I recently started working at Leiden University as a research assistant to Dr. Letty ten Harkel, who obtained a starting grant from the Faculty of Archaeology for the project ‘Living in an emporium: An isotopic investigation of diet and mobility in early medieval Dorestad (Netherlands)’. For this project, we will be investigating migration and eating habits at the settlement of Dorestad, situated at modern-day Wijk bij Duurstede. In order to do so, we will study human skeletal remains from one of Dorestad’s cemeteries, both through physical anthropology as well as through isotope analysis. We are still in the early phases of this project, so I would like to take this opportunity to outline what we will be doing.

Dorestad: an emporium

Dorestad was situated at the junction of both the Lek and the Kromme Rijn rivers. As such, it held an ideal position in the landscape for riverine trading. It had both access to the German Rhineland to the east, as well as the North Sea and all its surrounding coasts to the west. Dorestad fits in with several other riverine settlements that all emerged between the seventh and ninth centuries CE around the North Sea, which together formed a trading network: the emporia. Apart from their role as important commercial hubs, the emporium settlements were also characterized by their function as production centres. Many imported artefacts have been found at Dorestad, as well as evidence of textile production, metalwork, amber, bone and wood-working, ship-building and basket production (Hodges, 1982; Hodges, 2012; Dijkstra & Williams, 2010; Williams (Ed.), 2013). Dorestad also minted its own coins, which underlines its economic significance at the time. Other emporium settlements include Domburg in the Netherlands, London and Ipswich in England, and Ribe in Denmark. Dorestad was in its heyday during the late eighth to early ninth centuries CE, after which it declined.

As it does anywhere, life in Dorestad eventually included its end. The settlement therefore had multiple cemeteries in use. One of these, located at De Geer II, has been excavated in 2010-2011 by ADC ArcheoProjecten. Over 500 individuals have been excavated, which include over 230 from primary burials. Radiocarbon dating of six individuals was undertaken, resulting in a dating between the late seventh and late ninth centuries CE (the Carolingian period). After the excavation, the resources needed to analyse these individuals further were not available at the time (Williams (Ed.), 2013). With the onset of our current project, we are now able to collaborate with Gavin Williams and Dr. Henk van der Velde of ADC and to study the remains from De Geer II using a new methodology, in order to gain insight into who the people buried at Dorestad were and what their daily lives may have looked like. Because Dorestad formed an important point of connection with the wider North Sea area, it was frequently visited by merchants from abroad. It will therefore be exciting to see if research into diet and mobility at the site will reveal the presence of non-local people, or people with differing diets indicative of different cultural habits.

Isotope analysis

Our method of choice is isotope analysis, which I will briefly explain here. Because the cells of the human body are built out of atoms derived from food that is consumed during life, the elemental composition of these cells can provide information on what a person may have eaten. Additionally, because food and drink in the past was mostly sourced from the local environment and ecosystem, the study of human tissues can also grant insight into where someone may have lived. In archaeology, human remains mainly survive in the form of bones and teeth, such as those excavated at Dorestad. The way to examine these remains on an elemental level in order to gain information on diet and mobility, is through isotope analysis.

But what are isotopes? Summarised, atoms contain protons and neutrons in their nucleus. While the number of protons is set for a specific element, the number of neutrons can vary from atom to atom. These variations amongst atoms of the same element are called isotopes. In archaeology, stable carbon and nitrogen isotopes are often used for diet reconstruction, while strontium and stable oxygen are used to investigate migration and mobility (Katzenberg & Waters-Rist, 2018). More recently, the use of stable sulphur isotopes is starting to become more common. Sulphur can be used for both dietary and mobility studies (Richards, 2023). The ratio of one isotope to another in bones or teeth will reflect that same ratio in the food and drink that was consumed, which in turn is tied to the local environment. This forms the basis of isotope analysis in archaeology.

Multi-isotope, multi-sample

The methodology for this project is quite innovative, because it combines all five elements mentioned above (carbon, nitrogen, strontium, oxygen and sulphur) in order to paint as complete of a picture as possible. Using all five elements has (as far as we know) not been done before in archaeology in the Netherlands. Therefore, apart from gaining knowledge on the population of Dorestad, another aim of this project is to test out this methodology to see how feasible it is to study a Dutch assemblage this way.

Another important aspect of this research is that multiple samples per individual will be taken. Different parts of the skeleton form at different phases in life. For example, the enamel and dentine of teeth form during childhood, with each tooth forming around a different specific age. Bones, on the other hand, remodel during life. This means that the cells are constantly renewing. The isotope values in bone therefore reflect on average the last ten to twenty years of life, while the isotope values in teeth reflect diet and provenance during specific years in childhood. By sampling both teeth as well as bone, developments during the life course of each individual person can be reconstructed. This way, we might be able to conclude that someone was born abroad, but migrated to Dorestad during their lifetime. Or, for example, that someone had a mostly plant-based diet in childhood, but switched to a diet that included more animal products or fish in later life. This will give information on the human dynamics that shaped Dorestad. After all, it was its people who made Dorestad into the bustling trading settlement it was.

Looking to the future

Since the project has only just gotten started, I do not have any results to share yet. For now, we will focus on selecting twenty individuals to include in this study. Personally, I will be involved as a research assistant for the first year of the project, and my main contribution will entail the reconstruction of diet. I will then hand over the proverbial torch to a new research assistant who will focus on the mobility portion of this study. The hope is that this method will prove fruitful. If it does, there may be opportunities for future research by analysing more individuals from Dorestad, either from De Geer II or from one of the settlement’s other cemeteries. Alternatively, other emporium sites could be studied the same way, and then be compared to Dorestad. Regardless, I am excited to be involved in a project that aims to test out a new methodology and to shed light on daily life at an early medieval emporium settlement.

References

• Dijkstra, J., & Williams, G. L. (2010). New research in Dorestad: Preliminary results of the excavation at the former fruit auction hall (‘Veilingterrein’) at Wijk bij duurstede. In A. Willemsen & H. Kik (Eds.), Dorestad in an international framework: New research on centres of trade and coinage in Carolingian times (pp. 59–68).
• Hodges, R. (1982). Dark Age economics: The origins of towns and trade, AD 600-1000. Duckworth.
• Hodges, R. (2012). Dark Age economics: A new audit. Bloomsbury Academic.
• Katzenberg, M. A., & Waters-Rist, A. L. (2018). Stable isotope analysis: A tool for studying past diet, demography, and life history. In M. A. Katzenberg, & A. L. Grauer (Eds.), Biological anthropology of the human skeleton (3rd ed.) (pp. 469–504). John Wiley & Sons, Inc. https://doi.org/10.1002/9781119151647.ch14
• Richards, M. P. (2023). Sulphur isotope ratios of archaeological human collagen as a mobility indicator. In T. D. Price (Ed.), Isotopic proveniencing and mobility: The current state of research (pp. 187–197). Springer International Publishing. https://doi.org/10.1007/978-3-031-25722-3_8
• Williams, G. L. (Ed.) (2013). Een nieuw stukje Dorestad: Een archeologische opgraving in Wijk bij Duurstede. ADC Rapport 3467. ADC ArcheoProjecten.

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