부산대학교 도서관

Dental anthropology provides an exceptional insight into biology, ecology and culture at both a population and individual level. However, the study of dental variation has often been limited to linear measurements in prehistoric samples. This thesis seeks to determine what new information can be gained from dental samples. Recent methodological advances have enabled the obtainment of new dental phenotypes. This thesis uses 'new' dental phenotypes to study dental variation in previously understudied samples. Through this research both methodological and bioarchaeological insights are sought. From initiation to eruption, dental development is under tight spatial and temporal control, as part of a complex adaptive system (Brook and O'Donnell, 2012). There is substantial evidence that dental form is under strong genetic control, however it can also be subject to environmental influences (Sperber, 2006; Lesot and Brook, 2009; Hughes and Townsend, 2013). A multifactorial model of dental development is becoming increasingly popular. According to this model the genes of dental development are influenced by other genes, epigenetic and environmental factors (Brook et al., 2009; Brook and O'Donnell, 2012; Hughes et al., 2016). Therefore, dental diversity has the ability to inform us on a myriad of factors. Studies of dental variation occur at a population or individual level. Between-population studies have focused on either geographic or diachronic differences. Diachronic studies have linked dental reduction to different masticatory regimes (Brace, 1967; Doyle and Johnston, 1977; Calcagno, 1986; Brace et al., 1987; Stefan and Trinkaus, 1998; Bailey and Lynch, 2005; Hanihara and Ishida, 2005; Harris and Lease, 2005). These studies focus largely on Pleistocene samples, this is unsurprising as the durability of teeth often results in their survival in paleoanthropological contexts. However, causation information has in some cases been inadequate and speculative (Kieser, 1990), often due to the lack of other evidence to aid interpretation. Historic samples have been comparatively understudied, despite the ability to incorporate a wide range of factors to help interpret the causation of variability. There has also been a focus on the crown; the root is largely absent in dental studies despite the crucial role that the root plays in tooth support (Scheid, 2007, p 278). Overall, the assessment of individual level differences in tooth form has been limited. This is illustrated in 'A Companion to Dental Anthropology' (Irish and Scott, 2016): in this up-to-date overview of the field there is little focus on intra- dentition tooth variation. In fact, in this volume, Hemphill (2016) advocates the need for additional studies to examine the range and nature of intrapopulation tooth size variation. This is important not only for the understanding of individual level differences, but also has ramifications on between-population studies. How teeth vary between and within individuals may affect whether differences are detected between populations. The detection of dental variability is, in-part, dependent in how teeth are quantified. Recent years have seen a move away from traditional linear and non-metric measurements, which are plagued with issues with error and information loss (Kato et al., 2011; Townsend et al., 2012; Marado, 2017). There has been a movement towards new dental phenotypes, which has been facilitated by developments in micro-computed tomography (micro-CT). Micro-CT produces data suitable for volumetric and morphological analyses, in the form of new size and shape phenotypes (Rowe et al., 2001; Ziegler et al., 2010; Abel et al., 2011). It has been predicted that the obtainment of new dental phenotypes may lead to major research advances (Townsend et al., 2016). The use of new dental phenotypes may unlock previously inaccessible information held within the tooth. It is evident that far more information can be obtained from the dentition, through the application of new dental phenotypes to new dental samples. The overarching question of this thesis is: how does tooth form vary within and between historic and modern samples?