Human Impact on Precolonial West Coast Marine Environments of South Africa
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GRBQ335-3427G-C12[279-296].qxd 01-31-2008 01:45 PM Page 279 APTARA(GRG QUARK) 12 Human Impact on Precolonial West Coast Marine Environments of South Africa Antonieta Jerardino, George M. Branch, and Rene Navarro ITH VERY EXTENSIVE, diverse, and ogy to modern society extends beyond its per- W productive coastlines, it is no surprise ceived status as a highly specialized and rather that South Africa offers a superb opportunity to esoteric field (Erlandson and Rick, this volume). understand how marine ecosystems function, As demonstrated below, we also propose that and the effects of people on these environments. this multidisciplinary dialogue benefits the way This prospect is heightened by the realization of coastal archaeological sites are studied, by bring- the tremendous time depth of human occupa- ing a more exhaustive and systematic approach tion, including the first emergence of modern to answering questions, and by highlighting humans in Africa and, by default, in the world their main trait as archives of both human and (Erlandson 2001; Marean et al. 2007). This environmental history. Seen in this perspective, endeavor is multidisciplinary by necessity: the protection, conservation, and management marine ecology and archaeology go hand in of coastal archaeological sites must be a priority hand, along with other closely related specialities as promoted by the current South African her- such as oceanography, geology, and palaeo- itage legislation (National Heritage Resources environmental studies. While ecological studies Act, No. 25, 1999). can provide an understanding of the ecology of In this chapter, we explore the relationship present species, their vulnerability to harvest- that people established with the marine envi- ing, and the way they are influenced by physical ronment on the South African West Coast over factors, archaeology and palaeoenvironmental several millennia. Such effects have frequently studies offer a window into the past where such been demonstrated for terrestrial environments ecological relationships and physical variables worldwide (Redman 1999), but few convincing can be seen changing through time. The result cases have been made for marine systems. A of this multidisciplinary dialogue not only feeds broad account of the long-term precolonial much needed academic debate but also brings human settlement of the West Coast of South new and important dimensions into marine Africa sets the background for a more focused conservation policies and fisheries manage- analysis of selected archaeological sequences in ment. Because of this, the relevance of archaeol- the Lamberts Bay area. An integrated approach 279 GRBQ335-3427G-C12[279-296].qxd 01-31-2008 01:45 PM Page 280 APTARA(GRG QUARK) FIGURE 12.1. Map of the study area showing location of sites and places mentioned in the text. that combines sampling of faunal remains employed to answer questions regarding from archaeological sites, current knowledge of human impacts on marine harvested species: the ecology of the species exploited in the past, not all changes in populations are necessarily and detailed palaeoenvironmental reconstruc- related to the same causes. Consequently, all tions is employed as a powerful tool for unrav- possible lines of evidence and hypotheses eling long-term variability in marine ecosys- deserve serious and equal attention when tack- tems and their responses to human intervention. ling these types of questions. A case is made for human harvesting having been responsible for the local depletion of black PREHISTORIC EXPLOITATION OF mussels and limpets stocks, as reflected by MARINE INVERTEBRATES ON THE WEST shrinking mean sizes at a time when human COAST OF SOUTH AFRICA population densities were peaking and when reliance on marine resources was greatest. A Some of the earliest evidence for the exploita- concurrent decline in rock lobster size for the tion of marine resources in the world is found Lamberts Bay area (Figure 12.1) is interpreted in South Africa, mostly from deeply stratified differently, given the likely resilience of this sequences along the South Coast dating to species to subsistence harvesting and its sus- between 165,000 and 120,000 years BP (Jacobs ceptibility to environmental changes. This adds et al. 2003a, 2003b; Marean et al. 2007; Thack- a note of caution in terms of the methodology eray 1988; Vogel 2001). A few Middle Stone 280 PRECOLONIAL IMPACT IN SOUTH AFRICA GRBQ335-3427G-C12[279-296].qxd 01-31-2008 01:45 PM Page 281 APTARA(GRG QUARK) Age (MSA) West Coast sites confirm that sub- period. Moreover, there are many factors other sistence harvesting is very ancient, including than exploitation that influence the size compo- reasonably well developed shell middens near sition of marine invertebrates, including differ- the towns of Yzerfontein and Saldanha dated to ences or changes in environmental conditions about 70,000 years ago (Klein et al. 2004; Vol- and the intrinsic properties of the species them- man 1978). It is possible that marine resources selves. As shown in this chapter, zonation, were collected before this time too, but many of exposure to wave action, aquatic productivity, these sites are likely to have been washed out and turbidity can profoundly affect the size due to a high sea-level stand before the last composition of limpets and black mussels. It interglacial period around 127,000 years ago also remains to be explained why black mussel (Klein et al. 2004; Parkington 2003). sizes remained relatively constant through time The number of marine species present at despite the facts that (1) the black mussel is the these early MSA sites is similar to that observed most abundant species in MSA and LSA sites, in younger and nearby Later Stone Age (LSA) and (2) rocky-shore mussels are susceptible to sites. Only a few species such as rock lobster overexploitation as reflected by reductions in (Jasus lalandii) and fish are either not present their mean sizes caused by modern subsistence in MSA sites or their presence there cannot be harvesting (Lasiak 1992). Data on early shell- attributed to human agency with certainty. The fish gathering behavior in southern Africa is species diversity, however, appears to differ still preliminary. It needs to be recognized that between MSA and LSA sites (Klein et al. 2004). the number, and at times the size, of available Whether this reflects behavioral or environ- MSA shellfish samples is small when com- mental fluctuations is yet to be established, and pared to those analyzed from LSA sites resolution will require more systematic excava- (Jerardino 1993, 1997, 2007; Jerardino and tion of MSA sites and analysis of larger shell- Yates 1997; Tonner 2005). Thus, more variables fish samples. Another pattern emerging from need to be assessed when explaining the West Coast MSA sites is the significantly larger observed reductions in limpet sizes between mean sizes of at least three limpet species when MSA and LSA sites, and more; as well, larger compared to those of LSA sites (Halkett et al. samples of MSA shellfish are also necessary to 2003; Parkington 2003; Steele and Klein 2005). support any interpretation. No changes in the mean sizes of black mussels A considerable time gap separates coastal (Choromytilus meridionalis), however, are occupation of MSA sites and those of earliest observed in previous comparisons of MSA and LSA age, probably because most, if not all, for- LSA sites. Less-intense harvesting of limpets mer coastal sites dating to this gap were drowned during the MSA due to lower human popula- by rising sea levels, and only a few of these may tion levels at that time, and greater ecological have survived on the Atlantic continental shelf resilience of black mussels have been invoked (Miller 1990; van Andel 1989). Given the to explain these patterns (Klein et al. 2004; focused research efforts in the Elands Bay and Parkington 2003; Steele and Klein 2005). Lamberts Bay areas for the last 30 years (Figure Although this scenario seems plausible, it is 12.1), it is not surprising that the earliest LSA also important to consider other explanations, radiocarbon-dated evidence for the exploitation such as marked differences in the residential of marine invertebrates along the West Coast of permanence of human groups with similar South Africa comes from several caves and shel- population levels during both MSA and LSA ters at these adjacent locations. Shell midden times. In other words, low exploitation pressure horizons appear for the first time in Elands Bay on MSA limpets could well have resulted from Cave and Tortoise Cave around 12,000 and shorter visits by people to the coast, while rela- 7700 BP (all dates presented in this chapter are tively longer visits characterized the latter uncalibrated), respectively (Parkington 1981; PRECOLONIAL IMPACT IN SOUTH AFRICA 281 GRBQ335-3427G-C12[279-296].qxd 01-31-2008 01:45 PM Page 282 APTARA(GRG QUARK) Robey 1987), and well-developed shell lenses vesting along the West Coast of South Africa to dating to ca. 8400 BP have been excavated from have a more solid empirical foundation. Some Steenbokfontein Cave (Jerardino and Swanepoel of these subregions have been sampled and 1999) (Figure 12.1). Bedrock at this latter site is studied more extensively than others, with the far below these deposits, and further excava- Lamberts Bay and Elands Bay area (hereafter tions are likely to uncover older shell lenses. referred to as “the study area”) offering more Early Holocene evidence for shellfish collec- numerous and chronologically deeper se- tion might also be present in Spoegrivier Cave, quences. This chapter presents a case study located about 200 km north of Lamberts Bay, from this particular subregion and attempts to although no radiocarbon dates are yet available ascertain the nature of the interaction between for these basal deposits (Webley 2002). Once humans and their marine environment during sea level transgressed to within a few kilome- the Late Holocene.