Selected projects
4.19.26 The molecular identifications of geese remains from the Middle Late Saxon vertebrate assemblage from Flixborough, Lincolnshire
The identification of bird remains from archaeological sites can provide important palaeoecological and palaeobiogeographical information, as well as details of the hunting, management, and exploitation patterns of past societies. Interpretation, however, is limited by the ability to assign bones to species on criteria of accepted shape and size, and for many species such criteria do not exist, or are wholly inadequate for close identification. The recent application of biomolecular techniques to archaeological remains can now provide a powerful tool for addressing this problem.
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The remains of geese are often found in large numbers on archaeological sites, particularly for the Saxon period. The similar appearance of the five species of wild grey geese Anser, ie. greylag, pinkfoot, bean, white-front, and lesser white-front geese) renders identification difficult. This problem is compounded when dealing with fossil material, since there are no reliable morphological criteria for distinguishing their bones and there is often considerable overlap in size, reducing analysis of metric data to little more than educated guesswork. Added to this is the particular problem of differentiating wild from domestic individuals, and the possible presence in assemblages of the smaller black geese (Branta, ie. barnacle and brent geese).
The vertebrate assemblage from Flixborough includes a very large component of bird bones (c 22,000 identifiable elements) and is one of most important Middle to Late Saxon assemblages to have been recovered in this country. For this period, it is important to establish the significance to the local economy of wild and domestic geese, but hitherto this has been limited by our inability to identify their bones confidently to species level. Although thousands of geese fragments were excavated from Flixborough, only very general statements can be made about wildfowling techniques and habitat exploitation by humans on the Trent and Humber floodplains during the Middle and Late Saxon period. It is therefore essential that a technique can be devised that separates archaeological remains into definitive species categories.
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At the University of York, biomolecular techniques for identifying all the modern goose species present in Britain today have already been established and a unique DNA sequence has been discovered that can be used to identify domestic geese (probably representing the eastern greylag subspecies Anser anser rubirostris, generally regarded as the ancestor of the domestic goose). A major achievment has been the successful extraction and sequencing of ancient DNA from archaeological goose remains of Iron Age, Saxon, and post-medieval date and to make, for the first time, definitive identifications of barnacle, pink-footed, and even domestic geese from archaeological material. For this kind of data to be useful statistically, however, it is important that DNA is extracted and sequenced from multiple specimens from a single site in order to establish the real range and frequency of the different species present. English Heritage has provided a substantial grant to do this for the Flixborough goose remains.
The objectives of this work will be:
- to establish the range and frequency of species of wild and domestic geese using the biomolecular techniques already established
- to chart any changes in these frequencies through the tightly dated Middle to Late Saxon phases of occupation
- to compare these results with the measurement data already collected
- to explore the relationship between DNA survival and bird bone structure
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Although preliminary work has shown that DNA survives in some goose bones from the site, methods of predicting which bones will produce it are insufficiently accurate. In a batch of 40 randomly selected goose wing-bones selected for DNA extraction, only four produced DNA that could be sequenced and could then be identified to species (only 10%). The project will explore in detail the histological and chemical characteristics of bones exhibiting varying states of preservation in order to produce definitive criteria that can be used to predict the likelihood of DNA survival. Our aim for the Flixborough material is to produce a success rate of specimens with DNA of perhaps as high as 80-90%.