abstract: Early hominins present an unusual pattern of sexual dimorphism. On one hand, the canine teeth of these species are weakly size-dimorphic, vertically short, and nonhoning, suggesting a social system characterized by infrequent, low-intensity intermale competition and monogamous pair-bonding. On the other hand, marked size variation in skeletal remains attributed to species of Australopithecus is thought to reflect strong body-mass dimorphism, which is more consistent with intense intermale competition. Reconciling these conflicting signals and understanding their adaptive significance is a major goal of paleoanthropology. This dissertation research contributes to this objective by investigating factors that may constrain or reduce canine height in extant anthropoid primates. Two hypotheses regarding the relationship between canine height and other elements of the masticatory system were tested using phylogenetic comparative methods. According to the first hypothesis, canine reduction is a pleiotropic by-product of changes in the sizes of other components of the dentition. With respect to canine height, the results of this study fail to support this idea. There is limited evidence for a relationship between basal canine crown dimensions and incisor and postcanine size, but significant interspecific correlations between these variables are not strong and are restricted primarily to the female maxillary dentition. These results indicate that if pleiotropy influences canine size, then its effects are weak. The second hypothesis proposes that canine reduction is a consequence of selection for increased jaw-muscle leverage. This hypothesis receives some support: there is a clear inverse relationship between canine height and the leverage of the masseter muscle in male anthropoids. Females do not exhibit this association due to the fact that dimorphism in muscle leverage is weak or absent in most anthropoid species; in other words, female muscle leverage tracks male muscle leverage, which is linked to canine height. Leverage of the temporalis muscle is not correlated with canine height in either sex. Two specimens of the 3.0-3.7-million-year-old hominin Australopithecus afarensis fall at or beyond the upper end of the great ape range of variation in masseter leverage, which is consistent with the idea that hominin canine evolution was influenced by selection for increased jaw-muscle leverage. / Dissertation/Thesis / Ph.D. Anthropology 2010

No / There is a series of common assumptions about prehistoric sex, associated with the prejudice that it must have been more natural because it happened closer to our evolutionary origins. The development of primate studies reveals a high degree of social variation between and within primate species, along with evidence for the practice of non-reproductive sex both recreationally and for expressing dominance relations. Yet, hypotheses about the behavior of human ancestors and early modern humans have been hampered by a lack of an integrated methodology. Although there is no single trajectory for either the elaboration or restriction of sexual behaviors after the emergence of culture, I argue here that it is possible to identify key turning points with more or less universal validity. These points include the reasons for and implications of brain size increase at the time of the emergence of genus Homo, the crystallization of impersonal gender by mid-Upper Paleolithic Ice Age societies, the early development of systems of control over both fertility and the projection and alteration of sexual identity, and the inferred emergence of homonegativity in early, reproduction-oriented farming societies. Further, archaeological data allows naturalist assumptions to be effectively refuted.

Stunned by the implications of Colage's analysis of the cultural activation of the brain's Visual Word Form Area and the potential role of cultural neural reuse in the evolution of biology and culture, the authors build on his work in proposing a context for the first rudimentary hominin moral systems. They cross-reference six domains: neuroscience on sleep, creativity, plasticity, and the Left Hemisphere Interpreter; palaeobiology; cognitive science; philosophy; traditional archaeology; and cognitive archaeology's theories on sleep changes in Homo erectus and consequences for later humans. The authors hypothesize that the human genome, when analyzed with findings from neuroscience and cognitive science, will confirm the evolutionary timing of an internal running monologue and other neural components that constitute moral decision making. The authors rely on practical modern philosophers to identify continuities with earlier primates, and one major discontinuitysome bright white moral line that may have been crossed more than once during the long and successful tenure of Homo erectus on Earth.

M.Phil. (Anthropology) / The primary aim of this study was to undertake the description and analysis of the manual and pedal hominin phalanges from Drimolen, South Africa. The specimens were contextualized by examining their counterparts in a series of extant and extinct specimens. As Drimolen preserves the remains of both Paranthropus robustus and early Homo, it provides an opportunity to contribute to our understanding of morphological variation and differences between these taxa, as well as providing an important first step in conceptualizing their evolutionary history and palaeobiology. The first section focused on the manual and pedal phalanges, while the second focused exclusively on the first metatarsal. Numerous studies have analyzed Plio-Pleistocene manual and pedal phalanges to evaluate tool-related behaviours and locomotion in early hominins. In this dissertation nine phalanges were described and analyzed for the first time. The manual specimens consist of one proximal (DNH 9), two proximal pollical (DNH 116 and DNH 119), four intermediates (DNH 48, DNH 63, DNH 65 and DNH 66) and one distal pollical phalanx (DNH 13). There is currently only one pedal proximal phalanx (DNH 117). As at Swartkrans, assignment of postcranial elements was hampered by the fact that two hominin species have been found at the site, namely Paranthropus robustus and early Homo. To analyze the specimens, multivariate statistics (PCA and CVA) were conducted on the specimens using raw and size-adjusted data. This was done within the context of a large extinct and extant dataset to compare size and shape data. In general, PCA and CVA yielded similar results but only the raw data was useful in discriminating between taxa. There was poor discrimination in the analyses based upon size-adjusted data because of the huge degree of overlap between fossil and extant taxa. Consequently, results were not diagnostic and it wasn’t possible to assign specimens confidently to either Paranthropus or Homo. This was exacerbated by the isolated nature of the remains, the presence of two hominin taxa and taxonomic uncertainties of several Swartkrans phalanges. Despite these difficulties, these specimens do provide insight into the degree of morphological variation present in the phalanges from the Plio-Pleistocene of South Africa. The second section described the fragmentary first metatarsal and quantified it by using laser scanning and calculating the curvature of the proximal articular surface. Univariate statistics were then calculated in order to examine the degree of curvature between each of the extant taxa and whether these differences were statistically significant. Finally, a simple bivariate plot was generated using the curvature results which showed that this joint surface was most curved in chimpanzees and western gorillas, moderately curved in eastern gorillas, and flattened in modern humans and baboons. Highly curved joint surfaces in this region suggest a more mobile hallux, whereas flattened surfaces suggest reduced joint mobility. The fossil specimens SK 1813, STW 573, STW 595 and OH-8 all grouped closely with modern humans; A.L. 333-54 and SKX 5017 grouped with chimpanzees, while DNH 115 grouped with eastern gorillas. Overall, these results indicate that SKX 5017 was the most curved of the South African specimens and is attributed to Paranthropus (Susman, 1988). It grouped closely with DNH 115 which suggested that climbing activities may have continued to play an important role in the behavioral repertoire of these individuals during the Plio-Pleistocene.

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

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