, dabbing of the eyes for the use of, was produced.

The breed still survives, and examples can be seen trotting happily past all over Italia, evidently well adapted to the summer climate – less so to the winter. My Lady’s Westie has the opposite adaptation.

Comment by livius drusus
2015-10-01 13:13:59

They can’t still be where they were found because once the plaster was poured into the cavity, the hardened ash all around it was chiseled away. They must have been removed before the cast was made. I suspect they were stored elsewhere and then lost track of or forgotten.

There are some very similar lupine dogs roaming the ancient city still today. You can adopt one!

 
 
Comment by nightsmusic
2015-10-01 12:35:06

How very eerie. I’m always so fascinated by Pompeii. I would still love to know the process that allowed the bones to remain static while the cast was made. I’ve not seen much on that but admittedly, haven’t done a great deal of research on it either.

Comment by livius drusus
2015-10-01 13:16:32

I explained the basics of the process and how it came about in this post. It’s one of the greatest breakthroughs in the history of archaeology, I believe.

 
 
Comment by nightsmusic
2015-10-01 14:02:37

Thanks! I can’t read it all now and will finish it tonight, but I truly appreciate the link. Don’t know how I missed it. I’ve been following your blog for a long time now…hmmm

Comment by livius drusus
2015-10-01 16:39:54

Oh, I miss/forget things all the time. Human brains are funny things. Thank you for reading! :thanks:

 
 
Comment by JD
2015-10-01 16:11:14

Must admit that I remain kind of sceptical about the dog. How did they achieve to remove all the tiny bones without destroying such a fragile imprint ? And why all that fuss about removing the bones :eek: ?

Comment by livius drusus
2015-10-01 16:38:25

Oh, it’s not fragile at all. It’s literally hard as rock. Vesuvius’ victims died from being struck or from asphyxia and their bodies were coated in fine ash and pumice. The whole town was then covered by a flow of superheated gases and molten rock which quickly hardened. The pyroclastic flow did not burn the bodies. It just sort of locked them in under their coating of ash and pumice. Over the centuries, the bodies decayed leaving only bones and a cavity shaped like their bodies.

Excavators found cavities with bones inside while digging through the very hard volcanic rock. At first they just removed the bones and kept digging, looking for the city structures and artifacts, but in 1863 the director of works at Pompeii figured out that you could pour plaster into the cavity and once it’s set, dig away the hard rock shell leaving the cast capturing the last moments of the people and animals of Pompeii.

So it wouldn’t have been hard to remove the skeletal remains from the cavity — just a matter of reaching into the cavity from the access hole — and I understand why they would have done it for humans. I don’t know why they’d do it for the dog, though. Maybe to have an example of a canine victim in their stores? Maybe one of the team was a dog lover? It’s remotely possible his bones decayed into nothingness. That happens with acidic soil all the time, but not so much in the alkali environment of a volcanic eruption.

 
 
Comment by Caligula Minus
2015-10-01 17:48:47

Yeah, the casts were done first, in order to chisel them out later, and thus to find out what the object could have been. The dog’s bones might indeed have received a Christian burial, and if so, may those removed charred bones rest in peace.

At several hundred degrees Celsius, however, combined with a swift coverage in ash, things were not in fact ‘burned’, but their ‘integrity’ was definitely harmed. Maybe a bit like marble exposed to really high temperature is said to get a little chalky.

:hattip:

 
Comment by nightsmusic
2015-10-01 18:41:33

Okay, so I’m going to ask the proverbial unasked question…I understand doing a cat scan. I worked in a hospital. So, that said, what was holding the bones together do you think, in the casts? There’s obviously no soft tissue left, no tendons, no nothing. Why then don’t the bones show up just in a jumbled pile at the bottom of the casts? I can see the top two, they’re shopped to show the muscular structure, but not the others. Unless they are…enquiring minds…

 
Comment by Helena Worth
2015-10-02 00:10:25

I thought the technique for creating the plaster molds meant it would have been near impossible to remove the bones whilst retaining the case enough to create a perfect cast. Was there another less-publicised technique being used?

 
Comment by Cerdig
2015-10-02 03:23:32

I hadn’t realised that the castings were anything but solid plaster. I had assumed the actual human remains had burned away to leave cavities into which the plaster was poured.

 
Comment by Jeff Wood
2015-10-02 09:37:49

Nightsmusic, I can see that gravity would tend to take the bones straight down to the bottom of the cavity. The distance is small, so minimal disturbance absent ground movement, and there would be little of that.

Viewed from above or from below, in many cases all would look normal. From the side, as with the scan up and to the right of the pup, there would be more sign of jumble.

 
Comment by Jeff Wood
2015-10-02 09:40:24

Cerdig, I sympathise. It was here I learned we had the bones, despite half a dozen visits to the place in the past.

 
Comment by Jeff Wood
2015-10-02 09:41:39

I cannot resist:

:skull:

 
Comment by GoryDetails
2015-10-02 11:43:38

Thanks so much for the article! I’ve been fascinated by the Pompeii “ghosts” ever since I first read about them (I think it was in a National Geographic article many, manymanymany years ago).

Re the dog-cast: Is it possible that the existing cast isn’t the original? Perhaps there was an earlier one that did contain the dog’s bones, and replicas were made because it’s such a stunning image (and/or because the original may have had flaws). If the provenance is conclusive, then never mind!

 
Comment by Lapinbizarre/Roger Mortimer
2015-10-02 14:48:17

Easy enough, actually, for the skilled or semi-skilled to make a plaster cast of any old dead dog and pass it of as Roman. Not as though forgery was an art-form alien to the 19th century Italian, now is it?

 
Comment by Ottoman Empire
2015-10-07 09:30:17

This is very fantastic.

 
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