Olduvai Gorge Research Articles

On time scales and “synchronic” variability in the archaeology of human origins: short-term technological variations at SHK (Olduvai Gorge, Tanzania)

On time scales and “synchronic” variability in the archaeology of human origins: short-term technological variations at SHK (Olduvai Gorge, Tanzania)

Wide & deep learning for predicting relative mineral compositions of sediment cores solely based on XRF scans, a case study from Pleistocene Paleolake Olduvai, Tanzania

This study develops a method to use deep learning models to predict the mineral assemblages and their relative abundances in paleolake cores using high-resolution XRF core scan elemental data and X-ray diffraction (XRD) mineralogical results from the same core taken at coarser resolution. It uses the XRF core scan data along with published mineralogical information from the Olduvai Gorge Coring Project (OGCP) 2014 sediment cores 1A, 2A, and 3A from Paleolake Olduvai, Tanzania. Both regression and classification models were developed using a Keras deep learning framework to assess the predictability of mineral assemblages with their relative abundances (in regression models) or at least the mineral assemblages (in classification models) using XRF core scan data. Models were created using the Sequential class and Functional API with different model architectures. The correlation matrix of element ratios calculated from XRF element intensity records from the cores and XRD-derived mineralogical information was used to select the most useful features to train the models. 1057 training data records were used for the models. Lithological classes were also used for some models using Wide & Deep neural networks since those combine the benefits of memorization and generalization for mineral prediction. The results were validated using 265 validation data records unseen by the model and discuss the accuracy of models using six test records. The optimized Deep Neural Network (DNN) classification model achieved over 86% binary accuracy while the regression models were also able to predict the relative mineral abundances of samples with high accuracies. Overall, the study shows the efficacy of a carefully crafted Deep Learning (DL) model for predicting mineral assemblages and abundances using high-resolution XRF core scan data.

Assessing Habitat Suitability: The Case of Black Rhino in the Ngorongoro Conservation Area

Efforts to identify suitable habitat for wildlife conservation are crucial for safeguarding biodiversity, facilitating management, and promoting sustainable coexistence between wildlife and communities. Our study focuses on identifying potential black rhino (Diceros bicornis) habitat within the Ngorongoro Conservation Area (NCA), Tanzania, across wet and dry seasons. To achieve this, we used remote sensing data with and without field data. We employed a comprehensive approach integrating Sentinel-2 and PlanetScope images, vegetation indices, and human activity data. We employed machine learning recursive feature elimination (RFE) and random forest (RF) algorithms to identify the most relevant features that contribute to habitat suitability prediction. Approximately 36% of the NCA is suitable for black rhinos throughout the year; however, there are seasonal shifts in habitat suitability. Anthropogenic factors increase land degradation and limit habitat suitability, but this depends on the season. This study found a higher influence of human-related factors during the wet season, with suitable habitat covering 53.6% of the NCA. In the dry season, browse availability decreases and rhinos are forced to become less selective of the areas where they move to fulfil their nutritional requirements, with anthropogenic pressures becoming less important. Furthermore, our study identified specific areas within the NCA that consistently offer suitable habitat across wet and dry seasons. These areas, situated between Olmoti and the Crater, exhibit minimal disturbance from human activities, presenting favourable conditions for rhinos. Although the Oldupai Gorge only has small suitable patches, it used to sustain a large population of rhinos in the 1960s. Land cover changes seem to have decreased the suitability of the Gorge. This study highlights the importance of combining field data with remotely sensed data. Remote sensing-based assessments rely on the importance of vegetation covers as a proxy for habitat and often overlook crucial field variables such as shelter or breeding locations. Overall, our study sheds light on the imperative of identifying suitable habitat for black rhinos within the NCA and underscores the urgency of intensified conservation efforts. Our findings underscore the need for adaptive conservation strategies to reverse land degradation and safeguard black rhino populations in this dynamic multiple land-use landscape as environmental and anthropogenic pressures evolve.

New hominin dental remains from Olduvai Gorge (Tanzania)

New hominin dental remains from Olduvai Gorge (Tanzania)

OH 89: A newly described ~1.8-million-year-old hominid clavicle from Olduvai Gorge

OH 89: A newly described ~1.8-million-year-old hominid clavicle from Olduvai Gorge

Water, gravity, and trophic dynamics in the Misiam palimpsest, Olduvai Gorge

Misiam is a modern leopard-generated wildebeest bone accumulation located on the slope of a steep ravine within Olduvai Gorge (Tanzania). We present a taphonomic assessment of how leopard feeding behaviour shaped the bone assemblage, accumulated during the wet season, as well as contextualising the extent of secondary hyaenid scavenging. The spatial formation of this taphonomic palimpsest has resulted from the temporal sequence of interactions with the bone remains. The impact of additional agents and processes—such as fungi, insects, weathering, and, most importantly, gravitational displacement driven by water flows generated during the rainy season—adds to the complexity of this locality. This last factor may have played a decisive role in the density-mediated osteological attrition documented in the bone assemblage, perhaps to an even greater extent than hyaenid activity. Given the critical importance for analogical studies of documenting all relevant taphonomic factors at work in modern assemblages, our perspective allows for a comprehensive interpretive assessment of the site. The Misiam surface assemblage, a leopard-generated bone accumulation palimpsest with multiple taphonomic agents and processes at work within a short time span, has therefore significant implications for nuancing or complementing the interpretation of Early Pleistocene localities, such as FLK-North, FLK-Zinj or TK in Olduvai (Tanzania), Ubeidiya (Israel) or Barranco León in Orce (Spain), among others.

Biomechanical and taxonomic diversity in the Early Pleistocene in East Africa: Structural analysis of a recently discovered femur shaft from Olduvai Gorge (bed I)

Recent Plio-Pleistocene hominin findings have revealed the complexity of human evolutionary history and the difficulties involved in its interpretation. Moreover, the study of hominin long bone remains is particularly problematic, since it commonly depends on the analysis of fragmentary skeletal elements that in many cases are merely represented by small diaphyseal portions and appear in an isolated fashion in the fossil record. Nevertheless, the study of the postcranial skeleton is particularly important to ascertain locomotor patterns. Here we report on the discovery of a robust hominin femoral fragment (OH 84) at the site of Amin Mturi Korongo dated to 1.84 Ma (Olduvai Bed I). External anatomy and internal bone structure of OH 84 were analyzed and compared with previously published data for modern humans and chimpanzees, as well as for Australopithecus, Paranthropus and Homo specimens ranging from the Late Pliocene to Late Pleistocene. Biomechanical analyses based on transverse cross-sections and the comparison of OH 84 with another robust Olduvai specimen (OH 80) suggest that OH 84 might be tentatively allocated to Paranthropus boisei. More importantly, the identification of a unique combination of traits in OH 84 could indicate both terrestrial bipedalism and an arboreal component in the locomotor repertoire of this individual. If interpreted correctly, OH 84 could thus add to the already mounting evidence of substantial locomotor diversity among Early Pleistocene hominins. Likewise, our results also highlight the difficulties in accurately interpreting the link between form and function in the human fossil record based on fragmentary remains, and ultimately in distinguishing between coeval hominin groups due to the heterogeneous pattern of inter- and intraspecific morphological variability detected among fossil femora.

Age-depth model for uppermost Ndutu Beds constrains Middle Stone Age technology and climate-induced paleoenvironmental changes at Olduvai Gorge (Tanzania)

Olduvai Gorge in northern Tanzania is part of a globally important archeological and paleoanthropological World Heritage Site location critical to our understanding of modern human evolution. The Ndutu Beds in the upper part of the geological sequence at Olduvai Gorge represent the oldest unit to yield modern Homo sapiens skeletal material and Middle Stone Age technology. However, the timing of the deposition of the Ndutu Beds is poorly constrained at present, which limits our understanding of the paleoenvironments critical for contextualizing H. sapiens and related technologies in the Olduvai Basin. Using a suite of 15 luminescence ages of sedimentary core samples, combined with Bayesian statistics, this study provides a new higher-resolution age-depth model for the deposition of the uppermost Upper Ndutu and Naisiuiu Beds cored by the Olduvai Gorge Coring Project. The luminescence and modeled ages are presented as ±1 σ uncertainties. The Ndutu Beds intersected by the Olduvai Gorge Coring Project cores are dated to between 117.1 ± 17.9 and 45.3 ± 4.2 ka (between 125.9 ± 26.5 and 45.8 ± 8.2 ka modeled ages), while a probable overlying layer of Naisiusiu Beds dates to 23.7 ± 10.9 to 12.1 ± 1.7 ka (25.7 ± 18.9 ka and 12.0 ± 3.4 ka modeled age). Time-averaged accretion rates are derived during this time: (1) initially low rates (<5 cm ka−1) from the bottom of the core at 117.1 ± 17.9 ka up to 95.3 ± 11.1 ka (125.9 ± 26.5 to 95.5 ± 23.3 ka modeled ages); (2) the middle section spanning between 95.3 ± 11.1 and 62.7 ± 5.7 ka (95.5 ± 23.3 to 61.9 ± 10.4 ka modeled ages) with mean rates above 15 cm ka−1; and (3) the last 62.7 ± 5.7 ka (61.9 ± 10.4 ka modeled age) where the accretion rate reduces to below 5 cm ka−1. This reduction can be explained by the evolution of the gorge system that was likely driven by subsidence of the Olbalbal depression and changes in climate, particularly precipitation and resulting lake and base level changes. Older Upper Ndutu and Lower Ndutu Beds are contained within proto-gorges within the modern gorge system.

Core-Shaped Tools from the Early Pleistocene Deposits at Bairaki, Moldova

This a rticle deals with a series of core-shaped tools from Early Pleistocene deposits (layers 5 and 6) of the stratifi ed site of Bairaki, located on high above-fl oodplain terrace VII of the Dniester, in the outskirts of Dubăsari, Moldova. The site was discovered in 2010 by the joint Russian-Moldovan archaeological expedition and excavated in 2011– 2014. The interdisciplinary studies revealed six layers with Early Paleolithic artifacts. Two lowest layers (5 and 6) are associated with the channel alluvium of terrace VII. The paleomagnetic studies have shown that these deposits correspond to the Jaramillo episode of the Matuyama epoch. The lithic industry of layers 5 and 6 are comparable to the Late Oldowan. Most artifacts are made of poor quality fl int; there are also pebble tools made of non-silicic rocks. Most lithics are small. A distinct series of core-shaped end-scrapers and side-scrapers made on residual cores (9 spec.), fragments (1 spec.), and fl akes (5 spec.) is identifi ed. All these tools are robust and had been processed in a similar way. They are made of pebbles no larger than 6 сm. The steep working edges of all implements in this series are heavily retouched. Similar items have been recorded from the Early Paleolithic materials of the region. Such tools were widespread in the Early Paleolithic of Africa and Eurasia. The earliest pieces were found in the Bed I assemblage of the Olduvai Gorge.

The geoheritage of Olduvai Gorge, Tanzania: providing geological answers to human origin questions

Abstract While Olduvai Gorge, Tanzania, is most famous for its impressive and formative record of early human technology, Pleistocene fauna and hominin fossils, its geological record is equally important. At Olduvai, palaeoanthropologically significant sites are often preserved in primary context (not redeposited), and they can be contextualized within the palaeoenvironments in which the hominins lived. This has provided an exceptional opportunity to assess not only hominin evolutionary changes over time, but also to understand their adaptive behaviour including toolmaking, foraging and sociality. Abundant volcanic material from the nearby Ngorongoro Volcanic Highlands, interspersed within and between archaeology-bearing deposits, made Olduvai a target for some of the earliest applications of radiometric dating using the K/Ar system. Ultimately, the 40 Ar/ 39 Ar dating system has produced ages with exceptional precision. Early radiometric dating at Olduvai helped establish the antiquity of the hominin lineage, and early palaeomagnetic studies (and the ‘Olduvai event,’ the longest normal subchron within the reversed Matuyama Chron) were critical in establishing the importance of Olduvai in the field of geochronology. More recently, high-resolution palaeoclimate studies of the palaeolake that once occupied the Olduvai Basin have helped to reconstruct the palaeoenvironments encountered by hominin species. Over a century of geological research has secured Olduvai's status as an important site for geoheritage.

Tracking Early Hominin Foraging Behavior at DS Site (Bed I, Olduvai Gorge)

Academic discussions about African Early Stone Age site formation, animal carcass acquisition by hominins, the regularity of meat consumption or the use of central places have mainly relied on taphonomic studies of a few archaeofaunal assemblages, such as FLK Zinj (1.84 Ma [million years] ago, Olduvai Gorge Bed I, Tanzania). The DS site lies on the same paleosurface as FLK Zinj and constitutes an equally well-preserved, vertically-discrete deposit. The site has been extensively excavated in recent years (554 m²) and represents an invaluable opportunity to address key and long debated issues regarding early hominin lifeways with new approaches based on using robust and reliable statistical methods, including machine learning. Taphonomic studies can also greatly benefit from including the spatial component in the interpretations of a site’s formation and functionality. The results of the taphonomic and spatial study of DS point to the following behavioral components of hominin lifeways with regard to their foraging strategies: 1) regular primary access to animal carcasses; 2) selective animal carcass acquisition; and 3) collective animal carcass consumption in central-provisioning places. These features also point to cooperation and food sharing. The evidence from DS indicates that early Homo showed significant behavioral complexity relative to extant primates and a cohesive social structure. Two more newly discovered anthropogenically supported sites from the same period (PTK and AGS, Bed I Olduvai Gorge) that are currently being analyzed will soon shed further light on these adaptations.

Earliest Acheulian paleolandscape reveals a 1.7 million-year-old megasite at Olduvai Gorge (Tanzania)

FLK West (Bed II, Olduvai Gorge) contains the oldest association of Acheulian stone tools and exploitation of fauna (including megafauna) by hominins in the Pleistocene. Recently, the FLK West paleolandscape has been intensively studied, unveiling a spatial association between archaeological materials and hydrothermal resources. A new type of landscape use by hominins has also been documented around the area where the pene-contemporaneous FLK West and HWK site complex were formed, resulting in an array of habitats spanning thousands of square meters covered with large amounts of lithic artefacts. Here, we show how the intensive use of certain environments by hominins resulted in these “megasites”, in which hominins engaged in a variety of activities, complementary to those performed at discrete archaeological clusters like FLK West. Despite using these habitats redundantly as quarries, hominins performed extensive core reduction of several types of raw materials indicating a dexterity and careful planning undocumented in earlier periods. Here, we also show how palaeoecological reconstructions must be based on fine-scale geological analyses, given the palimpsestic nature of both geological and anthropogenic processes. The research reported here also uncovered an additional unknown source of metamorphic rocks for hominins at Olduvai, which questions a large part of previous modeling based on hominin provisioning exclusively at Naibor Soit. We also show that the manufacture of handaxes was slightly older than documented at FLK West and that they occur in isolation on the landscape in addition to being clustered at sites. This implies that at the beginning of the Acheulian, hominins were not only using and discarding handaxes at specific loci, but they also transported these tools for various activities across the landscape as part of their strategized adaptation to those environments. The occurrence of these intensively-used megasites hints at some territorial behaviors by early Acheulian hominins.

The crystalline quartz-rich raw material from Olduvai Gorge (Tanzania): why is it called quartzite when it should be called quartz?

The major raw material documented in the archeological sites of Olduvai Gorge (Tanzania) is a geological material with crystalline appearance, white or colorless, foliated or seemingly massive only at the outcrop scale, with a very high quartz-rich composition, and apparently of metamorphic origin, named by us in this paper: Crystalline Quartz-rich Raw Material (CQRM). Since the early days of research in Olduvai Gorge, a long-lasting terminological imprecision has allowed defining this material in a confused way as quartz or quartzite. Stubbornness in terminological imprecision reflects the complexity and specificity of CQRM related to a protracted and complex geological history composed by quartz-bearing metamorphic rocks of varied types and origins from recycling and/or tectonic reworking of much older Precambrian orogens and cratons. Currently the term quartzite is preferred by most researchers, despite being materials that have an appearance macro- and microscopic similar to quartz and show a response to fracture mechanics, and cutting-edge functional response is closer to quartz. In our view, it is crucial to undertake a comprehensive analysis of the CQRM from the structural, metamorphic, and petrological perspectives. Bearing this in mind, the main objective of the present study is to build a robust and conclusive petrological background that will enable an accurate identification and classification of this quartz-rich mineral resource. This geological material should be identified as “quartz.” The most diagnostic features supporting this interpretation can be summarized as some of the microstructural relics identified concur undoubtedly with a hydrothermal origin of the quartz and the recognition of special deformational structures at macro and micro scale point to tectono-metamorphic overprint of the hydrothermal quartz under granulite-facies conditions during the Panafrican orogenesis about 640 Ma ago.

Searching for intra-site spatial patterns in the African Early Acheulean: the lowermost archaeo-units at FLK West (Olduvai Gorge, Tanzania)

Searching for intra-site spatial patterns in the African Early Acheulean: the lowermost archaeo-units at FLK West (Olduvai Gorge, Tanzania)

Using Radiometric Dating, Magnetostratigraphy, and Tephrostratigraphy to Calibrate Rates of Hominin Evolution in the East African Rift

Age-calibration of hominin fossils and artifacts in the East African Rift is principally achieved through dating of associated volcanic-sedimentary strata. The dominant dating techniques for sites ≳100 ka are the 40Ar/39Ar radiometric dating method, magnetostratigraphy, and tephrostratigraphy. The 40Ar/39Ar technique relies on the occurrence of volcanic deposits in the target strata, which are often present as a consequence of the interplay of rift formation and volcanic activity. The frequency of datable material may be limited; however, by also applying the relative dating methods of magnetostratigraphy and tephrostratigraphy to these same strata, a chronostrati-graphic framework can be built and applied to fossiliferous strata. This chapter provides examples of the application of these techniques at Olduvai Gorge, Tanzania, and two areas of the East African Rift in Ethiopia.

Paleoecological evidence for environmental specialization in Paranthropus boisei compared to early Homo.

Since the discovery of Paranthropus boisei alongside early Homo at Olduvai Gorge and East Turkana, paleoanthropologists have attempted to understand the different evolutionary paths of these two hominin lineages. Conventional wisdom is that their prolonged phase of sympatry in eastern Africa reflects different adaptive strategies, with early Homo characterized as the ecologically flexible generalist and Paranthropus as the less versatile specialist. If correct, this should imply differences in their use of ancient environments, with early Homo occurring in a broader range of environmental contexts than Paranthropus. This prediction has yet to be subject to rigorous quantitative evaluation. In this study, we use the 2.0-1.4Ma fossil bovid assemblages associated with early Homo and P.boisei at East Turkana (Kenya) to quantify the breadth of their environmental associations. We find that early Homo occurs in faunal assemblages indicative of a broader range of environments than P.boisei. A null model taking sampling into account shows that the broad environmental associations of early Homo are indistinguishable from random, whereas P.boisei is one of just a handful of large mammal taxa from East Turkana that has a narrower range of environmental associations than expected by chance. These results support the characterization of P.boisei as an ecological specialist relative to the more generalist Homo. Moreover, the narrow environmental associations observed of P.boisei, unlike those of almost all other C4 grass-consumers in the Turkana Basin, suggest that it likely did not feed on a spatially widespread C4 resource like the leaves, seeds, or rhizomes of grass.

Paleolakes of Eastern Africa: Zeolites, Clay Minerals, and Climate

The eastern branch of the East African Rift System hosts many shallow modern lakes and paleolakes, which can be sensitive recorders of changing climate conditions (complicated by tectonics) during the past few million years. However, many of such lakes are saline–alkaline (salty and high pH), and these conditions do not easily preserve pollen and other biologically derived paleoclimate indicators. Fortunately, some preserved minerals that formed in these extreme environments reflect subtle shifts in lake water chemistry (controlled by changes in climate conditions) and therefore provide a continuous record of local and regional climate change. We present two different mineral proxies (zeolites and clays) from two different paleolake basins (Olduvai Gorge, Tanzania, and Chew Bahir, Ethiopia) as examples.

Identifying intentional flake production at the dawn of technology: A technological and 3D geometric morphometric study

The production of sharp-edged stone flakes is often viewed as a unique adaptation specific to the hominin lineage. The discovery of large stone cores and flakes dated to 3.3 Ma has shown that the earliest evidence of hominin stone flake production differs from the later Oldowan (dated to 2.6 Ma) record. Recent discoveries have shown that capuchin monkeys (Sapajus libidinosus) can unintentionally produce sharp-edged flake assemblages as a by-product of percussive behaviour. Capuchin monkeys are the only wild primate to intentionally strike two stones together (stone-on-stone percussion) to produce quartz powder. In doing so, they unintentionally produce high frequencies of sharp-edged flakes. It has been suggested that these possess the same technological attributes commonly used to describe intentional hominin stone flakes. Here we directly compare the basic morphometric descriptions, technological and 3D morphometric properties of unintentional capuchin flakes with experimentally produced flakes derived from two intentional flaking techniques employed during the Plio-Pleistocene, freehand and passive hammer knapping and a sample of Oldowan freehand flakes from Olduvai Gorge (Tanzania). Our results show that unintentional stone-on-stone flakes overlap in terms of their shape, size and technological attributes with those produced through intentional knapping techniques. We, however, identify attributes that may be critical for differentiating between intentional knapping techniques documented in the early archaeological record and unintentional flakes. Using these data we show that Oldowan flakes more closely resemble intentional freehand techniques.

Radiometric dating of the Ootun palaeosol and its implication for the age of the Shifting Sand in Ngorongoro Lengai Geopark (Arusha, Tanzania)

The Shifting Sand is a barchan dune in Ngorongoro Lengai Geopark in Arusha, Tanzania. The geopark, a UNESCO World Heritage Site, is protected by the Ngorongoro Conservation Area Authority. The dune ranks amongst the main geosites that have been attracting numerous tourists; it formed as a result of volcanic ash eruptions that led to tephra deposition on a palaeosol (palaeosurface) in the Ootun area. The easterly winds modified the ash into dunes and headed to the Olduvai Gorge area. The age of the Shifting Sand dune is not known in detail. In the present study, we employ the radiocarbon (14C) dating method to date a subsurface palaeosol bed in the Ootun area where the tephra (i.e., original Shifting Sand materials) was originally deposited. An Accelerator Mass Spectrometer was used to determine the carbon-14 date of the palaeosol so as to estimate the age of the Shifting Sand dune, and an Energy Dispersive X-ray Fluorescent Spectrometer to determine the chemical composition of the Shifting Sand material and the tephra bed for correlative purposes. A radiocarbon (14C) date of 2510 ± 30 years BP for the Ootun palaeosol was obtained to estimate the minimum age of the Ootun subsurface tephra deposited in the area; since then, this started to move westwards towards the Olduvai Gorge area, where it is today defined as the Shifting Sand. The current findings add educational value to the Shifting Sand in Ngorongoro Lengai Geopark and improve our understanding of the eruption history of the Gregory Rift volcanoes.

A taphonomic analysis of PTK (Bed I, Olduvai Gorge) and its bearing on the interpretation of the dietary and eco-spatial behaviors of early humans

Here, we present a thorough taphonomic analysis of the 1.84 million-year-old site of Phillip Tobias Korongo (PTK), Bed I, Olduvai Gorge. PTK is one of the new archaeological sites documented on the FLK Zinj paleolandscape, in which FLK 22 level was deposited and covered by Tuff IC. Therefore, PTK is pene-contemporary with these sites: FLK Zinj, DS, AMK and AGS. The occurrence of these sites within a thin clay unit of ∼20 cm, occupying not only the same vertically discrete stratigraphic unit, but also the same paleosurface, with an exceptional preservation of the archaeological record in its primary depositional locus, constitutes a unique opportunity to explore early hominin behavioral diversity at the most limited geochronological scale possible. The Olduvai Bed I sites have been the core of behavioral modelling for the past half a century, and the newly discovered sites, excavated with 21st century technology, will increase significantly our understanding of early human adaptive patterns. Here, we present PTK as another assemblage where faunal resources were acquired by hominins prior to any carnivore, and where stone-tool assisted bulk defleshing was carried out. The abundance of juvenile individuals extends our understanding, as in Kanjera (Kenya), about the hunting skills of early Homo sensu lato. The increasing number of sites, where bulk defleshing of small and medium-sized carcasses took place is underscoring the importance of meat in the diets of some of the early hominins, and their patterned use of the space for food processing and consumption. The patterning emerging has a profound importance for the evolution of some of the features that have traditionally been used to identify the behavior of the genus Homo.