Prehistoric pottery use – the path to and start of a PhD

“The important thing is not to stop questioning. Curiosity has its own reason for existing.”
Albert Einstein
Oliver and Julia at Skara Brae in August 2021.

Professor Oliver Craig and Julia Becher at Skara Brae in August 2021.

By Julia Becher

For as long as I can remember, curiosity was my constant companion.

Combined with a fascination for details, I always tried to understand the world around me, leading me to two major questions – how did humans evolve and why are we the way we are?

After a gap year in Australia (Work ‘n’ Travel), I started a Bachelor degree in Pre- and Protohistory, Medieval Archaeology and Scientific Archaeology at the University of Tuebingen (Germany). Back then, I still had a very “romantic” view of the life of an archaeologist, especially in terms of job opportunities and being able to travel to exotic countries, such as South Africa and Israel.

Throughout the years and talking to many scholars, it became more evident that academia and research is not as “romantic” as I imagined, especially with regard to the job situation.

Towards the end of my Bachelors, I decided that I won’t give up so easily, but I needed a Plan B.

I continued with the Master’s degree in Pre- and Protohistory and additionally started a Bachelor’s degree in chemistry as a fallback. In school I never loved chemistry because of the generalist approach in teaching but at university I encountered a much more in-depth to these sciences and their mystery was revealed!

The combination of archaeology and chemistry unlocked new possibilities that I wasn’t aware of before.

Whereas I focused on Stone Age archaeology during my Bachelors, I developed an increasing interest also in younger periods, e.g. the Iron Age of southern Africa. The combination with chemistry opened new pathways: my love for African archaeology with the detailed work of Organic Residue Analysis (ORA).

Together with my first supervisor Dr Cynthianne Spiteri (now University of Turin) and my second supervisor Prof Alex Schoeman (University of the Witwatersrand), I was able to create an amazing project to investigate vessel use from early farming communities in South Africa. This work intensified my fascination for organic analytical chemistry, and therefore I wanted to continue with a PhD within this field.

In autumn 2020, while I was in the middle of writing my Master thesis, the ChemArch project was announced, and platforms opened to submit letters of interests. One specific project caught my interest as it was focusing on ORA from a site in Orkney. Besides my research in Africa, I always had a keen interest in the European Stone Age.

The application platforms of ChemArch opened in December 2020 forcing me to submit, both the application and the Master thesis at the same time. Shortly after passing my master defence, I received the invitation to a job interview with the University of York. I was very excited as I was invited to the Orkney project!

Besides being a huge Outlander series fan, the Wellerman song sung by the Scottish Nathan Evans was released at the time when I got the approval. All signs were pointing towards Scotland…

…then in September 2021, I started my PhD journey within the ChemArch network.

My project focuses on the Ness of Brodgar site and is supervised by Prof. Oliver Craig (University of York), Dr Martine Regert (CNRS, Nice) and Prof. Mark Edmonds (University of York). The PhD programme provides the possibility to obtain a double degree by spending two years at the home institution and one year at the partner institution, which are in my case York (BioArCh) and Nice (CEPAM).

The project is funded by the European Union’s Horizon 2020 research and innovation programme, whereas ChemArch specifically is a Marie Skłodowska-Curie innovative training network (ITN) which provides doctoral training in archaeological chemistry and biomolecular archaeology.

The research of my PhD project will focus on the investigation of vessel use through time and space at the Ness of Brodgar by using lipid residue analysis – specifically a combined approach of Gas Chromatography-Mass Spectrometry (GC-MS) and compound specific isotope analysis (GC-c-IRMS).

Lipid residue analysis is a well-established technique to identify the contents and function of ceramic vessels.

Identified compounds include:

  • Pork (Mukherjee et al. 2007; Mukherjee et al. 2008)
  • Beef (Craig et al. 2015; Evershed et al. 1997a; Regert 2011)
  • Leafy vegetables (Charters et al. 1997; Dunne et al. 2017; Evershed et al. 1991; Rageot et al. 2019a)
  • Dairy products (Copley et al. 2003; Copley et al. 2005; Evershed et al. 2008)
  • Resins and tars (Connan and Nissenbaum 2003; Rageot et al. 2019b; Stern et al. 2003)
  • Beeswax (Charters et al. 1995; Evershed et al. 2003; Evershed et al. 1997b; Heron et al. 1994; Regert et al. 2001; Regert et al. 2005).
Julie's sunset encounter with the Ring of Brodgar.

Julia’s sunset encounter with the Ring of Brodgar.

The Ness of Brodgar lies at the heart of one of the largest Neolithic ceremonial complexes in Britain (Card et al. 2020) and dates to the Orcadian Late Neolithic, spanning over 1,000 years of occupation (Card et al. 2020).

Distinctive Grooved Ware pottery vessels were deposited across the site’s many structures and spaces. Some of the pottery from the Ness of Brodgar is likely to have been used in large-scale communal feasting, while other deposits may reflect the more day-to-day use of vessels for storage, cooking and food consumption (Towers et al. 2020).

With the application of organic residue analysis (ORA), we aim to provide insights into vessel use by comparing the pottery from various contexts. These include house structures and middens, but also in a finer resolution the beginnings, main uses, and abandonment of structures.

If people in the past used different areas of the site for different purposes, this can be traced by sampling a substantial amount of pottery sherds from various contexts and comparing these through time and space. This sampling strategy will further result in one of the largest ORA studies ever conducted on one site.

Julie with some of the Ness of Brodgar team on site.

Julia and Oliver with some of the Ness of Brodgar team on site.

In August 2021, Oliver and I visited Orkney in order to meet the Ness of Brodgar team and discuss our project goals and sampling strategy. The trip included excursions to relevant archaeological sites on the Orkney Mainland, such as the Stones of Stenness, the Barnhouse settlement, Ring of Brodgar and Skara Brae.

Fun fact: note on the picture above the locals are in light clothing whereas I (previously working in Africa) am covered in layers of clothing! I’m still getting used to the northern climates!

At the beginning of October, the ChemArch network held its first workshop in Barcelona!

We were able to finally meet all the other Early Stage Researchers (ESRs) and supervisors (see photo 4).

The workshop covered an introduction to the network, with guidance on collaborative tools and PhD management specifically for the European Joint Doctorate network as well as Intellectual Property and academic integrity. The next workshop will take place in Nice, France, in June 2022.

ChemArch network group photo with supervisors and ESRs.

ChemArch network group photo with supervisors and ESRs.

In October I started working on the organic residues.

All sherds chosen for ORA have been carefully documented, such as sherd descriptions and photographs.

In order to conduct lipid residue analysis, 1-3g of powdered sherd is required (depending on analysis) to obtain a sufficient amount of lipids when present.

The powder can be either gained through drilling with a hand-held rotary drill or the crushing of sherd fragments with a pestle and mortal.

Lipids are omnipresent in our daily lives, such as the oils and fats from our skin, in cremes, and food sources. In order to avoid contamination, the handled first layers of a sherd will be removed with the drill and all laboratory equipment coming in direct contact with a sample have been previously sterilised.

This makes the process of organic residue analysis more time-consuming compared to other archaeological scientific techniques, but the data can provide very useful information on the manufacture and use life of a vessel.

This includes for example sealing techniques (beeswax, resins), the processing of animal fats (beef, pork, dairy products), or the processing of plant products (cereals, leafy vegetables).

Set-up of crushing fragments of sherds and weighing out powder for the first analysis.

Set-up of crushing fragments of sherds and weighing out powder for the first analysis.

The pottery from the Ness is often very fragmented and crumbly, which is why crushing was our only option in some cases. In order to be consistent, we decided to crush all our samples (see picture above) so, either the pottery fragments are already very small or (in most cases) we break off a small pottery fragment which will then be used for sampling.

Currently, we are focusing on the sampling, so that most of it is finished before my move to Nice where I will conduct more in-depth analysis.

In the next blog I will focus on the laboratory work and show how we carry out the extractions and analysis.

I will also further provide background information on organic residues and the methods used.

Stay tuned and curious!

Notes

  • Card, N., Edmonds, M. R., & Mitchell, A. (2020). The Ness of Brodgar – As it Stands. Kirkwall: The Orcadian.
  • Charters, S., Evershed, R. P., Blinkhorn, P. W., & Denham, V. (1995). Evidence for the Mixing of Fats and Waxes in Archaeological Ceramics. Archaeometry, 37(1), 113-127.
  • Charters, S., Evershed, R. P., Quye, A., Blinkhorn, P. W., & Reeves, V. (1997). Simulation Experiments for Determining the Use of Ancient Pottery Vessels: the Behaviour of Epicuticular Leaf Wax During Boiling of a Leafy Vegetable. Journal of Archaeological Science, 24(1), 1-7.
  • Connan, J., & Nissenbaum, A. (2003). Conifer tar on the keel and hull planking of the Ma’agan Mikhael Ship (Israel, 5th century BC): identification and comparison with natural products and artefacts employed in boat construction. Journal of Archaeological Science, 30(6), 709-719.
  • Copley, M. S., Berstan, R., Dudd, S. N., Docherty, G., Mukherjee, A. J., Straker, V., et al. (2003). Direct chemical evidence for widespread dairying in prehistoric Britain. Proceedings of the National Academy of Sciences, 100(4), 1524.
  • Copley, M. S., Berstan, R., Mukherjee, A. J., Dudd, S. N., Straker, V., Payne, S., et al. (2005). Dairying in antiquity. III. Evidence from absorbed lipid residues dating to the British Neolithic. Journal of Archaeological Science, 32(4), 523-546.
  • Craig, O. E., Shillito, L.-M., Albarella, U., Viner-Daniels, S., Chan, B., Cleal, R., et al. (2015). Feeding Stonehenge: cuisine and consumption at the Late Neolithic site of Durrington Walls. Antiquity, 89(347), 1096-1109.
  • Dunne, J., Mercuri, A. M., Evershed, R. P., Bruni, S., & di Lernia, S. (2017). Earliest direct evidence of plant processing in prehistoric Saharan pottery. Nature Plants, 3(1), 16194.
  • Evershed, R. P., Dudd, S. N., Anderson-Stojanovic, V. R., & Gebhard, E. R. (2003). New Chemical Evidence for the Use of Combed Ware Pottery Vessels as Beehives in Ancient Greece. Journal of Archaeological Science, 30(1), 1-12.
  • Evershed, R. P., Heron, C., & Goad, L. J. (1991). Epicuticular wax components preserved in potsherds as chemical indicators of leafy vegetables in ancient diets. Antiquity, 65(248), 540-544.
  • Evershed, R. P., Mottram, H. R., Dudd, S. N., Charters, S., Stott, A. W., Lawrence, G. J., et al. (1997a). New Criteria for the Identification of Animal Fats Preserved in Archaeological Pottery. Naturwissenschaften, 84(9), 402-406.
  • Evershed, R. P., Payne, S., Sherratt, A. G., Copley, M. S., Coolidge, J., Urem-Kotsu, D., et al. (2008). Earliest date for milk use in the Near East and southeastern Europe linked to cattle herding. Nature, 455(7212), 528-531.
  • Evershed, R. P., Vaughan, S. J., Dudd, S. N., & Soles, J. S. (1997b). Fuel for thought? Beeswax in lamps and conical cups from Late Minoan Crete. Antiquity, 71(274), 979-985.
  • Heron, C., Nemcek, N., Bonfield, K. M., Dixon, D., & Ottaway, B. S. (1994). The Chemistry of Neolithic Beeswax. Naturwissenschaften, 81(6), 266-269.
  • Mukherjee, A. J., Berstan, R., Copley, M. S., Gibson, A. M., & Evershed, R. P. (2007). Compound-specific stable carbon isotopic detection of pig product processing in British Late Neolithic pottery. Antiquity, 81(313), 743-754.
  • Mukherjee, A. J., Gibson, A. M., & Evershed, R. P. (2008). Trends in pig product processing at British Neolithic Grooved Ware sites traced through organic residues in potsherds. Journal of Archaeological Science, 35, 2059-2073.
  • Rageot, M., Mötsch, A., Schorer, B., Gutekunst, A., Patrizi, G., Zerrer, M., et al. (2019a). The dynamics of Early Celtic consumption practices: A case study of the pottery from the Heuneburg. PLOS ONE, 14(10), e0222991.
  • Rageot, M., Théry-Parisot, I., Beyries, S., Lepère, C., Carré, A., Mazuy, A., et al. (2019b). Birch Bark Tar Production: Experimental and Biomolecular Approaches to the Study of a Common and Widely Used Prehistoric Adhesive. Journal of Archaeological Method and Theory, 26(1), 276-312.
  • Regert, M. (2011). Analytical strategies for discriminating archeological fatty substances from animal origin. Mass Spectrom Rev, 30(2), 177-220.
  • Regert, M., Colinart, S., Degrand, L., & Decavallas, O. (2001). Chemical Alteration and Use of Beeswax Through Time: Accelerated Ageing Tests and Analysis of Archaeological Samples from Various Environmental Contexts. Archaeometry, 43(4), 549-569.
  • Regert, M., Langlois, J., & Colinart, S. (2005). Characterisation of wax works of art by gas chromatographic procedures. Journal of Chromatography A, 1091(1), 124-136.
  • Stern, B., Heron, C., Corr, L., Serpico, M., & Bourriau, J. (2003). Compositional variations in aged and heated Pistacia resin found in Late Bronze Age Canaanite amphorae and bowls from Amarna, Egypt. Archaeometry, 45(3), 457-469.
  • Towers, R., MacSween, A., Blatchford, J., & Smith, E. (2020). The age of clay: pottery by another name. In N. Card, M. R. Edmonds, & A. Mitchell (Eds.), The Ness of Brodgar – As it Stands (pp. 254-265). Kirkwall: The Orcadian.

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