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Abstract

The large mammalian fauna of southern Africa is characterised by strong niche separation into grazer and browser species, with few falling into the intermediate mixed-feeder niche. Moreover, the modern fauna is reduced in species diversity compared to the Pleistocene, following the extinction of several specialized grazers in the late Pleistocene and early Holocene. How did this state develop, and how might it be connected to climatic change during the Holocene? To better understand this development, we obtained extensive carbon and oxygen stable light isotope data from herbivore tooth enamel samples from Wonderwerk Cave, South Africa, spanning about 12,000e500 cal. BP. This is a unique dataset since it is the only site in the southern Kalahari with a robust chronometric record and well-preserved faunal remains for the last 12,000 years without significant gaps. Combining the stable isotopes with pollen and micromammal data from Wonderwerk Cave, we have explored shifts in the proportions of C 3 and C 4 plants and moisture availability. Although climate remained generally semi-arid for much of this period, the results show significant hydrological and vegetation shifts in the sequence, particularly with the strengthening of summer rainfall in the mid-Holocene. The results for the sixteen herbivore species reveal a reinforcement of the grazer-browser niche partitioning through the Holocene and shows how niche specialization follows changes in local vegetation composition. In the light of this reconstruction of the local ecology we discuss grazer extinctions, human adaptations, and the drivers behind climatic changes in the summer rainfall zone of southern Africa.

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... Wonderwerk Cave (27 • 50.787 ′ S, 23 • 33.231 ′ E) contains long archaeological and palaeoenvironmental records spanning close to two million years. It produced fossil fauna, art mobilier (Beaumont, 1990(Beaumont, , 2004Butzer, 1984aButzer, , 1984bThackeray et al., 1981), some of the earliest evidence for the use of fire, macro-botanical and phytolith records Chazan et al., 2012;Rossouw, 2016;Ecker et al., 2018). Pollen was only preserved in the late Pleistocene and Holocene layers (Strata 2-4) and derived from: i) sixteen sediment samples (van Zinderen Bakker, 1982;Scott and Thackeray, 2015), ii) thirty-two stalagmite samples, and iii) six hyrax dung samples. ...
... Both the Wonderwerk and Equus Cave pollen records indicate warm conditions with Savanna vegetation in the region from 11 ka onwards peaking at c. 8 to 5.6 ka. However, the development of moisture is less clear with most sites showing variations that cannot always be easily correlated due to low resolution of the records (Lee- Thorp and Ecker, 2015;Ecker et al., 2018). At Wonderwerk Cave, tooth enamel isotopes suggest weak tropical grass cover (Thackeray and Lee-Thorp, 1992) and the relatively high Asteraceae pollen content supports this (Scott and Thackeray, 2015). ...
... At Wonderwerk Cave, more than one proxy indicates moisture increase by 5.5 ka (Thackeray and Lee-Thorp, 1992;Lee-Thorp and Ecker, 2015;Scott and Thackeray, 2015;Ecker et al., 2018) that lasted until about 2.8 ka (Fig. 7B). At the sinkhole fill of Kathu Pan to the west, the pollen data suggest an early dry event at 5.1 ka that shifted to varying conditions later. ...
Article
We have reassessed the palynological record of Equus Cave in the Savanna Biome of the southern Kalahari, one of the longest Late Quaternary pollen records for the semi-arid central interior of South Africa. We combined published pollen results from the cave, derived from hyena coprolites and the rubified deposits in which they occur, into a single sequence. By re-considering the chronology of this sequence, we critically evaluated the palaeoenvironmental record for the site. We compared the pollen evidence from Equus Cave to that from the longer Wonderwerk Cave records (stalagmite, sediments and dung), also located in the Savanna Biome. Then, we contrasted Equus and Wonderwerk records with other previously published pollen sequences derived from a range of sources from several sites in central South Africa. These sites follow a broad northwest to southeast transect of c. 500 km through the Grassland and Nama Karoo Biomes of the Free State and Eastern Cape. Applying Principal Components Analysis to the pollen data, we derived climatic signals at a regional scale to refine reconstructions of Late Quaternary changes for central South Africa.
... Wonderwerk Cave (27 • 50.787 ′ S, 23 • 33.231 ′ E) contains long archaeological and palaeoenvironmental records spanning close to two million years. It produced fossil fauna, art mobilier (Beaumont, 1990(Beaumont, , 2004Butzer, 1984aButzer, , 1984bThackeray et al., 1981), some of the earliest evidence for the use of fire, macro-botanical and phytolith records Chazan et al., 2012;Rossouw, 2016;Ecker et al., 2018). Pollen was only preserved in the late Pleistocene and Holocene layers (Strata 2-4) and derived from: i) sixteen sediment samples (van Zinderen Bakker, 1982;Scott and Thackeray, 2015), ii) thirty-two stalagmite samples, and iii) six hyrax dung samples. ...
... Both the Wonderwerk and Equus Cave pollen records indicate warm conditions with Savanna vegetation in the region from 11 ka onwards peaking at c. 8 to 5.6 ka. However, the development of moisture is less clear with most sites showing variations that cannot always be easily correlated due to low resolution of the records (Lee- Thorp and Ecker, 2015;Ecker et al., 2018). At Wonderwerk Cave, tooth enamel isotopes suggest weak tropical grass cover (Thackeray and Lee-Thorp, 1992) and the relatively high Asteraceae pollen content supports this (Scott and Thackeray, 2015). ...
... At Wonderwerk Cave, more than one proxy indicates moisture increase by 5.5 ka (Thackeray and Lee-Thorp, 1992;Lee-Thorp and Ecker, 2015;Scott and Thackeray, 2015;Ecker et al., 2018) that lasted until about 2.8 ka (Fig. 7B). At the sinkhole fill of Kathu Pan to the west, the pollen data suggest an early dry event at 5.1 ka that shifted to varying conditions later. ...
Article
We have reassessed the palynological record of Equus Cave in the Savanna Biome of the southern Kalahari, one of the longest Late Quaternary pollen records for the semi-arid central interior of South Africa. We combined published pollen results from the cave, derived from hyena coprolites and the rubified deposits in which they occur, into a single sequence. By re-considering the chronology of this sequence, we critically evaluated the palaeoenvironmental record for the site. We compared the pollen evidence from Equus Cave to that from the longer Wonderwerk Cave records (stalagmite, sediments and dung), also located in the Savanna Biome. Then, we contrasted Equus and Wonderwerk records with other previously published pollen sequences derived from a range of sources from several sites in central South Africa. These sites follow a broad northwest to southeast transect of c. 500 km through the Grassland and Nama Karoo Biomes of the Free State and Eastern Cape. Applying Principal Components Analysis to the pollen data, we derived climatic signals at a regional scale to refine reconstructions of Late Quaternary changes for central South Africa.
... However, the paucity of long-duration terrestrial paleoecological archives from the interior of southern Africa, exacerbated by a lack of overall research focus in this region (compared to, for example., the coastal belt) has limited the opportunity to apply such methods. Furthermore, this affects our ability to reconstruct high precision regional vegetation and climatic patterns through time for this region (Ecker et al., , 2018Scott et al., this volume). Wonderwerk Cave, located 45 km south of Kuruman, in the South African Northern Cape is an exception to this pattern. ...
... More recent analyses of finds recovered from these excavations have yielded important and interesting insights into the paleoecology of the LSA period (e.g. Brook et al., 2010;Brook et al., 2015;Lee-Thorp and Ecker, 2015;Scott and Thackeray, 2015;Thackeray, 2015b;Bamford, 2016;Ecker et al., 2018;House et al., this volume). However, these studies are inherently limited by the low-resolution nature of the provenience data collection methods common at the time of excavation. ...
Article
In 2018, we initiated renewed excavation of the Later Stone Age (LSA) deposits at Wonderwerk Cave. Here we describe the goals and initial results of the first two seasons of excavation, including the first micromorphological description of these deposits. We employed a small-scale excavation technique to emphasize precision recording and limit the destruction of sensitive deposits. Our preliminary results indicate that meaningful patterns in material culture records and paleoecological proxy materials can be derived from such investigations. Bioturbation of the LSA deposits is widespread in our micromorphological samples, suggesting that some post-depositional movement of the sediment occurred but did not impact overall stratigraphic integrity. This is supported by the radiocarbon chronology (derived from various material records), which indicates that this movement had a limited effect on the material record. Three technocomplexes (the Kuruman/Oakhurst, Wilton, and Historic) were identified in the new Wonderwerk lithic material record, alongside increasing evidence for a period of intensified use and/or occupation of the site during the Wilton – a pattern previously identified by the F. Thackeray's and A. Thackeray's 1970s excavations. New radiocarbon ages support previous determinations placing the timing of this intensification at ca. 6200 years cal BP. Faunal and ostrich eggshell records also support previous findings, confirming an anthropogenic origin for the faunal remains and suggesting that different pathways of OES bead production were employed at the site at different times. The presence of herbivore dung and associated spherulites in a micromorphology thin section provides a new potential line of evidence to support the Thackeray's tentative suggestion for sheep herding at the site ca. 2000 years BP. While this evidence is far from conclusive, it suggests that the Wonderwerk Cave LSA record may have a role to play in resolving the timing of the adoption of sheep by hunter-gatherers on the Ghaap Plateau. Our work on the LSA at Wonderwerk Cave serves as a touchstone within the more regionally focused Northern Cape Archaeology and Ecology Project (NCAEP) – an international and interdisciplinary research project studying the LSA paleoenvironment of the South African arid interior. Ultimately, NCAEP is designed to produce a multi-proxy diachronic climatic record of the Northern Cape firmly situated within new and existing radiocarbon chronologies.
... This is corroborated by stable isotope and other climate proxies that were examined for the Holocene layers in the cave (e.g. Scott and Thackeray 2015;Lee-Thorp and Ecker 2015;Ecker et al., 2018a). Low δ 18 O values in tooth enamel and ostrich eggshells, as well as grass short cell phytoliths, in Strata 11-10 indicate less strong seasonality in rainfall as opposed to the regime of predominantly summer rainfall observed in the Holocene. ...
... Stratum 10, constrained to ~1 Ma, further includes the identification of clay and silt balls within the sediment, indicating the presence of lakes and pans in proximity to the cave (Goldberg et al., 2015). Although the resolution at Wonderwerk Cave is not high enough to attribute strata to discrete glacial or interglacial periods, the long-term trend is a shift from C 3 -to C 4 -dominated landscapes, culminating in the near-total dominance of C 4 grasses in the Holocene Ecker et al., 2018a). ...
Article
When considering the pan-African process of human evolution in the Pleistocene it is important to review our understanding of climate on a regional scale, including heterogeneity due to regional variability in the relative strengths of forcing mechanisms. Research in the Kuruman Hills at the southern edge of the Kalahari in South Africa has recently provided new insights into the complexity and distinctiveness of southern African palaeoclimate. Here we compare these records, obtained from Kathu Pan, Wonderwerk Cave, and Mamatwan Mine, focusing on the presence of water bodies from c. 2 million years before present to the end of the Pleistocene. Through the synthesis of multiple proxies we create a picture of localized water availability as it would have affected hominin adaptation. These records are then framed within a larger discussion of regional climate and environmental change. The emerging record from the southern Kalahari suggests that the distribution of zones of rainfall seasonality varied significantly throughout the Pleistocene and a hominin presence is particularly found in association with wetter phases which supported lakes, springs and pans.
... These wet conditions did not reach the Kalahari as the cenotes in the Otavi Mountains (S10) are not affected (Brook et al., 1999). The dry conditions at Omongwa Pan in the early Holocene are consistent with dry conditions at surrounding sites and at Wonderwerk Cave (S4, Ecker et al., 2018;Scott and Thackeray, 2015). Changes in the late Holocene (< 4 ka) at Omongwa Pan correspond to wet conditions at Drotsky's Cave, Wonderwerk Cave, and at Lake Ngami (Brook et al., 1998;Brook et al., 1996;Brook et al., 2015;Cordova et al., 2017;Ecker et al., 2018;Scott and Thackeray, 2015). ...
... The dry conditions at Omongwa Pan in the early Holocene are consistent with dry conditions at surrounding sites and at Wonderwerk Cave (S4, Ecker et al., 2018;Scott and Thackeray, 2015). Changes in the late Holocene (< 4 ka) at Omongwa Pan correspond to wet conditions at Drotsky's Cave, Wonderwerk Cave, and at Lake Ngami (Brook et al., 1998;Brook et al., 1996;Brook et al., 2015;Cordova et al., 2017;Ecker et al., 2018;Scott and Thackeray, 2015). In conclusion, the climate of Omongwa Pan since the Late Pleistocene strongly depends on the expansion and the precipitation intensity of summer rainfall. ...
Article
Conventional continental geoarchives are rarely available in arid southern Africa. Therefore, palaeoclimate data in this area are still patchy and late Quaternary climate development is only poorly understood. In the western Kalahari, salt pans (playas, ephemeral lakes) are common and can feature quasi-continuous sedimentation. This study presents the first climate-related biomarker record using sediments from the Omongwa Pan, a Kalahari salt pan located in eastern Namibia. Our approach to reconstruct vegetation and hydrology focuses on biogeochemical bulk parameters and plant wax-derived lipid biomarkers (n-alkanes, n-alkanols, and fatty acids) and their compound-specific carbon and hydrogen isotopic compositions. The presented record reaches back to 27 ka. During the glacial, rather low δ²H values of n-alkanes and low sediment input exclude a strong influence of winter rainfall. n-Alkane and n-alkanol distributions and δ¹³C values of n-hentriacontane (n-C31) indicate a shift to a vegetation with a higher proportion of C4 plants at the end of the Last Glacial Maximum until the end of Heinrich Stadial I (ca. 18–14.8 ka), which we interpret to indicate an abrupt excursion to a short wetter period likely to be caused by a temporary southward shift of the Intertropical Convergence Zone. Shifts in δ²H values of n-C31 and plant wax parameters give evidence for changes to drier conditions during early Holocene. Comparison of this dataset with representative continental records from the region points to a major influence of summer rainfall at Omongwa Pan during the regarded time span and demonstrates the potential of southern African salt pans as archives for biomarker-based climate proxies.
... Ma) assemblages 6 (Extended Data Fig. 1) or to substantial changes in the diet of A. africanus over time in response to the substantially changing South African ecosystems of the early Pleistocene (about 2.3-2.1 Ma) 11,12 . Although seasonal changes in ecosystems dominated by tropical grassland (frequently referred to as the savannah biome) are associated with only minor variations in temperature, important oscillations in rainfall produce lengthy dry and wet periods 13 . This has a considerable effect on food availability, and leads to long alternating periods of abundance and scarcity of nutritious food. ...
... This cyclical rhythm of dry open grassland in winter and wet blooming woodland in summer has prompted mammals to adapt either by undertaking long annual migrations to more-clement regions or by adopting seasonal strategies in food consumption, including the use of fall-back resources (which have poor nutritional values, and are eaten only when preferred foods are scarce or unavailable) 14,15 . This climatic cycle has consequences for the physiological (for example, nursing, reproduction and infant development) and ecological (for example, diet, grouping of individuals and territory size) behaviour of endemic species-particularly for non-migrating individuals [13][14][15] . ...
Article
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Reconstructing the detailed dietary behaviour of extinct hominins is challenging¹—particularly for a species such as Australopithecus africanus, which has a highly variable dental morphology that suggests a broad diet2,3. The dietary responses of extinct hominins to seasonal fluctuations in food availability are poorly understood, and nursing behaviours even less so; most of the direct information currently available has been obtained from high-resolution trace-element geochemical analysis of Homo sapiens (both modern and fossil), Homo neanderthalensis⁴ and living apes⁵. Here we apply high-resolution trace-element analysis to two A. africanus specimens from Sterkfontein Member 4 (South Africa), dated to 2.6–2.1 million years ago. Elemental signals indicate that A. africanus infants predominantly consumed breast milk for the first year after birth. A cyclical elemental pattern observed following the nursing sequence—comparable to the seasonal dietary signal that is seen in contemporary wild primates and other mammals—indicates irregular food availability. These results are supported by isotopic evidence for a geographical range that was dominated by nutritionally depauperate areas. Cyclical accumulation of lithium in A. africanus teeth also corroborates the idea that their range was characterized by fluctuating resources, and that they possessed physiological adaptations to this instability. This study provides insights into the dietary cycles and ecological behaviours of A. africanus in response to food availability, including the potential cyclical resurgence of milk intake during times of nutritional challenge (as observed in modern wild orangutans⁵). The geochemical findings for these teeth reinforce the unique place of A. africanus in the fossil record, and indicate dietary stress in specimens that date to shortly before the extinction of Australopithecus in South Africa about two million years ago.
... The sites are ordered from oldest to youngest. The full site names are left to right: Sterkfontein Member 4 , Haasgat Cave , Swartkrans Member 2 (Lee- Thorp et al., 2000;Steininger, 2012), Cornelia-Uitzoek (Codron et al., 2008), Wonderwerk Cave Stratum 7 (Ecker et al., 2018b), Florisbad Spring (Codron et al., 2008), Florisbad Old Collection (Lee-Thorp, 1989, Equus Cave Stratum 2b, Equus Cave Stratum 2a, Equus Cave Stratum 1b (all Lee-Thorp and Beaumont, 1995), Wonderwerk Cave Stratum 5 (Ecker et al., 2018b), Swartkrans Member 5 (Lee- Thorp, 1989), Wonderwerk Cave Stratum 4c (Ecker et al., 2018a). Error bars are standard derivations. ...
... Several palaeoenvironmental studies showed vegetation changes in the early and mid-Holocene, including less grass percentage in the vegetation in the early Holocene compared later (e.g. Scott and Lee-Thorp, 2004;Scott et al., 2012;Ecker et al., 2018a). The change in grasslands combined with the loss of larger grazers facilitating access to new growth for A. bondi have been suggestion as reason for its extinction (Brink and Lee-Thorp, 1992). ...
Article
Full-text available
The common springbok (Antidorcas marsupialis), with its characteristic dorsal fan and stotting movement is the national animal of South Africa. In the Pleistocene, this species shared the subcontinent with the extinct Bond's springbok (Antidorcas bondi), and differences in their ecological relationship has been of long-standing interest to palaeontologists. Brink (1987) proposed that Bond's springbok, as a characteristic species for the Florisian Land Mammal Age, was an essential part of a Pleistocene grazing community that likely occupied open grasslands in the interior. This niche contrasts markedly with the flexible browsing habits of the extant springbok, which can tolerate arid habitats. Here we revisit the dietary ecological history of A. bondi by means of published species distribution data through time, and carbon stable isotope data. The results suggest that its specialist grazing ecology remained stable from the Mid-Pleistocene onwards until its extinction in the early Holocene (c. 8-10ka). The results are discussed in the context of Pleistocene palaeoenvironmental change in southern Africa.
... There may be some evidence of faunal change in response to the mid-Holocene altithermal, a warm period between 7 and 5 ka (Fitchett, 2019). At Wonderwerk Cave, grazer abundance and isotopic data show that the expansion of grasslands there reached a maximum around 6 ka (Thackeray and Lee-Thorp, 1992;Thackeray, 2015) with isotopic analyses of equid teeth indicating a shift from dryer to wetter conditions in the mid-Holocene (Thackeray, 2015;Ecker et al., 2018). There is also evidence of more moisture at Toteng in Botswana in the mid-Holocene (Robbins et al., 2008). ...
Article
Analyses of faunal remains are a key means of inferring palaeoenvironmental change. In this paper, the use of faunal remains as a proxy for environmental conditions from Marine Isotope Stage 6 to the Holocene in southern Africa is reviewed. The focus of this review is on large herbivore abundance and how these fluctuate temporally and regionally in accordance with palaeo-climatic shifts. Here, southern Africa is divided into four eco-regions loosely based on climatic, biotic and zoogeographic traits: the Cape Floristic Region, the arid and semi-arid region, the savanna and grassland region, and the wetter eastern region. The relative abundance of large herbivores within these regions are noted, and temporal trends are inferred. On the whole, most eco-regions maintain similar herbivore compositions over time showing the regional ecological resilience of these taxa to local-scale environmental change. Yet some changes in faunal frequencies are apparent. The Cape Floristic Region shows evidence of significant faunal turnover from the Late Pleistocene to the Holocene. Here, grazers are significantly more abundant during glacial periods, probably linked to the terrestrial expansion of the palaeo-Agulhas coastal plain. Shifts in ungulate abundance in the currently xeric central interior, also indicate wetter periods in the Pleistocene. Holocene faunas are generally similar to historic distributions but shifts between xeric and mesic periods are also evident.
... Fluctuations in the water table supporting doline sediment infill resulted in sinkhole formation that exposes sedimentary sequences in nine localities that include Pleistocene and Holocene components with archaeological evidence of hominin activity and associated faunal remains (Lukich et al., 2019(Lukich et al., , 2020Porat et al., 2010). The only other relevant Holocene paleoclimatic records from the region are found at Wonderwerk Cave, approximately 50 km to the southeast of Kathu Pan (Humphreys and Thackeray, 1983;Beaumont et al., 1984;Berna et al., 2012;Chazan et al., 2012;Ecker et al., 2018aEcker et al., , 2018bBrook et al. 2010Brook et al. , 2015. ...
Article
In this study we investigate the timing and nature of moisture availability in the Late Holocene by examining a multiproxy paleoenvironmental record from Kathu Pan at the southern edge of the Kalahari. In a region where organic proxy records are scarce, Kathu Pan provides a unique record of changes in past environmental conditions. Pollen, spore, charcoal, and stable isotope records were obtained from organic deposits at Kathu Pan and examined within a radiocarbon-constrained chronological framework. The Kathu Pan record registers a relatively moist phase occurring between 4.8 ka and 2.5 ka cal BP. Local environmental conditions at Kathu Pan shift gradually beginning around the terminal Northgrippian ∼4.8 ka cal BP. Kathu Pan reaches maximum moisture availability with marsh-like conditions signaled by increased organic content, dominance of Cyperaceae pollen, presence of freshwater fungi, and δ13C values consistent with local C3 vegetation, around the inception of the Meghalayan Stage, although due to uncertainties in the age-depth model these changes may have taken place 1–2 centuries on either side of the formal date for the onset of the Meghalayan at 4.2 ka cal BP. This interval also corresponds with the highest charcoal concentrations, indicating the importance of adequate moisture conditions to support the growth of biomass which eventually becomes a fuel source. The moist phase lasts ca. 2000 years until a hypothesized shift to arid conditions occurs c. 2.5 ka cal BP leading to a change in local hydroclimate that may have terminated the accumulation of organic-bearing sediments.
... Changing proportions of micromammals further indicate a shift to less arid environments in stratum 11 compared to stratum 12, potentially as a result of changing rainfall patterns 11 . Mean enamel δ 18 O values across all sampled species, reflecting animal water intake and physiology (Supplementary Information), are generally below 36‰, considerably lower than throughout the Holocene for the same species 12 (Fig. 2 ...
Article
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The influence of climatic and environmental change on human evolution in the Pleistocene epoch is understood largely from extensive East African stable isotope records. These records show increasing proportions of C4 plants in the Early Pleistocene. We know far less about the expansion of C4 grasses at higher latitudes, which were also occupied by early Homo but are more marginal for C4 plants. Here we show that both C3 and C4 grasses and prolonged wetlands remained major components of Early Pleistocene environments in the central interior of southern Africa, based on enamel stable carbon and oxygen isotope data and associated faunal abundance and phytolith evidence from the site of Wonderwerk Cave. Vegetation contexts associated with Oldowan and early Acheulean lithic industries, in which climate is driven by an interplay of regional rainfall seasonality together with global CO2 levels, develop along a regional distinct trajectory compared to eastern South Africa and East Africa.
... In this paper we deal with pollen-derived Pleistocene palaeoenvironments of Southern Africa, namely the period in which important steps in the early evolution of our genus Homo took place under marked global climatic cycles that ended before the current warm phase, viz., the Holocene, and which included interstadials and glacial stages. Complex climate and cultural changes place the Holocene beyond the scope of this review and it is discussed in separate studies Ecker et al., 2018). Earlier time periods such as the Neogene are also excluded from this study because the evidence of marked changes that have been found in the south-western Cape from these periods cannot be associated with the peopling of South Africa (Coetzee and Rogers, 1982;Roberts et al., 2017). ...
Article
An investigation of the vegetation and climate from the Middle Pleistocene until the end of the Late Pleistocene reveals a plethora of terrestrial and marine biological, geological and archaeological evidence for marked and complex climate cycles of change, which reflect on past circulation patterns. While acknowledging the usefulness of diverse proxies for detecting these changes, an efficient way to summarize past events is to focus on one of them, viz. fossil pollen, which, although providing scattered and incomplete records, gives fairly direct reflections of past climates and vegetation growth. The findings are structured according to six subregions and reveal distinct changes in temperature and moisture patterns, e.g. during the Last Glacial Maximum (LGM) and the Younger Dryas. The data suggest an environmental background against which cultural evolution took place, e.g., the appearance of Fauresmith, Still Bay, Howiesons Poort and Later Stone Age lithic industries. The pollen archives can be associated with global climate changes, as recorded in isotopes in marine sequences (Marine Isotope Stages or MISs). The observations show differences between regions, which can serve as a base for improving palaeo-data to eventually simulate past and future climates and to better understand the role of past global climates in relation to human and animal occupation in Southern Africa.
Article
Establishing body mass from skeletal remains of an animal is of importance to researchers in the fields of ecology, palaeontology and archaeozoology. Establishing such standards requires that different body parts follow allometric growth curves, and that one can access a sufficiently large sample of individuals of known size and weight for the target species. Here, we have used data collected from modern living and dead leopard tortoises Stigmochelys pardalis (Bell, 1928Bell, 1928), to reconstruct body size and mass from measurements taken on individual postcranial bones. The results show high correlations in both mass and size for various dimensions taken on most skeletal elements, enabling reconstruction of these parameters from individual skeletal measurements. To highlight the application of such data to fossil fauna, allometric equations derived from regression analyses of the modern animals were applied to a sample of Later Stone Age (ca. 14,000 BP to present) leopard tortoise remains from Wonderwerk Cave located in the central interior of South Africa. Results for this archaeological sample show significant changes in size and body mass over time. These best correlate with shifts in paleoenvironmental conditions rather than with anthropogenic pressures that has commonly been implicated in size reduction or biased sex ratios in tortoise populations.
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As described in Part 1 & 2 (Private Game Issue 1 & 2), Earth’s path follows a sequence of natural oscillations effecting global dynamics of constant vegetation and habitat change. Consequently, phyllo-biogeographic existence and evolution (distribution, performance, genetic integrity, survival, and speciation trades) of animal species are affected. Animals move, adapt, or die as a result of changing environmental conditions. The conservation applications of palaeozoological data are numerous (Lyman 2006). One such application concerns the determination whether or not a species is native to a region. Such insight is essential to informing species translocations and to restoring biodiversity in disturbed habitats.
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This study investigates the mid-Pleistocene paleoenvironment and dietary behaviour of ancient herbivores in the South African central interior, today part of the semi-arid Kalahari savanna. Analyses were undertaken of carbon (δ¹³C) and oxygen (δ¹⁸O) stable isotopes in tooth enamel carbonate of twelve fossil herbivore species from Layers 4b and 4a, associated with Earlier Stone Age (ESA) and transitional ESA-Middle Stone Age (Fauresmith) industries respectively, at the archaeological site of Kathu Pan 1. The data are compared with other early to mid-Pleistocene herbivore assemblages located in the central interior, namely Cornelia-Uitzoek, Wonderwerk Cave and the Florisbad Spring. Results indicate that the median δ¹³C values for all ungulate taxa at Kathu were >-4‰, indicating predominantly C4 based diets, although in certain taxa, some individuals included a significant C3 component in their diet. The δ¹⁸O values of most of species at Kathu were relatively low, suggesting a cooler and/or wetter climate. Carbon isotope evidence for C4 dominated habitats at Kathu, but with a larger C3 component amongst grazers than today, resembles the other early to mid-Pleistocene assemblages in the region. Similarly, δ¹⁸O values for Kathu supplement existing evidence that the region was substantially wetter than in modern times.
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This paper presents the first insight into the interpretation of the wood charcoal from the Holocene layers of Wonderwerk Cave. Situated in the Northern Cape Province in the arid interior of South Africa, the site provides a unique and valuable chronological record of past environmental fluctuations and responding human behavioural adaptations spanning the last two million years. The Holocene strata have been dated to cover the last 12.5 ka cal BP years, but exclude the last 100 years because of contamination. A sizeable amount of charcoal was recovered from these strata and remnants have been identified, described and the species composition amongst the strata compared. Most identified species are those that tolerate hot, dry conditions, signalling an arid trend during the Holocene. Comparison with present day species distributions suggests an eastwards shift in modern vegetation. The charcoal data also indicate that during the mid Holocene there was a wetter period from 6.2 to 4.5 ka cal BP, coinciding with stratum 4a.
Article
Several studies have highlighted the importance of collecting well-dated records of palaeoenvironmental changes on desert margins, particularly in the semi-arid interior of southern Africa. Here we describe sediments at three sites in Kathu Pan, a pan complex overlying karstic bedrock at the southern edge of the Kalahari Basin. Sinkholes have exposed sedimentary sequences dating back to the Pleistocene, making it possible to document multiple palaeoenvironmental regimes in this landscape. Using a multi-analytical sedimentological approach, including micromorphology, energy dispersive X-ray spectrometry, electron microprobe, loss-on-ignition, laser diffractometry and luminescence dating, we demonstrate that the sediments at Kathu Pan represent an environment fluctuating among a number of thresholds for accumulation of different kinds of transported and authigenic sediments. Within the Pleistocene sands at the base of our studied sedimentary sequence, the presence of palygorskite, indicative of less extreme evaporative control, represents a semi-arid environment from 156 ± 11 ka to 32 ± 2 ka (Marine Isotope Stages 6–3). Increased moisture availability at 84 ± 4 ka and at 96 ± 5 ka (possibly during Marine Isotope Stages 5a and 5c, respectively) is reflected in the sands by the formation of palygorskite in concert with the deposition and oxidation of organic material. As the climate became increasingly arid, possibly in response to global cooling during the Last Glacial Maximum (21 ± 2 ka), Kathu Pan crossed a threshold, and deposition of CaCO3 dominated over that of palygorskite. In the Holocene beds within our studied unit, alternating CaCO3- and organic-dominated deposits, sometimes in very fine laminae, reflect an increase in the amplitude of either seasonal or annual changes in water availability.
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Wonderwerk Cave has yielded one of the longest and most complete Holocene Later Stone Age (LSA) records for the arid interior of South Africa. This paper presents the results of a new radiocarbon dating program for Excavation 1 that is explored within a Bayesian model of all existing Wonderwerk Cave radiocarbon ( ¹⁴ C) dates for the Holocene. The proposed model, using Phases within an OxCal Sequence model, provides robust age estimates for changes in the technological and paleoenvironmental record at the site. The more precise dates allow a comparison of the timing of climate shifts across the interior of southern Africa and begin to allow us to identify whether hiatuses in human occupation, or cultural shifts, are synchronous across broader areas of the subcontinent, or not.
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Southern Africa is differentiated from other centres of aridity in Africa by the presence of an extended island of elevated, essentially treeless habitat in the central interior, known as the Highveld and the Karoo. This area coincides botanically with the Nama-Karoo and the Grassland Biomes. The large geographic extent of this habitat is unique to southern Africa, since it has no exact equivalent in modern-day east or north Africa. This uniqueness is reflected in the large herbivores of the central interior, the grazers and mixed feeders adapted to permanently available open habitat, which defines the endemic faunal character of the subregion. This contribution presents some of the faunal evidence for the appearance of permanently open habitat in central southern Africa, a process that formed part of a longer-term trend of faunal adaptation to aridification and global cooling that was initiated within the last 1 Ma, in a time known as the Cornelian Land Mammal Age (LMA). A secondary and overlapping theme deals with the appearance of lakes and wetlands on a subregional scale during the Florisian LMA, which lasted from c. 0.6 Ma to the end of the Pleistocene/early Holocene. The end of the Florisian LMA coincided with the regional extinction of wetland faunas in the interior and with the extinction of specialised grazing ungulates over the entire subregion, leading into the semi-arid conditions seen in the larger part of modern-day southern Africa.
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We describe and discuss the large vertebrates recovered from the basal layers (Strata 12 and 11) of Excavation 1 at Wonderwerk Cave, a site located in the Kuruman Hills, Northern Cape Province, South Africa. Stratum 12 is associated with a small core and flake Oldowan assemblage while Stratum 11 contains some Acheulean material. Based on palaeo-magnetism, the time span covered by these Strata is estimated to date to ca.1.8–1.1 million years ago. Taxa identified include late Makapanian forms, such as Procavia transvaalensis, Procavia antiqua, a hipparionine and an unnamed species of large caprine, also found in the Makapan Limeworks deposits, confirming the antiquity of these layers. The bones are highly fragmented due to the action of multiple agencies, both pre- and postdepositional, which prevented diagnosis in many cases to lower levels of taxonomy. In support of other palaeo-environmental proxies from Strata 12 and 11, the large mammal remains reflect a semi-arid ecotone palaeo-environment, consisting of a mix of taxa associated with broken, montane habitat and semi-arid grassland-savanna plains habitat.
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Horizontal cores from a large stalagmite and two tufa deposits in the entrance to Wonderwerk Cave, South Africa, dated by radiocarbon methods, have provided climate proxy data on late Holocene environments near the cave. The δ18O and δ13C time series from stalagmite Core WW1–3 and tufa Core WW3 correlate well with isotope records for other sites in the summer rainfall zone of southern Africa and suggest that late Holocene warm periods in the Northern Hemisphere, including the Medieval Warm period, Roman Warm period, and Minoan Warm period, were times of increased moisture in this rainfall zone. In contrast, late Holocene cold intervals in the Northern Hemisphere, including the Dark Ages Cold period and Sub-Atlantic Cold period, were times of drier climate in the summer rainfall zone. Comparison of the Wonderwerk records with information on human settlement patterns, agricultural expansion or decline, and population growth or decline, shows that growth occurred preferentially during wetter climate periods and declines, including the abandonment of the important town of Mupungubwe in the Shashe-Limpopo area of northeast South Africa and the fall of Great Zimbabwe, which occurred during periods of low precipitation.
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Ungulate and small mammalian fauna have been recovered from Holocene deposits at Wonderwerk Cave, in the interior of South Africa, in the area of excavation 1. Statistical analyses of relative abundances of rodents and insectivores indicate that conditions were warm (between 19.1 and 19.3 °C) and very dry in the early Holocene in the Wonderwerk palaeo-environment, becoming moister in the mid-Holocene and still moister in the late Holocene. Temperatures in the late Holocene appear to have been about 1 °C lower than conditions in the early to mid-Holocene. In terms of habitats reflected by rodents, the early Holocene is associated with an abundance of the arid-indicator species, Desmodillus auricularis. The degree of aridity subsequently decreases, associated with an increase in a woodland savanna species, Saccostomus campestris. A later increase in abundance of Mystromus albicaudatus reflects an increase in open grassland in the Late Holocene. Equids (zebras) and alcelaphines (including wildebeest and hartebeest) dominate the ungulate assemblages. Two extinct species are represented in the early Holocene, namely Equus capensis (the giant zebra) and Megalotragus priscus (a large alcelaphine). Possible causes of their extinction may include both environmental and cultural factors. Homo sapiens was probably the main agent of accumulation of the Holocene deposits at Wonderwerk, although leopards (Panthera pardus) may have temporarily used the cave in the mid-Holocene at a time when wind-blown Kalahari sands were introduced.
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The only antelopine species found today in southern Africa is the springbok, Antidorcas marsupialis. However, a close relative, A. bondi, was abundant and widespread during the Late Pleistocene. This animal died out at the beginning of the Holocene, ca. 7000 years ago. In a recent study of Florisbad fossil mammals, it was proposed that the extinct springbok was an exclusive grazer on the basis of its specialized dental features, in contrast to the modern springbok, which is a mixed feeder. We provide evidence in support of this hypothesis from stable carbon isotopic analysis of fossil and modern sprinbok teeth. The results are also in accordance with the interpretation that A. bondi coexisted with a wide range of larger-bodied grazing ungulates in a system similar to the grazing succession described for the Serengeti in East Africa.
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Wonderwerk Cave, Northern Cape Province (South Africa) is one of few sites in the subcontinent where fossil pollen has been preserved in Holocene cave floor deposits. With the exception of biogenic deposits and stalagmite layers near the cave opening, older material has yielded no pollen. Pollen recorded in previous and new samples from late Pleistocene-Holocene deposits in Excavation 1 at the cave are combined in a calibrated age model based on a selection of published radiocarbon dates. The results confirm patterns observed previously by the late E. M. van Zinderen Bakker, but a new interpretation of the environmental implications and history of the pollen sequence at the site is proposed, viz., dry karroid vegetation in the early Holocene and relatively humid grassy conditions between ca. 5,500 and 4,400 cal yr BP. The results are consistent with those of microfaunal and isotopic studies, and form part of growing proxy evidence for past environmental conditions in the South African interior.
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Sparse records and discontinuous and/or poor chronologically resolved data hinder construction of reliable palaeoenvironmental sequences for the interior of South Africa. Wonderwerk Cave occupies a central position in the interior where the Kalahari Thornveld/dry woodland vegetation and generally arid conditions are expected to be sensitive to subtle past climate perturbations, and evidence from this site has been key to forming views on environmental change in the interior. A compilation of existing data including principal component analysis of pollen suggested broad trends, ranging from variably arid and open in the early Holocene to moister conditions from about 7500 to 5000 years, followed by aridity thereafter. In an effort to better establish the nature and timing of shifts from the Late Pleistocene sequence onwards, we analyse carbon and oxygen isotope ratios in a robust sample of ostrich eggshell from Wonderwerk Cave. The resulting data are then placed within a temporal framework established by Bayesian modelling of existing radiocarbon dates and compared against shifts in the Wonderwerk cultural sequence. Several shifts and trends in aridity include an arid to moist shift in layer 4b near 6000 years, coincident with a cultural shift within the Wilton assemblage, and thereafter an aridification trend culminating at about 2000 years with the appearance of the ceramic LSA.
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Modern savannah grasslands were established during the late Miocene and Pliocene (8-3 million years ago). In the tropics, grasslands are dominated by grasses that use the C4 photosynthetic pathway, rather than the C3 pathway. The C4 pathway is better adapted to warm, dry and low-CO2 conditions, leading to suggestions that declining atmospheric CO2 levels, increasing aridity and enhanced rainfall seasonality allowed grasses using this pathway to expand during this interval. The role of fire in C4 expansion may have been underestimated. Here we use analyses of pollen, microscopic charcoal and the stable isotopic composition of plant waxes from a marine sediment core off the coast of Namibia to reconstruct the relative timing of changes in plant composition and fire activity for the late Miocene and Pliocene. We find that in southwestern Africa, the expansion of C4 grasses occurred alongside increasing aridity and enhanced fire activity. During further aridification in the Pliocene, the proportion of C4 grasses in the grasslands increased, while the grassland contracted and deserts and semi-deserts expanded. Our results are consistent with the hypothesis that ecological disturbance by fire was an essential feedback mechanism leading to the establishment of C4 grasslands in the Miocene and Pliocene.
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The International Atomic Energy Agency (IAEA), in cooperation with the World Meteorological Organization (WMO), has been conducting a world-wide survey of hydrogen (2H/1H) and oxygen (18O/16O) isotope composition of monthly precipitation since 1961. At present, 72 IAEA/WMO network stations are in operation. Another 82 stations belonging to national organizations continue to send their results to the IAEA for publication. The paper focuses on basic features of spatial and temporal distribution of deuterium and 18O in global precipitation, as derived from the IAEA/WMO isotope database. The internal structure and basic characteristics of this database are discussed in some detail. The existing phenomenological relationships between observed stable isotope composition of precipitation and various climate-related parameters such as local surface air temperature and amount of precipitation are reviewed and critically assessed. Attempts are presented towards revealing interannual fluctuations in the accumulated isotope records and relating them to changes of precipitation amount and the surface air temperature over the past 30 years.
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Mid- to late-Holocene pollen data from Florisbad in the central Free State, South Africa, reveal a number of moisture fluctuations. Commencing at c. 6500 BP the pollen sequence indicates an arid climate but shows more availability of moisture under grassy conditions from summer rain at c. 6300 BP and again at c. 4420 BP. The interval between these dates is characterized by a dry episode with karroid shrubs some time between 5500 and 4500 BP, possibly as a result of less marked summer seasonality. After 4220 BP, moisture conditions gradually fluctuated in intensity or seasonal availability until c. 2100-1700 BP when strong summer evaporation is indicated at the upper end of the sequence. The data are complemented by previously published results on environmental change from the nearby Deelpan site to the west. Although some distinct events correlate regionally over South Africa, summer rains appear to have been significant at Florisbad at an earlier stage in the mid-Holocene than in the Karoo to the south.
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Spring deposits exposed during building operations in downtown Windhoek, and lake sediments retrieved from underneath 50 m of water in a sinkhole (Lake Otjikoto), contain pollen profiles which reflect environmental changes in Namibia during the Holocene. At Windhoek moist local conditions are reflected by pollen in the spring deposits which were radiocarbon-dated to between ca. 7000 and 6000 BP. They remained relatively favourable until 5630 BP despite signs of drying. Weedy Compositae (Lactucoideae or Liguliflorae) increased until the end of this record ca. 2410 BP, indicating local disturbance. Deposits from Lake Otjikoto were dated to the late Holocene although an accurate chronology could not be estabiished for the sequence due to unexpected results with radiocarbon measurements. Pollen accumulation values and composition indicate relatively dry conditions after 3500 BP which were followed temporarily by a wetter climate during more recent times.
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Between 8 and 6 million years ago, there was a global increase in the biomass of plants using C 4 photosynthesis as indicated by changes in the carbon isotope ratios of fossil tooth enamel in Asia, Africa, North America and South America. This abrupt and widespread increase in C 4 biomass may be related to a decrease in atmospheric CO 2 concentrations below a threshold that favoured C 3-photosynthesizing plants. The change occurred earlier at lower latitudes, as the threshold for C 3 photosynthesis is higher at warmer temperatures.
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Free-living steenbok (Raphicerus campestris, Thunberg, 1811) were studied for one year in the Kruger National Park, South Africa. Habitat selection data showed a consistently strong preference for Acacia tortilis savanna throughout the year. Mean home range area was 0.62 km2. Diurnal activity consisted of about 33% foraging, with most of the rest of the day spent ruminating and resting. Nocturnal activity included a larger foraging component, amounting to 57% of a night in the dry season. Virtually all feeding time was spent on dicotyledonous plants (57% forbs, 41% woody plants, 1% creepers, on average over the year). This study confirms that steenbok are purely browsers by preference, and not mixed feeders as has previously been assumed. On a étudié des steenboks (Rhaphicerus campestris, Thunberg, 1811) en liberté, pendant un an au Parc National Kruger, en Afrique du Sud. Les données sur le choix de l'habitat montraient une nette préférence pour la savane àAcacia tortilis, tout au long de l'année. La surface moyenne d'un territoire était de 0,62 km2. L'actogramme diurne révélait que presque 33% du temps se passait à brouter et presque tout le reste à ruminer et se reposer. L'activité nocturne voit les animaux consacrer une grande partie du temps à se nourrir, jusqu'à 57% en saison séche. Ils broutent presque exclusivement des dicotylées: 57% de forbs, 41% de plantes ligneuses et 1% de plantes rampantes en moyenne, pour l'année). Cette étude confirme que les steenboks sont de vrais brouteurs et n'ont pas une nourriture mixte, comme on l'avait dit précédemment.
Article
A radiocarbon dated pollen and microscopic charred particle record from the Holocene section of the Tswaing Crater in the Savanna Biome of South Africa give new evidence for environmental changes during the period c. 9400–1800 cal years BP. Pollen grains are scarce or absent in layers dating from before 9400 cal years BP but deposits rich in pollen occur in overlying layers. The section dated between 9400 cal years BP and c. 7200 cal years BP contains grass, Asteraceae and dry savanna pollen types that suggest fluctuating but generally dry moisture conditions. Later between c. 7200 and 1800 cal years BP, broad leaved savanna woodland elements and local swamp pollen indicate relatively stable vegetation and wetter mildly fluctuating climatic conditions, which is consistent with previously published biomarker analysis. Between c. 6200 and 5500 cal years BP, the numbers of charred particles increased slightly. This indicates burning activity, which can probably be attributed to dry season ignition of denser fuel under relatively moist conditions. A decrease of local swamp pollen between c. 3600 and 3500 cal years BP suggests that conditions became briefly drier again as pollen of woody elements declined in favour of open grassland pollen. A comparison between the Tswaing pollen profile and various other sequences within the central interior of South Africa suggests generally similar conditions over the central interior of the sub-continent during the Holocene deviating from sequences further afield along the coastal areas of southern Africa. Between 9400 cal years BP and ca. 7200 cal years BP, the western and southern coasts were probably controlled by different atmospheric and oceanic circulation regimes under the influence of a strong westerly winter–rain system while the north-eastern area where, Tswaing is situated, experienced weaker precession and less summer rain from the Intertropical Convergence Zone.
Article
In order to define criteria for long-term climate change models in Southern Africa, an overview of the available pollen data during the Late Quaternary is needed. Here we reassess the paleo-climatic conditions in southern Africa by synthesising available fossil pollen data that can provide new insights in environmental change processes. The data considered here include the latest as well as previously published information that has been difficult to assess. Available calibrated pollen sequences spanning the Late Pleistocene and Holocene were subjected to Principal Components Analysis (PCA) to monitor taxa sensitive to moisture and temperature fluctuations. The PCA values are presented graphically as indicators of climate variability for the region. The results cover different biomes that include the summer-rain region in the north and east, the winter-rain area in the south and the dry zone in the west. The PCA plots directly reflect major changes of terrestrial environments due to variations in temperature and moisture. Mostly sub-humid but fluctuating conditions are indicated during the cold Marine Isotope Stage (MIS) 2, which were followed by a dry phase soon after the beginning of the Holocene but before the middle Holocene in the northern, central and eastern parts of the sub-continent. Marked but non-parallel moisture changes occurred in different subregions during the Holocene suggesting that climatic forcing was not uniform over the entire region. Some events seemed to have had a more uniform effect over the sub-continent, e.g., a relatively dry summer rain event at c. two thousand years ago, which can possibly be related to the ENSO phenomenon. The role of anthropogenic activities in some of the most recent vegetation shifts is likely.
Article
Quaternary palynological information from the Savanna Biome of South Africa is limited due to the scarcity of suitable pollen traps and new extensive pollen records of palaeoenvironments in the region are unlikely to be obtained easily. Those that are available, including the Tswaing Crater and the Wonderkrater spring sequences, can, however, be reassessed and their data optimised. These two pollen records are relevant to palaeo-environmental research in the area, although they have chronologies beyond the radiocarbon dating range that complicate interpretations. The Tswaing sequence in this study focuses on the upper 34 m of pollen-rich layers out of a total of 90 m of lake deposits. A new chronology is experimented with for this upper part of the sequence. It differs slightly from the previous one in that it does not rely on adjustments of the ages according to the precession cycle. Accordingly the age at 34 m is estimated to be c. 75 ka based on interpolation of the radiocarbon sequence and a basal fission track date of c. 200 ka at 90 m. In the case of the second site, Wonderkrater, recently published excavation and dating of the deposits and comparisons with the Tswaing pollen sequence provide new clues for the age of the lowermost deposit of the original borehole sequence of peats, sands and clay, which is estimated at c. 60 000 years. The new results better situate the two pollen sequences in a wider regional and global palaeoenvironmental framework.
Article
To better understand Holocene vegetation and hydrological changes in South Africa, we analyzed pollen and microcharcoal records of two marine sites GeoB8331 and GeoB8323 from the Namaqualand mudbelt offshore the west coast of South Africa covering the last 9900 and 2200 years, respectively. Our data corroborate findings from literature that climate developments apparently contrast between the summer rainfall zone (SRZ) and winter rainfall zone (WRZ) over the last 9900 years, especially during the early and middle Holocene. During the early Holocene (9900–7800 cal. yr BP), a minimum of grass pollen suggests low summer rainfall in the SRZ, and the initial presence of Renosterveld vegetation indicates relatively wet conditions in the WRZ. Toward the middle Holocene (7800–2400 cal. yr BP), a rather moist savanna/grassland rich in grasses suggests higher summer rainfall in the SRZ resulting from increased austral summer insolation and a decline of fynbos vegetation accompanied by an increasing Succulent Karoo vegetation in the WRZ, which possibly suggests a southward shift of the Southern Hemisphere westerlies. During the last 2200 years, a trend toward higher aridity was observed for the SRZ, while the climate in the WRZ remained relatively stable. The ‘Little Ice Age’ (ca. 700–200 cal. yr BP) was rather cool in both rainfall zones and drier in the SRZ while it was wetter in the WRZ.
Article
The spatial pattern of precipitation variability in tropical and subtropical Africa over the late Quaternary has long been debated. Prevailing hypotheses variously infer (1) insolation-controlled asymmetry of wet phases between hemispheres, (2) symmetric contraction and expansion of the tropical rainbelt, and (3) independent control on moisture available in Southern Africa via sea surface temperatures in the Indian Ocean. In this study we use climate-model simulations covering the last glacial cycle (120. kyr) with HadCM3 and the multi-model ensembles from PMIP3 (the Palaeoclimate Model Intercomparison Project) to investigate the long-term behaviour of the African rainbelt, and test these simulations against existing empirical palaeohydrological records. Through regional model-data comparisons we find evidence for the validity of several hypotheses, with various proposed processes occurring concurrently but with different regional emphasis (e.g. asymmetric shifts at the seasonal extremes and symmetric expansions/contractions towards West equatorial regions). Crucially, variations in rainfall are associated with multiple forcing mechanisms that vary in their dominance both spatially and temporally over the glacial cycle an important consideration when interpreting and extrapolating from often relatively short palaeoenvironmental records.
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The turnover-pulse hypothesis (TPH) makes explicit predictions concerning the potential responses of species to climate change, which is considered to be a major cause of faunal turnover (extinction, speciation, and migration). Previous studies have tested the TPH primarily by examining temporal correlations between turnover pulses and climatic events. It is rarely possible to dissect such correlations and observe turnover as it is occurring or to predict how different lineages will respond to climate change. Thus, whether climate change drives faunal turnover in the manner predicted by the TPH remains unclear. In this study, we test the underlying mechanics of the TPH using well-dated Quaternary ungulate records from southern Africa's Cape Floristic Region (CFR). Changes in sea level, vegetation, and topographic barriers across glacial-interglacial transitions in southern Africa caused shifts in habitat size and configuration, allowing us to generate specific predictions concerning the responses of ungulates characterized by different feeding habits and habitat preferences. Examples from the CFR show how climatically forced vegetation change and allopatry can drive turnover resulting from extinction and migration. Evidence for speciation is lacking, suggesting either that climate change does not cause speciation in these circumstances or that the evolutionary outcome of turnover is contingent on the nature and rate of climate change. Migrations and extinctions are observed in the CFR fossil record over geologically short time intervals, on the order of Milankovitch-scale climate oscillations. We propose that such climate oscillations could drive a steady and moderate level of faunal turnover over 10 4 -year time scales, which would not be resolved in paleontological records spanning 10 5 years and longer. A turnover pulse, which is a marked increase in turnover relative to previous and subsequent time periods, requires additional, temporally constrained climatic forcing or other processes that could accelerate evolutionary change, perhaps mediated through biotic interactions.
Article
The Miocene expansion of C4 plants (mainly tropical grasses) between 8 and 4 million years (Ma) remains an enigma since regional differences in the timing of the expansion rules out decreased CO2 (pCO2) as a dominant forcing [e.g. Tipple and Pagani, 2007. The early origins of terrestrial C4 photosynthesis. Annu. Rev. Earth Planet. Sci. 35, 435–461]. Other environmental factors, such as low-latitude aridity and seasonality have been proposed to explain the low tree versus grass ratio found in savannahs and tropical grasslands of the world, but conclusive evidence is missing. Here we use pollen and stable carbon (δ13C) and hydrogen (δD) isotope ratios of terrestrial plant wax from a South Atlantic sediment core (ODP Site 1085) to reconstruct Miocene to Pliocene changes of vegetation and rainfall regime of western southern Africa. Our results reveal changes in the relative amount of precipitation and indicate a shift of the main moisture source from the Atlantic to the Indian Ocean during the onset of a major aridification 8 Ma ago. We emphasize the importance of declining precipitation during the expansion of C4 and CAM (mainly succulent) vegetation in South Africa. We suggest that the C4 plant expansion resulted from an increased equator-pole temperature gradient caused by the initiation of strong Atlantic Meridional Overturning Circulation following the shoaling of the Central American Seaway during the Late Miocene.
Article
We present a synthesis of diet information for all 78 species of extant African Bovidae (excluding goats and sheep), based on an extensive survey of the literature. We compiled data on food types (percentages of fruits, dicotelydons, and monocotyledons), seasonal and geographic variability, and body mass. Information reported in the literature was evaluated critically to assess its reliability. We performed cluster analyses to identify 6 discrete dietary strategies: frugivores, browsers, generalists, browser-grazer intermediates, variable grazers, and obligate grazers. We identified a positive correlation between an increase in the proportion of monocots in the diet and body mass, and a negative correlation between increases in proportions of dicots and fruits and body mass. We found some degree of correspondence between taxonomic groupings and dietary strategies. Species in the tribes Alcelaphini, Hippotragini, and Reduncini have high proportions of monocots in their diets. Cephalophini, with the exception of Sylvicapra, are frugivores. Tragelaphini and Neotragini, with the exception of Ourebia, have diets that include high proportions of dicots.
Article
The long-term Quaternary vegetation and climate history in South Africa’s savanna biome since ca. 190,000yrBP, is elucidated by the palynological record of lake sediments in the Tswaing Crater (the Pretoria Saltpan), and spring deposits from Wonderkrater, despite hiatuses in both sequences. Palaeotemperature trends from the two places are presented by means of Principal Components Analysis (PCA) of pollen data, allowing a new regional palaeoenvironmental reconstruction. Correlation in the older sections of the sequences, beyond radiocarbon dating, is tentative, suggesting that the Wonderkrater sequence is roughly 4 times younger than the Tswaing sequence. Combined, temperature indications from the two sites suggest cooling at ca. 14,000 yr BP and slight warming at ca. 15,000yrBP. Although no data are available between ca. 15,000 and 21,000, and 25,000 and 31,000yrBP, generally cool conditions are suggested between ca. 11,000 and 33,000yr BP. Between ca. 33,000 and an extrapolated age of ca. 80,000yrBP, at least three warmer pulses of varying intensity occurred. No data are available between ca. 80,000 and 150,000yr, but between 150,000 and ca. 190,000yrBP, two cool and two moderately warm phases are suggested.
Article
Long environmental proxy records are very scarce in semi-dry continental areas and often those available present conflicting interpretations. However, more in-depth investigation of apparent contradictions, can address these problems. For example, comparison of the upper parts of pollen and sediment sequences from the Tswaing Crater and Wonderkrater spring (South Africa) and isotopes in a speleothem at Lobatse Cave (Botswana) from the Savanna Biome establishes a basis for understanding of long-term regional environmental processes in central Southern Africa over the last 60 ka. The different proxies for the vegetation can hypothetically be reconciled on condition that the chronologies on which they are based and environmental controls are firm. We discuss the ratio of woody elements, under-storey herb-cover and the vegetation's general C4/C3 status in the central savanna region, in relation to seasonal rainfall and temperature variations and long-term climate forcing.
Article
Presented here are stable nitrogen isotope data from a rock hyrax (Procavia capensis) middens from northwestern Namibia that record a series of rapid aridification events beginning at ca. 3800 cal yr BP, and which mark a progressive decrease in regional humidity across the Holocene. Strong correlations exist between this record and other terrestrial and marine archives from southern Africa, indicating that the observed pattern of climate change is regionally coherent. Combined, these data indicate hemispheric synchrony in tropical African climate change during the Holocene, with similar trends characterising the termination of the [`]African Humid Period' (AHP) in both the northern and southern tropics. These findings run counter to the widely accepted model of direct low-latitude insolation forcing, which requires an anti-phase relationship to exist between the hemispheres. The combined dataset highlights: 1) the importance of forcing mechanisms influencing the high northern latitudes in effecting low-latitude climate change in Africa, and 2) the potential importance of solar forcing and variations in the Earth's geomagnetic shield in determining both long-term and rapid centennial-scale climate changes, identifying a possible mechanism for the variations marking the AHP termination in both the southern and northern tropics.
Article
Variations in the nature and extent of southern Africa's winter rainfall zone (WRZ) have the potential to provide important information concerning the nature of long-term climate change at both regional and hemispheric scales. Positioned at the interface between tropical and temperate systems, southern Africa's climate is influenced by shifts in the Intertropical Convergence Zone, the westerlies, and the development and position of continental and oceanic anticyclones. Over the last glacial–interglacial cycle substantial changes in the amount and seasonality of precipitation across the subcontinent have been linked to the relative dominance of these systems. Central to this discussion has been the extent to which the region's glacial climates would have been affected by expansions of Antarctic sea-ice, equatorward migrations of the westerlies, more frequent/intense winter storms and an expanded WRZ. This paper reviews the developing body of evidence pertaining to shifts in the WRZ, and the evolution of ideas that have been presented to explain the patterns observed. Dividing the region into three separate axes, along the western and southern margins of the continent and across the interior into the Karoo and the Kalahari, a range of evidence from both terrestrial sites and marine cores is considered, and potential expansions of the WRZ expansions are explored. Despite the limitations of many of the region's proxy records, a coherent pattern has begun to develop of a significantly expanded WRZ during phases of the last glacial period, with the best-documented being between 32–17 ka. While more detailed inferences will require the recovery and analysis of longer and better-dated records, this synthesis provides a new baseline for further research in this key region.
Article
For the past century, woody plants have increased in grasslands and savannas worldwide. Woody encroachment may significantly alter ecosystem functioning including fire regimes, herbivore carrying capacity, biodiversity and carbon storage capacity. Traditionally, increases in woody cover and density have been ascribed to changes in the disturbance regime (fire and herbivores) or rainfall. Increased atmospheric CO2 concentrations may also contribute, by increasing growth rates of trees relative to grasses. This hypothesis is still heavily debated because usually potential CO2 effects are confounded by changes in land use (disturbance regime). Here we analyse changes in woody density in fire experiments at three sites in South African savannas where the disturbance regime (fire and herbivores) was kept constant for 30 and 50 years. If global drivers had significant effects on woody plants, we would expect significant increases in tree densities and biomass over time under the constant disturbance regime. Woody density remained constant in a semiarid savanna but tripled in a mesic savanna between the 1970s and 1990s. At the third site, a semiarid savanna near the southern limits of the biome, tree density doubled from the mid 1990s to 2010. Interpretation of the causes is confounded by population recovery after clearing, but aerial photograph analysis on adjacent non-cleared areas showed an accompanying 48% increase in woody cover. Increased CO2 concentrations are consistent with increased woody density while other global drivers (rainfall) remained constant over the duration of the experiments. The absence of a response in one semiarid savanna could be explained by a smaller carbon sink capacity of the dominant species, which would therefore benefit less from increased CO2. Understanding how savannas and grasslands respond to increased CO2 and identifying the causes of woody encroachment are essential for the successful management of these systems.
Article
Stable carbon and oxygen isotope analyses of ungulate grazers from four archaeological sites located in different environs within the Caledon River Valley have provided a relatively well-dated proxy palaeoenvironmental and palaeoclimatic sequence for the period between 16 000 and 6000 calendar (cal.) yr BP. Within the overall trend towards hot mid-Holocene temperatures and a summer rainfall pattern, stable carbon isotope results show that there were three periods when growth season temperatures were cool enough for C3 grasses to be present: 16 000–14 000; 10 200–9600, and 8400–8000 cal. yr BP. Similar trends were recorded in stable oxygen isotope values, reflecting shifts in either temperature or available moisture. Although having a similar pattern to that of the lower altitude site, sites situated in foothills and montane portions of the valley consistently maintained lower temperatures until the mid-Holocene altithermal. At this time growth season temperatures warmed sufficiently for a 100% C4 grassland to expand in altitude from the warmer low lying localities. In relation to present understanding of synoptic and global climatic patterning, these findings suggest that the early to middle Holocene transition was not a gradual warming trend, but rather it was marked by a series of climatic fluctuations. Of particular note is the possible global, rather than regional, occurrence of the 8200 cal. yr BP ‘event’. Copyright © 2002 John Wiley & Sons, Ltd.
Article
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