Rock Hyraxes (Procavia capensis) and Their Environments: 13 15 δ Ccollagen and δ Ncollagen as environmental indicators Lesa la Grange Supervised by Dr Deano Stynder and Prof Judith Sealy University of Cape Town Dissertation submitted in fulfilment of the requirements for the degree of Master of Philosophy (MPhil) in Archaeology Department of Archaeology University of Cape Town 20 July 2015 The copyright of this thesis vests in the author. No quotation from it or information derived from it is to be published without full acknowledgement of the source. The thesis is to be used for private study or non- commercial research purposes only. Published by the University of Cape Town (UCT) in terms of the non-exclusive license granted to UCT by the author. University of Cape Town Abstract Rock hyraxes (Procavia capensis) are a common component of faunal assemblages at South African archaeological sites. Previous studies have focused on their remains as proxies for aspects of diet and mobility in prehistoric human populations. They have also been recognized as valuable palaeoenvironmental indicators due to the fact that their stratified communal middens record shifts in stable isotopes, palynology, and molecular biomarkers that appear to reflect environmental change. Previous studies conducted in east Africa have concluded that rock hyraxes are preferential grazers. There is comparatively little evidence, however, for the dietary preference of South African rock hyraxes, although it has been suggested that they consume more browse. This research aims to quantify the carbon isotopic ratios in their bone collagen to reconstruct diet. Results support preferential browsing in South African rock hyraxes, with a mean δ13C value for all animals in this study of -20.3 ± 1.9‰ (n = 210) indicating a C3 dietary contribution of 73.4 ± 13.3%. Rock hyraxes are drought-tolerant animals. They therefore exhibit high δ15N values compared to other species, particularly in arid environments. There is uncertainty regarding the extent to which this is the result of high δ15N in plants in arid areas, and/or of metabolic processes within the animal, possibly including urea recycling as a water conservation mechanism. This study includes rock hyraxes collected across South African environmental gradients, allowing the relative importance of environmental and metabolic determinants of δ15N to be investigated. Results show that δ15N decreases by 1‰ for every additional 100 mm of rainfall, although there is a high degree of variability, indicating that δ15N values are not driven by moisture availability alone. Other climatic variables, and additional fractionation of the isotopes during physiological processes within the rock hyraxes may play a role in determining tissue δ15N. 13 The fact that δ Ccollagen indicates preferential browsing limits the degree to which one can use rock hyrax remains to interpret shifts in the extent of the winter, summer, and year-round rainfall zones. Furthermore, 15 the relatively low correlation between δ Ncollagen values and rainfall suggests that further investigation into 15 the primary determinants of δ Ncollagen values is required. ii Acknowledgements • I thank my supervisors, Dr Deano Stynder and Prof Judith Sealy, for their guidance and assistance throughout the course of this degree. Their comments on draft versions of this thesis were valuable and constructive. • I thank Ms Julie Luyt, Ms Nandi Masemula, Mr Ian Newton, and Mr John Lanham for their assistance with sample preparation • I acknowledge the following persons for their assistance in assembling the hyrax sample analysed in this study: Dr Jurie du Plessis, Dr Nico Avenant, Prof Louis Scott, Dr Teresa Kearney, Mr Len Edwards, Mr Morné Brits, Ms Louisa Hutten, Ms Philippa Haarhof, Dr Alexandra Sumner, Mr Mark Duckitt, Mr Pierre Nel, Mr John Adendorff, Mr Nardus du Plessis, Mr Nick de Goede, Mr Adrian Fortuin, Mr Bernard van Lente, Ms Nicole Grunert, Dr Alex Mackay, Mr Ross Lyall, Mr James McGrath, Ms Emily Hallinan, Mr James McPherson, and Mr Philip la Grange • I acknowledge the following institutions for granting permission to sample skeletal material in their care: The West Coast Fossil Park, South African National Parks, The Ditsong National Museum of Natural History, The National Museum of Bloemfontein, and the Western Cape Nature Conservation Board. • I thank Dr Alastair Potts, Mr Thomas Slingsby, and Ms Ushma Galal for their assistance with statistical analyses and GIS data generation. • I acknowledge financial support from the South African Research Chairs Initiative (SARChI) of the Department of Science and Technology (DST) and National Research Foundation (NRF) of South Africa, which provided both bursary support and research running costs. Further bursary support was received from the DST-NRF Centre of Excellence for Palaeosciences (CoE-Pal) and the Palaeontological Scientific Trust (PAST). • I thank the examiners for their valuable reviews. Their recommendations greatly enhanced the final version of this thesis. iii Contents Abstract .............................................................................................................................. ii Acknowledgements ............................................................................................................ ii List of Tables ...................................................................................................................... vi List of Figures .................................................................................................................... vii Chapter One: Introduction ............................................................................................... 1 1.1 - The use of rock hyraxes as archaeological and palaeoenvironmental proxies . 1 1.2 - Thesis outline ................................................................................................... 2 Chapter Two: Stable Carbon and Nitrogen Isotopes .................................................... 4 2.1 - Introduction ..................................................................................................... 4 2.2 - Stable isotopes of carbon in the atmosphere, plants, and consumers .............. 5 2.3 - Stable isotopes of nitrogen in the atmosphere, soils and plants, and consumers .................................................................................................... 13 2.4 - Stable isotope ratios in bone collagen ............................................................ 15 2.5 - Summary ......................................................................................................... 16 Chapter Three: Rock Hyraxes ......................................................................................... 18 3.1 - Taxonomy ....................................................................................................... 18 3.2 - Distribution, habitat and colony structure ....................................................... 19 3.3 - Social structure, behaviour, and reproduction ................................................ 22 3.4 - Diet .................................................................................................................. 23 3.5 - Stable isotope analysis of rock hyrax middens ............................................... 25 3.6 - Summary ......................................................................................................... 26 Chapter Four: Materials and Methods ........................................................................... 28 4.1 - Sample selection criteria, provenance, and accession ..................................... 28 iv 4.2 - General notes relating to environmental data used ......................................... 30 4.3 - Winter rainfall zone samples ........................................................................... 31 4.4 - Year-round rainfall zone samples ................................................................... 32 4.5 - Summer rainfall zone samples ........................................................................ 33 4.5 - Sample preparation ......................................................................................... 45 4.6 - Sample analysis and reproducibility of measurements ................................... 46 Chapter Five: Results ........................................................................................................ 48 5.1 - Collagen quality assessment ........................................................................... 48 5.2 - Stable isotope ratios ........................................................................................ 58 5.2.1 - Carbon .............................................................................................. 58 5.2.2 - Nitrogen........................................................................................... 64 5.3 - Summary ......................................................................................................... 75 Chapter Six: Discussion and Conclusions ....................................................................... 76 6.1 - Quantifying rock hyrax dietary preference: carbon mixing models ............... 76 6.2 - Investigating the determinants of bone collagen δ15N .................................... 83 6.3 - Conclusions and suggestions for future research ........................................... 85 References .........................................................................................................................