The Euan MacKie Legacy Fund enabled PhD student Lucy Koster FSAScot to carry out new triple stable isotope analysis of diet on remains from the Neolithic chambered Cairn on Rousay, Orkney.

The Society of Antiquaries of Scotland provided funding through the Dr Euan MacKie Legacy Fund to support new stable isotope analysis of δ34S values, as well as reanalysis of δ13C and δ15N values, of human bone collagen from the Knowe of Rowiegar chambered cairn. The aim of this research is to use triple stable isotope analysis to provide a more nuanced understanding of diet at the site than can be obtained from existing δ13C and δ15N values, as well as to gain insights into potential lifetime mobility.  

The Knowe of Rowiegar is an Orkney-Cromarty type tomb on the island of Rousay, Orkney. Human remains deposited in the cairn date to the Middle Neolithic, c. 3525-2875 cal. BCE (95.4% probability) (Bronk Ramsey, 2009; Reimer et al., 2020), a broad range due to the Middle Neolithic radiocarbon calibration plateau which reduces the precision of calibrated dates, although the tomb may have been used for some time after the final deposition event. During the Iron Age a souterrain structure was constructed in the centre and south-east of the tomb, resulting in only six of the original twelve cells remaining (Hutchison et al., 2015). Original excavations of the site were carried out by workmen from the Trumland estate under the direction of landowner and archaeological enthusiast Walter G. Grant in 1937, and the human bone assemblage was subsequently sent to the University of Aberdeen, where it is now housed in Marischal Museum. This assemblage is comprised of 20 discrete skulls and over 160 identifiable postcranial bones (Hutchison et al., 2015).  

The new dietary stable isotope data funded by the Dr Euan MacKie Legacy Fund are part of a wider project undertaking multi-isotope and aDNA analysis on the human bone assemblage from the Knowe of Rowiegar to better understand the lifeways of the people interred in the tomb, and how they may have related to each other. New osteoarchaeological analysis is being undertaken by Dr Rebecca Crozier and Prof Marc Oxenham, Department of Archaeology, University of Aberdeen. 

The key debate relating to Neolithic diet surrounds the Mesolithic-Neolithic transition in northern Europe, and a potentially rapid shift from exploitation of marine resources in the Mesolithic to a much heavier reliance on terrestrial resources in the Neolithic, after the introduction of agriculture (Rowley-Conwy, 2004). Whilst British zooarchaeological assemblages dating to the Neolithic comprise predominantly domesticated sheep, pigs, and cattle, supporting a more terrestrially based diet (e.g., Rowley-Conwy, 2004), there has been some evidence of marine resource exploitation, especially in the form of shellfish middens (e.g., Wickham-Jones, 2007). Whilst in general stable isotope studies of Neolithic coastal sites in northern Europe have suggested little to no consumption of marine resources, there have been notable exceptions which demonstrate marine resource exploitation in coastal and particularly island areas (e.g., Montgomery et al., 2013).  

Previous analysis of δ13C and δ15N values of human bone collagen from the Knowe of Rowiegar by Gigleux et al. (2017) showed a predominantly terrestrial diet, consistent with the zooarchaeological record. However, there was inter-individual variation, with a correlation between more negative δ13C values and elevated δ15N values. This could indicate either that certain individuals were consuming greater quantities of low-trophic level marine resources such as cockles (which the current zooarchaeological record does not support), or inter-individual variation in the specific animal products eaten, with higher δ13C values due to greater exploitation of resources such as seaweed-foddered sheep (Gigleux et al., 2017). 

Funding from the Society has enabled the reanalysis of previously extracted collagen from nine individuals for carbon, nitrogen, and sulphur stable isotope data. These individuals were selected as they had also been sampled for ancient DNA and strontium and oxygen isotope analysis, and therefore this analysis maximised information possible from destructive testing. Reanalysis of a further four collagen samples was funded by a Philip Leverhulme Prize to Prof Kate Britton. Sulphur stable isotope data are particularly useful as high δ34S values in collagen can be associated with consumption of marine resources and residence near to the coast (Nehlich, 2015). The addition of sulphur isotopes as a third dietary proxy can therefore provide greater insight into whether the inter-individual differences seen in the carbon and nitrogen data at the Knowe of Rowiegar could be the result of marine resource exploitation. Preliminary analysis of the sulphur isotope data funded by the Society, alongside new carbon and nitrogen isotope data, confirms the presence of inter-individual dietary variation and suggests differing consumption of marine resources amongst the individuals interred at the Knowe of Rowiegar. This will be further discussed in forthcoming publications.  

 References 

Bronk Ramsey, C. (2009). ‘Bayesian analysis of radiocarbon dates.’ Radiocarbon 51(1):337-360 https://doi.org/10.1017/S0033822200033865  

Gigleux, C., et al. (2017). ‘Reconstructing diet at the Neolithic stalled cairn of the Knowe of Rowiegar, Rousay, Orkney, using stable isotope analysis.’ J. Archaeol. Sci. Rep. 13:272-280 https://doi.org/10.1016/j.jasrep.2017.03.048  

Hutchison, M., et al. (2015). ‘The Knowe of Rowiegar, Rousay, Orkney: description and dating of the human remains and context relative to neighbouring cairns.’ Proc. Soc. Antiq. Scot. 145:41-89 http://journals.socantscot.org/index.php/psas/article/view/9826  

Montgomery, J., et al. (2013). ‘Strategic and sporadic marine consumption at the onset of the Neolithic: increasing temporal resolution in the isotope evidence.’ Antiquity 87(338):1060-1072 https://doi.org/10.1017/S0003598X00049863  

Nehlich, O. (2015). ‘The application of sulphur isotope analyses in archaeological research: A review.’ Earth-Science Reviews 142:1-17 https://doi.org/10.1016/j.earscirev.2014.12.002  

Reimer, P., et al. (2020). ‘The IntCal20 Northern Hemisphere radiocarbon age calibration curve (0-55 cal kBP).’ Radiocarbon 62(4):725-757 https://doi.org/10.1017/RDC.2020.41  

Rowley-Conwy, P. (2004). ‘How the West Was Lost: A Reconsideration of Agricultural Origins in Britain, Ireland, and Southern Scandinavia.’ Current Anthropology 45(S4):S83-S113 https://doi.org/10.1086/422083  

Wickham-Jones, C.R. (2007). ‘Middens in Scottish prehistory: Time, Space and Relativity.’ In Milner, N., et al. (eds.). Shell Middens in Atlantic Europe. Oxford: Oxbow Books. pp.86-93.