Archaeological Sciences 1995

Anthony Sinclair, Elizabeth Slater, John Gowlett

• Publisher: Oxbow Books
• Year: 2017
• eBook ISBN: 9781785708060
• Topic: Social Sciences
• Subtopic: Archaeology
• Index: Social Sciences

A huge collection of papers on scientific analysis in archaeology from a conference held in Liverpool in 1995. Papers are grouped under ten headings: Scientific analysis of Petrology ( 3 papers ); of Glass ( five papers ); of Ceramics ( 7 papers ); Metallurgy ( 9 papers ); Chronological Studies ( 9 papers ); Dendrochronological Studies ( 3 papers ); The Study of Ancient Enviroments ( 16 papers ); Remote Sensing ( 2 papers ); The Analysis of Human Remains ( 5 papers ) and Perspectives on Human Evolution and Early Hominid Artefacts ( 9 papers ). Subjects studied include Stonehenge dolerites, early Egyptian glass, Greek Archaic transport amphorae, Roman brooches, South Indian bronzes, dendrochronological datings of Viking ships, phytolith analysis from the Indus Valley, Pakistan, the microflora of the Milos catacombs, Greece and Medieval glass making technology.

A Qualitative Approach to Dental Microwear Analysis

Ingrid L. Mainland

Department of Archaeology and Prehistory, University of Sheffield, Northgate House, West Street, Sheffield S4 1ET

Introduction: Recent Dental Microwear Research and Methodologies

Recent research has established that microscopic tooth wear patterns, dental microwear, is correlated with diet in several modern mammal species. There is known to be a relationship between broad dietary adaptations and dental microwear in primates (Teaford and Walker 1984; Teaford and Runestad 1992), hyaenids, large canids and felids (van Valkenburgh et al. 1990), Viverridae (Taylor and Hannam 1987), Chiroptera (Strait 1993), ruminating and-non-ruminating ungulates (Walker et al. 1978; Solounias and Moelleken 1992; Solounias and Hayek 1993). More specific, seasonal dietary variations have been associated with microwear patterns in hyraxes (Walker et al. 1978) and Cebus nigrivittatus (Teaford and Robinson 1989). It is maintained that these relationships can be used to identify diet in individuals from archaeological or palaeontological contexts and several such studies have been undertaken on ancient humans and various extinct mammals (e.g. Teaford and Walker 1984; Grine 1986; Solounias and Moelleken 1992; van Valkenburgh et al. 1990; Molleson et al. 1993).

Most microwear studies have employed similar methodologies. A scanning electron microscope (SEM) is used to examine the enamel and dentine surfaces of actual teeth or of replicas. Micrographs are taken at magnifications between 100–650x and are examined for variability in microwear patterning using one of two general analytical approaches: quantitative, based on metrical data, or qualitative, based on descriptive information. Diet-microwear studies typically employ quantitative techniques. Microwear defects are recorded for frequency and dimension, thus reducing visual data to a numeric format and allowing statistical manipulation. This approach can claim objectivity and can be standardised between different researchers. It is, therefore, considered more appropriate for identifying pattern variability relating to diet (Gordon 1988; Teaford 1991).

At its simplest level, qualitative analysis attempts to distinguish between various diets through the visual identification of distinctive microwear features or enamel surface characteristics. Walker et al. (1978) were, for example, able to contrast the heavily striated surfaces of grazing hyraxes with the polished surfaces of browsing species. Qualitative methods have not been favoured by researchers interested in the identification of diet-microwear relationships; they are criticised for being subjective and are thought to have a limited application because ‘it is impossible to mentally store and access more than a few images at a time’ (Gordon 1988:1139). It can be argued, however, that these comments refer mainly to the simple types of descriptive analysis outlined above. More sophisticated methods of examining visual data are found and can go some way towards reducing these criticisms. The approach of Puech et al. (1983) to hominid microwear, in which patterns are recorded for the presence and absence of 19 different descriptive categories, demonstrates how a large volume of descriptive data can be observed without recourse to memory. Although not attempted by Puech, such presence/absence data can also be quantified (e.g. Ryan and Johanson 1989; Harmon and Rose 1988). The visual categorisation of microwear patterns through presence/absence data or descriptive categories thus permits the use of statistical techniques in qualitative studies, eliminating some of the potential subjectivity. It has been demonstrated that a qualitative approach of this type can be used to examine fairly subtle differences in diet or microwear pattern, particularly when combined with basic microwear defect statistics like pit or striation frequency (Bullington 1991; Harmon and Rose 1988; Kelley 1990).

A qualitative approach to diet-microwear relationships has arguably been undervalued and neglected because of a desire for the objective accuracy of quantitative methods. There is, however, considerable scope for inaccuracies to enter into quantitative microwear statistics: SEM conditions, surface morphology of the specimen, casting defects and digitising error will all contribute towards a loss of accuracy (Gordon 1988). Furthermore, a degree of subjectivity is present in quantitative analyses: decisions on where a feature is measured, feature definition (i.e. pits, small pits, etc.) or recording accuracy will each vary between researchers. It might, therefore, be suggested that analysts have been overconfident in assuming that quantitative studies represent a thoroughly objective approach to microwear. Quantitative techniques can also be criticised because they ignore a potentially valuable aspect of microwear: the surface appearance and texture of enamel surfaces. In several studies surface characteristics were found to be useful dietary discriminators: e.g., polished surfaces were characteristic of a browsing diet in hyraxes (Walker et al. 1978) and were related to a vegetal diet in gorillas (Ryan and Johanson 1989). Moreover, feature densities on their own can be less discriminating than when combined with descriptive information concerning their location or edge morphology (Harmon and Rose 1988; Kelley 1990). These variations are not detected in quantitative studies and theoretically, therefore, two microwear patterns with vastly different surface characteristics could appear similar in a metrical analysis.

A qualitative approach has been developed as part of a larger study into the relationship between diet and dental microwear in domestic sheep and goats (Mainland 1994). In the following article, this approach and its application is discussed with reference to the identification of dietary trends in the dental microwear of domestic sheep and goats.

Dental Microwear in Domestic Sheep and Goats

The overall aim was to establish whether dental microwear could be used to identify the diet of domestic sheep/goats in the archaeological past; to this end, it was necessary to examine microwear patterns in modern populations with known diets. Research focused on three aspects of sheep/goat microwear: (i) how do microwear patterns vary across the occlusal surface of sheep/goat teeth, (ii) does the microwear of fodder-fed sheep/goats differ from that of grazing sheep/goats, (iii) do grazing microwear patterns vary with season or pasture type? These questions were explored using a combination of qualitative and quantitative analytical techniques; a qualitative approach was used to identify microwear patterning pertaining to occlusal location while diet-related microwear patterning was identified qualitatively and quantitatively. This article considers only the qualitative analysis of diet-related microwear patterns in fodder-fed and grazing sheep and goats. For a discussion of occlusal variation and quantitative diet-microwear relationships in sheep and goats, see Mainland (1994).

Methodology: a Qualitative Approach to Dental Microwear Analysis

The samples

Grazing and grassy hay-fed sheep were provided by the Macaulay Land Use Research Institute, henceforth referred to as MLURI. Mandibles from leafy hay fed sheep and goats were collected from the village of Plikati in the Epirus region of Greece. In all cases diet was known for at least three months prior to examination.

The grazing sample

Twenty-nine sheep were grazed on two pastures in the Scottish borders: (1) a rough, indigenous grassland dominated by Nardus stricta; (2) a semi-indigenous pasture reseeded with rye-grass (Lolium sp.). To allow the identification of seasonal trends in microwear pattern, thirteen sheep were examined in summer (‘rough pasture’ = 6, ‘sown pasture’ = 7) and sixteen in winter (‘rough pasture’ = 8, ‘sown pasture’ = 8). The grazing population can, therefore, be divided into four groups; summer rough pasture, summer sown pasture, winter rough pasture and winter sown pasture.

The grassy hay-fed sample

Five wethers were kept at the MLURI animal house in Edinburgh for a period of three months. During this time they were fed an unspecified type of grassy hay, though ryegrass is the most probable (I. Wright, pers. comm.).

The leafy hay-fed sample

Seventeen sheep (n=9) and goat (n=8) mandibles were collected from Plikati during April 1992. These animals had been fed a mixture of grassy hay and leafy hay supplemented with bran and grain during the previous winter (Halstead, pers. comm.). The grassy hay was derived either from locally available sown pasture (alfalfa) or naturally occurring meadow grassland. The leafy hay consisted mainly of Turkey oak (Quercus cerris). For simplicity the Plikati sample is henceforth referred to as leafy hay though it is recognised that the animals also consumed some grassy hay.

Sampling Methods: magnification level used, tooth and area of enamel examined

Araldite replicas (Araldite MY 753, hardener HY 956, Ciba-Geiby) were made of the lower deciduous fourth premolar (dP4) and were examined for microwear using a scanning electron microscope (SEM). A single micrograph was taken at a magnification of 640x from a specific area of enamel on the anterior facing buccal enamel band of the posterior cusp. The choice of tooth was made largely on practical grounds: the dP4 was erupted and in wear in all individuals examined. The buccal enamel band was selected because a survey of intratooth variation in microwear pattern had demonstrated this area of the tooth to be particularly suitable for the identification of diet-microwear relationships in domestic ovicaprids (Mainland 1994). One micrograph was excluded from the analysis because of a poor quality image. The total sample thus consists of 50 individuals (leafy hay n=16, summer rough n=6, winter rough n=8, summer sown n=7, winter sown n=8, grassy hay n=5).

Recording Qualitative Microwear Patterns

Twenty categories were created to describe the type of microwear present on the enamel surface of sheep and goat teeth. These range from the identification of feature type to an impression of surface texture and can be broadly divided into four groups:

(i) presence/absence of feature types: pits, parallel striations, non-parallel striations, pit lines

(ii) description of features: features with sharp/rounded edges, deep/shallow features, features with anterior-posterior orientation, features with bucco-lingual orientation, features with a definite shape, featur...

Table of contents

• Cover
• Title
• Copyright
• Preface
• Contents
• The Scientific Analysis of Artefacts: Petrography
• The Scientific Analysis of Artefacts: Glass
• The Scientific Analysis of Artefacts: Ceramics
• The Scientific Analysis of Artefacts: Metallurgy
• Chronological Studies
• Dendrochronological Studies
• The Study of Ancient Environments
• Remote Sensing
• The Analysis of Human Remains
• Perspectives on Human Evolution and Early Hominid Artefacts