Combined visual and biochemical analyses confirm depositor and diet for Neolithic coprolites from Skara Brae

Archaeological and Anthropological Sciences https://doi.org/10.1007/s12520-020-01225-9 (2020) 12:274 ORIGINAL PAPER Combined visual and biochemical analyses confirm depositor and diet for Neolithic coprolites from Skara Brae Andrzej A. Romaniuk 1,2 & Elsa Panciroli 2,3,4 & Michael Buckley 5 & Manasij Pal Chowdhury 5 & Carla Willars 6 & Jeremy S. Herman 2 & Lore G. Troalen 7 & Alexandra N. Shepherd 8 & David V. Clarke 9 & Alison Sheridan 9 & Bart E. van Dongen 5 & Ian B. Butler 3 & Robin Bendrey 1 Received: 7 May 2020 / Accepted: 11 October 2020 # The Author(s) 2020 Abstract Coprolites (fossilized faeces) can provide valuable insights into species’ diet and related habits. In archaeozoological contexts, they are a potential source of information on human-animal interactions as well as human and animal subsistence. However, despite a broad discussion on coprolites in archaeology, such finds are rarely subject to detailed examination by researchers, perhaps due to the destructive nature of traditional analytical methods. Here, we have examined coprolitic remains from the Neolithic (third millennium BCE) settlement at Skara Brae, Orkney, using a range of modern methods: X-ray computed tomography, scanning electron microscopy, lipid and protein analysis (shotgun proteomics of the coprolite matrix as well as collagen peptide mass fingerprinting of isolated bone fragments). This combined approach minimised destructiveness of sampling, leaving sufficient material for subsequent study, while providing more information than traditional morphological examination alone. Based on gross visual examination, coprolites were predominantly attributed to domestic dogs (Canis familiaris), with morphologically identified bone inclusions derived from domestic sheep (Ovis aries) and common voles (Microtus arvalis). Partial dissection of a coprolite provided bone samples containing protein markers akin to those of domestic sheep. Considering the predominance of vertebral and distal limb bone fragments, Skara Brae dogs were probably consuming human butchery or meal refuse, either routinely fed to them or scavenged. The presumably opportunistic consumption of rodents may also have played a role in pest control. Keywords Neolithic . Coprolite . Diet . X-ray computed tomography . Mass spectrometry . Scanning electron microscopy Supplementary Information The online version of this article (https:// doi.org/10.1007/s12520-020-01225-9) contains supplementary material, which is available to authorized users. * Andrzej A. Romaniuk 1 School of History, Classics and Archaeology, University of Edinburgh, Edinburgh EH8 9AG, UK 2 Department of Natural Sciences, National Museums Scotland, Edinburgh EH1 1JF, UK 3 School of Geosciences, University of Edinburgh, Edinburgh EH9 3FE, UK 4 Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK 5 School of Natural Sciences, University of Manchester, Manchester M1 7DN, UK 6 School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, UK 7 Department of Collections Services, National Museums Scotland, Edinburgh EH1 1JF, UK 8 Skara Brae Publication Project, 509 King Street, Aberdeen AB24 3BT, UK 9 Department of Scottish History and Archaeology, National Museums Scotland, Edinburgh EH1 1JF, UK 274 Page 2 of 15 Introduction A serious concern when using finite remains to study the past is the destructive nature of many widely adopted methods. It is an especially serious concern in the case of archaeological remains, which are at best a finite resource and often unique (Maschner and Chippindale 2005; Renfrew and Bahn 2012; Frank et al. 2015). Coprolites are a prime example of this problem. Beyond examination of their external appearance and the identification of visible parts of inclusions, the predominant method used to analyse coprolites involves dissection, usually after dissolving (“rehydrating”) the coprolite matrix in a specific solution (Callen 1963), or dry-pulverizing its contents (Heizer 1963), in order to isolate and visually identify any inclusions. However, such approaches narrow the retrievable data strictly to the inclusions and preclude further examination, for example of the internal arrangement of the coprolite content or its chemical composition. Moreover, it precludes the further assessment of those finds in the future with other methods. On archaeological sites where coprolitic finds are relatively common, this problem can be mitigated, for example by utilising subsampling and leaving some coprolites or parts of them for future research. However, many sites provide only a sparse number of coprolites, often as singular finds, and the potential loss of information is too important for a dissection method to be applied. Because of these drawbacks, in recent decades, there has been a surge in publications exploring potential nondestructive approaches towards archaeological material (e.g. Biró 2005; Borgwardt and Wells 2017). In the case of coprolites, X-ray computed tomography (μCT) scanning has been utilised for the past two decades to avoid destructive analysis, facilitate replicability and create raw data for future research. Initially used only to generate 2-dimensional cross-sectional data (e.g. Farlow et al. 2010), it has more recently been combined with 3-dimensional (3D) digital imaging techniques for more comprehensive analysis of content and structure (Milàn et al. 2012a, b; Bravo-Cuevas et al. 2017; Wang et al. 2018). This has permitted identification of the coprolite depositor as well as its prey and other food items. Meanwhile, in destructive sampling, one can see a trend towards standardisation of sampling protocols and reduction of sample numbers, which is important to allow replication and therefore reproducibility, and to leave material for analysis with subsequently developed techniques (see Wood and Wilmshurst 2016). Multiple approaches are rarely combined in the study of coprolites; researchers often prefer to use one specific method, and even if this does not destroy a sample, it constrains the diversity of data obtained. A number of coprolites were found during the excavations of the Neolithic settlement of Skara Brae (Orkney, UK) in 1972-3 (Clarke 1976a, 1976b) and in 1977 (Clarke DV and Shepherd AN pers. comm.). The majority of intact coprolites, Archaeol Anthropol Sci (2020) 12:274 alongside many heavily fragmented finds, were retrieved from the settlement core (Trench I). The settlement periphery (Trench II) and off-site Trench III provided only a few finds, in each case confined to a single context. Assuming domestic dogs, Canis familiaris, as likely depositors, a parasitological study by Hopkins (Hopkins J pers. comm.) examined 58 samples in search of transmission stages of parasites. While the parasitological results were negative, “rehydration” of the coprolites revealed that most contained large numbers of bone fragments. Alongside the general absence of plant (...truncated)