Thesis is submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Science, School of Geosciences, University of the Witwatersrand, Johannesburg, 2018 / Teeth make up the bulk of hominin fossil material and are useful in taxonomic assessments. In this thesis, discriminant function, principal components and randomised CV analyses on large samples of lower second molars (n=778) from five extant reference species, both sexually dimorphic and non-dimorphic, provide estimates of ranges of size-shape variability to be expected within a single species. However, there is evidence that diet-driven tooth-size reduction and cusp simplification has expanded the ranges of shape and size variability of Homo sapiens in some populations, in areas exposed to soft, undemanding diets since the transition to agriculture and increased use of cooking, food processing and ceramics from about 12500 years ago. Molar size and shape changes are less evident in communities retaining a hunter-gatherer subsistence strategy, requiring strong dentognathic structures with robust teeth to masticate harder, tougher foodstuffs. These factors, driving divergent variability in tooth size and shape, are unique to modern humans. Using a novel mathematically-based landmarking methodology, developed to allow the inclusion of severely worn teeth, intra-species size-shape variability was assessed from 63 lower M2s representing nine African Plio-Pleistocene species. The first hypotheses tested in this thesis address the question of which extant hominoid species might be suitable for use as analogue species for comparisons with fossil hominin molars, and whether uniquely modern-human anomalous size-shape variability exhibited by lower second molars might disqualify modern Homo sapiens for such analyses. Secondly, where lower second molar size-versus-shape variability ratios measured for fossil species do not match those of either a sexually dimorphic or a non-dimorphic extant species, evaluations are made as to whether samples attributed to single hominin species might actually represent specimens from more than one species present in the relevant assemblages, whether sexual dimorphism may have been greater in fossil species than in extant species, and whether some individual specimens attributed to any fossil species might be misclassified. Results of the analyses indicate that uniquely human subsistence strategy divergences are identifiable in the size-shape variability of lower second molars. Furthermore, specimens representing Australopithecus afarensis, Australopithecus africanus and Paranthropus robustus in this study exhibit very high variability and may indicate the presence of more than one species in their respective assemblages. / EM2018

Thesis--State University of Utrecht. / T.P. in Dutch. Includes bibliographical references.

Thesis--State University of Utrecht. / T.P. in Dutch. Includes bibliographical references.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, October 29, 2014. / Teeth are the most common element in the fossil record and play a critical role in taxonomic assessments. Size, relative width and cusp arrangements on enamel crown surfaces are used to help assess relationships between specimens. In this exploratory study, a model is developed for the placement of landmarks on images of lower first molars to maximise key information from crown surfaces of molars of African Plio-Pleistocene hominin fossils representing species of Australopithecus, Paranthropus and Homo. Lower first molar data of four extant species (Pan paniscus, Pan troglodytes, Gorilla and Homo sapiens) are visualised in a principal components analysis to detect whether landmark placements are adequate to identify species groupings and overlaps and patterns indicative of sexual dimorphism. The role of size as a differentiator between extant species is visualised using Procrustes Form Space as the basis for the analysis. A series of analyses, including linear diameter plots, Procrustes averaging, principal components analyses, discriminant function analyses and log sem (based on regression analyses) are used to test whether species groupings agree with currently accepted taxonomic classifications of thirty-six African Plio-Pleistocene hominin lower 2 first molars. Specimens in the sample that consistently fail to group with current species designations are flagged as “anomalous”. Six specimens are identified as anomalous and these are ultimately removed from the analyses. The resultant principal components plot of the fossil specimens appears to show distinctions between currently accepted species groups. The statistical regression analyses (log sem) confirm the results from the geometric morphometric analyses, and are associated with an average log sem value of -1.61 for conspecific pairwise comparisons. The log sem value of -1.61 has been proposed by Thackeray (2007a) as an approximation of a biological species constant (T), based on pairwise comparisons of modern vertebrate taxa, using cranial data. The anomalies confirm the hypothesis that certain specimens from the sample may have been misclassified, and that certain species groups as currently defined may comprise more than one morphotype.

The aim of this study was to compare the size of the teeth of a sample of small-bodied fossil humans from the island of Palau, Micronesia, with modern and fossil human populations from mainland southern Africa. Four modern human population groups and a sample of Holocene human remains were examined for comparison. These included Zulus, Tswanas, Khoisan and Europeans, from the Dart Collection, University of the Witwatersrand. Several measurements of the different tooth classes were obtained from the modern population groups and compared to the Palauan sample using Univariate and Bivariate statistical methods. In addition, frequencies of anomalies were recorded for the entire modern human Dart Collection (n. 3000), and a sample of Holocene human skeletons (n. 69) for comparison with the Palauan material. The Palauans have been found to have absolutely and relatively very large teeth compared to modern and Holocene population groups. Their mesiodistal diameter (MD) and buccolingual diameter (BL) exceed the normal range of modern human populations, whereas the same measurements at the cervical enamel junction are smaller. Total root length and crown height of the Palauans are equal to those of modern humans. Estimating body size from tooth size is thus shown to be unreliable, indicating that tooth size should be viewed in relation to other factors, such as diet, which may lead to phenomena like island dwarfism. Frequencies of third molar agenesis, incisiform canines, caniniform premolars and rotated premolars were very high in the Palauan sample: third molar agenesis, incisiform canines, caniniform premolars and rotated premolars. These anomalies are mostly due to crowding, which results in erupting teeth looking like their neighbours, or failing to develop at all, as in the case of third molars, which free up space for the remaining teeth to develop.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 400-428). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 400-428). Also available on the Internet.