Ivory working and flows of raw materials – artefactual and isotopic studies

During the early medieval period, ivory was a key commodity flowing through different entrepots across the globe. What is particularly interesting about this period is that ivory was only available from certain regions of the world and from certain species - namely elephants in sub-Saharan Africa and India, dugong from the Indian Ocean, and walrus from the north Atlantic. Different social, economic, political, and technological factors influenced the degree of availability of these different ivories, the scale of extraction, their use for different kinds of objects, the way the ivory was worked and the overall popularity of the different types. Identifying the species from which the ivory used for a specific artefact was made, and determining its geographical origin can therefore help towards understanding the changing patterns of connectivity in different exchange networks as they became increasingly global. 

This 6-month pilot project will attempt to develop isotopic methods for identifying and provenancing the two most important ivories traded during this period: walrus (Odobenus rosmarus) and elephant (Loxodonta africana, Loxodonta cyclotis, Elephas maximus). 

During the Viking Age, walrus ivory was an important natural products, as it was widely available (especially from c. 1100 AD onwards, when supply lines opened up from Norse Greenland; Roesdahl 2005) and the by-products obtained from hunting the walrus (hides, meat, fat) gave further added value.  To supply this trade, large populations of walrus were exploited for their ivory across the north Atlantic region (Greenland, to a lesser extent Iceland) and also in northern Norway and the White Sea.  Consequntly, walrus ivory artefacts found in archaeological deposits of the early medieval period across Europe may have various geographical origins, and one aim of this project is to establish ways of determining more precisely which sources were used for specific objects and whether one or more area was preferred at different times and/or by different communities. 

Much like the other work packages on the Entrepot project which seek to identify source regions of raw materials, this pilot project will attempt to identify source regions of walrus ivory during the early Middle Ages using a multiple isotopic approach (208Pb/207Pb, 208Pb/204Pb, δ18O).  To do this, it will first be necessary to test material from these key regions (provenanced walrus ivory) to determine if they can be separated using this method.  The project shall sample early medieval archaeological finds of walrus ivory in collaboration with J. Arneborg (The National Museum, Copenhagen), and further participants from the North Atlantic Biocultural Organisation (NABO).

Although this project marks an initial attempt to source archaeological walrus ivory using a multi-isotope method, there have been recent studies exploring the isotopic heterogeneity in modern walrus populations, focused on stocks hunted in the Canadian Arctic and Greenland.  Because walruses feed on sedentary filter-feeders such as clams, their heavy, radiogenic isotope signatures should reflect the local marine geological range of this food source.  For example, it has been shown that by using lead (Pb) isotope analysis, it is possible to distinguish walrus populations between the eastern coast of Canada and western coast of Greenland due to walrus stocks having a very localised feeding range, and therefore conserving the local geological marine bedrock in the lead signatures measured in their teeth (Outridge et al. Arctic 2003, 82-90). Since the geologies between the source regions of interest during the early medieval period (Greenland, Iceland, White Sea, for example) are significantly different, we will aim to determine whether these geological differences are reflected in the heavy isotope values analysed in the walrus ivory due to its conservative ecological niche. If this is the case, then in principle the method should be able to reliably differentiate archaeological walrus ivory that was obtained from different geographical areas.

Elephant ivory was an increasingly important trade commodity during the early Middle Ages, particularly with the rise of Islamic trade networks operating in northern and eastern Africa.  From the 7th century, the demand for elephant ivory from consumers in China and India soared, and thus elephant ivory was travelling vast distances between places as distant as Africa, India, and China.  The Red Sea region was an integral link and crossroads for this traded ivory.  Early Islamic Red Sea ports such as Aylah (Aqaba), Jordan would have likely been a key location where ivory goods were exchanged – and the recovery of a remarkable range of ivory objects found during the 2010 excavations at Aylah offers an excellent opportunity to establish where elephant ivory was being sourced by merchants in Aylah during the early medieval period. In collaboration with K. Damgaard (Copenhagen University) and with generous permission from The Department of Antiquities in Jordan, we want to examine whether ivory in Aylah was being obtained from one or more source regions and if it is possible to determine more precisely where specific piece of ivory originated. Identifying and sourcing this ivory with bioarchaeological techniques (DNA and isotope analysis) will also connect it with the other Entrepot work packages focused on Indian Ocean trade (J. Hawkes and S. Wynne-Jones).