Huw Groucutt

Despite occupying a central geographic position, investigations of hominin populations in the Arabian Peninsula during the Lower Palaeolithic period are rare. The colonization of Eur-asia below 55 degrees latitude indicates the success of the genus Homo in the Early and Middle Pleistocene, but the extent to which these hominins were capable of innovative and novel behavioural adaptations to engage with mid-latitude environments is unclear. Here we describe new field investigations at the Saffaqah locality (206±76) near Dawadmi, in central Arabia that aim to establish how hominins adapted to this region. The site is located in the interior of Arabia over 500 km from both the Red Sea and the Gulf, and at the headwaters of two major extinct river systems that were likely used by Acheulean hominins to cross the Peninsula. Saffaqah is one of the largest Acheulean sites in Arabia with nearly a million artefacts estimated to occur on the surface, and it is also the first to yield stratified deposits containing abundant artefacts. It is situated in the unusual setting of a dense and well-preserved landscape of Acheulean localities, with sites and isolated artefacts occurring regularly for tens of kilometres in every direction. We describe both previous and recent excavations at Saffaqah and its large lithic assemblage. We analyse thousands of artefacts from excavated and surface contexts, including giant andesite cores and flakes, smaller cores and retouched artefacts, as well as handaxes and cleavers. Technological assessment of stratified lithics and those from systematic survey, enable the reconstruction of stone tool life histories. The Acheulean hominins at Dawadmi were strong and skilful, with their adaptation evidently successful for some time. However, these biface-makers were also technologically conservative, and used least-effort strategies of resource procurement and tool transport. Ultimately, central Arabia was depopulated, likely in the face of environmental deterioration in the form of increasing aridity.

We challenge the view that our species, Homo sapiens, evolved within a single population and/or region of Africa. The chronology and physical diversity of Pleistocene human fossils suggest that morphologically varied populations pertaining to the H. sapiens clade lived throughout Africa. Similarly, the African archaeological record demonstrates the polycentric origin and persistence of regionally distinct Pleistocene material culture in a variety of paleoecological settings. Genetic studies also indicate that present-day population structure within Africa extends to deep times, paralleling a paleoenvironmental record of shifting and fractured habitable zones. We argue that these fields support an emerging view of a highly structured African prehistory that should be considered in human evolutionary inferences, prompting new interpretations, questions , and interdisciplinary research directions.

The Middle to Later Stone Age transition in Africa has been debated as a significant shift in human technological, cultural, and cognitive evolution. However, the majority of research on this transition is currently focused on southern Africa due to a lack of long-term, stratified sites across much of the African continent. Here, we report a 78,000-year-long archeological record from Panga ya Saidi, a cave in the humid coastal forest of Kenya. Following a shift in toolkits ~67,000 years ago, novel symbolic and technological behaviors assemble in a non-unilinear manner. Against a backdrop of a persistent tropical forest-grassland ecotone, localized innovations better characterize the Late Pleistocene of this part of East Africa than alternative emphases on dramatic revolutions or migrations.

Most of the world's presently hyper-arid desert regions have experienced previous periods of significantly higher humidity and milder environmental conditions. The timing of these 'greening events' is critical to research upon global climatic fluctuations and for studies of hominin palaeodemography and range expansion, contraction, and extinction, but dating these climatic shifts via terrestrial sedimentary records can be difficult. Here, we outline the challenges inherent in the radiometric dating of carbonate-and evaporite-rich sediments preserved in the Jubbah basin (Nefud Desert, northern Saudi Arabia), a critical area for reconstructing the evolution of local hydrological regimes across long timescales. The Jubbah basin is surrounded by sandstone jebels (bedrock outcrops), which have prevented significant leeward dune accumulation for at least 400,000 years. The sedimentary sequences in the basin indicate repeated fluctuations between arid and humid climatic conditions, and provide key hydroclimatic records for northern Arabia. Quartz OSL and feldspar pIRIR 290 luminescence measurements and radio-carbon dating efforts are reported from four palaeoenvironmental sections in the Jubbah basin. Dates from sand-rich levels are relatively unproblematic, but significant difficulties were encountered when calculating luminescence ages from carbonate and evaporite-rich sediments. Examination of the age-depth profiles, elemental composition, and sedimentological characteristics of these sections indicates that both secular disequilibrium and post-depositional alteration of the sediments has resulted in inaccurate dose rate assessment for multiple samples. In particular, we suggest that multiple groundwater pulses in the Jubbah basin have caused carbonate re-precipitation and concurrent uranium enrichment in subsurface deposits, whereas 'perched' sections (such as the carbonate-topped remnants reported elsewhere across the Nefud) seem to be free from such alteration. These difficulties highlight important considerations for the production of chronologies from comparable settings elsewhere. Careful evaluation of all results, however, yields a robust chronology indicating the presence of varying levels of groundwater from the Holocene, MIS 3, 5, and probably older sediments from MIS 7 through to 9 or 11. We therefore provide a detailed discussion of the production of a reliable chronological framework for the Jubbah basin as an exemplar of the challenges to be overcome in such settings, and the amount of information that can be derived in so doing.

The Levantine sites of Skhul and Qafzeh have been interpreted as indicating an early, short and unsuccessful expansion of Homo sapiens out of Africa. Chronometric age estimates, however, indicate a history of prolonged occupation, and suggest that Skhul (~130e100 thousand years ago [ka]) may have been occupied earlier than Qafzeh (beginning ~110e90 ka). Morphologically, the Skhul individuals can be described as somewhat more primitive in comparison to the Qafzeh fossils. Though the lithic assemblages of sites such as Skhul and Qafzeh are often described as being technologically similar, as part of the 'Tabun C' phase/industry, limited detailed information on the Skhul lithic assemblage has been published, and little comparative work has been conducted. Here, we present an analysis of the Skhul stone tool assemblage to describe its characteristics, to evaluate the lithic results against the fossil and chronological data, and for inter-site regional comparison. Our findings indicate that the Skhul lithic assemblage differs from other Levantine Marine Isotope Stage (MIS) 5 sites, such as Qafzeh. For example, there was more of an emphasis on diverse methods of point production at Skhul, and the available samples indicate a greater emphasis on preferential rather than recurrent Levallois reduction at Skhul. The current findings suggest that neither the Levantine Middle Palaeolithic in general, nor MIS 5 assemblages in particular, were technologically homogeneous. These data are consistent with either a long occupation of the Levant by Homo sapiens in MIS 5, or at least two phases of occupation (early MIS 5 and mid to late MIS). Whatever the fate of the Skhul and Qafzeh population(s), their occupation of the Levant was neither short nor culturally uniform. Our findings add to the growing pool of evidence that the dispersal of our species 'Out of Africa' was more complex than hitherto thought. Further work on MIS 5e contexts in the Levant and elsewhere in Southwest Asia should be a research priority.

Mid-latitude dune fields offer significant records of human occupations in southwest Asia, reflecting human responses to past climate changes. Currently arid, but episodically wetter in the past, the Nefud desert of northern Saudi Arabia provides numerous examples of human-environment interactions and population movements in the desert belt. Here we describe results from interdisciplinary surveys in the western Nefud that targeted palaeolake deposits identified using satellite imagery. Surveys indicate the presence of thousands of discrete palaeolakes and palaeowetlands, providing valuable palaeoenvironmental records, and numerous archaeological and palaeontological assemblages. Geomorphological investigations suggest that many further deposits remain buried. Forty-six prehistoric archaeological sites have been identified in association with freshwater deposits, spanning the Lower Palaeolithic to the pre-Islamic Holocene. Lower Palaeolithic sites appear concentrated close to raw material sources near the Nefud fringe, despite the presence of freshwater and fauna deeper in the dune field. Middle Palaeolithic occupations extend more broadly, and by the early Holocene humans were at least periodically occupying areas deep in the desert. We present the first records of Neolithic sites in this dune field, including substantial hearth complexes distributed relatively deep within the dunes, potentially indicating increased mobility during this period. Later Holocene sites with stone structures are present around the dune fringes. Our results indicate that, during wet periods of the Pleistocene and Holocene, water in the western Nefud may have been more readily available than elsewhere in northern Arabia due to the high density of depressions where wetlands can form. The high frequency of lakes or marshes appears to have facilitated human occupations and dispersal through the region.

Several hundred Middle Palaeolithic (MP) archaeological sites have now been identified in the Arabian Peninsula. However, the study of lithic raw material properties and related procurement behaviours is still in its infancy. Here we describe raw material procurement and early stage lithic reduction at MP sites in the Jubbah palaeolake basin, in the Nefud Desert, northern Saudi Arabia. We describe the sites identified during our surveys, and we use petrographic studies to demonstrate that MP assemblages were mostly produced from differing forms of ferru-ginous quartzite. These raw materials do not substantially vary in composition, although they are not identical in terms of factors such as grain size and the proportion of iron oxide. We then describe the lithic technology at these sites, with a particular focus on the largest assemblage identified, Jebel Katefeh-12 (JKF-12), which provides detailed information on lithic reduction at a quartzite source. Analyses from this site are then considered together with data from other MP sites in the Jubbah basin, where similar raw material was used. The results indicate that factors such as initial clast size/shape and reduction intensity play important roles in influencing aspects of morphological and technological variability. Our results suggest that incursions of MP populations into northern Arabia were probably temporally limited, as might be expected in a marginal and generally arid region. MP raw material procurement sites provide a highly visible signal of these ephemeral incursions, providing information on the ways that human populations adapted to the challenging conditions of the Saharo-Arabian arid belt.

The evolutionary origins of Homo sapiens and associated behavioural changes are increasingly seen as complex processes, involving multiple regions of Africa. In West Africa, Terminal Pleistocene/Holocene aged human fossils, demonstrating the late continuity of archaic morphological features in the region have been linked to models of surprisingly recent admixture processes between late archaic hominins and H. sapiens. However, the limited chronological resolution of the archaeological record has prevented evaluation of how these biological records relate to patterns of behaviour. Here, we provide a preliminary report of the first excavated and dated Stone Age site in northern Senegal which features the youngest Middle Stone Age (MSA) technology yet documented in Africa. Ndiayène Pendao features classic MSA core axes, basally thinned flakes, Levallois points and denticu-lates mostly made from chert. Similar technological features characterise several, larger surface sites in the vicinity. From this, it is postulated that populations using 'anachronistic' technologies in the Lower Senegal Valley around the transition to the Holocene may have been widespread, in sharp contrast to other areas of Senegal and West Africa. The chronology and technology of Ndiayène Pendao provides the first cultural evidence to support a complex evolutionary history in West Africa. This is consistent with a persistently high degree of Pleisto-cene population substructure in Africa and the spatially and temporally complex character of behavioural and biological evolution.

The early part of Marine Isotope Stage (MIS) 3 (ca. 60–50 ka) is a crucial period for studying human demography and behaviour in southwest Asia, and how these relate to climatic changes. However, the archaeological and palaeoenvironmental records for MIS 3 in critical areas such as the Arabian Peninsula remain poorly developed. Here, we present findings from the Al Marrat basin in the Nefud desert, which provides the first clear evidence for both increased humidity and human occupation of the interior of northern Arabia during early MIS 3. A Middle Palaeolithic assemblage, dated by optically stimulated luminescence to ca. 55 ka, was found stratified within a sequence of relict palustrine deposits indicative of shallow water body formation in the Al Marrat basin. Hominin presence in northern Arabia at this time coincides with the intensification and northward displacement of monsoon rainfall systems during a period of maximum insolation. These findings add to a growing corpus of palaeoenvironmental evidence, which indicates that the Arabian interior was neither arid nor unpopulated during early MIS 3, and that hydrodynamic responses to enhanced moisture availability facilitated demographic expansions into the Arabian interior.

The timing and extent of palaeoenvironmental connections between northeast Africa, the Levant and the Arabian Peninsula during the Middle and Late Pleistocene are critical to debates surrounding dispersals of hominins, including movements of Homo sapiens out of Africa. Although there is evidence that synchronous episodes of climatic amelioration during the late Middle and Late Pleistocene may have allowed connections to form between northern Africa and western Asia, a number of palaeoclimate models indicate the continued existence of an arid barrier between northern Arabia and the Levant. Here we evaluate the palaeoenvironmental setting for hominin dispersals between, and within, northeast Africa and southwest Asia during Marine Isotope Stages (MIS) 7e5 using reconstructions of surface freshwater availability as an environmental proxy. We use remotely sensed data to map palae-ohydrological features (lakes, wetlands and rivers) across the presently hyper-arid areas of northern Arabia and surrounding regions, integrating these results with palaeoclimate models, palae-oenvironmental proxy data and absolute dating to determine when these features were active. Our analyses suggest limited potential for dispersals during MIS 7 and 6, but indicate the formation of a palaeohydrological corridor (the 'Tabuk Corridor') between the Levant and the Arabian interior during the MIS 6-5e glacialeinterglacial transition and during MIS 5e. A recurrence of this corridor, following a slightly different route, also occurred during MIS 5a. These palaeohydrological and terrestrial data can be used to establish when proposed routes for hominin dispersals became viable. Furthermore, the distribution of Arabian archaeological sites with affinities to Levantine assemblages, some of which are associated with Homo sapiens fossils, and the relative density of Middle Palaeolithic assemblages within the Tabuk Corridor, are consistent with it being utilised for dispersals at various times.

The current paucity of Pleistocene vertebrate records from the Arabian Peninsula e a landmass of over 3 million km 2 e is a significant gap in our knowledge of the Quaternary. Such data are critical lines of contextual evidence for considering animal and hominin dispersals between Africa and Eurasia generally, and hominin palaeoecology in the Pleistocene landscapes of the Arabian interior specifically. Here, we describe an important contribution to the record and report stratigraphically-constrained fossils of mammals, birds and reptiles from recent excavations at Ti's al Ghadah in the southwestern Nefud Desert. Combined U-series and ESR analyses of Oryx sp. teeth indicate that the assemblage is Middle Pleistocene in age and dates to ca. 500 ka. The identified fauna is a biogeographical admixture that consists of likely endemics and taxa of African and Eurasian affinity and includes extinct and extant (or related Pleistocene forms of) mammals (. alba) and reptiles (Varanidae/Uromastyx sp.). We infer that the assemblage reflects mortality in populations of herbivorous animals and their predators and scavengers that were attracted to freshwater and plant resources in the inter-dune basin. At present, there is no evidence to suggest hominin agency in the accumulation of the bone assemblages. The inferred ecological characteristics of the taxa recovered indicate the presence, at least periodically, of substantial water-bodies and open grassland habitats.

The animal species depicted in the rock art of Shuwaymis, Saudi Arabia, provide a record of Holocene climatic changes, as seen by the engravers. Of 1903 animal engravings, 1514 contained sufficient detail to allow identification with confidence. In addition, the stratigraphy of the engravings and the depiction of domesticates provide a broad chronological framework that allows a division into images created during the Holocene humid phase and animals represented after the onset of desert conditions. Despite the large sample size, only 16 animal species could be identified, which represents an extraordinarily narrow species spectrum. Comparison with the scarce faunal record of the Arabian Peninsula shows that all larger animals that are thought to have been present in the area were also depicted in the rock art. The contemporaneous presence of at least four large carnivores during the Holocene humid phase suggests that prey animals were abundant, and that the landscape consisted of a mosaic of habitats, potentially with thicker vegetation along the water courses of the wadis and more open vegetation in the landscape around them. Community Earth System Models (COSMOS) climate simulations show that Shuwaymis was at the northern edge of the African Summer Monsoon rainfall regime. It is therefore possible that Shuwaymis was ecologically connected with southwestern Arabia, and that an arid barrier remained in place to the north, restricting the dispersal of Levantine species into Arabia.

The Pleistocene archaeological record of the Arabian Peninsula is increasingly recognized as being of great
importance for resolving some of the major debates in hominin evolutionary studies. Though there has been
an acceleration in the rate of fieldwork and discovery of archaeological sites in recent years, little is known
about hominin occupations in the Pleistocene over vast areas of Arabia. Here we report on the
identification of five new Middle Palaeolithic sites from the Nejd of central Arabia and the southern
margins of the Nefud Desert to the north. The importance of these sites centers on their diversity in terms
of landscape positions, raw materials used for lithic manufacture, and core reduction methods. Our
findings indicate multiple hominin dispersals into Arabia and complex subsequent patterns of behavior
and demography.

The importance of Africa in human origins is widely recognised, yet knowledge remains strongly biased towards certain regions of the continent at the expense of others. West Africa in particular is a vast area with extremely limited archaeological, environmental and fossil records. In this paper, we contribute towards redressing this imbalance though a summary of the state of knowledge of the West African Middle Stone Age (MSA), and the presentation of preliminary analyses of ten newly discovered MSA archaeological sites situated along the Senegal River. Archaeological, fossil and genetic data relevant to the West African MSA, a period currently thought to span from at least ~150 thousand years ago (ka) until the Terminal Pleistocene, are first discussed.  Technological analyses of newly discovered MSA assemblages in Senegal are then presented and contextualised with the ecology and environmental evolution of West Africa. Our preliminary findings suggest an overall high level of technological diversity along the Senegal River, but identify common technological features between assemblages in northern Senegal. These include an emphasis on centripetal methods of Levallois reduction (both preferential and recurrent). The discovery of tools in northern Senegal with basal modifications consistent with tanging may also suggest some form of connection with North African assemblages and is commensurate with the role of Senegal as a transitional zone between sub-Saharan and Saharan Africa. Although preliminary, the emerging results demonstrate the potential of the region to contribute to debates on intra-African dispersals, including population persistence and turnovers.

In Arabia the transition to a Neolithic economy is thought to be characterised by a shift to mobile pastoralism, rather than the traditional icons of the Neolithic such as sedentism and crop cultivation. However, in the absence of detailed archaeological research, the Early Holocene prehistory of central, northern and northwestern Saudi Arabia remains largely unknown. Here we use the engraved rock art recorded on 254 panels in Shuwaymis, Ha’il Province, and in particular depictions of hunting and herding scenes, to identify evidence on the character of the Neolithic transition in the region. Due to high levels of erosion it was not possible to carry out spatial analysis of the sites. However, the content and stratigraphic relationship of hunting and herding panels, re-engraving events, and cultural markers related to human figures were analysed. The results show that the engravings can be divided into an exclusive hunting period, where equids are frequently being hunted. Domestic cattle are often placed over and integrated into existing hunting scenes by re-engraving parts of the scene and turning hunting figures into herding figures. Cultural markers associated with human depictions such as headdresses and possible penis sheaths continue across both periods. The evidence in the rock art indicates that herding was adopted by local hunters. Moreover, the rock art shows that herders identified with the depicted hunters and that ibex hunting remained part of the image repertoire, and potentially of the subsistence economy, throughout the Holocene.

Current fossil, genetic, and archeological data indicate that Homo sapiens originated in Africa in the late Middle Pleistocene. By the end of the Late Pleistocene, our species was distributed across every continent except Antarctica, setting the foundations for the subsequent demographic and cultural changes of the Holocene. The intervening processes remain intensely debated and a key theme in hominin evolutionary studies. We review archeological, fossil, environmental, and genetic data to evaluate the current state of knowledge on the dispersal of Homo sapiens out of Africa. The emerging picture of the dispersal process suggests dynamic behavioral variability, complex interactions between populations, and an intricate genetic and cultural legacy. This evolutionary and historical complexity challenges simple narratives and suggests that hybrid models and the testing of explicit hypotheses are required to understand the expansion of Homo sapiens into Eurasia.

The Empty Quarter (or Rub' al Khali) of the Arabian Peninsula is the largest continuous sandy desert in
the world. It has been known for several decades that Late Pleistocene and Holocene deposits, representing
phases of wetter climate, are preserved there. These sequences have yielded palaeontological
evidence in the form of a variety of vertebrate and invertebrate fossils and have been dated using various
radiometric techniques. However, evidence for human presence during these wetter phases has until
now been ephemeral. Here, we report on the first stratified and dated archaeology from the Empty
Quarter, recovered from the site of Mundafan Al-Buhayrah (MDF-61). Human occupation at the site,
represented by stone tools, has been dated to the later part of Marine Isotope Stage (MIS) 5 using
multiple luminescence dating techniques (multigrain and single grain OSL, TT-OSL). The sequence consists
primarily of lacustrine and palustrine sediments, from which evidence for changing local environmental
conditions has been obtained through analysis of fossil assemblages (phytoliths and nonmarine
molluscs and ostracods). The discovery of securely-dated archaeological material at ~100 to
80 ka in the Empty Quarter has important implications for hypotheses concerning the timing and routes
of dispersal of Homo sapiens out of Africa, which have been much debated. Consequently, the data
presented here fill a crucial gap in palaeoenvironmental and archaeological understanding of the
southern Arabian interior. Fossils of H. sapiens in the Levant, also dated to MIS 5, together with Middle
Palaeolithic archaeological sites in Arabia and India are thought to represent the earliest dispersal of our
species out of Africa. We suggest that the widespread occurrence of similar lithic technologies across
southern Asia, coupled with a growing body of evidence for environmental amelioration across the
Saharo-Arabian belt, indicates that occupation of the Levant by H. sapiens during MIS 5 may not have
been a brief, localized ‘failed dispersal’, but part of a wider demographic expansion.

Understanding the structure and variation of Homo sapiens populations in Africa is critical for interpreting multiproxy evidence of their subsequent dispersals into Eurasia. However, there is no consensus on early Homo sapiens demographic structure, or its effects on intra-African dispersals. Here, we show how a patchwork of ecological corridors and bottlenecks triggered a successive budding of populations across the Sahara. Using a temporally and spatially explicit palaeoenvironmental model, we found that the Sahara was not uniformly ameliorated between ~130-75 thousand years ago (ka), as has been stated. Model integration with multivariate analyses of corresponding stone tools then revealed several spatially defined technological clusters which correlated with distinct palaeobiomes. Similarities between technological clusters were such that they decreased with distance except where connected by palaeohydrological networks. These results indicate that populations at the Eurasian gateway were strongly structured, which has implications for refining the demographic parameters of dispersals out of Africa.

The interpretation of Acheulean landscape use through the analysis of artefact distributions over a range of environmental settings is vital for understanding early hominin behaviour. Such approaches have been successfully applied in areas such as East Africa and South Africa, where long-term and sustained archaeological research has led to the development of robust environmental frameworks within which to analyse hominin land-use patterns. Much less is known about Acheulean hominin behaviour in the Arabian Peninsula, which is increasingly being recognised as an important area for studying early hominin dispersals and adaptations to new environments. To address this lacuna, we have undertaken the first multi-scale systematic survey of Acheulean occupation evidence at Dawadmi, in the centre of the Arabian Peninsula. Specifically, we carried out systematic transect surveys over a large andesite dyke at Saffaqah, on which the majority of 26 known Acheulean sites are associated, as well as across narrow drainage channels, desert pavements and hills located within 5 km of the dyke. Survey transects also crossed neighbouring dykes and adjacent landscape units with a 25 20 km area. Our surveys at Saf- faqah have led to the discovery of 14 new Acheulean sites. Initial lithic analyses reveal differences be- tween sites in terms of typology, but further work on the assemblages is required to determine if these differences are behavioural or a product of post depositional processes. A broad regional survey was undertaken to identify the full extent of Acheulean activity around Dawadmi. This led to the discovery of a further 22 sites. There is a strong correspondence between Acheulean sites and fine-grained andesite dykes, which were major lithic raw material sources. No Acheulean sites in the study area were found away from dykes or their adjacent landscape units. Based on dyke distributions, the geographic range of Acheulean activity is estimated to be 100 55 km, making Dawadmi one of the largest Acheulean landscapes in the world.

Freshwater availability is critical for human survival, and in the Saharo-Arabian desert belt repeated fluctuations between aridity and humidity over the Quaternary mean the distribution of freshwater was likely a primary control upon routes and opportunities for hominin dispersals. However, our knowledge of the spatio-temporal distribution of palaeohydrological resources within Arabia during MideLate Pleistocene episodes of climatic amelioration remains limited. In this paper we outline a combined method for remotely mapping the location of palaeodrainage and palaeolakes in currently arid regions that were formerly subject to more humid conditions. We demonstrate the potential of this approach by mapping palaeochannels across the whole Arabian Peninsula, and palaeolakes and marshes for select regions covering c. 10% of its surface. Our palaeodrainage mapping is based upon quantitative thresh- olding of HydroSHEDs data, which applies flow routing to Digital Elevation Model (DEM) data, while our palaeolake mapping uses an innovative method where spectral classification of Landsat Thematic Mapper (TM) imagery is used to detect palaeolake deposits within endorheic (closed) basins, before modelling maximum lake extents by flooding the basin to the level of the elevation of the highest detected deposit. Field survey in the Nefud desert and the Dawadmi and Shuwaymis regions of Saudi Arabia indicates accuracies of 86% for palaeodrainage mapping, and 96% for identifying former palae- olake basins (73% accuracy of classification of individual deposits). The palaeolake mapping method has also demonstrated potential for identifying surface and stratified archaeological site locations, with 76% of the surveyed palaeolake basins containing archaeological material, including stratified Palaeolithic archaeology. Initial examination of palaeodrainage in relation to archaeological sites indicates a relationship between mapped features and previously recorded Palaeolithic sites. An example of the application of these data for period-specific regional palaeohydrological and archaeological re- constructions is presented for a region of Northern Saudi Arabia covering the southern Nefud desert and adjacent lava fields.

The Nefud Desert is crucial for resolving debates concerning hominin demography and behaviour in the Saharo-Arabian belt. Situated at the interface between the Mediterranean Westerlies and African Monsoonal climate systems, the Nefud lies at the centre of the arid zone crossed by Homo sapiens dispersing into Eurasia and the edges of the southernmost known extent of the Neanderthal range. In 2013, the Palaeodeserts Project conducted an intensive survey of the western Nefud, to: (1) evaluate Pleistocene population dynamics in this important region of the Saharo-Arabian belt and (2) contribute towards understanding early modern human range expansions and interactions between different hominin species. Thirteen Lower and Middle Palaeolithic sites were discovered in association with palaeolake basins. One of the sites, T'is al Ghadah, may feature the earliest Middle Palaeolithic assemblage of Arabia. Preliminary analyses show that the Lower and Middle Palaeolithic sites discovered display diverse technological characteristics, indicating that the Nefud was important for population turnovers and exchanges throughout the Pleistocene. Periodic environmental amelioration appears to have attracted hominin incursions into the region, and subsequent ephemeral occupations structured around lakes and, to a lesser extent, raw material sources. However, differences between the Lower and Middle Palaeolithic sites are indicative of greater mobility during the later Pleistocene. A rarity of formal tools, but strong similarities in lithic production techniques, are also suggestive of demographic affinities across the Nefud during the Pleistocene, and perhaps beyond. These preliminary results support the view that the Arabian Peninsula was a critically important region of southwest Asia during the Late Pleistocene, in which demographic responses to climatic amelioration may have structured connectivity across the Saharo-Arabian belt, the Levant and as far as India.

Climate models are potentially useful tools for addressing human dispersals and demographic change. The Arabian Peninsula is becoming increasingly significant in the story of human dispersals out of Africa during the Late Pleistocene. Although characterised largely by arid environments today, emerging climate records indicate that the peninsula was wetter many times in the past, suggesting that the region may have been inhabited considerably more than hitherto thought. Explaining the origins and spatial distribution of increased rainfall is challenging because palaeoenvironmental research in the region is in an early developmental stage. We address environmental oscillations by assembling and analysing an ensemble of five global climate models (CCSM3, COSMOS, HadCM3, KCM, and NorESM). We focus on precipitation, as the variable is key for the development of lakes, rivers and savannas. The climate models generated here were compared with published palaeoenvironmental data such as palaeolakes, speleo- thems and alluvial fan records as a means of validation. All five models showed, to varying degrees, that the Arabia Peninsula was significantly wetter than today during the Last Interglacial (130 ka and 126/ 125 ka timeslices), and that the main source of increased rainfall was from the North African summer monsoon rather than the Indian Ocean monsoon or from Mediterranean climate patterns. Where available, 104 ka (MIS 5c), 56 ka (early MIS 3) and 21 ka (LGM) timeslices showed rainfall was present but not as extensive as during the Last Interglacial. The results favour the hypothesis that humans potentially moved out of Africa and into Arabia on multiple occasions during pluvial phases of the Late Pleistocene.

The dispersal of Homo sapiens out of Africa has been extensively researched across several disciplines. Here we review the evidence for spatial and temporal variability in lithic (stone tool) technologies relative to the predictions of two major hypotheses: 1) that a single successful dispersal occurred 60–50 thousand years ago (ka), marked by a trail of geometric/microlithic technologies, and 2) that multiple dispersals occurred, beginning much earlier (probably in Marine Isotope Stage [MIS] 5), associated with Middle Palaeolithic technology in its early phase. Our results show that Late Pleistocene geometric/microlithic technologies exhibit significant temporal and regional differences between each other. These differences suggest independent, convergent origins for these technologies, which are likely to have been repeatedly re-invented. In contrast, we identify similarities between East African lithic technologies from MIS 8 onwards and Middle Palaeolithic assemblages as far east as India by MIS 5. That this constellation of technological features – particularly an emphasis on centripetal Levallois reduction reflecting interchangeable preferential and recurrent methods, along with particular retouched forms such as points – transcends ecologies and raw material types suggests that it is unlikely to entirely reflect technological convergence (analogy). Our results indicate an early onset of multiple dispersals out of Africa. The hypothesis of an early onset to successful dispersal is entirely consistent with the possibility of further subsequent (post-MIS 5) dispersals out of Africa. Testing such hypotheses through quantified comparative lithic studies and interdisciplinary research is therefore likely to significantly advance understanding of the earliest H. sapiens dispersals.

The dispersal of human populations out of Africa into Arabia was most likely linked to
episodes of climatic amelioration, when increased monsoon rainfall led to the activation of drainage systems, improved freshwater availability, and the development of regional vegeta- tion. Here we present the first dated terrestrial record from southeast Arabia that provides evidence for increased rainfall and the expansion of vegetation during both glacial and inter- glacial periods. Findings from extensive alluvial fan deposits indicate that drainage system activation occurred during Marine Isotope Stage (MIS) 6 (ca. 160–150 ka), MIS 5 (ca. 130–75 ka), and during early MIS 3 (ca. 55 ka). The development of active freshwater systems during these periods corresponds with monsoon intensity increases during insolation maxima, sug- gesting that humid periods in Arabia were not confined to eccentricity-paced deglaciations, and providing paleoenvironmental support for multiple windows of opportunity for dispersal out of Africa during the late Pleistocene.

The Arabian Peninsula is situated at an important crossroads for the movement of Pleistocene human populations out of, and into, Africa. Although the timings, routes and frequencies of such dispersals have not yet been confirmed by genetic, fossil or archaeological evidence, expansion into Arabia would have been facilitated by humid periods driven by incursions of monsoon rainfall, potentially from both Indian Ocean and African monsoon systems. Here we synthesise terrestrial and marine core palaeoclimatic data in order to establish the spatial and temporal variability of humid periods in Arabia between late Marine Isotope Stage (MIS) 7 and 3. Incursions of monsoon rainfall occurred during periods of insolation maxima at ca. 200e190, 170, 155, 130e120, 105e95, 85e75 and 60e55 ka, providing multiple ‘windows’ of favourable climatic conditions that could have facilitated demographic expansion through Arabia. Strong summer monsoons are generally associated with mid-high latitude interglacials, however, enhanced monsoon convection also brought rainfall into Arabia during global glacial phases, possibly due to a strengthened winter monsoon and a greater influence of southern hemispheric temperature changes. Key periods for dispersal into northern regions of Arabia correspond with the synchronous intensifica- tion of both eastern Mediterranean and monsoon rainfall systems at insolation maxima during MIS 7 and MIS 5, which may have facilitated demographic connectivity between the Levant and the Arabian interior. Environmental conditions throughout southern and southeast regions were also favourable to expansion during these times, although strong monsoons in these regions during MIS 6 and MIS 3 suggest further opportunities for demographic expansion and exchange. Terrestrial and marine evidence show that during early MIS 3 (ca. 60e50 ka), a strengthened monsoon led to the activation of interior drainage systems and increased productivity in coastal zones, indicating that favourable environmental conditions existed along both coastal and interior routes at that time.

Recent archaeological discoveries indicate that the Arabian Peninsula played an important role in Late Pleistocene hominin dispersals. The presence of Middle Palaeolithic archaeological sites in the Nefud Desert of northern Saudi Arabia demonstrates that hominins moved far inland, probably following networks of ancient lakes and rivers deep into the Arabian interior. These Middle Palaeolithic sites, located close to the spatial and temporal boundary between Neanderthals and Homo sapiens, are critical for our understanding of Late Pleistocene demographic processes and hominin behaviour. Here we present the first detailed analysis of a Middle Palaeolithic lithic assemblage from the north Arabian desert interior. The Late Pleistocene site of Jebel Katefeh-1 (JKF-1) is located beside a palaeolake at Jubbah in the Nefud Desert. The assemblage appears to reflect a relatively short-lived occupation. Reduction produced Levallois flakes of diverse morphologies as well as more expedient small flakes. Our results emphasise that factors such as differential reduction intensity and raw material characteristics need to be considered along with putatively cultural interpretations of Middle Palaeolithic variability. Consideration of assemblage affinities indicates similarities with both the African and Levantine Middle Palaeolithic, perhaps reflecting the location of Jubbah at a crossroads of the highlands of western Arabia, the Levant and the Euphrates/Tigris river system. JKF-1 demonstrates both the potential and the complexity of the Arabian Middle Palaeolithic record in debates on hominin dispersal and adaptation.

The Arabian Peninsula is a key region for understanding climate change and human occupation history in a marginal environment. The Mundafan palaeolake is situated in southern Saudi Arabia, in the Rub’ al-Khali (the ‘Empty Quarter’), the world’s largest sand desert. Here we report the first discoveries of Middle Palaeolithic and Neolithic archaeological sites in association with the palaeolake. We associate the human occupations with new geochronological data, and suggest the archaeological sites date to the wet periods of Marine Isotope Stage 5 and the Early Holocene. The archaeological sites indicate that humans repeatedly penetrated the ameliorated environments of the Rub’ al-Khali. The sites probably represent short-term occupations, with the Neolithic sites focused on hunting, as indicated by points and weaponry. Middle Palaeolithic assemblages at Mundafan support a lacustrine adaptive focus in Arabia. Provenancing of obsidian artifacts indicates that Neolithic groups at Mundafan had a wide wandering range, with transport of artifacts from distant sources.

Plio-Pleistocene faunal turnovers and their implications for hominin dispersals have recently received considerable attention. Exploration and palaeontological study of faunal exchanges has traditionally centred on East Africa, North Africa and the Levant in Southwest Asia. Despite this attention, considerable debate surrounding the timings, rates, and directions of hominin dispersals remain. Notwithstanding its close geographical proximity to these regions and a landmass of over 3 million km 2 , the Arabian Peninsula has largely been excluded from these discussions, mostly owing to the paucity of its Pleisto-cene vertebrate record. However, recent palaeoenvironmental studies have demonstrated that Arabia experienced periods of climatic amelioration during the Pleistocene, resulting in the establishment of large, perennial water sources and open-grasslands; conditions vastly different than today. This interpretation is further underpinned by archaeological and palaeontological data, and it is now clear this region is important for understanding faunal and hominin movements between Africa and Eurasia. Examination of the Arabian Middle to Late Pleistocene fossil record in a biogeographical context indicates the composite nature of the Arabian faunal record, with Eurasian and African intrusions present in addition to well-established endemics. Open grassland habitats and taxonomic similarities between Pleistocene Arabia on the one hand, and the Levant and Africa on the other, suggests that hominin dispersal into Arabia did not require significant behavioural and/or technological innovations, while subsequent climatic deterioration likely resulted in hominin retreat/extirpation.

The workshop “Comparative Analysis of Middle Stone Age Artefacts
in Africa (CoMSAfrica)” aimed to reflect upon a common and replicable analytical framework, as well as proposing concrete solutions for
its implementation. It builds on previous efforts to standardize panAfrican comparisons which focused on higher taxonomic entities specific categories of stone artifacts, or individual regions. Organized
by C. Tryon and M. Will, the workshop brought together 12 international
scholars (see author list) working in different periods and regions of
Africa, with varied methodological backgrounds. The workshop was held
between November 5th and 6th 2018 at Harvard University (USA),
and funded through the Accelerator Workshop Program of the
Radcliffe Institute for Advanced Study (https://projects.iq.harvard.
edu/comsafrica). The meeting included short introductory presentations
by all participants followed by a series of more focused roundtable discussions to define the main problems and issues confronting comparative lithic analyses of African MSA assemblages. The final goal was the development of a unified analytical approach. As a two-day workshop was obviously insufficient to solve problems of such magnitude, the final discussion focused on outlining a working model and roadmap for future meetings and collaborations through the CoMSAfrica network.