Palaeopathological studies of human remains sometimes yield information on diet. Marks and irregularities on human bones and teeth can evidence metabolic diseases, which are caused by the absence of certain nutrients in the diet at discrete episodes during the life of the individual (Larsen 1997, 40-5; Roberts and Manchester 1995 166-80). Despite a significant quantity of human remains from Caithness, Orkney and Arran, relatively little of this kind of research has hitherto been undertaken, although major studies of the human remains from Isbister (Lawrence 2006) and Quanterness (Schulting et al. 2010) chamber tombs have been undertaken, with very interesting results.
Dental pathologies are directly related to diet. The presence or absence of dental caries is often cited as an indicator of carbohydrate richness. Among prehistoric populations globally, the teeth of agricultural populations are more frequently infected by caries than those of hunter-gatherers, for example (Larsen 1995). There are, however, many exceptions to this rule, including Scottish Neolithic sites, where caries is infrequently observed, occurring in 1% or less of teeth (Chamberlain and Witkin 2003; Chesterman 1979; McLaughlin 2008 see also Dommett et al. 2000). Such low rates of caries probably reflect a very abrasive diet and the absence of sugar rich foods such as honey (Larsen 1995).
Dental wear can indicate the overall abrasiveness of diet although since it is also used as an indicator of age at death, its applicability is limited unless the ages of the individuals concerned can be controlled, which is currently very difficult with Neolithic material. Dental microwear analysis offers a more detailed view of food as an abrasive agent; quantitative analysis of microwear fabrics give an insight into the size of the particles and offer some idea about the foods that caused them. McLaughlin (2008) analysed human remains from sites in Orkney (Quanterness, Holm of Papa Westray North), Caithness (Tulach an T'Sionnaich, Tulloch of Assery A and B, Embo) and Arran (Clachaig, Torlin). The similarity of dental microwear fabrics of Scottish Neolithic individuals to those of samples from elsewhere in Britain and Europe suggests a wear agent that was common to the foods of the majority of these people. Given that Neolithic microwear patterns tend to be dominated by large, coarse scratches, the likely candidate to be this wear agent is grit from stone tools used to processes food such as cereal crops. Interestingly, samples from Neolithic sites on Arran also displayed fine scratches, which may be explained by the presence of fine-grained volcanic rocks nearby, if these were used as grinding tools. Hence dental microwear suggests tentatively that stone-ground cereal foods were an important dietary component in Neolithic Scotland (and elsewhere), although more work is needed to attempt to correlate the microwear patterns with artefactual evidence of food-grinding tools from Orkney, Arran and Caithness.
Stable isotope analysis
Stable isotope analysis investigates the composition of the protein component of human bone, hence ultimately the protein component in the diet of each human individual analysed in this way. Carbon-13 analysis can discriminate between the different types of plants that fix carbon from CO2 in the atmosphere or in water in different ways, thus providing a very useful indicator of terrestrial versus marine based diets. In addition to this, nitrogen isotopes can be used to investigate the tropic level of the food in the diet (e.g. meat versus plant consumption), although a sample of similarly dated herbivore and carnivore bones from the same area as the human remains are needed to fully interpret the results. Staple isotope analyses of Scottish Neolithic individuals has been performed on samples from Holm of Papa Westray , Clachaig, Cultoquhey, Glecknabae, Haylie House, Rattar, Torlin and Embo (Schulting and Richards 2002; Schulting n.d.).
With the exception of Holm of Papa Westray North, all the Neolithic individuals analysed had terrestrial diets, with little detectable input from marine food resources. The Holm of Papa Westray North individuals do however show a slight contribution from marine protein in their diet, although this may be the result of consuming sheep whose own marine protein levels were elevated due to the consumption of seaweed as fodder (R. Schulting pers. com.; cf. Balasse et al. 2006; Balasse and Tresset 2009). Nitrogen isotope analysis suggests that meat or dairy produce, rather than plants, were the dominant sources of dietary protein (Schulting and Richards 2002). One possible complicating factor in the interpretation of stable Nitrogen isotope data is the effect of manuring cereal crops, and the resulting enrichment of nitrogen-15 in the food (Bogaard et al. 2007), although the understanding of this phenomenon is still at an early stage, and work to assess its effect is only just under way. Early indications from the as yet unpublished analysis of human bones at Isbister is that stable isotope analysis can potentially identify gender and age differences in diet.
The discovery that Early Neolithic individuals (and indeed most Neolithic individuals studied from Scotland, as elsewhere in Britain and Ireland) had a predominantly or wholly terrestrial diet, in contrast to the Mesolithic inhabitants of these islands, has been a major element in the debate about the nature of the Mesolithic-Neolithic transition, with Schulting & Richards interpreting the sudden and radical dietary shift as evidence for immigrant farmers (e.g. Schulting & Richards 2002); others taking issue with this (e.g. Milner et al. 2004) and rebuttals being made (e.g. Richards & Schulting 2006). The evidence from coastal areas does, however, appear to support the idea of a radical change, and a 'turning of the back to the sea', even if, several centuries later, some farmers did choose to exploit marine resources.
Outstanding research questions