Half-information and the Capitoline Wolf
Thursday, 10 July 2008 15:06![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
strange_complexI 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.
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.
