Heritage Cases

INTRODUCTION The southern African sub-region provides some of the richest archaeological records for a key phase in human evolution, dating to the Late Pleistocene, when modern humans are thought to have been displaying advanced behaviours, and then dispersed from Africa (i.e. Marean et al. 2014). Multidisciplinary palaeoanthropological work conducted over the last several decades has resulted in an increased knowledge of how climate shifts shaped human behavioural evolution. Major shifts in global climate and environment may have affected past populations in relation to their habitat and the availability of natural resources. The climate of Southern Africa is strongly influenced by the position of the subcontinent in relation to the major circulation systems of the southern hemisphere. Today there are three climate zones: the western Winter Rainfall Zone (WRZ), eastern Summer Rainfall Zone (SRZ) and wedged in between the Year-round Rainfall Zone (YRZ). These zones have shifted, however, in response to long-term variations in the Inter-Tropical Convergence Zone (ITCZ) to a greater or lesser extent, and might have affected the southern Hemisphere in regards to the amount and seasonality of precipitation and changes in temperature. These shifts in climate conditions and the coastlines might have affected the distribution of plant resources and, therefore, human plant exploitation strategies. The study of plant remains from archaeological deposits is relevant to the understanding of the appearance and evolution of complex forager strategies during the Late Pleistocene, and ultimately to the diversification of human landscape adaptations. This project uses phytoliths to investigate changes in environmental conditions and the response to human foraging strategies of past hunter-gatherers’ populations during the critical but poorly documented period of the Last Glacial Maximum and the Last Glacial/Interglacial Transition in the south-eastern coast of South Africa. This project aims to expand previous efforts on the study of plant remains from the Waterfall Bluff deposits by the applicant and colleagues published in 2020 in Quaternary Science Reviews, to investigate 1) the differences in plant preservation conditions across deposits; 2) the distribution of grasses across the site to decipher their possible agent of contribution; 3) detect any changes in the plant phytolith composition that might indicate changes in the local environments such as changes in the distribution of C3 and C4 grasses, Cyperaceae and Restionaceae plants among glacial and interglacial deposits; and 4) comparing the plant phytolith record with other bioarchaeological evidence in order to provide new empirical evidence on the relationship between coastal foraging adaptation and modern human behavioural evolution. BACKGROUND TO WATERFALL BLUFF ROCK SHELTER Excavations at Waterfall Bluff rock shelter in eastern Mpondoland (Eastern Cape Province) have documented the first direct evidence of coastal occupation and coastal foraging during a glacial maximum and across a glacial-interglacial transition in Africa (Fisher et al. 2019). These high-resolution records demonstrate that hunter-gatherers repeatedly visited Waterfall Bluff from ~39,000 years ago until ~11,000 years ago and exploited a wide range of terrestrial and marine plant and animal resources. These studies now provide a rare insight into the lives of those prehistoric people who lived in a persistent coastal environment as the world transitioned from the Pleistocene to the Holocene. Multi-proxy paleoenvironmental analyses has shown that all modern vegetation zones were present in eastern Mpondoland during the LGM, the Last Glacial/Interglacial transition, and the early Holocene (Esteban et al. 2020). Podocarpus/Afrocarpus forests likely grew along the steep riverine slopes, perhaps even on the cliffs around Waterfall Bluff. Thicket and woody vegetation would have grown in other fire-protected areas while dry and hygrophilous grasslands likely dominated the escarpments and much of the continental shelf. At the coast, there would also have been patches of coastal forests. Importantly, each of these habitats would have provided local hunter-gatherer populations with different resources. During the Last Glacial Maximum, the archaeological records from Waterfall Bluff show that hunter-gatherers collected brown mussel (Perna perna), multiple species of limpets, occasional oysters, and also marine fish from estuarine environments. Additionally, charcoal from LGM layers has been taxonomically identified to wood species that grow exclusively in coastal forests, providing yet another tangible link between the rock shelter and the coast (Esteban et al. 2019). The terrestrial fauna from LGM layers includes Eland (Tragelaphus onyx) and common duiker (Sylvicapra grimmia), both of which are found today in mixed habitats that point to a mosaic environment around the shelter at that time. Paleoenvironmental proxies suggest that open habitats expanded during the Last Glacial / Interglacial transition at the expense of woody / forested vegetation (Esteban et al. 2019). This trend continued into the Early Holocene with locally warm and humid conditions in coastal Mpondoland. Evidence for coastal intertidal foraging increases at this time, but the species representation still suggests a focus on local estuarine environments where fish and shellfish could be collected. The terrestrial fauna show that hunter-gatherers continued to exploit a variety of habitats. Southern reedbuck (Redunca arundinum) remains point to grassier environments and permanent sources of water whereas bushbuck (Tragelaphus scriptus), African buffalo (Syncerus africanus), and bontebok/blesbok (Damaliscus pygargu) would have preferred bushier environments. The remains of mountain reedbuck (Redunca fulvorufula) and grey rhebok (Pelea capreolus) further indicate exploitation of rocky steep-sloped habitats, like those found along the numerous major river drainages in the region today whereas blue duiker (Philantomba monticola) and vervet monkey (Ceropithecus pygerythrus) remains would have been commonly found in forests or thickets. Taken together, the archaeological, archaeobotanical, and zooarchaeolgoical data from Waterfall Bluff suggests that coastal hunter-gatherers exploited a variety of habitats throughout the Late Pleistocene and into the Early Holocene. MATERIALS The materials to study are 64 sediment samples from various Stratigraphic Aggregates dating from Marine Isotope Stage 3 to the Early Holocene. METHODOLOGY Phytoliths, silica remains formed in plants, are a useful tool for plant identification in fossil records. Phytolith extraction will be carried out at the University of Barcelona following standard extraction procedures. An initial sediment weight of between 30 and 50 mg will be required. Carbonate minerals will be dissolved by adding 50 µl of hydrochloric acid. 450 µl of 2.4 g/ml sodium polytungstate solution is then added. The tube is vortexed, sonicated and centrifuged for 5 min at 5000 rpm. The supernatant is subsequently removed to a new 0.5 ml centrifuge tube, vortexed and 50 µl placed into a microscope slide for their microscopic analysis.