Huw Groucutt | University of Malta (original) (raw)

Papers by Huw Groucutt

Acheulean technology and landscape use at Dawadmi, central Arabia, 2018

Despite occupying a central geographic position, investigations of hominin populations in the Ara... more 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.

The dispersal of hominins (our species and our closely related bipedal ancestors) out of Africa i... more The dispersal of hominins (our species and our closely related bipedal ancestors) out of Africa is a major topic in human evolutionary studies. As a geographic crossroad between continents, the Arabian Peninsula has a significant role to play in understanding the movement of hominin populations and the effect of climate change in shaping demographic history throughout the Pleistocene. However, the Palaeolithic evidence in Arabia has often been marginalized in prominent Out of Africa models, with the assumption that hominins would have avoided the hyper-arid desert belt, and utilized coastlines for their movement, especially along the Indian Ocean rim. Two interdisciplinary archaeological projects, named DISPERSE and PALAEODESERTS, have been conducted in Saudi Arabia in recent years in order to address dispersal models, and to improve our understanding of the hominin occupation history of the Red Sea coastline ("Blue Arabia") and the interior of the peninsula, especially during wet periods ("Green Arabia"). While acknowledging the importance of the Red Sea region as a potential zone for hominin occupation in the Pleistocene, we emphasize the crucial significance of the terrestrial environments for repeated hominin expansions during ameliorated periods in the Pleistocene, when a mosaic of ecosystems and plentiful rivers, wetlands and lakes were present.

We challenge the view that our species, Homo sapiens, evolved within a single population and/or r... more 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 hum... more 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 sign... more 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 u... more 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, reflec... more 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 Ara... more 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... more 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 hu... more 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... more 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 ... more 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 Holoc... more 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 bein... more 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.

Acheulean technology and landscape use at Dawadmi, central Arabia, 2018

Plio-Pleistocene faunal turnovers and their implications for hominin dispersals have recently rec... more 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.

Evolutionary Anthropology, 2019

The workshop “Comparative Analysis of Middle Stone Age Artefacts in Africa (CoMSAfrica)” aimed to... more 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.