Objectives: This article presents estimates of narrow-sense heritability and bivariate genetic correlation for 14 tooth crown morphological variants scored on permanent premolars, first molars, and second molars. The objective is to inform data collection and analytical practices in dental biodistance and to provide insights on the development of molar crowns as integrated structures. Materials and Methods: African American dental casts from the Menegaz-Bock collection were recorded for the Arizona State University Dental Anthropology System. Estimates of narrow-sense heritability and genetic correlation were generated using SOLAR v.8.1.1, which included assessment of age, sex, and birth year as covariates. Both continuous scale and dichotomized estimates are provided. Results: Heritability estimates were nonsignificant for the majority of variables; however, for variables yielding significant estimates, values were moderate to high in magnitude and comparable to previous studies. Comparing left and right-side heritability estimates suggests directional asymmetry in the expression of environmental variance, something not seen in anterior tooth traits. Genetic correlations were moderate among antimeres and metameres and low for different traits scored on the same tooth crown. Although several negative correlations were noted, few reached statistical significance. Results affirm some of the current data cleaning and analytical practices in dental biodistance, but others are called into question. These include the pooling of males and females and combining left and right-side data into a single dataset. Conclusions: In comparison to anterior tooth crown traits, postcanine heritabilities were more often non-significant; however, those traits with significant heritability also tended to produce higher estimates. Genetic correlations were unremarkable, in part, because they were underpowered. However, M1 results may provide insight into the complex relationship between genes, environment, and development in determining ultimate crown form.

Presented in the session “Global Leadership in Dental Anthropological Research: A symposium in honor of G. Richard Scott." The Arizona State University Dental Anthropology System (ASUDAS) or Turner-Scott System revolutionized the use of dental morphology for reconstructing evolutionary processes in past populations. By providing globally-recognized data collection standards, the system has elevated the status of dental morphology to an indispensable line of evidence in biodistance research. The efficacy of morphological data rests upon foundational assumptions about underlying tooth crown biology; namely, that the traits are highly heritable and minimally sexually dimorphic. Scott and colleagues have also outlined best practices for the application of dental morphology to biodistance studies, most aimed at curtailing genetic redundancy in multivariate datasets (see Turner et al., 1991). Quantitative genetic approaches have the potential to validate these assumptions. Here, we present the first robust estimates of heritability and genetic correlation for ASUDAS crown characters. Data were collected from a casted sample of South Carolina Gullah individuals (N=469) and analyzed using maximum likelihood variance components analysis. While several postcanine traits yielded heritability estimates of 0.0, mean estimates across statistically significant models were moderate to high (anterior=0.34; postcanine=0.75). Results of covariate screening support the long-held assumption that ASUDAS traits are sexually monomorphic, with the exception of canine marginal/cingular ridge characters and certain molar accessory cusps. Additionally, patterns of heritability and genetic correlation groundtruth most prescribed biodistance practices: dichotomizing trait expression, collapsing bi-antimeric datasets, and prioritizing traits scored on key (sensu Scott et al., 2018) teeth. Notwithstanding, our results suggest that certain assumptions require reconsideration and underscore the importance of continued validation work in additional populations.

Objectives: This article presents estimates of narrow-sense heritability and bivariate genetic correlation for a series of morphological crown variants of the anterior dentition. These results provide insight into the value of dental phenotypes as evolutionary proxies, as well as the development of tooth crowns as integrated or modular structures. Materials and Methods: African American dental casts from the Menegaz-Bock collection were scored for a standard set of dental morphological variables using the Arizona State Dental Anthropology System. Estimates of narrow-sense heritability and genetic correlations were generated using SOLAR v. 8.1.1, controlling for the covariates of age, sex, and birth year. Analyses were run using ordinal/continuous scale variables that were then dichotomized at various breakpoints, consistent with standard practices in dental anthropology. Results: Heritability estimates were low to moderate for most traits, and lower in magnitude than those reported for odontometric data from the same study sample. Only winging, canine shoveling, and canine double shoveling returned narrow-sense heritabilities that did not differ significantly from zero. Genetic correlations were high among antimeres and metameres and low for different traits scored on the same tooth crown. These results affirm standard data cleaning practices in dental biodistance. Double shoveling was atypical in returning strong negative correlations with other traits, shoveling in particular. Conclusions: Additive genetic variation contributes to dental morphological variation, although the estimates are uniformly lower than those observed for odontometrics. Patterns of genetic correlation affirm most standard practices in dental biodistance. Patterns of negative pleiotropy involving lingual and labial crown features suggest a genetic architecture and developmental complex that differentially constrain morphological variation of distinct surfaces of the same tooth crown. These patterns warrant greater consideration and cross-population validation.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第25143号 / 理博第5050号 / 新制||理||1719(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 本川 雅治, 准教授 中野 隆文, 教授 森 哲 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Dental anthropology played a seminal role in early studies of the peopling of the New World, and was a foundation of the early three wave model proposed by Greenberg, Turner and Zegura. In recent years, however, developments in anthropological genetics, craniometry, and archaeological discoveries have largely omit-ted dental anthropology from debates regarding Native American origins. Here we consider this situation and reassert dental anthropology's relevance to the topic by presenting an inter-individual analysis of Paleoindian and Paleoamerican dentitions. A small set of dental morphological variables was used to estimate Gower similarity coefficients between individual specimens. The resulting similarity matrix was ordinated using multidimensional scaling; all analyses were per-formed in Clustan v. 7.05. While results should be considered preliminary, patterns of variation suggest morphological similarity along both coasts of North and South America with a somewhat distinct grouping of North American Paleoindians deriving from more inland portions of the continent. This pattern is consistent with recent genetic scenarios, notably the bicoastal model presented by O'Rourke and Raff (2010), which indicates that Paleoindians may have taken multiple migration routes from Beringia, moving along both coasts as well as through the ice free corridor. Future studies may build on this work to reintegrate dental data and analysis into research concerning the peopling of the New World.

No description available.

No description available.

No / Dietary ecology is one key to understanding the biology, lifeways, and evolutionary pathways of many animals. Determining the diets of long-extinct hominins, however, is a considerable challenge. Although archaeological evidence forms a pillar of our understand-ing of diet and subsistence in the more recent past, for early hominins, the most direct evidence is to be found inthe fossils themselves. Here we review the suite of emerging biochemical paleodietary tools based on stable isotopeand trace element archives within fossil calcified tissues.We critically assess their contribution to advancing our understanding of australopith, early Homo, and Neander-thal diets within the broader context of non-biogeochemical techniques for dietary reconstruction, such as mor-phology and dental microwear analysis. The most signifi-cant outcomes to date are the demonstration of hightrophic-level diets among Neanderthals and Late Pleistocene modern humans in Glacial Europe, and the persis-tent inclusion of C4 grass-related foods in the diets of Plio¿Pleistocene hominins in South Africa. Such studies clearly show the promise of biogeochemical techniques for testing hypotheses about the diets of early hominins.Nevertheless, we argue that more contextual data from modern ecosystem and experimental studies are needed if we are to fully realize their potential.

This thesis investigates the morphology of internal tooth structures of fossils attributed to the genus Homo and explores the implications for the systematics of the earliest members of our genus. The origins and evolution of the genus Homo are poorly understood, and one of the major unresolves issues concerns the relationship between the species Homo habilis and other taxa. The enamel-dentine junction (EDJ) is useful for studies of hominin systematics because its morphology contains taxonomically important information that may otherwise be lost due to the effects of occlusal dental wear. Few studies focus on the EDJ morphology of early Homo due to a lack of microtomographic scans that preserve adequate contrast between dental tissues. This thesis presents the first analysis of new scans of important H. habilis specimens from Olduvai Gorge in Tanzania, including the type specimen OH 7. Overall EDJ shape is quantified using landmark-based geometric morphometric methods, revealing that a number of H. habilis specimens retain a very primitive EDJ morphology, largely within the range of Australopithecus. Conversely, H. habilis specimen OH 16 shows a suite of derived traits, particularly in the premolars, suggesting considerable variability within the species hypodigm. Analysis of the mandibular premolar EDJ of the species Homo naledi reveals a distinctive and remarkably consistent morphology that differs in several key traits from those of comparative taxa, including H. habilis and H. erectus. However, two specimens from sites in South Africa show H. naledi-like traits, suggesting a possible phylogenetic link with much earlier hominins. Finally, the thesis also investigates the EDJ expression of mandibular molar accessory cusps, outlining a scoring system for these traits at the EDJ. There are taxon-specific patterns in accessory cusp expression, with early Homo molars frequently displaying a lingual accessory cusp but no distal accessory cusp. However, the EDJ reveals a number of developmental complexities. This is well-illustrated by three Olduvai H. habilis first molars; each has a lingual accessory cusp, but the form of the trait clearly differs in each, raising questions over the use of accessory cusps for taxonomy. This thesis demonstrates the importance of studying the EDJ of fossil hominin teeth alongside the outer enamel surface and improves our understanding of the dental morphology of early Homo.:Acknowledgements............i Bibliographical Data............iii Summary............1 Zusammenfassung............8 Chapter 1............15 Chapter 2............29 Chapter 3............57 Appendix............81 Supplementary Information – Chapter 1............82 Supplementary Information – Chapter 2............95 Supplementary Information – Chapter 3............265 Co-author contributions............279 Certificate of exclusive authorship – Chapter 3............282 Declaration of independent work............284

No description available.