Heritage Cases

Recently, advances have been made in the use of amino acid geochronology for dating Quaternary samples (Penkman et al., 2008, 2011). This dating technique measures changes in amino acid molecules by the time elapsed since they were formed. Briefly, all biological tissues such as teeth contain amino acids. All amino acids (except glycine) are optically active, having a stereo-center at their α-C atom. The amino acid can have two different configurations, ‘D’ or ‘L’ which are mirror images of each other. Living organisms keep all their amino acids in the ‘L’ configuration, but when an organism dies, control over the configuration of the amino acids ceases, and the ratio of D to L moves from a value near 0 towards an equilibrium value near 1, a process called racemisation. Measuring the ratio of D to L in a sample enables an estimation how long ago the specimen died. In the past, this method of dating could only be applied to molluscs and eggshells, but recent advances makes it now possible to use tooth enamel (Dickinson et al. 2019). The use of amino acid racemisation allows the possibility to obtain dates from archaeological samples like the CoH that was excavated several decades ago. The University of York in the UK, in particular Dr. Marc Dickinson and Prof. Kirsty Penkman (co-applicants) pioneered the use of enamel in amino acid racemisation dating. Very few molluscs and eggshells are present in the CoH faunal assemblage (<5 specimens, personal observation) and would therefore not be suitable. Moreover, this dating technique has been correlated with radiocarbon dates at various sites in the world to test the accuracy of the method. A current research programme is underway by Prof. Penkman to date samples from the Quaternary elsewhere in Africa, and the samples from the CoH will allow them to expand the application of this dating technique. For this dating technique, the following are required: - 10 to 30 milligrams of enamel extracted from animal teeth. - The animals selected for dating should have been identified to family level or lower, and the same taxon is ideal. - A minimum of 3 to 5 samples are required per layer. Following the excavations from several decades ago, the large mammal fauna was identified by Cooke (1969, 1988), the taphonomy of the ESA Beds 1-3 was studied by Ogola (2003, 2009), whilst Churcher (1970) investigated the Equidae (zebras), Ewer (1956) the Suids (pigs) and De Graaff (1960) the microfauna. The presence of carnivore chew marks, rodent gnaw marks (mostly by porcupines) and butchery evidence by hominins have been noted on the large mammal remains (Cooke 1969, 1988), suggesting a complex accumulation history for the fauna. At the time of the analyses of the large mammals remains, only teeth and crania were used for identification, a common approach several decades ago. More recently, some aspects of the MSA fauna have been restudied by postgraduate students if mine (Khoaele 2020, Masekwa 2020, Maloka 2021). From these recent studies, it is evident that the lack of more precise dates for the different beds at the CoH seriously undermines any meaningful future studies of the fauna from the CoH. Overall, the fauna from the CoH have not been properly quantified, nor has the postcranial remains been identified. Based on some 2500 catalogue book entries (located in the Evolutionary Studies Institute, University of the Witwatersrand), the sample contains large numbers of Equidae and Bovidae. Equidae (zebras) are particularly common in the sample, occurring in all beds at the CoH (except Bed 1, which contain a total of 3 specimens of primate and Bovidae). There are some 650 Equidae specimens in the CoH faunal assemblage, consisting of the extinct Cape horse (Equus capensis) and the modern plains zebra (Equus burchelli, today regarded as Equus quagga) in particular. With this application, I am seeking permission to select Equidae teeth specimens from the different beds at the CoH, and submit them to the University of York for amino acid racemisation dating. The following protocols will be applied: - Submit and sample a total of 38 Equidae teeth specimens. - This represents 3 specimens per bed, with more specimens from the mixed components. - Once permission has been granted by the ESI, a SAHRA export and destructive permit will be obtained. - Each specimen will be photographed and re-identified (to species-level, sides, element, upper or lower, and state of fragmentation). - The specimens will be send in batches per courier, sampled at the University of York by Dr. Dickinson, and returned to the ESI by courier. - As there are potential constraints in using this dating technique, the youngest samples will be analysed first, then progressing to older samples. - The focus of the sampling will be on fragmented teeth of the plains zebra, to minimally impact on the specimens of the extinct Cape horse. - I am including specimens from two components, in addition to Beds 2-11, in the application. These are 1) from breccia that was removed prior to the excavations, and stored in the adjacent Hyena Cave in 1947. These breccias, called Loose Breccia, likely belong to Beds 2 or 3. Then 2) most fauna from the assemblage were excavated from what Mason (1969, 1988) called the Shallow Hole (based on observations from the catalogue book). The Shallow Hole is a mixture of both ESA and MSA fauna, and dates on this component will be important to interpret the fauna. - Most tooth specimens are fragmented and the removal of 10 to 30 milligrams will have a minimal impact on the state of the specimens themselves (Appendix 1). - The 38 specimens represent 6% of all the Equid teeth in the CoH faunal assemblage, thus leaving a considerable portion of the sample intact.