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.
Each indicator of Neolithic subsistence discussed above addresses a different aspect of diet or dietary behaviour on differing scales, thus each has inherent biases and weaknesses. Furthermore, each is dependent, to some degree, on the state of preservation of the material to be analysed. This situation can make it difficult to compare two or more proxies in a valid way and it is impossible, in most cases, for one proxy to be used as an independent check on another one. Bearing these issues in mind, it is still possible to make a number of conclusions based on these data.
Central to the question of Neolithic subsistence is the question of cereal cultivation. Cereals are known from a wide range of different type throughout the Neolithic period in Scotland, and continue to be discovered regularly. Their importance as a food is also suggested by dental work, and corroborative evidence exists in the form of field systems, indicators of soil tillage, and quern stones. Known examples of which tend to date to the later part of the Neolithic, introducing the possibility that cultivation practices were forced to respond to the centuries of damage caused by intensive agriculture and erosion in the earlier phases of the Neolithic. This may be stretching the available evidence to a considerable degree, but it highlights the central fact that cereal cultivation cannot be dismissed as a marginal activity, rather it probably played a pivotal role in the structure of society and economy, from the beginning of the Neolithic onwards-an hypothesis that future work will continue to test with AMS dating of the cereals themselves and stable isotope studies of manuring practices and midden material.
The absence of formal field boundaries in mainland Scotland suggests that although cereal cultivation was relatively commonplace, it probably took place in ‘garden-plots’ and / or woodland clearances rather than within formalised fields. And patterns of cereal agriculture and domestic animal exploitation are markedly similar. Evidence for each is both as geographically widespread as the available data allows and occurs throughout the period of interest. Sheep and cattle were the most important animals in Neolithic Scotland (or rather Orkney and Harris, as data from elsewhere are largely unavailable), especially cattle when meat weight rather than bone frequency is considered. Pigs were apparently relatively unimportant, in contrast to sites in Southern Britain, perhaps reflecting the environment and lack of forest cover in the Northern and Western Isles. Unlike sheep and cattle, pig farming does not involve the production of secondary products, so perhaps animal husbandry practices were deliberately structured in this way.
The patterns of cereal agriculture and domestic animal exploitation are markedly similar. Evidence for each is both as geographically widespread as the available data allows and occurs throughout the period of interest. Sheep and cattle were the most important animals in Neolithic Scotland (or rather Orkney and Harris, as data from elsewhere are largely unavailable), especially cattle when meat weight rather than bone frequency is considered. Pigs were apparently relatively unimportant, in contrast to sites in Southern Britain, perhaps reflecting the environment and lack of forest cover. Unlike sheep and cattle, pig farming does not involve the production of secondary products, so perhaps animal husbandry practices were deliberately structured in this way. As Parks (2009) suggests, the lack of seasonality in Orcadian Neolithic fishing may be due to the fact that certain species are only abundant in the autumn, hence conflicting with the labour requirement of the cereal harvest. The potential for marine resources to have been ‘taboo’ amongst early farmers has also been suggested (Schulting & Richards 2002).
It is clear that much of the above discussion is heavily geographically biased, especially towards Orkney. This is perhaps unavoidable at present. Future work with lipids and plant macrofossils has the potential to address this issue and provide a space-time model of subsistence practices in Neolithic Scotland that is not as geographically imbalanced. Indeed, a recently-completed major research project at the University of Bristol, ‘Changing patterns of marine product exploitation in human prehistory via biomarker proxies in archaeological pottery’ (NERC-funded), has been doing just that with its lipid analysis of a considerable number of samples of Neolithic (and later) pottery in various parts of Scotland.
Outstanding research questions
While understanding of Neolithic diet and farming practices has increased significantly over the last two decades – especially through the application (over the last decade) of isotopic and lipid analysis – there nevertheless remain fundamental gaps, as follows:
- Very little is known about the specific cultivation practices and herding strategies of these farming groups, and our list of cultivated plant materials may well be incomplete.
- Flax has been noted at Balbridie, but to what extent was it cultivated, and was it principally a food crop (as opposed to a source of fibres for fabric manufacture and cordage)?
- How typical or atypical is the Orcadian evidence for subsistence strategies?
- How do deer fit into the equation? It has been suggested that they may have been deliberately introduced to the Orkney Islands, just as they had been introduced to Ireland, but do they constitute a partly-managed, partly-wild resource? How is the enigmatic evidence from the Links of Noltland – where a pile of deer carcases had been left, unscavenged and with a large fish on the top of the heap (Sharples 2000) – to be explained?
- To what extent were marine resources used as foodstuffs at different times and in different parts of Scotland?
- Is the elevated nitrogen isotope level that has been found in human remains in Orkney an indicator of the practice of manuring?