Browsing by Author "Lee-Thorp, Julia"

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    Analysis of dental pathologies in the Pliocene herbivores of Langebaanweg and their palaeoenvironmental implications
    (2002) Franz-Odendaal, Tamara; Chinsamy-Turan, Anusuya; Lee-Thorp, Julia
    This study evaluates the extent of dental pathologies in several ungulate species from the Pelletal Phosphate Member (PPM) at Langebaanweg, and uses this analysis, along with stable isotope analyses, to obtain fresh insight into the local palaeoenvironment during the Early Pliocene.
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    Climate change and agropastoralist settlement in the Shashe-Limpopo River Basin, southern Africa: AD 880 to 1700
    (2007) Smith, Jeannette; Lee-Thorp, Julia; Hall, Simon
    The expansion and decline of complex socio-political farming systems in the Shashe-Limpopo River Basin, southern Africa, has been linked to large-scale climate shifts in which increased rainfall favoured intensified agropastoral production and expanded settlement, while the onset of arid conditions led to collapse and abandonment of the area. This study uses stable nitrogen isotope ratios (C5Nf4N) from modern and archaeological fauna to construct a proxy-rainfall sequence for the region from AD 880 onwards. The resulting sequence provides a revised climatic context for agropastoral settlement of the river basin and evidence of greater climatic variation than previously documented. Stable nitrogen isotope data from the bone collagen of archaeological fauna show that settlement by Zhizo agropastoralists between AD 880 and 1010 took place under semi-arid conditions, with average annual rainfall of <500 mm. Results for sites dating between AD 1010 to 1290 are consistent with previous interpretations that the Leopard's Kopje A and B cultural period 'capitals' of K2 and Mapungubwe, respectively, rose to prominence under a trend towards increased average annual rainfall that was 2500 mm. The data indicate also that the phase of increased moisture extended beyond the abandonment of Mapungubwe at AD 1290 and continued to be evident in fauna dating to the Moloko/Icon cultural period between AD 1310 and 1415. Data from the Moloko/Khami cultural period sites suggest that markedly drier conditions were not evident in the area until after AD 1450. Based on the isotope data, increased rainfall appears to have coincided with the expansion and intensification of settlement in the Shashe-Limpopo River Basin. Reconsideration, however, needs to be given to the correlation between the abandonment of Mapungubwe with the onset of arid conditions unfavourable for agropastoralism; other explanations, encompassing socio-economic and political choices, also must be sought.
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    Mapping the elephants of the 19th century East African ivory trade with a multi-isotope approach
    (Public Library of Science, 2016) Coutu, Ashley N; Lee-Thorp, Julia; Collins, Matthew J; Lane, Paul J
    East African elephants have been hunted for their ivory for millennia but the nineteenth century witnessed strongly escalating demand from Europe and North America. It has been suggested that one consequence was that by the 1880s elephant herds along the coast had become scarce, and to meet demand, trade caravans trekked farther into interior regions of East Africa, extending the extraction frontier. The steady decimation of elephant populations coupled with the extension of trade networks have also been claimed to have triggered significant ecological and socio-economic changes that left lasting legacies across the region. To explore the feasibility of using an isotopic approach to uncover a 'moving frontier' of elephant extraction, we constructed a baseline isotope data set (δ 13 C, δ 15 N, δ 18 O and 87 Sr/ 86 Sr) for historic East African elephants known to have come from three distinct regions (coastal, Rift Valley, and inland Lakes). Using the isotope results with other climate data and geographical mapping tools, it was possible to characterise elephants from different habitats across the region. This baseline data set was then used to provenance elephant ivory of unknown geographical provenance that was exported from East Africa during the late nineteenth and early twentieth centuries to determine its likely origin. This produced a better understanding of historic elephant geography in the region, and the data have the potential to be used to provenance older archaeological ivories, and to inform contemporary elephant conservation strategies.
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    Stable isotope analysis of fauna and soils from sites in the Eastern Free State and Western Lesotho, Southern Africa : a palaeoenvironmental interpretation
    (1997) Smith, Jeannette; Sealy, Judy; Lee-Thorp, Julia
    This thesis examines the use of stable carbon isotopes as a means of reconstructing the palaeoenvironment of the Caledon River Valley of the eastern Free State, South Africa, and western Lesotho. In doing so, this work draws upon previous studies that have shown that the distinct distribution and δ¹³C values of C₃ and C₄ grasses are influenced by seasonality of rainfall and growth season temperatures. In general, C₃ grasses dominate in areas where conditions are cool/moist during the growth season, while C₄ grasses characterize those that are warm/arid. The isotopic composition of the grasses of an area, and thus climatic and environmental data, is passed along the trophic levels, through dietary intake by grazers, and decomposition into soil sediments. By measuring the ¹³C/¹²C ratios of carbon extracted from the calcified tissues of grazers and soil organic matter recovered from within an archaeological context, a palaeoenvironmental sequence has been reconstructed for the study area for the last 13 500 years. Results have shown that although C₄ grasses have dominated, the presence of C₃ grasses, at various times during this period, suggest that growth season temperatures fluctuated temporally and spatially.