Directional changes in Levallois core technologies between Eastern Africa, Arabia, and the Levant during MIS 5.
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ABSTRACT:
SUBMITTER: Blinkhorn J
PROVIDER: S-EPMC8169925 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The Middle Stone Age record in southern Africa is recognising increasing diversity in lithic technologies as research expands beyond the coastal-montane zone. New research in the arid Tankwa Karoo region of the South African interior has revealed a rich surface artefact record including a novel method of point production, recognised as Nubian Levallois technology in Late Pleistocene North Africa, Arabia and the Levant. We analyse 121 Nubian cores and associated points from the surface site Tweefontein against the strict criteria which are used to define Nubian technology elsewhere. The co-occurrence of typically post-Howiesons Poort unifacial points suggests an MIS 3 age. We propose that the occurrence of this distinctive technology at numerous localities in the Tankwa Karoo region reflects an environment-specific adaptation in line with technological regionalisation seen more widely in MIS 3. The arid setting of these assemblages in the Tankwa Karoo compares with the desert context of Nubian technology globally, consistent with convergent evolution in our case. The South African evidence contributes an alternative perspective on Nubian technology removed from the 'dispersal' or 'diffusion' scenarios of the debate surrounding its origin and spread within and out of Africa.
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Project description:ObjectivesThis study aimed to analyze the genetic relationships between honey bee subspecies using reference specimens and recently collected specimens from different parts of the world. The purity of these specimens was discussed in light of the obtained results.MethodsThe genetic networks were constructed between 21 subspecies of honey bees, Apis mellifera L.: 9 in Africa, 7 in Europe and 5 in Asia. The analysis was performed using the mtDNA of these subspecies and the Population Analysis with Reticulate Trees software. Some subspecies were represented by more than two specimens based on the available online sequences.Results and conclusionsThe subspecies A. m. sahariensis from Africa showed unique characteristics and is genetically isolated than all other studied bee subspecies. Specimens collected from Saudi Arabia showed genetic relatedness to A. m. jemenitica, A. m. lamarckii, and some European subspecies, suggesting high degree of hybridization. The close genetic relationship between the Egyptian bees, A. m. lamarckii, and the Syrian bees, A. m. syriaca, were emphasized. The overall genetic network showed the presence of three distinct branches in relation to geographical locations. The high accurateness of the used analysis was confirmed by previous phylogenetic studies as well as the genetic relationships between hybrid bees of A. m. capensis and A. m. scutellata. The genetic networks showed the presence of bee subspecies from Africa in all branches including Europe and Asia. The study suggests the impurity of some specimens mostly due to the hybridization between subspecies. Specific recommendations for future conservation efforts of bees were presented in light of this study.
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Project description:Arp2/3 complex is an actin polymerization nucleator and localized in the leading protrusions of migrating cells. It has been unclear how this complex is targeted to the protrusions and whether its localization is functionally important. We previously demonstrated that mRNAs encoding for the subunits of the complex were localized in the protrusions of fibroblasts, suggesting a mechanism to target the complex to the protrusions. We here present data demonstrating the importance of Arp2/3 complex mRNA localization in directional cell migration. Using a novel mechanism by which Dia1 mRNA is targeted to the perinuclear endoplasmic reticulum, we redirected the mRNA encoding Arp2, a subunit of the Arp2/3 complex, to the perinuclear region in fibroblasts. Knockdown of Arp2 alone caused dramatic reduction of the complex and resulted in narrow protrusions, increased random cell migration speed and loss of directionality. Rescue with a protrusion-localizing Arp2 mRNA restored normal cell migration behavior, whereas rescue with a mis-localizing Arp2 mRNA failed to restore speed and directionality. These results demonstrate that localization of Arp2/3 complex mRNAs in the leading protrusions is functionally important for directional cell migration.
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Project description:Interpreting human behavioral patterns during the Middle Paleolithic in the Levant is crucial for better understanding the dispersals and evolution of Homo sapiens and their possible interactions with other hominin groups. Here, we reconstruct the technological behavior, focusing on the centripetal Levallois method at Nesher Ramla karst sinkhole, Israel. Nesher Ramla karst sinkhole is dated to the Marine Isotope stages (MIS) 6 and 5 and represents one of the oldest occurrences of the centripetal Levallois reduction strategy in the Near East. The Levallois centripetal technology is often seen as a marker of human dispersals and adaptations in the Middle Paleolithic/Middle Stone Age of Africa and the Near East. This technology is documented in East African sites as early as 300 kya and in the Levant as early as 130 kya. However, the degree of similarity between African and Levantine centripetal technology and whether it originates from the same source remain under debate. In this paper, we focus on describing the lithic organization at Unit III of Nesher Ramla (dated to MIS 5), which is dominated by the centripetal Levallois method in association with other reduction sequences. Both preferential and recurrent centripetal Levallois modes were used at the site to produce oval and rectangular flakes. Other minor reduction sequences include unidirectional convergent method for Levallois points production and a specific method for the manufacture of naturally backed knives. The lithic data from Unit III of Nesher Ramla is further used in inter-site comparisons suggesting that the mid-Middle Paleolithic sites in the Near East possess common technological characteristics, especially the use of the centripetal Levallois method as predominant reduction strategy. This trend differs from what is usually observed in Africa and Europe, where the centripetal Levallois method is modestly represented during MIS 5 and is accompanied by other, more dominant, reduction strategies.
| S-EPMC7122790 | biostudies-literature
Project description:BackgroundMiddle Palaeolithic stone artefacts referred to as 'Levallois' have caused considerable debate regarding issues of technological predetermination, cognition and linguistic capacities in extinct hominins. Their association with both Neanderthals and early modern humans has, in particular, fuelled such debate. Yet, controversy exists regarding the extent of 'predetermination' and 'standardization' in so-called 'preferential Levallois flakes' (PLFs).Methodology/principal findingsUsing an experimental and morphometric approach, we assess the degree of standardization in PLFs compared to the flakes produced during their manufacture. PLFs possess specific properties that unite them robustly as a group or 'category' of flake. The properties that do so, relate most strongly to relative flake thicknesses across their surface area. PLFs also exhibit significantly less variability than the flakes generated during their production. Again, this is most evident in flake thickness variables. A further aim of our study was to assess whether the particular PLF attributes identified during our analyses can be related to current knowledge regarding flake functionality and utility.Conclusions/significancePLFs are standardized in such a manner that they may be considered 'predetermined' with regard to a specific set of properties that distinguishes them statistically from a majority of other flakes. Moreover, their attributes can be linked to factors that, based on current knowledge, are desirable features in flake tools (e.g. durability, capacity for retouch, and reduction of torque). As such, our results support the hypothesis that the lengthy, multi-phase, and hierarchically organized process of Levallois reduction was a deliberate, engineered strategy orientated toward specific goals. In turn, our results support suggestions that Levallois knapping relied on a cognitive capacity for long-term working memory. This is consistent with recent evidence suggesting that cognitive distinctions between later Pleistocene hominins such as the Neanderthals and anatomically modern humans were not as sharp as some scholars have previously suggested.
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Project description:The transition to food production, exploitation of 'secondary' products (e.g., milk), and advances in cookware technology have affected all aspects of human life. The aim of the present study was to follow changes in mandibular form and shape throughout the terminal Pleistocene-Holocene Levant. The hemimandibles of four populations were included in this study: Natufian hunter-gatherers (n = 10), Pre-pottery Neolithic early farmers (n = 6), Chalcolithic farmers (n = 9), Roman-Byzantine (n = 16), and modern (n = 63) populations. A surface mesh of each mandible was reconstructed from CT or surface scans. Changes in mandibular form and shape were studied using the Procrustes-based geometric morphometrics method. Univariate and multivariate analyses were carried out to examine differences in size and shape between the studied populations. Our results reveal considerable temporal changes in mandibular shape throughout the Holocene Levant, mainly between the pre-agricultural population (the Natufian) and the succeeding ones, and between the post-industrial (the Modern) and the pre-industrial populations. A tendency for a reduction in mandibular size was identified between the pre-agricultural population and the farmers. Most regions of the mandible underwent shape changes. In conclusion, substantial changes in mandibular shape occurred throughout the Holocene Levant, especially following the agricultural revolution. These changes can be explained by the "masticatory-functional hypothesis".
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Project description:Planar cell polarity (PCP) signaling controls the polarization of cells within the plane of an epithelium. Two molecular modules composed of Fat(Ft)/Dachsous(Ds)/Four-jointed(Fj) and a 'PCP-core' including Frizzled(Fz) and Dishevelled(Dsh) contribute to polarization of individual cells. How polarity is globally coordinated with tissue axes is unresolved. Consistent with previous results, we find that the Ft/Ds/Fj-module has an effect on a MT-cytoskeleton. Here, we provide evidence for the model that the Ft/Ds/Fj-module provides directional information to the core-module through this MT organizing function. We show Ft/Ds/Fj-dependent initial polarization of the apical MT-cytoskeleton prior to global alignment of the core-module, reveal that the anchoring of apical non-centrosomal MTs at apical junctions is polarized, observe that directional trafficking of vesicles containing Dsh depends on Ft, and demonstrate the feasibility of this model by mathematical simulation. Together, these results support the hypothesis that Ft/Ds/Fj provides a signal to orient core PCP function via MT polarization.
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Project description:Background and study aims Limited evidence suggests that endoscopy capacity in sub-Saharan Africa is insufficient to meet the levels of gastrointestinal disease. We aimed to quantify the human and material resources for endoscopy services in eastern African countries, and to identify barriers to expanding endoscopy capacity. Patients and methods In partnership with national professional societies, digestive healthcare professionals in participating countries were invited to complete an online survey between August 2018 and August 2020. Results Of 344 digestive healthcare professionals in Ethiopia, Kenya, Malawi, and Zambia, 87 (25.3 %) completed the survey, reporting data for 91 healthcare facilities and identifying 20 additional facilities. Most respondents (73.6 %) perform endoscopy and 59.8 % perform at least one therapeutic modality. Facilities have a median of two functioning gastroscopes and one functioning colonoscope each. Overall endoscopy capacity, adjusted for non-response and additional facilities, includes 0.12 endoscopists, 0.12 gastroscopes, and 0.09 colonoscopes per 100,000 population in the participating countries. Adjusted maximum upper gastrointestinal and lower gastrointestinal endoscopic capacity were 106 and 45 procedures per 100,000 persons per year, respectively. These values are 1 % to 10 % of those reported from resource-rich countries. Most respondents identified a lack of endoscopic equipment, lack of trained endoscopists and costs as barriers to provision of endoscopy services. Conclusions Endoscopy capacity is severely limited in eastern sub-Saharan Africa, despite a high burden of gastrointestinal disease. Expanding capacity requires investment in additional human and material resources, and technological innovations that improve the cost and sustainability of endoscopic services.
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Project description:Neanderthals occurred widely across north Eurasian landscapes, but between ~ 70 and 50 thousand years ago (ka) they expanded southwards into the Levant, which had previously been inhabited by Homo sapiens. Palaeoanthropological research in the first half of the twentieth century demonstrated alternate occupations of the Levant by Neanderthal and Homo sapiens populations, yet key early findings have largely been overlooked in later studies. Here, we present the results of new examinations of both the fossil and archaeological collections from Shukbah Cave, located in the Palestinian West Bank, presenting new quantitative analyses of a hominin lower first molar and associated stone tool assemblage. The hominin tooth shows clear Neanderthal affinities, making it the southernmost known fossil specimen of this population/species. The associated Middle Palaeolithic stone tool assemblage is dominated by Levallois reduction methods, including the presence of Nubian Levallois points and cores. This is the first direct association between Neanderthals and Nubian Levallois technology, demonstrating that this stone tool technology should not be considered an exclusive marker of Homo sapiens.
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Project description:The extent to which prehistoric migrations of farmers influenced the genetic pool of western North Africans remains unclear. Archaeological evidence suggests that the Neolithization process may have happened through the adoption of innovations by local Epipaleolithic communities or by demic diffusion from the Eastern Mediterranean shores or Iberia. Here, we present an analysis of individuals' genome sequences from Early and Late Neolithic sites in Morocco and from Early Neolithic individuals from southern Iberia. We show that Early Neolithic Moroccans (?5,000 BCE) are similar to Later Stone Age individuals from the same region and possess an endemic element retained in present-day Maghrebi populations, confirming a long-term genetic continuity in the region. This scenario is consistent with Early Neolithic traditions in North Africa deriving from Epipaleolithic communities that adopted certain agricultural techniques from neighboring populations. Among Eurasian ancient populations, Early Neolithic Moroccans are distantly related to Levantine Natufian hunter-gatherers (?9,000 BCE) and Pre-Pottery Neolithic farmers (?6,500 BCE). Late Neolithic (?3,000 BCE) Moroccans, in contrast, share an Iberian component, supporting theories of trans-Gibraltar gene flow and indicating that Neolithization of North Africa involved both the movement of ideas and people. Lastly, the southern Iberian Early Neolithic samples share the same genetic composition as the Cardial Mediterranean Neolithic culture that reached Iberia ?5,500 BCE. The cultural and genetic similarities between Iberian and North African Neolithic traditions further reinforce the model of an Iberian migration into the Maghreb.
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