Heritage Cases

The presence of organic residues on archaeological artefacts invites curiosity. Trace amounts of residue recovered from stone and bone tools in ancient archaeological deposits have been shown through chemical analysis to have been part of adhesive and poison applications (d’Errico et al. 2012; Charrié-Duhaut et al. 2013; Wooding et al. 2017). In most cases, plant exudates have formed the basis of these applicative substances. The understanding and harnessing of the chemical and pharmacological properties of plants and the ability to combine these into novel and complex recipes allowed humankind to successfully adapt to diverse environments. Whereas there is now a wide body of literature that explores some of these poison and adhesive recipes and their antiquity in southern Africa (e.g., Bradfield et al. 2015; Wadley et al. 2015; Chaboo et al. 2019), the same is not true for traditional medicines. Most of our knowledge about traditional medicines is derived from early travelogues and ethnographic accounts, with older medicinal remedies being largely inferred from these (Low 2008; Van Wyk 2008). In the absence of archaeological evidence, it is difficult to know how far back in time these traditional medicines date, or indeed how traditional medicines may have changed over time. We do not know whether the use of certain plants has a greater antiquity than others, nor how pre-colonial medicines were administered, nor whether the plants that were used were always pharmacologically effective in the treatments for which they were administered. The presence of plants with medicinal properties in Middle Stone Age deposits (Wadley et al. 2011) suggests that people were aware of these properties, but gives no indication as to whether and to what extent different plant ingredients may have been combined together to create applicative ointments or oral remedies. The recent discovery of a 500-year-old medicine horn in the Eastern Cape has revealed several plant-based ingredients were combined to form a compound recipe (Bradfield et al. accepted). The organic chemistry was identified by means of GC-MS at the Centre for Plant Metabolomics at the University of Johannesburg. Results show that all the identified compounds have medicinal applications, making this the oldest unequivocal evidence in the region for the creation of complex medicines and the use of animal horns to contain them. Horns are known to have been used as medicine containers throughout Africa, although in the southern African context tortoise shell and ostrich eggshell are far more common for this purpose (Marshall 1969, 1999; Lander & Russell 2020). Our knowledge of horn containers derives exclusively from the historical period. Several cattle horn containers from the 19th century are preserved in museums around the world. Snuff containers made from decorated cattle horns collected in 1892 and attributed to the Shona and Sotho are housed in the British Museum (Stephenson no date). Two cattle horn medicine containers, collected in 1871 from southern Tanzania and northern Zimbabwe, were donated to the Harvard Peabody Museum (Moore 1940). A similar medicine horn collected between 1890 and 1930 from the Belgian Congo pops up on a JSTOR search of ethnographic collections in the UK, but no further information is available on this item. Certain San groups in the Kalahari and the Bemba in Zimbabwe used antelope horns as medicine containers. Duiker horns were favoured in the Kalahari to store medicine associated with witchcraft (Guenther 1992), while the Bembe used different antelope horns to store different medicines, preferring duiker and bushbuck (Moore 1940). In neither case were special attributes attached to the horn container itself. At Kruger Cave in the Magliesberg, Mason (1988) described a ~5000-year-old bovid femur that was used as a quiver. Thinking that the sediment in the femur quiver contained poison, Mason removed about 200 mg of sediment and placed it in a jar (accession number 35/83/1439) for future chemical analysis. This was never done. We know that most San poisons used plant materials (Bradfield et al. 2015) and GC-MS is suited to pick up traces of most plant-based compounds (Wooding et al. 2017). A previous attempt to analyse poison from an arrowhead from Kruger Cave proved unsuccessful (Bradfield 2017), but given the recent success with a 500-year-old medicine horn (Bradfield et al. in press), we hope to be able to get results with this pre-removed sample. Despite all the examples of medicine horns we are unaware of any attempts to analyse the contents of the horns to identify what type of medicine they contain, what ingredients were used and which ailments they were intended to cure. This therefore seems to us to be a natural gap in our knowledge of traditional medicines, which we hope to address through a chemical study of the contents of the horn containers at the Ditsong Museum’s ethnographic collections. Methods Approximately 10 mg of powder will be removed from each of the horn containers and the Kruger Cave glass jar and transferred into 2 mL Eppendorf tubes, into which will be added 600 µL high purity mass spectrometry-grade organic solvents for extraction. These solvents are (i) methanol, (ii) acetone and (iii) isopropanol (SpS, Romil, Cambridge, UK). The samples will be vortexed and incubated at room temperature for 5 days to dissolve. Extracts will be analysed on a GC–MS–QP2010 system (Shimadzu, Kyoto, Japan) equipped with an electron impact (EI) ion source and a single quadrupole mass analyser. We use a Restek Rtx 5 MS, diphenyl dimethyl polysiloxane capillary column (30.0 m x 0.25 mm; 0.25 µm thickness) (Leco Africa, Kempton Park, South Africa). Analytes present in the extracts will be separated with temperature gradient programming and detected with mass spectrometry. Chromatographic conditions are as follows: (injection temperature: 250C; oven temperature: 50C, hold time 3.00 min; increase to 300C and hold time 5.00 min, increased at a rate of 25C/min; carrier gas: Helium, flow rate 1.05 mL/min. The MS conditions are as follows: solvent cut of 2 min; detector voltage: 1.39 kV; ion source temp: 200C; interface temp: 250C. The MS data will be acquired in scan mode over a 50 - 350 m/z range with a mass spectral acquisition rate of 1111 u/s. Al samples will be analysed in triplicate and method blanks with methanol, acetone and isopropanol included. Data acquisition will be by means of the GC-MS Solutions software (Shimadzu, Kyoto, Japan). Organic compound identifications are acquired by matching mass spectral data (mass quality cut-off criterion ≥ 80%) to the Wiley Registry / NIST library, ver. 8 (https://sciencesolutions.wiley.com; John Wiley & Sons, Hoboken, NJ, USA) as well as the Flavour & Fragrance Natural & Synthetic Compounds GC-MS library (FFNSC 2, Shimadzu, Kyoto, Japan).