Microbotanical residues for the study of early hominin tools

More than 2 million years ago in East Africa, the earliest hominin stone tools evolved amidst changes in resource base, with pounding technology playing a key role in this adaptive process. Olduvai Gorge (now Oldupai) is a famed locality that remains paramount for the study of human evolution, also yielding some of the oldest battering tools in the world. However, direct evidence of the resources processed with these technologies is lacking entirely. One way to obtain this evidence is through the analysis of surviving residues. Yet, linking residues with past processing activities is not simple. In the case of plant exploitation, this link can only be established by assessing site-based reference collections inclusive of both anthropogenic and natural residues as a necessary first step and comparative starting point. In this paper, we assess microbotanical remains from rock clasts sourced at the same quarry utilized by Oldowan hominins at Oldupai Gorge. We mapped this signal and analysed it quantitatively to classify its spatial distribution objectively, extracting proxies for taxonomic identification and further comparison with freestanding soils. In addition, we used blanks to manufacture pounding tools for blind, controlled replication of plant processing. We discovered that stone blanks are in fact environmental reservoirs in which plant remains are trapped by lithobionts, preserved as hardened accretions. Tool use, on the other hand, creates residue clusters; however, their spatial distribution can be discriminated from purely natural assemblages by the georeferencing of residues and statistical analysis of resulting patterns. To conclude, we provide a protocol for best practice and a workflow that has the advantage of overcoming environmental noise, reducing the risk of false positive, delivering a firm understanding of residues as polygenic mixtures, a reliable use of controls, and most importantly, a stronger link between microbotanical remains and stone tool use. © 2022. The Author(s).Materials and methods Results - Blanks as environmental reservoirs - Utilization creates residue clusters - Anthropogenic residue distribution - Of lichen habitability, proxy palimpsests, and hardened accretions - A protocol to study plant residue from Oldowan pounding tool

Earliest Olduvai hominins exploited unstable environments ~ 2 million years ago

Rapid environmental change is a catalyst for human evolution, driving dietary innovations, habitat diversification, and dispersal. However, there is a dearth of information to assess hominin adaptions to changing physiography during key evolutionary stages such as the early Pleistocene. Here we report a multiproxy dataset from Ewass Oldupa, in the Western Plio-Pleistocene rift basin of Olduvai Gorge (now Oldupai), Tanzania, to address this lacuna and offer an ecological perspective on human adaptability two million years ago. Oldupai’s earliest hominins sequentially inhabited the floodplains of sinuous channels, then river-influenced contexts, which now comprises the oldest palaeolake setting documented regionally. Early Oldowan tools reveal a homogenous technology to utilise diverse, rapidly changing environments that ranged from fern meadows to woodland mosaics, naturally burned landscapes, to lakeside woodland/palm groves as well as hyper-xeric steppes. Hominins periodically used emerging landscapes and disturbance biomes multiple times over 235,000 years, thus predating by more than 180,000 years the earliest known hominins and Oldowan industries from the Eastern side of the basin.Introduction Results - Stratigraphy and archaeology - Early Oldowan ecology at ~ 2 Ma Discussion Methods - Biomarkers - Energy dispersive X-ray fluorescence - Excavation - Fauna - Mineral geochemistry - Phytolith analysis - Pollen and microcharcoal - Stable carbon and oxygen isotope analysis of faunal dental enamel - Stone tool

Initial assessment of bioavailable strontium at Oldupai Gorge, Tanzania: potential for early mobility studies

Strontium isotope analysis is a useful tool for tracing mobility and migration in past populations. For it to be employed, the 87Sr/86Sr values of the landscape must be well-understood. Bioavailable strontium is a combination of geological and atmospheric strontium available for use by plants and animals. In this study we begin mapping bioavailable strontium values around the Oldupai Gorge region so that this method may be utilized on archaeological hominins and animals in the future. We analyzed three plants from 33 localities across volcanic and metamorphic bedrock, including the regional drainage sump, Olbalbal. We found that bioavailable strontium in the region is homogeneous overall, with trends towards increasing values to the north and northeast and in Olbalbal. There was no difference between 87Sr/86Sr values of metamorphic and volcanic areas. Migrants from outside the study area with different isotopic values will be easily identifiable from the local residents. As a proof of concept, we analyzed 7 animal teeth (hippopotamus, crocodile, and equid) from Engaji Nanyori, a Bed III and IV site at Oldupai Gorge. We found that enamel and dentine which had been acetic acid treated to remove diagenetic strontium were significantly different from one another. All animals had higher 87Sr/86Sr values than the plant values, suggesting that modern and ancient bioavailable strontium values may have been different, likely due to environmental differences.1. Introduction 2. Background 2.1. Using strontium values at the landscape level 2.2. Study area 2.3. Geology and palaeoanthropology 2.4. Palaeoenvironment and palaeoclimate 2.5. Engaji Nanyori 2.6. Plant and animal ecology 3. Materials and methods 3.1. Plant sampling 3.2. Excavation 3.3. Plant laboratory methods 3.4. Tooth preparation 3.5. Isotope analyses 3.6. Data analyses 4. Results 4.1. Bioavailable strontium 4.1.1. Geological variation 4.1.2. Geographical variation 4.1.3. Variation between plant types 4.2. Dental results 5. Discussion 5.1. Sources of variation 5.1.1. Bedrock 5.1.2. Atmospheric strontium 5.1.3. Hydrological strontium 5.1.4. Geographical factors 5.1.5. Plant and soil types 5.2. Dental tissues 5.2.1. Diagenesis 5.2.2. Taxonomy and migration 5.3. Modern vs. ancient bioavailable strontium 6. Conclusio

Hunter-gatherer environments at the Late Pleistocene sites of Mwanganda's Village and Bruce, northern Malawi

Mwanganda's Village (MGD) and Bruce (BRU) are two open-air site complexes in northern Malawi with deposits dating to between 15 and 58 thousand years ago (ka) and containing Middle Stone Age (MSA) lithic assemblages. The sites have been known since 1966 aOpen access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Petrographic Characterization of Raw Material Sources at Oldupai Gorge, Tanzania

Oldupai Gorge is located within the Ngorongoro Conservation Area, a UNESCO World Heritage Site in northern Tanzania along the western margin of the East African Rift System. Oldupai’s sedimentary record exhibits a complex sequence of inter-stratified lithic assemblages associated with the Early, Middle, and Later Stone Age. While diachronic technological change is perceptible, the totality of locally available rocks remained largely unchanged through time. Here, thin section petrography, Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy, and Electron Probe Micro Analysis were employed to characterize source lithologies in the Oldupai region. One of our goals was to determine if outcrops have rock types with unique mineral compositions amenable for sourcing lithic artifacts. Geological samples were collected in primary and secondary positions, from which sixty-two samples were selected for analysis. Comparative analyses show that five outcrops have quartzites with unique mineral compositions, seven meta-granite varieties are unique to five individual outcrops, Engelosin phonolite samples are texturally and mineralogically unique, and magmatic samples recovered in secondary position may be sourced to their volcanic center. Our results demonstrate it is feasible to differentiate between source materials using optical mineralogy which implies that sourcing lithic artifacts based on mineral compositions is possible. This is further substantiated by assigning the source/s for previously described fuchsitic quartzite artifacts from three archaeological sites at Oldupai as this raw material type uniquely occurs at two nearby outcrops. Systematic archaeological testing will allow future researchers to glean new understandings of hominin behavior and resource procurement within the Oldupai paleobasin

Petrographic Characterization of Raw Material Sources at Oldupai Gorge, Tanzania

Oldupai Gorge is located within the Ngorongoro Conservation Area, a UNESCO World Heritage Site in northern Tanzania along the western margin of the East African Rift System. Oldupai’s sedimentary record exhibits a complex sequence of inter-stratified lithic assemblages associated with the Early, Middle, and Later Stone Age. While diachronic technological change is perceptible, the totality of locally available rocks remained largely unchanged through time. Here, thin section petrography, Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy, and Electron Probe Micro Analysis were employed to characterize source lithologies in the Oldupai region. One of our goals was to determine if outcrops have rock types with unique mineral compositions amenable for sourcing lithic artifacts. Geological samples were collected in primary and secondary positions, from which sixty-two samples were selected for analysis. Comparative analyses show that five outcrops have quartzites with unique mineral compositions, seven meta-granite varieties are unique to five individual outcrops, Engelosin phonolite samples are texturally and mineralogically unique, and magmatic samples recovered in secondary position may be sourced to their volcanic center. Our results demonstrate it is feasible to differentiate between source materials using optical mineralogy which implies that sourcing lithic artifacts based on mineral compositions is possible. This is further substantiated by assigning the source/s for previously described fuchsitic quartzite artifacts from three archaeological sites at Oldupai as this raw material type uniquely occurs at two nearby outcrops. Systematic archaeological testing will allow future researchers to glean new understandings of hominin behavior and resource procurement within the Oldupai paleobasin