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Reconstructing past vegetation and modern human foraging strategies on the south coast of South Africa
Abstract
The importance of South Africa lies in the many caves and rock shelters containing well preserved evidence of human activity, cultural material complexity and a growing number of early modern human fossils dating to the Middle Stone Age (MSA). South Africa also hosts the world's smallest floral kingdom, now called the Greater Cape Floristic Region (GCFR), with high species richness and endemism. We use phytoliths –amorphous silica particles that formed in epidermal cells of plants–in order to study the evolution of plant exploitation strategies by first modern humans and to understand the response of GCFR environments to glacial-interglacial cycles and rainfall shifts and its implication with the evolution of first modern humans that inhabited the south coast of South Africa during the Upper Pleistocene. In paleoanthropological research, improving our capacity to reconstruct past climatic and environmental conditions can help us to shed light on survival strategies of hunter- gatherers. To do this, one must use actualistic studies of modern assemblages from extant habitats to develop analogies for the past and improve paleoenvironmental reconstructions. Accordingly, this thesis contemplates fossil and modern material: i) archaeological sediment samples from Pinnacle Point 5-6 site (PP5-6) located on the south coast of South Africa; ii) modern plants from the GCFR and susceptible to have been exploited by first modern humans inhabiting the south coast; iii) modern surface soil samples from different GCFR vegetation types of the south coast of South Africa. The modern plant reference collection is the first quantitative and morphological study conducted with wood and leaves of trees and shrubs, leaves, bulb scale leaves and edible part of the bulb of geophytes, restios–Restionaceae and grasses–Poaceae from the GCFR on the south coast of South Africa. We observed that grasses are the highest phytolith producers among plant types. We reported through thin sections and SEM that the characteristic restio phytoliths belong to and characterize the Restionaceae family and have been detected in the parenchyma sheath of the culms. Geophytes did not produce diagnostic phytolith morphotypes that can be used for taxonomic identification what might make difficult their identification in the fossil record. The results of the modern surface soil samples showed that phytolith concentration relates mostly to vegetation types and the dominant vegetation rather than to the type of soils. More abundant phytoliths from Restionaceae and woody/shrubby vegetation are also noted from fynbos vegetation and grass phytoliths are a recurrent component in all the vegetation types in spite of being a minor component in the modern vegetation. The grass silica short cells (GSSCs) from these plants, however, suggest a mix of C3 and C4 grasses in most of the vegetation types with a major presence of the rondels ascribed to C3 grasses. The exceptions are riparian, coastal thicket and coastal forest vegetation, which are characterized by the dominance of C4 grass phytoliths. The study of the modern plants and soils from the surrounding areas of Pinnacle Point were used as proxy for the reconstruction of past human foraging strategies and paleoenvironmental reconstruction through the phytolith record from PP5-6 site. The study of the archaeological sediment samples from this site indicated a wide range of plants used by first modern humans inhabiting the area including wood, leaves and fruits of trees and shrubs, grasses and restios. We reported for the first time the presence of restios in the South African archaeological record through the study of phytoliths. From an environmental perspective, the changes observed in the phytolith record from Pinnacle Point deposits are indicative of vegetation movements accordingly to climate changes and sea level fluctuations, in a continuous regional mosaic of habitats
... We used the classification system followed in Esteban's work (Esteban, 2016;Esteban et al., 2018Esteban et al., , 2017b for homogenizing the data. Accordingly, phytoliths were grouped into 14 categories based plant taxon and phytolith morphology, namely: grasses (Poaceae), restios (Restionaceae), papillae (probably Cyperaceae), spheroid echinates (probably Arecaceae), leaves, wood/bark and fruits of dicotyledonous plants (hereafter e dicots), spheroids (non-decorated surfaces), stomata, epidermal appendages, elongates with and without decorated margins, blocky morphotypes and irregular and indeterminate morphologies. ...
... Unfortunately, the potential of phytoliths to identify Vachellia is limited (e.g. Bamford et al., 2006;Esteban, 2016;Esteban et al., 2017b;Runge, 1996;Schiegl et al., 2004). We propose that people inhabiting Pinnacle Point during MIS 4 would benefit of extensive firewood from both thicket and riparian vegetation occurring on the PAP, and this would have been the source for the wood fuel. ...
The Cape south coast presents some of the world's most significant early modern human sites preserving evidence for complex human behaviour during the Middle Stone Age (MSA), and it is centrally located in the megadiverse Greater Cape Floristic Region. The extinct Palaeo-Agulhas Plain (PAP) once abutted this region, forming an important habitat for the subsistence strategies of past hunter-gatherers during the MSA. Here, we use phytoliths — amorphous silica particles that formed in cells of plants — extracted from archaeological deposits of two sites at Pinnacle Point (PP; cave 13B [PP13B] and site 5–6 [PP5-6]) to investigate the interactions between environments and hunter-gatherer foraging strategies along the Cape south coast during Marine Isotope Stage (MIS) 6 to MIS 3. To do this, we developed an analytical approach built on a modern plant and soil reference collection for using phytoliths from archaeological deposits for palaeoenvironmental reconstructions. In the latter phases of MIS 6, phytoliths indicate shrubby vegetation, possibly limestone fynbos, which might have occurred in inland landscapes, and this was the area preferred for plant foraging practices by the inhabitants of PP13B. During MIS 4, phytoliths at PP5-6 indicate the presence thicket and riparian vegetation on the rocky cliffs and the exposed PAP, along with some type of fynbos vegetation above the actual coastal cliffs. During interglacials MIS 5(c-e) and MIS 3 when the PAP was less exposed, the phytolith record points towards a mosaic of habitats with fynbos and thicket/forest, but also a constant presence of vegetation with high grass content dominated by a mix of both C 3 and C 4 species. Our data suggests a continuous inland regional mosaic of habitats with fynbos, thicket/forest and grassy vegetation that persisted during the glacial-interglacial periods. The changes observed in the phytolith record might be indicative of changes in plant foraging preferences along with slight vegetation movements in accordance with climate changes and sea level fluctuations.
... Finally, part of the phytoliths can be related in particular cases to post-depositional (non-anthropogenic) factors, such as wind, water flow, and animals transport into the cave (Zurro et al., 2016). As an example, phytoliths were successfully used at Pinneacle Point, another South African archaeological site contemporaneous to Klasies River, to provide information about human behaviours and uses of plants, and also to reconstruct the environment in which people were taking their resources (Albert and Marean, 2012;Esteban, 2016). Similarly, several occupation layers from the Klasies River Main Site were investigated for the presence of phytoliths. ...
... Already in 1988, modern grass phytolith data from Klasies River were produced with the aim of using them as a reference tool for interpreting the potential phytoliths that could have been preserved in the cave deposits (Schuurman, 1988); yet no non-grass plant taxa were studied in parallel. In fact, grasses have been indirectly the most studied for phytoliths in South Africa (Cordova, 2013;Cordova and Scott, 2010;Rossouw, 2009;Esteban, 2016;Esteban et al., 2017c). Researchers focused on grass phytoliths to utilise in combination with current rainfall and temperature gradients (Rossouw, 2009;Cordova, 2013), or else with grass photosynthetic pathways (Rossouw, 2009) for reconstructing southern African climate and its variations during the Pleistocene (Rossouw, 2016). ...
The archaeological site of Klasies River is famous for the richness of its Middle Stone Age deposits, which offer the opportunity to document behaviors of early modern humans in Africa, as well as the paleoenvironmental context of their occupation of the area during the late Pleistocene. The Main Site deposits (dated to ca. 115 to 55 ka) include botanical remains such as seeds and charcoal, which suggests that micro-plant particles like phytoliths could also have been deposited. Yet, no phytolith reference collection based on both modern plant and soil material has been produced for Klasies River, which complicates attempts of phytolith analysis of the site's deposits. One of our challenges was therefore to initiate a new and comprehensive phytolith reference collection of modern plants and soils occurring today in the vicinity of Klasies. For this purpose, we processed phytoliths from 24 modern plant specimens and 16 soil samples from different vegetation patches, all located today in a perimeter <5 km² around the Main Site. Our analyses indicate that ovate/orbicular and/or tabular polygonal phytoliths are the most recurrent and abundant morphotypes (>53% and up to 94%) produced in the leaf tissues of the Anacardiaceae, Asteraceae, Celastraceae, Ericaceae, Proteaceae, and Vitaceae species we studied, which are all eudicotyledoneous taxa. Regarding the Cyperaceae, Restionaceae, and one of the Proteaceae species (Leucadendron spissifolium, a fynbos shrub), they each produce distinct phytolith assemblages: the Restionaceae leaf/culm assemblage is dominated by psilate and decorated globular/spheroid phytoliths (94%), whereas the Cyperaceae leaf/culm content and the Proteaceae leaf content are both dominated by silicified papillae (-like) bodies (54% and 63%, respectively). Besides, both globular/spheroid and papillae (-like) phytoliths account for 34% and 8% in the fynbos soil collected. Our analyses also show that ovate/orbicular and/or polygonal phytoliths occur in very small amounts (<2%) in modern soils of the area although they are numerous in most of the eudicotyledoneous leaf tissues we analyzed. Conversely, grass silica short cell phytoliths are found abundantly in the soils collected in close proximity to the Main Site (>66%), where grasses do however occur sparsely in the current vegetation.
... We observed in various samples a robust BLOCKY morphotype that has a blocky polyhedral basal part and an upper conical part that are connected through a concavity with a striate surface ( Fig. 5e and f). This morphotype doesn't resemble any BLOCKY type observed before in South African plants (Esteban, 2016;Esteban et al., 2017b;Murungi, 2017; Esteban and Murungi, from personal experience). Although they do resemble those produced by Commelina seeds (Eichhorn et al., 2010), they are larger in size (height mean, 48 mm; width mean, 58 mm) but with similar height/width ratios of 0.6e1.1. ...
Border Cave is a well-known South African Middle and Early Later Stone Age site located in KwaZulu-Natal. The site has exceptional plant preservation, unparalleled in the African Middle Stone Age archaeological record. This study focuses on the phytolith and FTIR analysis of two Members (2 BS and 2 WA) of the under-documented post-Howiesons Poort occupations dating to~60 ka. These members contain complex successions of vertically overlapping, interdigitating light brown sediments, plant bedding and combustion features of various sizes. The complexity and distinctiveness of these deposits provide an excellent opportunity for the study of plant exploitation strategies and their associated human behaviour. Our taphonomic assessment inferred, through the variability of phytolith properties and minerals composing archaeological layers, that specific occupations suffered more physical weathering than others, for example in the form of trampling. The preservation of fragile and highly soluble phy-toliths (eudicot leaf phytoliths) and the high frequencies of articulated phytoliths indicates that some bedding deposits experienced little disturbance after their deposition. Not all bedding layers dating to ⁓60 ka show, from a phytolith perspective, the same plant composition, which could be explained in terms of changes in human preference for the use of plants over time to construct bedding or because distinct types of living floors are represented. Finally, the systematic application of phytoliths and FTIR to the complex archaeological sequence of Border Cave confirm these analyses can be used in the future to identify bedding deposits not visible to the naked eye, and behavioural patterns obscured by diagenetic or biased processes during sampling.
... We observed in various samples a robust BLOCKY morphotype that has a blocky polyhedral basal part and an upper conical part that are connected through a concavity with a striate surface ( Fig. 5e and f). This morphotype doesn't resemble any BLOCKY type observed before in South African plants (Esteban, 2016;Esteban et al., 2017b;Murungi, 2017; Esteban and Murungi, from personal experience). Although they do resemble those produced by Commelina seeds (Eichhorn et al., 2010), they are larger in size (height mean, 48 mm; width mean, 58 mm) but with similar height/width ratios of 0.6e1.1. ...
Border Cave is a well-known South African Middle and Early Later Stone Age site located in KwaZulu-Natal. The site has exceptional plant preservation, unparalleled in the African Middle Stone Age archaeological record. This study focuses on the phytolith and FTIR analysis of two Members (2 BS and 2 WA) of the under-documented post-Howiesons Poort occupations dating to~60 ka. These members contain complex successions of vertically overlapping, interdigitating light brown sediments, plant bedding and combustion features of various sizes. The complexity and distinctiveness of these deposits provide an excellent opportunity for the study of plant exploitation strategies and their associated human behaviour. Our taphonomic assessment inferred, through the variability of phytolith properties and minerals composing archaeological layers, that specific occupations suffered more physical weathering than others, for example in the form of trampling. The preservation of fragile and highly soluble phy-toliths (eudicot leaf phytoliths) and the high frequencies of articulated phytoliths indicates that some bedding deposits experienced little disturbance after their deposition. Not all bedding layers dating to ⁓60 ka show, from a phytolith perspective, the same plant composition, which could be explained in terms of changes in human preference for the use of plants over time to construct bedding or because distinct types of living floors are represented. Finally, the systematic application of phytoliths and FTIR to the complex archaeological sequence of Border Cave confirm these analyses can be used in the future to identify bedding deposits not visible to the naked eye, and behavioural patterns obscured by diagenetic or biased processes during sampling.
... The morphotype analysis was conducted using the International Code for Phytolith Nomenclature (ICPN, Madella et al., 2005) as well as in reference to Twiss et al. (1969) and Piperno (2006). Morphological groups distinguishing the different organs of the plants (i.e., phytoliths typical to grass leaves/ stems vs. inflorescences) are based on Albert et al. (2003), Regev et al. (2015, Appendix 3), Ramsey et al. (2016) and Esteban Alamá (2016). ...
Technological and social practices can be deciphered by deployment of multiple techniques that have been developed in the last years for the study of sun-dried and heated mud bricks. This research analyzed for the first time the chain of operational processes involved in the manufacture of heated mud bricks in the Neolithic of the Southern Levant. Heated mud bricks (and associated soil/sediment controls) were studied from four Neolithic sites in Israel; the submerged Pre-Pottery Neolithic C (PPNC) site of Atlit-Yam, the coastal PPNC site of Bene Beraq, the submerged late Pottery Neolithic/ Early Chalcolithic (PN/EC) site of Neve Yam and the coastal PN/EC site of 'Ein Asawir. In all sites, the bricks have been found in open areas within the settlements, in semi-circular concentrations of either pits or piles. The bricks have been characterized macroscopically (shape, size, color pattern) and a variety of micro-geoarchaeological techniques have been used to characterize the mud brick materials (and control soils/sediments) from the four sites. These included, Fourier Transform Infrared Spectroscopy (FTIR), Electrical Conductivity (EC), pH analysis, calcite content measurements, Loss on Ignition (LOI), phytolith analysis, and petrography. The results show that all bricks have been produced from sediments from the sites' vicinities. PPNC mud bricks are generally devoid of any type of temper and have been heated to a relatively wide range of high temperatures (600–900 °C) under heterogeneous atmospheric conditions. PN/EC mud bricks are enriched in calcite and include vegetal temper, and have been heated to a relatively narrow range of temperatures (500–700 °C) that is lower than that observed in PPNC mud bricks, and under standard oxidizing conditions. The grass component of temper in the PN/EC bricks may originate from emmer wheat, based on phytolith morphological analysis. Interestingly, FTIR criteria for heated clay minerals preserve underwater for millennia, and so do phytolith assemblages; these observations indicate that micro-geoarchaeological proxies can (and should) be utilized in studies of marine submerged prehistory. Overall, a diachronic perspective on the operational chain of PPNC and PN/EC mud bricks, from raw material procurement through tempering, moulding and firing is provided, which may be translated into developing pyrotechnological practices in light of increasing social complexity during the Neolithic. We propose that purposeful tempering by emmer wheat (agricultural by-products) may be related to socioeconomic factors such as symbolic addition of domestic surplus and that temper diversity in the PN/EC may also mirror sedentary life where domestic waste accumulated on local soil/sediment and thus incorporated into mud bricks. Furthermore, we propose that the more standardized pyrotechnological characteristics of PN/EC bricks are related to increased social control over this skill/craft.
... La identificació i caracterització del conjunt de fitòlits es va fer a partir de la seva comparació amb els resultats de la nostra col·lecció de referència de plantes i sòls moderns (Esteban, 2016;, 2017b, 2017c), així com amb estudis previs de la zona de Sud-àfrica (Rossouw, 2009;Cordova i Scott, 2010;Cordova, 2013;Novello [et al.], 2018;Murungi, 2017), altres regions geogràfiques (Albert i Weiner, 2001;Bamford [et al.], 2006;Tsartsidou [et al.], 2007;Mercader [et al.], 2009;Novello [et al.], 2012;Collura i Neumann, 2017;Albert [et al.], 2016 -disponible a www.phytcore.org) i literatura estàndard (Mulholland i Rapp, 1992;Piperno, 1988Piperno, , 2006Twiss [et al.], 1969). ...
A través de l’estudi de fitòlits (microrestes minerals d’origen vegetal)| la nostra investigació ha detectat diferents patrons i estratègies d’explotació de recursos vegetals per part de poblacions d’humans moderns que van habitar a la costa sud de Sud-àfrica| on es localitza la vegetació extratropical de més diversitat i endemisme| la Gran Regió Floral Capense| durant l’anomenada Middle Stone Age africana| i que de ben segur que va influenciar en el desenvolupament d’un comportament humà modern.
... The morphotype analysis was conducted using the International Code for Phytolith Nomenclature (ICPN, Madella et al., 2005) as well as in reference to Twiss et al. (1969) and Piperno (2006). Morphological groups distinguishing the different organs of the plants (i.e., phytoliths typical to grass leaves/ stems vs. inflorescences) are based on Albert et al. (2003), Regev et al. (2015, Appendix 3), Ramsey et al. (2016) and Esteban Alamá (2016). ...
... Fig. 8B shows the relative percentages of panicoid (bilobate and polylobate), chloridoid (saddles) and festucoid (rondels and trapeziform) short cells separately. Although there are limitations because these short cell morphotypes are not exclusive to each subfamily and are produced in varying concentrations, relative frequencies can give a coarse approximation of grass subfamilies (for a thorough review see recently Esteban, 2016). Approximately half of the archaeological samples (n ¼ 8/18, 44%) and all the reference pellets are dominated by festucoids. ...
This article presents a systematic methodological comparison of three archaeobotanical proxies (phytoliths, pollen and seeds) applied to an assemblage of dung pellets and corresponding archaeological refuse deposits from Early Islamic contexts at the site of Shivta. We set out with three main methodological questions: one, to evaluate the relative input of botanical remains from dung in refuse assemblages; two, to evaluate each archaeobotanical dataset and to test whether they are comparable, complementary or contradictory in their interpretations from dung; and three, infer herding practices at the site during the Early Islamic period. Our findings show that ovicaprine dung accumulated in Early Islamic Shivta during at least two periods: mid-7th–mid-8th centuries CE, and late-8th–mid-10th centuries CE. Methodologically, we see incomplete and incompatible reconstructions arise when each method is considered alone, with each proxy possessing its own advantages and limitations. Specifically, the amount of preserved seeds in dung pellets is low, which restricts statistical analysis and tends to emphasize small or hard-coated seeds and vegetation fruiting season; yet this method has the highest taxonomic power; pollen preserves only in uncharred pellets, emphasizes the flowering season and has an intermediate taxonomic value; phytoliths have the lowest taxonomic value yet complete the picture of livestock feeding habits by identifying leaf and stem remains, some from domestic cereals, which went unnoticed in both seed and pollen analyses. The combined archaeobotanical reconstruction from samples of the mid-7th–mid-8th centuries suggests that spring-time herding at Shivta was based on free-grazing of wild vegetation, supplemented by chaff and/or hay from domestic cereals. For the late-8th–mid-10th century samples, phytolith and pollen reconstruction indicates autumn-winter free-grazing with no evidence of foddering. Unlike the dung pellets, macrobotanical remains in the refuse deposits included domestic as well as wild taxa, the former mainly food plants that serve for human consumption. Plant remains in these refuse deposits originate primarily from domestic trash and are only partially composed of dung remains. The significance of this study is not only in its general methodological contribution to archaeobotany, but also to lasting discussions regarding the contribution of dung remains to archaeological deposits used for seed, pollen and phytolith analyses. We offer here a strong method for determining whether deposits derive from dung alone, are mixed, or absolutely do not contain dung. This has important ramifications for archaeological interpretation.
... The initial interest in phytolith type was focused on their diagnostic potential in plant taxonomy and phytoliths were observed in situ. Study of phytoliths morphotype in grasses and modern plants can be used for the identification of botanical remains in fossil records (Esteban et al., 2016). However, the physiological role of silicon in vascular plants is still an open subject; silicon may act as an essential or a beneficial element depending on the species. ...
Phytoliths are ergastic siliceous substances present abundantly within intercellular spaces as well as inside the cells of numerous plants. Being made up of silica, they are nondegradable and hence found preserved as microfossils in various substrata. This property of phytoliths extends its significance in the field of paleobotany, geology, and archaeology. Soil analysis for eking out phytoliths has been often exercised for reconstructing paleophytogeography of extinct grasslands. Plants accumulate silica and convert them into crystals when their concentration reaches certain maxima. Deciphering the types of phytoliths at historically rich sites, we can predict the culture of ancient farming. Finding such peerless opulence of phytoliths in paleobotany, the present review was designed to compile the data of phytoliths in various plants. The data compiled in this review will help researchers tracing the link between phytoliths and its source plant at the target sites.
Bedding of grass and ashes
The Border Cave site in the KwaZulu-Natal region of South Africa has been a rich source of archaeological knowledge about Stone Age humans because of its well-preserved stratigraphic record. Wadley et al. now report the discovery of grass bedding in Border Cave, dated to approximately 200,000 years ago. The bedding, identified with a range of microscopic and spectroscopic techniques, was mingled with layers of ash. It also incorporated debris from lithics, burned bone, and rounded ochre grains, all of which were of clear anthropogenic origin. The authors speculate that the ash may have been deliberately used in bedding to inhibit the movement of ticks and other arthropod irritants. These discoveries extend the record of deliberate construction of plant bedding by at least 100,000 years.
Science , this issue p. 863
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