Revisiting past excavations from South-Central Africa: palaeoenvironmental, biomolecular and geochronological analysis to improve archaeological understanding.

The South-Central African region contains many important archaeological and palaeoenvironmental sites, although the chronology of the region is not well understood. Most of the region’s known sites have been excavated over the last 30 years. Since this time, additional biomolecular techniques have been developed, applicable to the region’s fossil material.
A molluscan assemblage was extracted from Pleistocene sediments associated with Palaeolake Kafue, Zambia. Palaeoenvironmental analysis revealed varied past environments with terrestrial, marsh dwelling, and freshwater taxa. The first helicarionid to be listed from Zambia was also identified.
Dating is crucial to elucidate Pleistocene sites and to relate to mammalian (including hominin) evolutionary patterns. The shell of one commonly occurring terrestrial land snail, Achatina spp., was identified from Palaeolake Kafue, and was therefore investigated for its potential for the intra-crystalline protein degradation (IcPD) approach to amino acid geochronology (AAG). The three aragonitic layer (3AL) shell portion was shown to contain an intra-crystalline fraction of protein which appeared to adhere to closed system behaviour, showing predictable patterns of protein degradation. This biomineral therefore has potential for building AAGs across the African continent.
The IcPD approach to AAG was also undertaken on fossil tooth enamel from four taxa (bovid, equid, suid, rhinocerotid) from two Zambian archaeological sites: Twin Rivers and Mumbwa Caves. No direct dating of fossil material had been previously undertaken at Twin Rivers and these analyses revealed the complexity of this hilltop cave site’s depositional history. A potential taxonomic effect was observed in fossil tooth enamel, with differences in peptide chain hydrolysis. This was also indicated by the difference in relative rates of racemisation for two amino acids during forced degradation experiments of Rhinocerotidae in comparison to previously published Elephantidae data. This data therefore demonstrates the need for taxa-specific AAGs from tooth enamel.
Due to the low levels of degradation induced over two years of isothermal heating at 60, 70 and 80 °C, some patterns of protein degradation were difficult to elucidate from IcPD and palaeoproteomic data. It was, however, possible to improve upon the known enamel proteome sequences of woolly rhino. Experimental samples and fossils displayed similar regions of peptide preservation in AMEL, suggesting the heating experiments undertaken in this study may be somewhat reflective of environmental diagenesis. Overall, it is therefore recommended that forced degradation experiments at these lower temperatures be undertaken for a minimum of 10 years to induce sufficient degradation for improved comparative analysis to fossils.
This thesis therefore demonstrates the value of revisiting archival material to improve archaeological understanding with updated palaeoenvironmental, biomolecular and geochronological analyses.