Expanding on existing data, this thesis presents the largest (N=51) isotopic dataset for Iron Age (2000-100 years BP) agriculturalists in southern Africa. Four isotopic values are presented for each individual (δ¹³Cbone apatite, δ¹³Ctooth enamel, δ¹³Ccollagen, δ¹⁵Ncollagen). Dietary reconstructions using both typical 'fractionation factor' methods and recent bi- and multi-variate models are presented and compared. For this population, which consumed primarily C4 protein and energy sources (including protein-rich crops such as sorghum and millet), multiple tissue isotopes provide valuable insight into diet that cannot be achieved with single tissues, but current models are limited by the lack of isotopic diversity in the data on which they are based. Multi- and bi-variate models are unable to distinguish between C4 plants and animals in some cases, and recreation of cluster analysis including the Iron Age data results in a reduction in the parsimony of the dietary clusters derived in Froehle et al. 2012. Isotopic reconstructions suggest that C3 dietary components contributed limited protein or energy to Iron Age farmers, elaborating on archaeological evidence for their use. Iron Age agriculturalists are found to have consumed highly variable and heterogeneous diets, especially after the 18th century (for all agriculturalists: δ¹³Cbone apatite =-6.25±2.49‰, δ¹³Ctooth enamel =-2.88±2.48‰, δ¹³Ccollagen = -8.65±2.16‰, δ¹⁵Ncollagen=10.05±1.9‰). The expansion of settlement into higher-altitude grassland areas obscures the introduction of maize in the region in the 15th and 16th centuries, and there is no significant difference between the Early and Late Iron Age, with more diversity than expected overall. Environmental effects impact δ¹⁵Ncollagen significantly, but there is no distinct geographical patterning in ¹³C between grassland and savanna biomes. Evidence of regional variation including along rivers and coastal regions is apparent in both the Early and Late Iron Age. The pre-treatment of bone apatite for isotopic use was explored through a series of experiments that compared reaction time in acetic acid, sodium hypochlorite, and particle size of the bone powder to δ¹³Cbone apatite. Extremely small (<25 μm) particles were very sensitive to pre-treatment and significantly altered δ¹³Cbone apatite. Time in sodium hypochlorite was more impactful on the isotopic value of the sample than time in acid, but for short exposure times (<3.5 hours) even poorly preserved bone showed robust isotopic values. δ¹³Cbone apatite and δ¹³Ctooth enamel were uncorrelated (R²=0.24) and Δ¹³Ccollagen-bone apatite (4.77±1.42‰) and Δ¹³Ccollagen-enamel (5.67±1.66‰) are comparable to other published values indicating that tooth enamel and bone apatite are mineralogically and isotopically distinct. The effects of pre-treatment on isotope values in previous studies is examined and possible sources of difference in metabolic processes or fractionation for bone apatite and tooth enamel are explored.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uct/oai:localhost:11427/22719 |
| Date | January 2016 |
| Creators | Zhu, Madeline R M W |
| Contributors | Sealy, Judith |
| Publisher | University of Cape Town, Faculty of Science, Department of Archaeology |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Master Thesis, Masters, MSc |
| Format | application/pdf |
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