Dental Macrowear Research Articles

‘Do larger molars and robust jaws in early hominins represent dietary adaptation?’ A New Study in Tooth Wear

Diet imposes significant constraints on the biology and behaviour of animals. The fossil record suggests that key changes in diet have taken place throughout the course of human evolution. Defining these changes enables us to understand the behaviour of our extinct fossil ancestors. Several lines of evidence are available for studying the diet of early hominins, including craniodental morphology, palaeoecology, dental microwear and stable isotopes. They do, however, often provide conflicting results. Using dental macrowear analysis, this new UCL Institute of Archaeology project will provide an alternative source of information on early hominin diet. Dental macrowear has often been used to analyse diet in archaeological populations, but this will be the first time that this type of detailed study has been applied to the early hominin fossil record.

On the relationship of dental microwear to dental macrowear

Dental microwear analysts have demonstrated that hard diets leave numerous microscopic pits on occlusal surfaces. The relationship between occlusal pitting and gross macrowear, however, is not well known. The current study seeks to elucidate the relationship between dental microwear and macrowear by determining if microscopically pitted teeth are associated with greater expressions of macrowear. This study examined microwear and macrowear on mandibular second molars from 60 prehistoric adult Native Americans representing three dietary regimes (foraging, mixed economy, and agriculture). Initially, two dental microwear feature variables were studied: percentage of pits and mean scratch width. Standard macrowear scores ranged from 4 to 40. ANOVAs suggested that neither of the microwear variables was affected by age or sex, but age affected macrowear scores. Because of this, the sample had a balanced number of young and old adults (i.e., those below and above skeletal age 35). A Pearson's correlation showed no covariation between scratch width and the percentage of pits. Regression analysis indicated that macrowear was not a function of the percentage of pits. However, a significant positive relationship was found between dental macrowear and scratch width. A post priori test found a significant negative relationship between macrowear and the total number of scratches. It is concluded, then, that wide scratches remove more enamel and dentin than do numerous pits, although both cause dental wear. It is suggested here that the term "abrasive" be used to describe those microwear profiles that lead to heavy macrowear and have relatively wide scratches.

Dietary patterns during the late prehistoric/historic period in Cikobia island (Fiji): insights from stable isotopes and dental pathologies

The dietary patterns of eight adults and one child interred in the Korotuku burial mound (Cikobia, northern Fiji), dated from the late prehistoric/historic period (around AD 1850), have been investigated using carbon and nitrogen stable isotope signatures and dental and oral pathologies. Bone collagen isotopic compositions showed that (1) males and females had similar diets in terms of terrestrial C 3 resources and marine fish components and proportions; (2) the proportion of marine fish comprised around 25% of the protein fraction of the diet, and the proportion of vegetal food was high; and (3) one canid that was also studied had a different diet, probably rich in shellfish. Oral and dental examinations of the humans evidenced (1) a low level of dental macrowear, (2) a high rate of carious lesions—interproximal and cervical—of about 15%, and (3) a low amount of abscessing, as well as the presence of alveolar bone recession and calculus in most of the adults. This evidence suggests a diet relying mainly on vegetal food with very limited shellfish consumption. When viewed in the light of ethnohistoric information, this pattern suggests a particular sociocultural behaviour, including food selection, since the analyses of the canid remains indicate that more diversified food resources were available than those consumed by the humans. Overall observations suggest that the deceased in the Korotuku burial mound might be members of an elite living on the island, thus pointing to possible social stratification in the late prehistoric/historic Cikobia community.