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

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.

Palaeoproteomic analyses of dog palaeofaeces reveal a preserved dietary and host digestive proteome

“…For instance, methodological investigations are needed to understand the survival of proteins in palaeofaeces. Nunalleq is recognized for its exceptional biomolecular preservation owing to permafrost conditions, but faeces is a highly degradable material, and it is uncertain how proteins preserve in samples that are older or from different archaeological contexts [ 33 ].…”

“…Staining techniques have previously demonstrated the survival of proteins in palaeofaeces [ 31 ], a material which has long been used for macro- and microscopic dietary analyses [ 32 ]. However, palaeoproteomic analyses have only been applied to the substrate with limited success [ 33 ]. Ancient DNA evidence has shown palaeofaeces to preserve dietary information as well as evidence of the gut microbiome [ 34 , 35 ], but the scope of these studies has been limited owing to its complex and highly degradable nature [ 32 ].…”

Small Animals, Big Impact? Early Farmers and Pre- and Post-Harvest Pests from the Middle Neolithic Site of Les Bagnoles in the South-East of France (L’Isle-sur-la-Sorgue, Vaucluse, Provence-Alpes-Côte-d’Azur)

“…Wood mice were thus presumably attracted by the abundance of food at the settlement. Cucchi et al [ 43 ] pointed out that the Apodemus is regarded as a commensal species as early as the Neolithic despite the rarity of archaeozoological evidence. In any case, the Neolithic assemblage of Les Bagnoles seem to confirm this assumption.…”

“…Although small mammal remains are regularly recorded at Neolithic sites in Europe, these types of finds have served, for the most part, as sources of information on environmental and climatic conditions [ 37 , 38 , 39 , 40 ]. Certain small mammals also were a source of food for ancient populations [ 41 , 42 , 43 ]. Studies on the potential of rodents as pests in praehistoric and historic times mainly refer to species introduced in southern, western, and northern Europe, such as the house mouse ( Mus musculus ), the house rat ( Rattus rattus ), and the brown rat ( Rattus norvegicus ).…”

Leveraging palaeoproteomics to address conservation and restoration agendas

“…The introduction of herd animals, for example, has shaped the formation of open landscapes ( Ventresca Miller et al., 2020 ) as well as soil enriched hotspots ( Marshall et al., 2018 ), and in many of the world’s islands, domesticated and commensal species introduced by early colonizing populations have had a significant impact on endemic plant and animal populations ( Boivin et al., 2016 ). Proteomic and other biochemical analyses of coprolites from a Neolithic settlement on the Orkney Islands have provided further evidence of such trends, revealing the consumption of local micromammals by domestic dogs ( Romaniuk et al., 2020 ).…”