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Half-information and the Capitoline Wolf

I don't normally comment about the reporting of my subject area in the media, because I've long ago accepted that it's bound to seem flawed from my perspective, and am basically just happy it's in the news at all. But since today the alternative is further work on my Teaching Portfolio, I will!

The item that's caught my eye today is coverage of a story about the Capitoline Wolf. Some background: in the 18th century, Winckelmann decided that the wolf was probably Etruscan, based on the way its fur had been represented. However, in 2006, the wolf was examined closely by art historian Anna Maria Carruba as part of a restoration project, and she noted that it had been made using a technique that was not developed until the medieval period. Specifically, it had been cast in one piece from a wax mould, rather than being cast in separate pieces using the 'cire perdue' method, and then soldered together. This meant that the wolf was almost certainly medieval: although the paucity of surviving examples of Etruscan sculpture meant that the use of a similar technique in the Etruscan period could not be definitively ruled out.

So far, so reasonable. Now suddenly, today, the English-language press is full of pieces about how the wolf's medieval date has been proven by 'carbon-dating', which spring ultimately from this Italian-language article by Adriano la Regina in La Repubblica.

The problem: carbon-dating is only possible on organic remains. It measures the extent of decay of carbon-14 atoms, which are absorbed by all living organisms until the point of death, thus allowing a pretty accurate calculation to be made of how long ago the organism in question died, and hence the carbon-14 in it started decaying. (Best explanatory site I could find on a perfunctory Google was this one). So the wolf itself cannot possibly be dated using this technique: something which the English-language press don't even seem to be aware of.

Following up the story to its Italian source-article, I got little further illumination. Radio-carbon dating is indeed mentioned there, as is thermoluminescence (see last paragraph). But exactly what was tested using these techniques still remains obscure. And thermoluminescence is no more appropriate for dating the wolf itself than radio-carbon dating. This is partly because it works best on objects with a crystalline structure which have at some time been subjected to intense heat (e.g. pots, hearth-stones), but mainly because it measures background radiation absorbed by an object over time, and therefore relies on knowing exactly where that object has been throughout its lifetime, so that the general level of background radiation exposure can be measured. (Again, best explanatory site here). So it is totally inappropriate for a bronze object which is only known to have been stuck up on a pillar in the open air for most of the last millennium.

In other words, if such tests were indeed performed, they cannot have been performed on the wolf itself. The only possible basis for claiming that radio-carbon tests or thermoluminescence tests have yielded any information with a bearing on the date of the wolf would be if some organic and / or mineral material in some way intimately associated with the wolf (e.g. cast into the bronze) has been retrieved, and that has been tested.

Now, the man behind the Italian article, Adriano la Regina, is no crank. Until a couple of years ago, he was Rome's Superintendent for Archaeology (i.e. the man in charge of overseeing all archaeological work going on in the city), and he has a list of reputable publications as long as your arm. I absolutely trust him not to go round declaring new dating evidence for this sculpture without a sound scientific basis. But what's been reported in the Italian press, never mind the English, does not add up to such a basis. Critical information, such as what exactly was tested, and what relation it bears to the bronze of the wolf - information which la Regina himself must know - is missing. And meanwhile, the general public is expected to simply accept the bandying about of impressive terms like radio-carbon dating as enough to support the new dating claim, without any idea whatsoever about how appropriate or relevant they are.

I'm happy enough for the wolf to be medieval. In fact, I think that would be fantastically cool, since it would constitute a charming response to stories of the ancient past on the part of the medieval inhabitants of Rome. Good for them. But I am not happy that the general public should be asked to accept this redating on the basis of half-information.

Rant over. I guess I'd better get some work done.

Comments

( 17 comments — Leave a comment )
huskyteer
Jul. 10th, 2008 02:49 pm (UTC)
The theory I always heard was that the wolf was Etruscan and the twins were added centuries later, hence their looking more realistic. I really want this to be true.
strange_complex
Jul. 10th, 2008 02:55 pm (UTC)
You're pretty secure about the twins being a later addition. The question is really: how much later?
swisstone
Jul. 10th, 2008 02:58 pm (UTC)
The problem is, most people in the media have got fixed in their idea that radio-carbon dating is the Bestest Dating Trick Evah!, and trumps all others. I still recall an episode of The Archers from the early 1990s, where they were excavating under the church. They'd got a dendro date for some wood, and were now waiting for a radio-carbon date from the same material - of course, what the writers didn't realize was that if you've got a dendro date, you wouldn't bother with radio-carbon, because it can't possibly give you better information.

One does wonder what precisely is going on here. I wait with anticipation what Mary Beard has to say about it all.
strange_complex
Jul. 10th, 2008 03:01 pm (UTC)
That's not the whole problem, though, because la Regina does know better than that, and he is the author of the original article, complete with its vague references and half-information. He's actually feeding exactly that attitude - and he really should know better.

With you on Mary Beard, though.
swisstone
Jul. 10th, 2008 03:10 pm (UTC)
I wonder if there isn't an issue here whereby la Regina has been heavily edited? We shall see.

Edited at 2008-07-10 03:11 pm (UTC)
strange_complex
Jul. 10th, 2008 03:14 pm (UTC)
Yes, could be.

(And I am amused that you edited your comment about la Regina being edited: very meta-referential!)
chrisvenus
Jul. 10th, 2008 03:46 pm (UTC)
I don't know huge amounts baout this field but I had a vague impression that you *could* date metal stuff by carbon dating - the reason being that there are traces of carbon left in it. I'm a little hazy but roughly I understand the logic is that say you melt the metal over a wood burning furnace. Carbon particles from the wood will get into the melted metal and get stuck there.

I may be wrong on this but this is the impression I had been under and so what is said in the news article seems completely reasonable to me. I may of course be wrong. I've not found any nice readable things but I did find the following that suggests the theory is sound at least:

http://www.tms.org/pubs/journals/JOM/0305/Cook-0305.html


"The phrase “iron-based materials” is used to cover the three common groups of irons and steels: wrought irons, which are typically low carbon (e.g., less than about 0.05% carbon), steels (up to 2.1% carbon), and cast irons (over 2.1% carbon)."


I have no idea where more useful discussion on it might be. Simple searching didn't turn up much more than that one linked article. At least that refers to carbon contents of iron though. :)
chrisvenus
Jul. 10th, 2008 03:50 pm (UTC)
Though I am now noting that it is a bronze statue so thecomments on iron containing carbon are a little bit useless. Sorry. :)
chrisvenus
Jul. 10th, 2008 03:59 pm (UTC)
And actually thinking about the underlying comments I don't really think precise details of exactly how what and why were measured are actually relevant to the general public. Most of them don't understand carbon dating as you've suggested so suggesting that they should be given even more detailed technical information to support the claim seems odd. I would expect that information to be available somewhere for scholars or those particularly interested but not in the general press.

Personally I would accept the statement withotu them even having to say carbon dating if the source was reliable.

I guess it just goes back to your opening comment that it would seem flawed from your perspective - I think because its something you are more interested in you want a whole lot more information than the general public probably do. Isn't this what more specialist publications are there for? I'm sure there must be some archaeological magazines or journals or something that would likely cover this in much more detail...
strange_complex
Jul. 10th, 2008 04:11 pm (UTC)
Personally I would accept the statement without them even having to say carbon dating if the source was reliable.

I think this is the crux. I would have been happier for the reports just to say that the date had been confirmed on the basis of scientific testing, rather than wave the term 'carbon-dating' around as though it explains everything. That's unhelpful at the best of times, and positively misleading in this case. As swisstone notes, doing so just perpetuates its mythical status in the public mind.

Obviously I know that I could access more detailed scholarly publications on the issue if I wanted to (though la Regina states that the findings have only just been released). But I am concerned here with the sloppy and misleading way this has been presented to the general public.
the_lady_lily
Jul. 10th, 2008 04:24 pm (UTC)
I've just spent a half-hour reading the Italian excerpt that appeared on Rogue Classicism in an attempt to improve my rusty Italian... managed to get most of the info out of it. I think I've found the way to keep my languages at least vaguely in trim!

(And yes, I'm procrastinating too, but at least making sure my Italian is kind of servicable is sort of like work.)
strange_complex
Jul. 10th, 2008 04:42 pm (UTC)
Actually, I was quite glad to have the chance to use it for that purpose, too!
the_lady_lily
Jul. 10th, 2008 04:51 pm (UTC)
:) I'd been thinking the other day that I'd not used my Italian since learning it last year, so suddenly realising that Rogue Classicism occasionally posts snippets in both Italian and German has made me decide to wade through reading anything that turns up in those languages... regardless of whether I'm interested or not. At least, that's my plan...
qatsi
Jul. 10th, 2008 06:38 pm (UTC)
I initially assumed what chrisvenus had said: presuming some essentially organic carbon would have been incorporated as the piece was cast, radio-carbon dating would be a plausible method. There are other radiological dating techniques, though I'm not sure they're useful in a relatively modern archaeological context - Potassium-Argon dating, for example (though that wouldn't help in this case, either).

Edited at 2008-07-10 06:39 pm (UTC)
strange_complex
Jul. 10th, 2008 08:32 pm (UTC)
presuming some essentially organic carbon would have been incorporated as the piece was cast, radio-carbon dating would be a plausible method

Well, yes. That is exactly what I said in my original post (see the third paragraph up). My point is that this link in the logical chain from radio carbon dating to an accurate date for the Capitoline wolf has been casually discarded from the press articles about it.
paulgregory
Jul. 11th, 2008 12:16 am (UTC)
I'm dubious of the whole "dating" malarkey, and of the British press. It's worth remembering that although it feels like we're now keeping enough information about the world to mean future historians should just be able to look up how old something from our time actually is, there's enough inaccurate information out there to still make the truth a bit of a mystery.

Based on a composite of conjecture and random dice rolls I think it is a medieval copy (most likely in a misguided attempt at restoration) of an Etruscan design.
strange_complex
Jul. 11th, 2008 07:45 am (UTC)
That's a very plausible and interesting theory, actually - about the medieval copy. I could well see that happening in medieval Rome.
( 17 comments — Leave a comment )

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