Response to Sinding, Arneborg, Nyegaard and Gilbert, ‘Ancient DNA unravels the truth behind the controversial GUS Greenlandic Norse fur samples: the bison was a horse, and the muskox and bears were goats’, Journal of Archaeological Science, 53, 2015, 297-303 (on-line in November 2014).
It is obvious from the title that the authors consider themselves to have disproved the species identifications made by microscopy in four of the fibre specimens from the GUS excavation (published in 1998). The original analysis was by H M Appleyard, who is now deceased. Since I was the person who commissioned the work from Appleyard, it is left to me to defend him.
Harry Appleyard was a scientist, microscopist and author of Guide to the Identification of Animal Fibres, published by WIRA, Leeds, UK (1st edition 1960, 2nd edition 1978). He had little interest in archaeology, but regarded each archaeological sample simply as a fresh specimen to be viewed down the microscope. After years of commissioning work from him, I can say that his results were consistent and appropriate to the sites and periods from which they came.
I cannot make the records in the 2014 paper tally with my own. In 1998, I was already raising concerns over discrepancies between the photographs taken after we had returned the material to Denmark (one inserted into the 1998 report) and our records here. The problem has been compounded in the 2014 paper, where the text, figure captions and images contradict each other. For example, in Fig.2, there is no braiding visible in the ‘braided string’ of x633 (and x633 in our records was a fragment of animal pelt); the ‘fur tuft’ x2519 is clearly a plied cord; and the short disaggregated fibres of x1925 are in our records an intact staple 100 mm long. I could go on. It is therefore uncertain – possibly even unlikely – that the samples in the two studies were the same.
My suspicion is that the main authors have not read the 1998 report, but are working from a list of results. Otherwise they would not have said that the species identification was based on fibre morphology (it is a lot more than that) or that ‘the specific criteria that were originally used in the morphological analysis of the samples are unknown’ (p302), when Appleyard’s diagnostic features are clearly detailed, sample by sample, on p71 of the 1998 report. Nor could they have failed to notice that the single muskox identification, x479, was an uncertain one (they suggest multiple identifications, but, as far as I am aware, that is not correct). In 2006, I myself re-examined fresh samples of x479 and reported that it was more probably goat hair (which shares several characteristics with muskox fibre).
I wholeheartedly agree with the authors when they recommend that microscopy and aDNA analysis should be used together. That is exactly what the rest of us have been doing for quite some time now. We are finding a much better correlation between microscopy and biomolecular approaches than this paper would imply. More cautious teams with whom we have been collaborating are taking a long time to bring their projects to publication, but we ourselves have now begun to commission aDNA analyses, to run parallel with our own microscopy. In addition, two of my own species identifications by microscopy have been confirmed by Peptide Mass Fingerprinting (see Solazzo et al 2014 in the Bibliography).
I do not doubt that some contradictions will eventually emerge – it would be a miracle if they did not – but the correlation so far has been good.
To my mind, it is a great pity that what could have been a useful collaboration and an intelligent review of the pros and cons of microscopy and aDNA has been turned into an attack on the work of a responsible and hard-working scientist, who is no longer here to defend himself.
I hope to make a more formal response in due course, in the context of other, larger, studies.
Penelope Walton Rogers
The Anglo-Saxon Laboratory
29 December 2014