Brian M Chase
email: brian.chase@umontpellier.fr

J Tyler Faith

Alex Mackay

Manuel Chevalier

Andrew S Carr

Arnoud Boom

Sophak Lim

Paula J Reimer

Climatic controls on Later Stone Age human adaptation in Africa's southern

Keywords: paleoclimate, paleoecology, rock hyrax middens, microlithic, macrofauna, Boomplaas Cave

Africa's southern Cape is a key region for the evolution of our species, with early symbolic systems, marine faunal exploitation, and episodic production of microlithic stone tools taken as evidence for the appearance of distinctively complex human behavior. However, the temporally discontinuous nature of this evidence precludes ready assumptions of intrinsic adaptive benefit, and has encouraged diverse explanations for the occurrence of these behaviors, in terms of regional demographic, social and ecological conditions. Here, we present a new high-resolution multi-proxy record of environmental change that indicates that faunal exploitation patterns and lithic technologies track climatic variation across the last 22,300 years in the southern Cape. Conditions during the Last Glacial Maximum and deglaciation were humid, and zooarchaeological data indicate high foraging returns. By contrast, the Holocene is characterized by much drier conditions and a degraded resource base. Critically, we demonstrate that systems for technological deliveryor provisioningwere responsive to changing humidity and environmental productivity. However, in contrast to prevailing models, bladelet-rich microlithic technologies were deployed under conditions of high foraging returns and abandoned in response to increased aridity and less productive subsistence environments. This suggests that posited links between microlithic technologies and subsistence risk are not universal, and the behavioral sophistication of human populations is reflected in their adaptive flexibility rather than in the use of specific technological systems.

Introduction

South Africa's southern coastal margin is a key region for the evolution and development of our species [START_REF] Ambrose | Small things remembered: origins of early Microlithic industries in Sub-Saharan Africa[END_REF][START_REF] Ambrose | Social and ecological models for the Middle Stone Age in Southern Africa[END_REF][START_REF] Brown | An early and enduring advanced technology originating 71,000 years ago in South Africa[END_REF]Henshilwood et al., 2004a;[START_REF] Henshilwood | Emergence of modern human behavior: Middle Stone Age engravings from South Africa[END_REF][START_REF] Marean | Pinnacle Point Cave 13B (Western Cape Province, South Africa) in context: The Cape Floral kingdom, shellfish, and modern human origins[END_REF][START_REF] Powell | Late Pleistocene demography and the appearance of modern human behavior[END_REF]. The southern Cape archaeological record has reframed the debate about the evolution of human behavior, providing early examples of engravings, ornaments, heat treatment of tool-stone and the focussed consumption of marine resources [START_REF] Delagnes | Early Evidence for the Extensive Heat Treatment of Silcrete in the Howiesons Poort at Klipdrift Shelter (Layer PBD, 65 ka), South Africa[END_REF]Henshilwood et al., 2004b;[START_REF] Henshilwood | Emergence of modern human behavior: Middle Stone Age engravings from South Africa[END_REF][START_REF] Henshilwood | Klipdrift Shelter, southern Cape, South Africa: Preliminary Report on the Howiesons Poort layers[END_REF][START_REF] Marean | The origins and significance of coastal resource use in Africa and Western Eurasia[END_REF]. The region also exhibits regular technological turnover through the last 100,000 years, with the intermittent production of bladelets, bifacial points and backed artefacts and the use of fine-grained rock, interspersed with periods lacking regular retouched flake forms and dominated by locally available rocks such as quartzite and quartz [START_REF] Deacon | The Later Stone Age in southernmost Africa[END_REF]Wilkins et al., 2017). The links between these variable technological and subsistence records and their environmental contextnecessary to arguments about the evolution of human adaptationremain surprisingly unclear (Deacon, 1982;[START_REF] Roberts | Climate, environment and early human innovation: stable isotope and faunal proxy evidence from archaeological Sites (98-59ka) in the Southern Cape, South Africa[END_REF]. This reflects the region's particular climatic dynamism [START_REF] Chase | Late Quaternary dynamics of southern Africa's winter rainfall zone[END_REF] coupled with disagreement concerning the interpretation of its paleoenvironmental archives (e.g. [START_REF] Chase | Late Quaternary dynamics of southern Africa's winter rainfall zone[END_REF][START_REF] Deacon | Late Quaternary palaeoenvironments of southern Africa[END_REF]Faith, 2013b;[START_REF] Marean | Stone Age people in a changing South African Greater Cape Floristic Region[END_REF].

In this paper, we focus on the Later Stone Age record in the southern Cape, for which -in contrast with the Middle Stone Age -high resolution environmental and archaeological data are now available. We explore the strength of coupling between environments, subsistence behavior and lithic technology over the last 22,300 years to understand whether, and how closely, human behavior tracked environmental change. Spanning the transition from the Last Glacial Maximum (LGM;26.5-19 ka;[START_REF] Clark | The Last Glacial Maximum[END_REF] to the Holocene (11.7 ka to present [START_REF] Lowe | Synchronisation of palaeoenvironmental events in the North Atlantic region during the Last Termination: a revised protocol recommended by the INTIMATE group[END_REF], and episodes of the use of bladelet-rich technological systems, our data also have a bearing on broader debates about the role of what are often termed 'microlithic' technologies in issues of human adaptation and expansion.

Later Stone Age environments and archaeology in the southern Cape

Influenced by both temperate and tropical climate systems (Figure 1), long-term climate change in the southern Cape is characterized by significant and often abrupt fluctuations [START_REF] Bard | Migration of the subtropical front as a modulator of glacial climate[END_REF]Chase et al., 2013;[START_REF] Chase | Late Quaternary dynamics of southern Africa's winter rainfall zone[END_REF][START_REF] Heaton | Dissolved gas paleotemperatures and 18 O variations derived from groundwater near Uitenhage, South Africa[END_REF][START_REF] Quick | A late Pleistocene-Holocene multi-proxy record of palaeoenvironmental change from Still Bay, southern Cape Coast, South Africa[END_REF][START_REF] Quick | Vegetation and climate dynamics during the last glacial period in the fynbos-afrotemperate forest ecotone, southern Cape, South Africa[END_REF][START_REF] Talma | Late Quaternary paleotemperatures derived from a speleothem from Cango Caves, Cape Province, South Africa. QuRes 37, 203-213[END_REF]. Existing evidence indicates that during the Holocene the relative influences of the two dominant synoptic scale moisture-bearing systems -1) the southern westerly storm track, which expands/shifts northward in the winter, and 2) the tropical easterly flow, which transports moisture from the Indian Ocean during the summerhave varied significantly (Chase et al., 2013;Chase et al., 2015b). However, there is little detailed paleoenvironmental evidence pre-dating the Holocene (Carr et al., 2016b;[START_REF] Chase | Late Quaternary dynamics of southern Africa's winter rainfall zone[END_REF], and as a result there are contradictory opinions concerning conditions since the LGM [START_REF] Chase | Late Quaternary dynamics of southern Africa's winter rainfall zone[END_REF][START_REF] Deacon | Late Quaternary palaeoenvironments of southern Africa[END_REF]Faith, 2013b;[START_REF] Kohfeld | Southern Hemisphere westerly wind changes during the Last Glacial Maximum: paleo-data synthesis[END_REF][START_REF] Partridge | Synthetic reconstructions of southern African environments during the Last Glacial Maximum (21-18 kyr) and the Holocene Altithermal (8-6 kyr)[END_REF][START_REF] Partridge | Between Agulhas and Benguela: responses of southern African climates of the late Pleistocene to current fluxes, orbital precession and the extent of the circum-Antarctic vortex[END_REF][START_REF] Sime | Southern Hemisphere westerly wind changes during the Last Glacial Maximum: model-data comparison[END_REF][START_REF] Stone | Last Glacial Maximum conditions in southern Africa: are we any closer to understanding the climate of this time period? Progress in Physical Geography[END_REF], to the extent that some studies conclude that the region was exceptionally "harsh" and arid during the LGM [START_REF] Deacon | Late Quaternary palaeoenvironments of southern Africa[END_REF][START_REF] Scholtz | Palynological and Palaeobotanical Studies in the Southern Cape[END_REF], while others infer greater humidity and highly productive terrestrial environments (e.g. Faith, 2013b;[START_REF] Parkington | Palaeovegetation at the Last Glacial Maximum in the Western Cape, South Africa: wood charcoal and pollen evidence from Elands Bay Cave[END_REF]. This uncertainty has fundamentally hindered our understanding of past climate dynamics in the region, and, by extension, the impact of past climate change on hunter-gatherer adaptive and subsistence strategies during both the Later and Middle Stone Age.

In the southern Cape, the Later Stone Age archaeological sequence is typically divided into several industries or technocomplexes: early Later Stone Age (ELSA ~<40-24 cal kBP), Robberg (~24-12 cal kBP), Oakhurst (~12-8 cal kBP) and Wilton (~8-2 cal kBP), followed by the arrival of Khoikhoi herders in the last 2000 years [START_REF] Deacon | Correlation of palaeoenvironmental data from the Late Pleistocene and Holocene deposits at Boomplaas Cave, southern Cape[END_REF][START_REF] Deacon | Changing patterns in late Pleistocene / early Holocene prehistory in southern Africa as seen from the Nelson Bay Cave stone artifact sequence[END_REF][START_REF] Lombard | South African and Lesotho Stone Age sequence updated[END_REF][START_REF] Mitchell | The early microlithic assemblages of southern Africa[END_REF]. The ELSA is associated with the production of small flakes, often through bipolar reduction of cores, though it otherwise lacks unifying characteristics and has been described as a period of technological heterogeneity [START_REF] Mitchell | The early microlithic assemblages of southern Africa[END_REF]Wadley, 1993). The Robberg presents more coherent characteristics, including the production of large numbers of bladelets (small, elongate flakes usually less than 24 mm long) produced both from dedicated bladelet cores and from those worked by bipolar reduction [START_REF] Mitchell | The early microlithic assemblages of southern Africa[END_REF]. The Robberg also sees more concentrated, if episodic, use of fine-grained rocks such as a silcrete and chert than the preceding or subsequent phases [START_REF] Deacon | Changing patterns in late Pleistocene / early Holocene prehistory in southern Africa as seen from the Nelson Bay Cave stone artifact sequence[END_REF]Deacon, 1982). The Oakhurst (or Albany) is typified by fewer bladelets, larger flakes, a range of scraper forms and declining use of fine-grained rock, while the Wilton features both scrapers and backed artefacts and highly variable patterns of raw material use [START_REF] Deacon | Wilton: An assessment after fifty years[END_REF][START_REF] Deacon | Changing patterns in late Pleistocene / early Holocene prehistory in southern Africa as seen from the Nelson Bay Cave stone artifact sequence[END_REF][START_REF] Lombard | South African and Lesotho Stone Age sequence updated[END_REF]. While these units are coarse and mask considerable variation, they provide a useful heuristic for discussing broad patterns in technological change across the later LSA.

Consistent with the imprecise meaning of the term [START_REF] Pargeter | Lithic miniaturization in Late Pleistocene southern Africa[END_REF], the ELSA, Robberg and Wilton have all been described as 'microlithic' [START_REF] Bousman | Coping with risk: Later stone age technological strategies at Blydefontein Rock Shelter, South Africa[END_REF][START_REF] Deacon | The Later Stone Age in southernmost Africa[END_REF][START_REF] Mitchell | The early microlithic assemblages of southern Africa[END_REF]Wadley, 1993), but based on different characteristicssmall flakes in the case of the ELSA, bladelets in the case of the Robberg and backed artefacts in the Wilton [START_REF] Lombard | South African and Lesotho Stone Age sequence updated[END_REF]. The advent of dedicated bladelet production in particularas characterizes the Robberg is argued to have presented humans with a significant adaptive advantage during our evolution and dispersal [START_REF] Ambrose | Small things remembered: origins of early Microlithic industries in Sub-Saharan Africa[END_REF][START_REF] Bar-Yosef | The big deal about blades: Laminar technologies and human evolution[END_REF][START_REF] Clarkson | The oldest and longest enduring microlithic sequence in India: 35 000 years of modern human occupation and change at the Jwalapuram Locality 9 rockshelter[END_REF][START_REF] Foley | On stony ground: Lithic technology, human evolution, and the emergence of culture[END_REF]. Some researchers have linked an emphasis on bladelet production with responses to heightened subsistence risk associated with low or declining subsistence resource productivity [START_REF] Elston | Microlithic technology in Northern Asia: A riskminimizing strategy of the Late Paleolithic and Early Holocene[END_REF][START_REF] Petraglia | Population increase and environmental deterioration correspond with microlithic innovations in South Asia ca. 35,000 years ago[END_REF] (for discussion of the risk concept used here see [START_REF] Bamforth | Technology, flaked stone technology, and risk[END_REF]. Others have suggested that bladelet production provided benefits under conditions of high residential mobility [START_REF] Goebel | The "Microblade Adaptation" and recolonization of Siberia during the Late Upper Pleistocene[END_REF][START_REF] Neeley | Going microlithic: A Levantine perspective on the adoption of microlithic technologies[END_REF]. Both explanationsincreased subsistence risk and increased mobilityhave been posited for bladelet-rich systems in southern Africa during globally cooler conditions [START_REF] Ambrose | Small things remembered: origins of early Microlithic industries in Sub-Saharan Africa[END_REF][START_REF] Grosjean | From proxy data to paleoclimate interpretation: the mid-Holocene paradox of the Atacama Desert, northern Chile[END_REF][START_REF] Mccall | Behavioral ecological models of lithic technological change during the later Middle Stone Age of South Africa[END_REF][START_REF] Mccall | Still Bay and Howiesons Poort Foraging Strategies: Recent Research and Models of Culture Change[END_REF][START_REF] Mellars | Why did modern human populations disperse from Africa ca. 60,000 years ago? A new model[END_REF][START_REF] Mitchell | The organisation of Later Stone Age lithic technology in the Caledon Valley, Southern Africa[END_REF]. The Robberg specifically has been associated with increased residential mobility in response to inferred diminishing resource density [START_REF] Ambrose | Small things remembered: origins of early Microlithic industries in Sub-Saharan Africa[END_REF][START_REF] Mitchell | The organisation of Later Stone Age lithic technology in the Caledon Valley, Southern Africa[END_REF], and has been explained as a risk-dampening response to resource stress [START_REF] Mackay | History and Selection in the Late Pleistocene Archaeology of the Western Cape, South Africa, School of Archaeology and Anrthopology[END_REF]. Other researchers, however, have suggested that any tracking between LSA technological systems and paleoenvironmental variation was relatively weak, and occurred only at the broadest scale of environmental change (e.g. Deacon, 1982). The reality of coupling between technology, subsistence conditions and environmental change in this period is thus contested, and with it the viability of high-order explanations for the behavioral significance of artefacts such as bladelets.

Sites and regional setting

To explore the relationship between environmental change and human activities and technology, we focus on sites from the Swartberg mountains of South Africa's southern Cape, one of the major ranges in the east-west axis of the Cape Fold Mountains (Figure 1). From Seweweekspoort, a deep transversal valley in the central Swartberg mountains, a series of rock hyrax (Procavia capensis) middensstratified accumulations of dried urine and fecal pellets (see Chase et al., 2012) were identified, and six middens from two sites, Seweweekspoort-1 (SWP-1; 33.3668°S, 21.4144°E) and 33.4092°S,21.4031°), were analysed for this study. SWP-1 is located on a west-facing cliff on the northern slope of the pass (Figure 1). The SWP-1 middens were taken from several locations within the same larger shelter, formed by a ~100 m overhanging cliff. SWP-3 is located on a low eastern cliff in the central section of the valley near the valley bottom, and experiences a more humid microclimate relative to the exposed position of SWP-1.

<insert Figure 1> The SWP-1 site is located in the North Swartberg Sandstone Fynbos, but less than a kilometre to the north is the Matjiesfontein Shale Renosterveld [START_REF] Mucina | The vegetation of South Africa, Lesotho and Swaziland, Strelitzia[END_REF].

The former, depending on altitude and aspect, is predominantly asteraceous, proteoid and restioid fynbos, while the latter is dominated by asteraceous elements, particularly Elytropappus rhinocerotis, Eriocephalus sp. and Euryops sp., and by an increasing number of succulents, primarily from the Crassulaceae family [START_REF] Mucina | The vegetation of South Africa, Lesotho and Swaziland, Strelitzia[END_REF]. At SWP-1, these vegetation types inter-digitate to some extent, with the broad west-facing drainage just north of the site supporting more hydrophilic taxa, such as Protea. The north-facing rock shelves directly adjacent to the site maintain only shallow soils and a dominance of succulents.

Grasses in the region are a mixture of C3 (e.g., Erharta) and C4 (e.g., Aristida, Stipagrostis) varieties (http://sibis.sanbi.org/faces/DataSources.jsp; [START_REF] Rutherford | The South African National Vegetation Database: History, development, applications, problems and future[END_REF][START_REF] Rutherford | ACKDAT: A digital spatial database of distributions of South African plant species and species assemblages[END_REF]SANBI, 2003). SWP-3 is located in the South Swartberg Sandstone Fynbos, which at the site is primarily proteoid in character. In addition, there are numerous arboreal/Cape thicket elements (e.g., Podocarpus, Celastraceae, Dodonaea, Searsia, Euclea, Oleaceae) associated with drainages and the nearby riparian zones of the valley bottom.

The Seweweekspoort sites are located 70 km west of the well-stratified late Pleistocene / Holocene archaeological site of Boomplaas Cave. This site is also situated on the flanks of the Swartberg and occupies a very similar climatic regime, making it ideal for exploring linkages between climate, environment, subsistence and technology at high temporal resolution. Located on the southern flanks of the Swartberg range overlooking the Cango Valley, Boomplaas Cave was excavated by Hilary Deacon in the 1970s [START_REF] Deacon | Excavations at Boomplaas Cave : a sequence through the Upper Pleistocene and Holocene in South Africa[END_REF]. The excavated sediments were divided into a series of members, some of which were subdivided into units. The site is positioned within a transitional shrubland whose component species vary as a function of temperature and moisture gradients moving upslope from the floor of the valley (Vlok and Schutte-Vlok, 2010). The lowlands to the south are characterized by renosterveld habitats, which give way to fynbos vegetation along the slopes of the Swartberg. Along watercourses and ravines in the Cango Valley are more densely wooded habitats that include sweet thorn trees (Vachellia (Acacia) karroo) and ironwood (Olea spp.) among others [START_REF] Moffett | The Flora and Vegetation in the Surrounds of Boomplaas Cave: Cango Valley[END_REF]. As is also the case at Seweweekspoort, Boomplaas today receives contributions of both winter and summer rainfall (Figure 1). Thus, the limited grasses that do occur in the area today include a mixture of both C3 and C4 species.

Materials and methods

Rock hyrax middens accumulate over thousands of years and preserve continuous records of past climate change (Chase et al., 2012). The six middens from Seweweekspoort sites SWP-1 and SWP-3 were selected for analysis because they are composed almost entirely of hyraceum (no visible fecal pellets). Our experience suggests that such middens have superior stratigraphic integrity compared to more pellet-rich middens. Representative portions of the middens were processed as described in Chase et al. (2013;2012). Radiocarbon age determinations (n=36) were processed at the 14 CHRONO Centre, Queen's University Belfast using accelerator mass spectrometry (AMS) (Supplementary Online Material [SOM] Figure S1; Table S1). The radiocarbon ages were corrected for isotope fractionation using the AMS measured δ 13 C and calibrated using the SHCal13 calibration data (Hogg et al., 2013). The Bacon 3.0.3 software package (Blaauw and Christen, 2011) was used to generate all age-depth models (SOM Figure S1). Results indicate that these sequences continuously span the last 22,300 years.

The fossil pollen content of 82 adjacent, contiguous pollen samples were prepared with standard physical (600 μm sieving and decanting) and chemical (HCl, KOH, HF and acetolysis) methods [START_REF] Moore | Pollen Analysis[END_REF]. Lycopodium tablets were added to the weighed sample to estimate pollen concentrations [START_REF] Stockmarr | Tablets with spores used in absolute pollen analysis[END_REF]. A minimum pollen sum of 400 grains was counted at a magnification of ×400 under a light microscope, and identified with the help of the literature [START_REF] Scott | Late Quaternary fossil pollen grains from the Transvaal, South Africa[END_REF]van Zinderen Bakker, 1953, 1956;van Zinderen Bakker and Coetzee, 1959), and photographic and slide reference collections at the Universities of the Free State, Cape Town, and Montpellier.

The bulk stable nitrogen ( 15 N) and carbon ( 13 C) isotope contents of 767 overlapping hyraceum samples were measured at the Department of Archaeology, University of Cape Town following Chase et al. (2010;[START_REF] Mackay | History and Selection in the Late Pleistocene Archaeology of the Western Cape, South Africa, School of Archaeology and Anrthopology[END_REF]2011;2012), with contiguous/overlapping samples obtained from two series of offset 1 mm holes. For the stable isotope analyses, the standard deviation derived from replicate analyses of homogeneous material was better than 0.2‰ for both nitrogen and carbon. Nitrogen isotope results are expressed relative to atmospheric nitrogen (SOM Figure S2). Carbon isotope results are expressed relative to Vienna PDB (SOM Figure S3).

Stable isotope results from the different Seweweekspoort rock hyrax middens were combined into a single aggregate record using Local Regression (LOESS) curve fitting of the combined datasets (SOM Figures S2 andS3). As individual middens under the same climate regime may exhibit differences in their isotopic records due to microclimatic influences on individual foraging ranges (i.e., baseline  15 N variability), we have adjusted the δ 15 N to account for these differences prior to LOESS curve fitting. Using the SWP-1-1 and SWP-1-4b records as a datum, an estimated offset of 1.5‰ was added to the δ 15 N data from the SWP-3-1 to compensate for the more humid microclimate in which the midden was found, and 0.5‰ and 1‰ were added to SWP-1-5 and SWP-1-2a respectively to account for their more exposed positions.

The carbon isotopic composition of the hyraceum is representative of vegetation around a midden site (Carr et al., 2016a) and provides information on 1) the relative contribution of C3, C4 and CAM plants [START_REF] Smith | Natural abundance of the stable isotopes of carbon in biological systems[END_REF] to the animals' diet, and 2) variations in plant water-use efficiency (WUE) as a function of climate [START_REF] Ehleringer | Correlations between carbon isotope ratio and microhabitat of desert plants[END_REF][START_REF] Farquhar | Carbon isotope discrimination and photosynthesis[END_REF][START_REF] Farquhar | Isotopic composition of plant carbon correlates with wtaer-use efficiency of wheat genotypes[END_REF][START_REF] Pate | Carbon isotope discrimination and plant water-use efficiency: case scenarios for C3 plants[END_REF]. Throughout the broader region, the distribution of C3 and C4 grasses tracks the proportion of winter versus summer rainfall (Vogel, 1978). As mentioned, at Seweweekspoort today, grasses are a mosaic of C3 and C4 varieties [START_REF] Rutherford | The South African National Vegetation Database: History, development, applications, problems and future[END_REF][START_REF] Rutherford | ACKDAT: A digital spatial database of distributions of South African plant species and species assemblages[END_REF]SANBI, 2003), and where aspect and soil depth limit soil water content, CAM plants become increasingly abundant. As C3 plants are depleted in 13 C compared with most CAM and all C4 plants, higher δ 13 C values indicate more abundant warm season (C4) grasses and/or succulent plants (CAM), and generally warmer/more arid conditions.

Hyraceum δ 15 N is an indicator of changes in ecosystem water-availability (Carr et al., 2016a;Chase et al., 2013;Chase et al., 2015b;Chase et al., 2009;Chase et al., 2011). A positive relationship exists between aridity and δ 15 N in soils, plants and herbivores, with drier conditions correlating with enriched δ 15 N (Carr et al., 2016a), most likely as a result of denitrification processes in arid/semi-arid soils [START_REF] Handley | The 15 N natural abundance ( 15 N) of ecosystem samples reflects measures of water availability[END_REF][START_REF] Handley |  15 N and  13 C patterns in savanna vegetation: dependence on water availability and disturbance[END_REF][START_REF] Hartman | Are elevated δ 15 N values in herbivores in hot and arid environments caused by diet or animal physiology?[END_REF][START_REF] Heaton | The 15 N/ 14 N ratios of plants in South Africa and Namibia: relationship to climate and coastal/saline environments[END_REF]Murphy andBowman, 2006, 2009;Wang et al., 2010). In the hyraceum samples, the narrowly defined feeding range of the hyraxes (<60 m; [START_REF] Sale | The feeding behaviour of rock hyraces (genera Procavia and Heterohyrax) in Kenya[END_REF], and the accumulation rates of the middens (~20-60 years/sample) enforce a spatio-temporal averaging that reduces the δ 15 N variability observed in modern ecosystem studies (Carr et al., 2016a), and provides a more reliable index of past water variability (Carr et al., 2016a;Chase et al., 2012).

Boomplaas faunal and archaeological archives

The Boomplaas sequence spans much of the last >65,000 years (Deacon, 1982), though we focus here on the fauna and flaked stone artifacts from the upper stratigraphic units corresponding in age with the Seweweekspoort record (SOM Table S2). We use these data to explore the relationship between the paleoenvironmental changes documented at Seweweekspoort and mammal community composition, foraging efficiency, and technological organization. Ages for Boomplaas follow Deacon (1982), calibrated using SHCal13 (Hogg et al., 2013). These published data do present limitations, as they do not adequately bracket each stratigraphic unit. In an effort to maximize their utility, and estimate likely intervals of time that each unit may represent, we derived depths from the published stratigraphic diagrams and calculated a general age-depth model for the sequence. While apparently quasi-continuous, with a relatively constant depositional rate, the nature of the sequence, in terms of lithology, suggests more sporadic deposition. In plotting each unit, we have included both minimum and maximum weighted mean ages as well as potential minimum and maximum ages of the units considering potential sources of error related to radiocarbon calibration and assumptions of accumulation rates (SOM Figure S4). This highlights the clear need to initiate a systematic revision of the chronologies of many archaeological sites in the region (e.g. Loftus et al., 2016;[START_REF] Sealy | Late Quaternary environmental change in the Southern Cape, South Africa, from stable carbon and oxygen isotopes in faunal tooth enamel from Boomplaas Cave[END_REF] to enable more robust inter-site and inter-regional comparisons.

Taxonomic abundances (number of identified specimens: NISP) of ungulates from Boomplaas Cave were derived from Faith (2013a), with Klein's (1983) specimen counts used for the uppermost member DGL. Comparable data (minimum number of individuals: MNI) for the Boomplaas microfauna were derived from Avery (1982). To facilitate comparison with the SWP record, we conducted a detrended correspondence analysis (DCA) for both data sets, using the first axis (rescaled from 0 to 100) to broadly summarize faunal composition (Figure 3). The linear trends in both taxonomic groups closely parallel a decline in ungulate grazers (Figure 3), suggesting that the DCA axis 1 scores are related to the replacement of grasslands by more shrubby habitats (see also Faith, 2013a). Broadly parallel changes are also observed in the south coast faunal sequences from Nelson Bay Cave (Klein, 1983) and Byneskranskop 1 (Schweitzer and Wilson, 1983) (Figure 1), implying regional shifts in habitat structure.

Humans are the primary accumulator of the Boomplaas Cave macrofauna from stratum CL4 and above (Faith, 2013a; see also Faith, 2011). This allows us to explore how the environmental changes documented at SWP translate to changes in foraging efficiency. Based on models grounded in optimal foraging theory, we examine two zooarchaeological indicators of foraging efficiency. These include the relative abundance of small-bodied and presumably low-ranked prey (leporids and tortoises) and the average food utility index (FUI; [START_REF] Metcalfe | A Reconsideration of Animal Body-Part Utility Indices[END_REF])a proxy for energetic returns (e.g., meat, fat, marrow) of various ungulate body partsof large mammal (size classes 3 and 4: 84 to 900 kg) skeletal elements (data from Faith, 2011b). Given the evidence for attrition at Boomplaas Cave (Faith and Thompson, in press), we follow Cleghorn and Marean's (2004) taphonomic model of bone survivorship and restrict analysis to the long-bones (femur, tibia, humerus, radius, and metapodials) and skull elements (crania and mandibles). Building on previous studies conducted elsewhere (e.g., Grayson, 1991Grayson, , 2005;;Broughton, 1994Broughton, , 1999;;[START_REF] Cannon | A model of central place forager prey choice and an application to faunal remains from the Mimbres Valley, New Mexico[END_REF][START_REF] Faith | Changes in reindeer body part representation at Grotte XVI, Dordogne, France[END_REF]Munro 2004;), we predict that declining foraging efficiency will be characterized by (1) increasing frequencies of lowranked prey, reflecting declining availability of high-ranked prey (e.g., large game) on the landscape, and (2) increasing mean FUI values, reflecting intensified field processing due to an increase in carcass transport distances and/or search times. We recognize that because tortoises are slow-moving and easily captured, they might be considered a high-ranked prey type that should be collected whenever encountered (e.g. Stiner et al., 2000). However, the significant positive correlation between their abundances and those of leporids (Spearman's ρ: rs = 0.814, p ≤ 0.001), which are unequivocally a low-ranked prey type, suggests that we can treat tortoises as low-ranked prey in this context.

<insert Table 1> All lithic data are taken from Deacon (1982), standardized to site mean (standardized value = (layer valuesite mean) / site standard deviation). We focus on the abundance of bladelets (Figure 3d), and three indicators of technological delivery: ratio of cores to retouched flakes (Figure 3g), total proportions of retouched flakes (Figure 3e), and artefact density measured as total number of artefacts per bucket of excavated sediment following Deacon (1982) (Figure 3h). These last three values function, respectively, as proxies for the transport of retouched flakes vs tool-making potential (mode of technological 'provisioning' [START_REF] Kuhn | Mousterian Lithic Technology[END_REF]), frequency of flake curation, and intensity of site-use [START_REF] Barton | The formation of lithic assemblages[END_REF][START_REF] Kuhn | Artifact densities and assemblage formation: Evidence from Tabun Cave[END_REF][START_REF] Parry | Expedient core technology and sedentism[END_REF]; Riel-Salvatore and [START_REF] Riel-Salvatore | Late Pleistocene Technology, Economic Behavior, and Land-Use Dynamics in Southern Italy[END_REF]. Provisioning, which we define as the systems by which stone artefact technologies are delivered in anticipation of future needs, has been argued to mediate the response of mobility to environmental change [START_REF] Mackay | Coalescence and fragmentation in the late Pleistocene archaeology of southernmost Africa[END_REF]Wilkins et al., 2017). Under conditions of diminished residential mobility, we expect increases in core transport and artefact density, and lower rates of curation. The inverse is expected when mobility increases and the scheduling of movements becomes harder to predict. If bladelets are a response to diminishing subsistence returns, then their abundance should track humidity and resource productivity inversely.

Similarly, if bladelets are positively associated with increasing residential mobility and declining durations of site occupancy then we expect an inverse relationship with artefact density. We also consider the relative abundance of spatially-rare, fine-grained rocks such as silcrete and crypto-crystalline silicates (CCS, subsuming chert and chalcedony) (Figure 3f); it has recently been shown that the abundance of rocks such as silcrete is responsive to increases in overall artefact abundance (Will and [START_REF] Carr | Mid to Late Quaternary Landscape and Environmental Dynamics in the Middle Stone Age of Southern South Africa[END_REF], and may thus reflect diminished residential mobility and improved scheduling of movements.

Results

Climate change since the Last Glacial Maximum at Seweweekspoort

The Seweweekspoort record shows substantial changes in both δ 13 C (range 5.1‰) and δ 15 N (range 9.5‰) over the last 22,300 years, implying significant changes in vegetation and climate (Figure 2). These changes are coherent with the pollen data from the same material. Across this period, a strong first-order trend is apparent, with cool, humid glacial conditions (indicated by increased cryophilic Fynbos Biome vegetation pollen and lower δ 13 C and δ 15 N) transitioning into warmer, but substantially drier conditions during the Holocene (declining fynbos pollen and higher δ 13 C and δ 15 N; Figure 2). This aridification coincides with the deglacial decline in Antarctic sea-ice extent (using sea-salt sodium as a proxy) between 19-11 ka [START_REF] Fischer | Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica[END_REF][START_REF] Levine | Sea salt as an ice core proxy for past sea ice extent: a process-based model study[END_REF]Wolff et al., 2010) (Figure 2), which is considered to be a strong determinant on the position of the westerly storm track [START_REF] Bard | Migration of the subtropical front as a modulator of glacial climate[END_REF][START_REF] Stuut | On the relationship between Antarctic sea ice and southwestern African climate during the late Quaternary[END_REF]. The elevated grass pollen percentages during the last glacial period, coupled with low δ 13 C suggest the increased prevalence of cool growing season C3 grasses (Vogel, 1978), consistent with the model that much of the precipitation during this period fell during the winter months as a result of increased westerly influence. While recent work has indicated that variability in summer rainfall may have had some significant impact in the winter rainfall zone (Chase et al., 2015a;Chase et al., 2015b), long-term (i.e., glacial-interglacial timescales) precipitation trends in the summer rainfall zone [START_REF] Chevalier | Southeast African records reveal a coherent shift from highto low-latitude forcing mechanisms along the east African margin across last glacialinterglacial transition[END_REF] exhibit a clear antiphase relationship with humidity at Seweweekspoort (Figure 2), indicating that tropical systems played a limited role in the region at these timescales.

<insert Figure 2> Within this broad first-order trend of deglacial aridification at Seweweekspoort, significant second-order abrupt episodes of wetter conditions (centred at 14.5, 11 and 4 cal kBP, and the last millennium) indicate major reorganisations of regional climate dynamics. In southern Africa, where rainfall regimes are defined by their strong seasonality, the varying contribution of the non-dominant moisture-bearing system can have a substantial impact on regional environments, shortening or attenuating the impact of often pronounced drought seasons (Chase et al., 2015a). In this context, humid episodes within the last glacial-interglacial transition (LGIT; 18.5-11.7 ka)previously identified as being a period of exceptionally high effective precipitation in the region [START_REF] Scholtz | Palynological and Palaeobotanical Studies in the Southern Cape[END_REF] can be linked to the warming of both high southern latitudes [START_REF] Stocker | The seesaw effect[END_REF][START_REF] Stocker | A minimum thermodynamic model for the bipolar seesaw[END_REF] and the oceans surrounding southwestern Africa [START_REF] Barker | Interhemispheric Atlantic seesaw response during the last deglaciation[END_REF][START_REF] Farmer | Holocene and deglacial ocean temperature variability in the Benguela upwelling region: implications for low-latitude atmospheric circulation[END_REF][START_REF] Kim | Low-latitude control of interhemispheric sea-surface temperature contrast in the tropical Atlantic over the past 21 kyrs: the possible role of SE trade winds[END_REF], including a response to the slow-down of Atlantic Meridional Overturning Circulation (AMOC) during Heinrich stadial 1 (HS1; ~18-14.6 ka) [START_REF] Mcmanus | Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes[END_REF]) (Figure 2).

While the influence of the westerly storm track may have diminished as the Subtropical Front shifted poleward [START_REF] Barker | Interhemispheric Atlantic seesaw response during the last deglaciation[END_REF], increased evaporation from warmer oceans and the invigoration of the southern African monsoon system would have augmented the summer rain component in what was then primarily a winter rainfall regime, reducing rainfall seasonality and drought stress. At Seweweekspoort, peaks in humidity at 14.5 and 11 cal kBP typify this, with reductions in fynbos vegetation under slightly warmer conditions, and with increased grass cover as a function of more regular rains promoting shallow rooting vegetation.

With the onset of the Holocene, as warming continued, the combination of tropical and temperate systems that resulted in these phases of LGIT humidity broke down. Changes in global boundary conditions resulted in 1) a more permanent southerly position of the westerly storm track, and less winter rain, and 2) strong regional warming that intensified potential evapotranspiration, enhancing drought stress [START_REF] Chevalier | Determining the drivers of long-term aridity variability: a southern African case study[END_REF]. Combined, these factors are interpreted to have driven the marked aridification exhibited in the Seweweekspoort records (Figure 2).

Changing resources and technology

The climatic changes robustly identified at Seweweekspoort are strongly reflected in our newly synthesised faunal and archaeological records (Figure 3). Large mammals and microfauna from

Boomplaas Cave indicate open and grassy environments during the LGM, giving way to shrublands across the Pleistocene-Holocene transition; a phase marked by large mammal extinctions and shifts in faunal community composition throughout the region [START_REF] Faith | Climate change and faunal turnover: testing the mechanics of the turnover-pulse hypothesis with South African fossil data[END_REF]. These changes are evident in the DCA axis 1 scores (Figure 3). The abundance of ungulate grazers and axis 1 scores at the site closely tracks δ 13 C, δ 15 N (Figure 3), and changes observed in the pollen record at Seweweekspoort (Figure 2). Likewise, the carbon isotope composition of tooth enamel from Boomplaas grazers parallels the δ 13 C shifts at Seweweekspoort, with predominantly C3 grasses consumed during the LGM giving way to increased C4 grasses during the LGIT [START_REF] Sealy | Late Quaternary environmental change in the Southern Cape, South Africa, from stable carbon and oxygen isotopes in faunal tooth enamel from Boomplaas Cave[END_REF].

<insert Figure 3> These findings contrast with earlier interpretations from floral [START_REF] Deacon | Correlation of palaeoenvironmental data from the Late Pleistocene and Holocene deposits at Boomplaas Cave, southern Cape[END_REF][START_REF] Scholtz | Palynological and Palaeobotanical Studies in the Southern Cape[END_REF] and faunal assemblages (Avery, 1982;[START_REF] Klein | The late Quaternary mammalian fauna of Nelson Bay Cave (Cape Province, South Africa): its implications for megafaunal extinctions and environmental and cultural change[END_REF][START_REF] Klein | Environmental and ecological implications of large mammals from Upper Pleistocene and Holocene sites in southern Africa[END_REF]Klein, , 1983) ) from southern Cape archaeological sequences, wherein open grassland environmentsinferred primarily from a predominance of grazers in large mammal fossil recordswere interpreted as signs of increased aridity. Our results support inferences that evidence for grassier vegetation indicates the influence of more/more regular precipitation on the richer soils of the valleys and plains of the southern Cape [START_REF] Chase | South African palaeoenvironments during marine oxygen isotope stage 4: a context for the Howiesons Poort and Still Bay industries[END_REF]Faith, 2013b), which currently support relatively xeric karroid vegetation [START_REF] Cowling | Phytochorology and vegetation history in the south-eastern Cape, South Africa[END_REF]. In contemporary African ecosystems, elevated precipitation is typically associated with increased biomass of large herbivores [START_REF] Coe | Biomass and production of large African herbivores in relation to rainfall and primary production[END_REF][START_REF] East | Rainfall, soil nutrient status and biomass of large African savanna mammals[END_REF], a phenomenon likely to have been enhanced by increased plant nutrient content under reduced atmospheric CO2 concentrations (Faith, 2011a). The implication for human populations is that cooler, more humid late Pleistocene conditions presented a more productive resource base, including the proliferation of large grazing ungulates.

Zooarchaeological evidence from the human-accumulated vertebrate assemblages at Boomplaas Cave (CL4 and above) indicates that aridification through the LGIT is associated with a decline in foraging efficiency. Across the LGIT (CL4 to BRL5), tortoises and leporids increase in abundance relative to ungulates (tortoises: χ 2 trend = 90.332, p < 0.001; leporids: χ 2 trend = 64.854, p < 0.001). Because ungulates are larger and provide greater energetic returns than tortoises or haresin which case they should be pursued whenever encounteredthese trends imply a decline in their abundances on the landscape. This is also reflected in changes in carcass transport strategies. The average food utility index of large mammal high-survival skeletal elements increases steadily across the LGIT (Spearman's rho = 0.964, p < 0.001), indicating a greater emphasis on skeletal parts providing the highest energetic returns. Within an optimal foraging framework, this trend is consistent with an increase in carcass transport distances and/or search times stemming from diminished availability of large game [START_REF] Cannon | A model of central place forager prey choice and an application to faunal remains from the Mimbres Valley, New Mexico[END_REF][START_REF] Faith | Changes in reindeer body part representation at Grotte XVI, Dordogne, France[END_REF]. These parallel trends imply that the cooler and more humid conditions of the late Pleistocene provided a more productive vertebrate resource base with higher average energetic returns than did the more arid conditions of the early Holocene.

The decline in foraging efficiency through the deglaciation reverses through the Holocene. Barring an increase observed in the two upper units (Table 1), leporids decline in abundance relative to ungulates after the peak in BRL5 (~11-12 cal kBP) (χ 2 trend = 15.854, p < 0.001). This trend, which is consistent with an increase in ungulate abundances on the landscape, complements a decline in the mean FUI of large mammal skeletal parts (Spearman's rho = 0.821, p = 0.034).

From the LGM through the Holocene, there are marked temporal trends in lithic indicators of technological systems at Boomplaas Cave (Figure 3). Though not without some variation, there is a general decline through time in the abundance of bladelets (χ 2 trend = 1323.693, p < 0.001), cores relative to retouched flakes (χ 2 trend = 921.328, p < 0.001), and finegrained raw materials (χ 2 trend = 775.322, p < 0.001), coupled with an increase in the frequency of retouched pieces (χ 2 trend = 1510.282, p < 0.001). A relationship between technological systems and the environment is suggested by strong correlations between these indicators and the DCA axis 1 scores derived for both ungulates and microfauna (Figure 3b, c; Table 2).

Indeed, all the measures of technological change we employ for the Boomplaas assemblage are significantly correlated with changes in ungulate community composition, and most with the composition of micromammal communities (Table 2). Both sets of axis 1 scores track changing frequencies of grassland indicators at the site, as well as the δ 15 N and especially δ 13 C values from Seweweekspoort (Figure 3). It follows that technological change is tracking environmental change, including the patterns of climate-driven environmental change documented in the Seweweekspoort records.

<insert Table 2> During the LGM and early LGIT bladelets are abundant and artefact indicators are consistent with low residential mobility (Figure 3). With the exception of the earliest LGM members (GWA/HCA), for which taphonomic data suggest limited human occupation (Faith, 2013a), artefact densities are well above the overall mean at Boomplaas, flake curation is uncommon, and all core to retouched flake values pre-13 ka (CL member units) are higher than all those that follow. Associated high frequencies of rock such as silcrete and CCS before 12 cal kBP (CL + BRL 7) imply regular and predictable access to fine-grained rock through this period (Figure 3). These factors combined imply an emphasis on the transport of tool-making potential to sites.

Coincident with the onset of the first-order aridification trend after ~14 ka (BRL member units), artefact densities decrease, as do proportions of fine-grained rock and bladelets.

The period is broadly characterised by more common acquisition and reduction of readily available local rocks (quartz and quartzite), with diminishing intensity of site use and little transport of cores or curation of flakes. Investment in technological costs in the later LGIT appears minimal and may reflect greater allocation of energy to search and handling of subsistence packages in response to diminishing ungulate abundance (cf., [START_REF] Hames | Time allocation[END_REF][START_REF] Mackay | Costs and benefits of technological decision making under variable conditions: Examples from the late Pleistocene in southern Africa[END_REF]. From the beginning of the Holocene (BRL3 through to DGL member), and tracking diminishing humidity, artefact densities are low and locally abundant rock continues to dominate, but flake curation becomes markedly more commontechnological systems show a much greater emphasis on transportation and maintenance of implements in this period than in the Pleistocene.

Conclusions

The findings presented here overturn prevailing models of environmental and behavioral change in Africa's southern Cape. A continuous and high-resolution environmental base-line is provided for the first time, indicating a trend from relative humidity during the LGM to increased aridity during the Holocene, with marked shifts in moisture across the LGIT. Rather than being characterised by 'harsh,' conditions [START_REF] Deacon | Late Quaternary palaeoenvironments of southern Africa[END_REF][START_REF] Scholtz | Palynological and Palaeobotanical Studies in the Southern Cape[END_REF], the mesic environments of the late Pleistocene were highly productive, with more extensive grasslands existing in areas now dominated by drought resistant succulent shrublands.

Zooarchaeological data indicate proliferation of a diverse ungulate grassland community during this time, suggesting greater resource availability for humans living in the area, and reduced search and handling times for large game. While lithic technologies track these changes, we found no evidence to support an association between the production of bladelets during the LGM/early LGIT (Robberg) and diminished subsistence conditions. Indeed, bladelets seem to have flourished in a period of relative resource abundance. The period of lowest subsistence productivity inferred from the Seweweekspoort data probably occurred during the Holocene, associated with aridification and the concomitant loss of large ungulates and faunal diversity recorded at Boomplaas. This change led to increases in carcass processing at kill sites, as evidenced by more selective transport of high utility body parts, increased reliance on low-ranked prey, and a technological response in which flakes from locally acquired rocks were curated, core transportation was relatively rare, and bladelets were uncommon. In documenting the strong coupling of environmental, subsistence and technological behavior in Later Stone Age foragers, our data reflect the simple observation that all lithic technologies can be adaptive solutions, not only those often assumed to provide particular adaptive benefits. Wolff, E.W., Barbante, C., Becagli, S., Bigler, M., Boutron, C.F., Castellano, E., de Angelis, M., Federer, U., Fischer, H., Fundel, F., Hansson, M., Hutterli, M., Jonsell, U., Karlin, T., Kaufmann, P., Lambert, F., Littot, G.C., Mulvaney, R., Röthlisberger, R., Ruth, U., Severi, M., Siggaard-Andersen, M.L., Sime, L.C., Steffensen, J.P., Stocker, T.F., Traversi, R., Twarloh, B., Udisti, R., Wagenbach, D., Wegner, A., 2010. Changes in environment over the last 800,000 years from chemical analysis of the EPICA Dome C ice core. QSRv 29, 285-295.

Table Captions

Table 1: Zooarchaeological indicators of foraging efficiency at Boomplaas Cave. These include the relative abundance of tortoises (%), leporids (%), and mean food utility index (FUI) of high-survival body parts belonging to size 3-4 mammals. (Faith, 2013a;Klein, 1983) and microfauna (Avery, 1982), and (d-h) lithic data [START_REF] Deacon | Excavations at Boomplaas Cave : a sequence through the Upper Pleistocene and Holocene in South Africa[END_REF][START_REF] Deacon | Correlation of palaeoenvironmental data from the Late Pleistocene and Holocene deposits at Boomplaas Cave, southern Cape[END_REF]

Figure Captions

Faunal and archaeological archives

Taxonomic abundances of ungulates from Boomplaas Cave were derived from Faith (Faith, 2013), with Klein's (Klein, 1983) data used for the uppermost member DGL. Comparable data for the Boomplaas microfauna were derived from Avery (Avery, 1982). We conducted a detrended correspondence analysis (DCA) for both data sets, using the first axis (rescaled from 0 to 100) to broadly summarize faunal composition (Figure 3). The linear trends in both taxonomic groups closely parallel a decline in ungulate grazers (Figure 3), suggesting that the DCA Axis 1 scores are related to the replacement of grasslands by more shrubby habitats (see also Faith, 2013). Parallel changes are also observed at Nelson Bay Cave (Klein, 1983) and Byneskranskop 1 (Schweitzer and Wilson, 1983), implying regional shifts in habitat structure.

Zooarchaeological indicators of foraging efficiency at Boomplaas Cave (Table S2),

including the relative abundance of small-bodied prey (leporids and tortoises) and the average utility of high-survival body parts (following the taphonomic model of bone survivorship outlined in Cleghorn and Marean (Cleghorn and Marean, 2004)), were derived from Faith (Faith, 2011). Despite small body size, because tortoises are slow-moving and easy to capture, they might be considered a high-ranked prey type that should be collected whenever encountered (e.g. Stiner et al., 2000). While this makes tortoises a somewhat ambiguous indicator, the parallel increase in leporidsunequivocally a low-ranked prey typeacross the

LGIT more definitively suggests a decline in foraging efficiency that parallels changing body part representation for large-bodied prey. Ages for Boomplaas follow Deacon (1982), calibrated using SHCal13 (Hogg et al., 2013). All lithic data are taken from Deacon (1982), standardised to site mean (standardised value = (layer valuesite mean) / site standard deviation). We use core to tool ratios to track changes in the way in which technology was delivered; alternative measures such as core to flake ratios may increase or decrease with changing intensity of core reduction independent of delivery systems. All the measures of technological change we employ for the Boomplaas assemblage are significantly correlated with changes in ungulate community composition, and most with the composition of micromammal communities (Table S3).

As with the faunal data, the technological trends noted for Boomplaas are replicated at Byneskranskop (Schweitzer and Wilson, 1983) (Table S4) and Nelson Bay Cave (Deacon, 1982) (Table S5) (methods as per Boomplaas), with the exception of changes in artefact density. Given the coastal location of these two sites, changes in artefact densityeffectively number of artefacts per unit sedimentare likely to have been influenced by changes in sedimentation associated with sea level fluctuations [START_REF] Chase | Multiphase late Quaternary aeolian sediment accumulation in western South Africa: Timing and relationship to palaeoclimatic changes inferred from the marine record[END_REF]. Microlithic technologies in the forms of bladelets do reappear at Byneskranskop and Nelson Bay Cave during the more arid conditions of the mid-Holocene, along with backed artefacts, reinforcing arguments for the diversity of contexts in microlithic systems were deployed [START_REF] Hiscock | Big debates over little tools: ongoing disputes over microliths on three continents[END_REF].

Figure 1 :

 1 Figure 1: (A) Map of southern Africa showing seasonality of rainfall and climatic gradients dictated by the zones of summer/tropical (orange) and winter/temperate (blue) rainfall dominance. Winter rainfall is primarily a result of frontal systems embedded in the westerly storm track. Major atmospheric (white arrows) and oceanic (blue arrows) circulation systems and the austral summer positions of the Inter-Tropical Convergence Zone (ITCZ) and the Congo Air Boundary (CAB) are indicated. The location of the study site in the transitional southern Cape region is shown. (B) Map of southwest African coastal region with the Seweweekspoort sites and other key palaeoenvironmental and archaeological sites indicated (shading as for panel 'A'). (C) Topographical map of Seweweekspoort, with the SWP-1 and SWP-3 sites indicated.

Figure 2 :

 2 Figure 2: Comparison of δ 15 N (e),δ 13 C values (b), fynbos (c) and grass (d) pollen percentages from the Seweweekspoort hyrax middens with relevant palaeoenvironmental records including the northern summer rainfall zone wet season precipitation reconstruction (a; Chevalier and Chase, 2015), the Bermuda Rise record of Atlantic Meridional Overturning Circulation (AMOC) strength and the northward oceanic transport of heat (f; McManus et al., 2004), foraminifera records indicating conditions in the ocean to the south of the Africa (g, h;[START_REF] Barker | Interhemispheric Atlantic seesaw response during the last deglaciation[END_REF] and sea salt sodium concentrations from the EPICA DML ice core in Antarctica (i;[START_REF] Fischer | Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica[END_REF].

Figure 3 :

 3 Figure 3: Comparison of δ 15 N (j) and δ 13 C (i) values from the Seweweekspoort hyrax middens with zooarchaeological records (ac) of macrofauna(Faith, 2013a; Klein, 1983)

Figure S1 :

 S1 Figure S1: Stable nitrogen isotope results from the Seweweekspoort rock hyrax midden considered in thisstudy with associated age models. Age-depth models were generated using the Bacon 3.0.3 software package(Blaauw and Christen, 2011).

Figure S2 :

 S2 Figure S2: Stable nitrogen isotope results from the Seweweekspoort rock hyrax midden shown individually in relation to the aggregate record obtained using Local Regression (LOESS) curve fitting of the combined datasets. For comparability, 1.5‰was added to the δ 15 N data from the SWP-3-1 to compensate for the more humid microclimate, relative to the SWP-1 site, in which the midden was found.

Figure S3 :

 S3 Figure S3: Stable carbon isotope results from the Seweweekspoort rock hyrax midden shown individually in relation to the aggregate record obtained using Local Regression (LOESS) curve fitting of the combined datasets.

  The findings afforded by high resolution analysis of late Pleistocene and Holocene climate imply more generally that the lack of certain kinds of technologiessuch as bladelets, backed artefacts and bifacial points -in the earlier stages of human evolution need not carry inherent meaning. The ability of foragers to track rapid climatic and environmental changes with adaptive cultural responses is a better arbiter of cognitive 484 complexity than the deployment of any specific technological system. 485van Zinderen Bakker, E.M., 1953. South African pollen grains and spores. Part I. Balkema, Amsterdam/Cape Town. van Zinderen Bakker, E.M., 1956. South African pollen grains and spores. Part II. Balkema, Amsterdam/Cape Town. van Zinderen Bakker, E.M., Coetzee, J.A., 1959. South African pollen grains and spores. Part III. Balkema, Amsterdam/Cape Town. Vogel, J.C., 1978. Isotopic assessment of the dietary habits of ungulates. SAJSc 74, 298-301. Wadley, L., 1993. The Pleistocene Later Stone Age south of the Limpopo River. Journal of World Prehistory 7, 243-296. Wang, L., D'Odorico, P., Ries, L., Macko, S.A., 2010. Patterns and implications of plant-soil δ 13 C and δ 15 N values in African savanna ecosystems. QuRes 73, 77-83. Wilkins, J., Brown, K.S., Oestmo, S., Pereira, T., Ranhorn, K.L., Schoville, B.J., Marean, C.W., 2017. Lithic technological responses to Late Pleistocene glacial cycling at Pinnacle Point Site 5-6, South Africa. PLoS One 12, e0174051. Will, M., Mackay, A., 2016. What factors govern the procurement and use of silcrete during the Stone Age of South Africa? Journal of Archaeological Science: Reports.

Table 2 :

 2 The correlation (Spearman's ρ) between lithic technological indicators and faunal community composition (DCA Axis 1 scores) for ungulates and microfauna at Boomplaas Cave. Significant values in bold.

Table S2 :

 S2 . Zooarchaeological indicators of foraging efficiency at Boomplaas Cave. These include the relative abundance of tortoises (%), leporids (%), and mean food utility index of high-survival body parts belonging to size 3-4 mammals (FUI).

	CL3	47.1	4.4	1840
	CL4	54.5	0.0	1458
	Stratum	% Tortoises	% Leporids	FUI
	BLD3	74.6	30.9	1405
	FBL/BLA	79.1	28.7	1737
	BRL/BRL1	61.8	10.4	1465
	BRL2	71.7	13.5	1910
	BRL3	78.1	24.2	1610
	BRL4	74.1	24.2	2245
	BRL5	80.3	36.2	2432
	BRL6	68.2	15.2	2246
	BRL7	70.9	22.3	2188
	CL1	68.9	8.5	2028
	CL2	71.9	3.6	2037

Table S3 :

 S3 The correlation between lithic technological indicators and faunal community composition (DCA Axis 1 scores) for ungulates and microfauna at Boomplaas Cave. Significant values in bold.

		Ungulates		Microfauna
		rs	p	rs	p
	%Bladelets	-0.696	0.004	0.878	<0.001
	Core/tool	-0.842	<0.001	0.680	0.015
	Tool/aft	0.732	0.002	-0.674	0.012
	CCS+Silcrete	-0.604	0.017	0.484	0.094
	Density	-0.618	0.014	0.355	0.234

Table S4 :

 S4 Technological measures of the assemblage from Byneskranskop. Ages following(Loftus et al., 2016).

	Layer	Age (cal yr BP)	Core/tool	Tool/aft	CCS+Silcrete Density	Bladelets
	1	1715-1870	-0.568	-0.232	-0.954	-0.834	-1.084
	2	3450-3818	-0.616	1.608	-0.142	-1.253	-0.868
	3		-0.589	1.579	0.325	-0.581	0.740
	4	3720-3970	-0.605	1.380	0.387	-0.682	-0.696
	5	6015-6290	-0.665	1.591	1.947	0.031	0.845
	6	6315-6495	-0.617	1.223	1.542	0.090	1.119
	7	5905-6180	-0.564	0.650	0.828	0.218	1.665
	8	6285-6410	-0.578	0.314	1.339	1.017	0.540
	9	6740-6945	-0.593	0.162	0.845	0.634	0.752
	10		-0.511	-0.350	0.537	0.194	-0.475
	11	6505-6740	-0.522	-0.708	-0.010	2.304	1.288
	12	8342-8725	-0.457	-0.509	0.413	1.936	-0.548
	13		-0.196	-0.711	-0.557	-0.448	-0.514
	14	10796-11245	0.053	-0.988	-1.174	-0.939	-1.372
	15	11245-11695	1.926	-1.004	-1.439	-1.315	-1.359
	16		0.963	-1.002	-1.359	-1.013	-1.046
	17	13855-14320	0.168	-0.992	-0.689	-0.728	0.290
	18		0.886	-0.986	-1.254	0.534	-0.827
	19	16060-16535	3.086	-1.025	-0.583	0.835	1.549
		16550-17105

Table S5 :

 S5 Technological measures of the assemblage from Nelson Bay Cave. Ages following(Loftus et al., 2016).

Acknowledgements

Funding was received from the European Research Council (ERC) under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC Starting Grant "HYRAX", grant agreement no. 258657, and the International Union for Quaternary Research (INQUA), project no. 1205P. We would like to thank Matthew Britton and Ian Newton for assistance in collecting and analysing the material.

Supplementary Information

Material and methods

The Seweweekspoort middens were selected for analysis because they are composed almost entirely of hyraceum (no visible pellets). Our experience suggests that such middens have superior stratigraphic integrity compared to more pellet-rich middens. Representative portions of the middens were processed according to the methods described by Chase et al. (Chase et al., 2013;Chase et al., 2012). Radiocarbon age determinations were processed at the 14 CHRONO Centre, Queen's University Belfast using accelerator mass spectrometry (AMS) (Figure S1; Table S1). The radiocarbon ages were corrected for isotope fractionation using the AMS measured δ 13 C and calibrated using the SHCal13 calibration data (Hogg et al., 2013).

The Bacon 3.0.3 software package (Blaauw and Christen, 2011) was used to generate all agedepth models (Figure S1). Stable isotope analysis of bulk midden samples were performed at the Department of Archaeology, University of Cape Town according to the methods described in Chase et al. (2010;[START_REF] Mackay | History and Selection in the Late Pleistocene Archaeology of the Western Cape, South Africa, School of Archaeology and Anrthopology[END_REF]2011;2012), with a contiguous/overlapping samples obtained from two series of offset 1 mm holes. For the stable isotope analyses, the standard deviation derived from replicate analyses of homogeneous material was better than 0.2 ‰ for both carbon and nitrogen. Carbon isotope results are expressed relative to Vienna PDB. Nitrogen isotope results are expressed relative to atmospheric nitrogen. Table S1: Radiocarbon ages were calibrated using the SHCal13 calibration data (Hogg et al., 2013), except for the surface sample from SWP-1-4b, which was not calibrated, and UBA-19558, which was calibrated with CALIBomb using SHCal13 and the SHZ1_2 dataset of Hua et al. [START_REF] Hua | Atmospheric radiocarbon for the period 1950-2010[END_REF].