A dissertation submitted to the School of Geography, Archaeology and Environmental Studies, Faculty of Science University of the Witwatersrand, Johannesburg for the degree of Master of Science. Johannesburg 2013. / Tool manufacturing played a major role in the development and evolution of our species, and by studying the tools left behind by our ancestors we gain valuable insight into their development and behaviours through time. This study was conducted on the Swartkrans Oldowan (2.2 - 1.7 Ma), early Acheulean (1.5 - 1 Ma), and Middle Stone Age (<110 ka) assemblages to determine the degree of lithic raw material selectivity for making stone tools, and if they practiced ever increasing selection towards better quality stone over time. The presence of quality selection was determined by comparing the various Swartkrans assemblages with experimentally created lithic tools from rock types found in the study area. Three main characteristics that determine selection of rock types were isolated: flaking predictability, durability and sharpness. Analysis of the data provided further evidence that our early stone tool making ancestors had the ability to understand how different rock types behave when knapped and tended to select rocks that had a high flaking predictability, high durability and could produce fairly sharp edges. It was also apparent that they could identify features that diminish the above mentioned characteristics. Variables such as the impurity encounter rate, fracture encounter rate, weathering, grain size and homogeneity were semiquantitatively recorded for the three techno-complexes at Swartkrans and compared to each other to help identify the degree of selectivity that was practiced over time. The data revealed that selection for quality of lithic raw materials was practiced to some extent during the Oldowan and improved slightly in the early Acheulean. The most marked selection for quality was seen for the Middle Stone Age when modern humans used the site. These results indicate that as time progressed in the Sterkfontein valley, and the stone tool technologies became more complex, so too did the selective pressures and thus an increase in selection for quality lithic raw materials over the course of time.

Swartkrans Cave, famous for abundant hominin fossils of P. robustus and the site where the first evidence of the co-existence of two hominin species was recovered, has yielded a wealth of information on early hominin behaviour. In 2005 a new program of research and excavation began at the site, and its results form the central part of this thesis. This study has focused on the early Pleistocene Member 1 deposits which include an Earlier Stone Age industry and the late Pleistocene Member 4 Middle Stone Age deposits. The thesis has four areas of focus. First the new work has resulted in clarification and new interpretations for the formation of the hominin rich Hanging Remnant deposit of Member 1, which lacks stone tools. This extensive calcified conglomerate which spans most of the north wall of the cave is now seen as a non-homogenous unit that represents material entering from at least four avens. However, this study also established that the newly exposed central portion of the Hanging Remnant and the hominin fossil-rich northwest corner infill worked by Robert Broom in the 1940s derived from the same depositional episode. Secondly, the new excavations in the Lower Bank of Member 1 have resulted in an enlargement of the previously ambiguous Earlier Stone Age assemblage. Analysis of this new assemblage, in conjunction with recently released dating results, has now confirmed that the artefacts belong to the Oldowan Industrial Complex. Thirdly, new excavations in the Member 4 deposit have resulted in the recovery of over 3,200 Middle Stone Age (MSA) stone tools and a clearer understanding of their context. The stone tool-bearing deposits of Member 4 are now understood to derive from a surface colluvium, rather than a cave infill. This MSA assemblage consists of a high number of retouched pieces that are dominated by steep-sided scrapers and denticulated scrapers with a near-absence of points. The technology of a variety of core types suggests a superior understanding of raw material flaking qualities by the tool makers. The limited types of formal tools suggest that the site was used for one or more specific activities, rather than for a range of activities by the tool makers. Fourthly, excavation of the deposits underlying the Member 4 colluvium has resulted in the discovery of two previously unknown hominin-bearing deposits. It is now established that what was originally called Member 4 is composed of three distinct deposits. The lowest of these is an east extension of the Member 1 Lower Bank (LB East Extension), which has yielded P. robustus fossils. This is overlain by a large talus cone (TCD), which also has yielded P. robustus fossils. The latter is capped by flowstone dated to ~110,000 years, followed by the MSA-tool bearing colluvium.

This research better resolves the environmental mosaic that is typically reconstructed for the A. robustus-bearing faunal assemblages of South Africa and evaluates whether A. robustus were habitat specialists or habitat generalists by testing whether they are associated with numerous, different reconstructed habitats, or if they can be associated with a single, more homogeneous habitat type. Determining the habitat preferences of A. robustus holds important implications for understanding the behavior of these hominins and, potentially, for understanding whether their ultimate extinction might have been climatically influenced, as fluctuations in the environments associated with the robust australopiths provide direct evidence about the responses of hominins to environmental change. To achieve this, a 2-dimensionsal morphometric tool was developed for accurately identifying the abundant bovid teeth that are found in direct association with the hominins using Elliptical Fourier Function Analysis. More accurate taxonomic identifications facilitate more precise estimates of the relative abundance of ecologically sensitive bovids, allowing for finer resolution when segmenting the various components of the reconstructed habitat mosaics. The fossil bovids abundances were compared across the assemblages over time in order to define the environmental mosaic in each assemblage and to determine if environmental heterogeneity existed across the assemblages. The relative abundances of the bovid fossil assemblages and A. robustus were compared to assess the habitat preferences of these hominins. A. robustus were not consistently associated with a particular habitat type suggesting that perhaps they were habitat generalists, capable of surviving in multiple types of habitats.