Core Reduction Research Articles

Late Middle Paleolithic Technological Organization and Behavior at the Open-Air Site of Barozh 12 (Armenia)

Barozh 12 is a late Middle Paleolithic open-air locality in western Armenia dating from ~ 60,000 to 31,000 years ago. Stratified deposits with high densities of obsidian artifacts permit the analysis of diachronic trends in manufacture, reduction, discard, and toolstone provisioning as related to technological organization in the context of hunter-gatherer mobility and land use. Throughout much of Marine Isotope Stage (MIS) 3, the occupants of Barozh 12 employed consistent unidirectional-convergent and unidirectional Levallois and “para-Levallois” core reduction techniques. Site occupation intensity varied over time, with changing emphasis on local core reduction and tool discard. Obsidian artifact sourcing indicates predominantly local toolstone exploitation, while blanks bearing retouch were intermittently transported to Barozh 12 over distances up to ~ 190 linear km. As a repeatedly visited, persistent place in regional settlement systems, this site records a range of mobility strategies and differential use of diverse eco-geographic zones. This study—a detailed analysis of late Middle Paleolithic technological organization at an open-air site in the Armenian highlands—broadens the regional record of Late Pleistocene hominin technological behaviors and settlement dynamics during a crucial period of human evolution.

Influence of Body Temperature on Bispectral Index-Guided Anesthetic Management in Off-Pump Coronary Artery Bypass Grafting

Abstract Background Perioperative hypothermia is not uncommon in surgical patients due to anesthetic-induced inhibition of thermoregulatory mechanisms and exposure of patients to cold environment in the operating rooms. Core temperature reduction up to 35°C is often seen in off-pump coronary artery bypass graft (OP-CABG) surgery. Anesthetic depth can be monitored by using bispectral (BIS) index. The present study was performed to evaluate the influence of mild hypothermia on the anesthetic depth using BIS monitoring and correlation of BIS with end-tidal anesthetic concentration at varying temperatures during OP-CABG. Materials and Methods In a prospective observational study design in a tertiary care teaching hospital, patients who underwent elective OP-CABG under endotracheal general anesthesia, were included in the study. Standard technique of anesthesia was followed. BIS, nasopharyngeal temperature, and end-tidal anesthetic concentration of inhaled isoflurane was recorded every 10 minutes. The BIS was adjusted to between 45 and 50 during surgery. Results There were 40 patients who underwent OP-CABG during the study period. The mean age was 51.2 ± 8.7 years, mean body mass index 29.8 ± 2.2, and mean left ventricular ejection fraction was 55.4 ± 4.2%. Anesthetic requirement as guided by BIS between 45 and 50 correlated linearly with core body temperature (r = 0.999; p < 0.001). The mean decrease in the body temperature at the end of 300 minutes was 2.2°C with a mean decrease in end-tidal anesthetic concentration of 0.29%. The reduction in end-tidal anesthetic concentration per degree decrease in temperature was 0.13%. None of the patients reported intraoperative recall. Conclusion In this study, BIS monitoring was used to guide the delivery concentration of inhaled anesthetic using a targeted range of 45 to 50. BIS monitoring allowed the appropriate reduction of anesthetic dosing requirements in patients undergoing OP-CABG without risk of awareness. There was a significant reduction in anesthetic requirements associated with reduction of core temperature. The routine use of BIS is recommended in OP-CABG to titrate anesthetic requirement during occurrence of hypothermia and facilitate fast-track anesthesia in this patient population.

The technology and ecology of Lesotho's highland hunter-gatherers: A case study at Sehonghong rock shelter

Here we evaluate the hypothesis that during cold climatic phases, people and resources became increasingly packed along highland Lesotho's riverine corridors as the viability of palatable grasslands for large mammal hunting on the upland plateaus declined. These intensification efforts resulted in increased reliance on lower-ranked aquatic (fish) resources with knock-on effects for lithic technological organization. We compare data on the relative contribution of fishing to the diets of highland hunter-gatherers at Sehonghong rockshelter with a faunal proxy widely argued to correlate with subsistence intensification (faunal assemblage evenness). In addition, we compare these data with two measures of lithic technological intensification (cutting edge production and core reduction intensity) to test whether diet intensification tracks technological intensification. We show that at Sehonghong, aquatic resource exploitation is not always correlated with faunal assemblage evenness. We find that some layers (i.e. RF) show spikes in aquatic resource use irrespective of changes in faunal assemblage evenness. Other layers (i.e. RBL/CLBRF) were intensively occupied, but they do not have many fish. Our data also demonstrate that aquatic resource use is not correlated with lithic technological intensification. These results suggest that while aquatic resource exploitation was a ‘fallback’ option for some of Lesotho's highland hunter-gatherers, there is considerable variability. Our data show that multiple intensification dimensions were variably combined through the Late Pleistocene at Sehonghong as they were elsewhere in southern Africa.

The Fauresmith of South Africa: A new assemblage from Canteen Kopje and significance of the technology in human and cultural evolution

The Fauresmith was a term first coined by archaeologists in the 1920s to describe a cultural development intermediate between the Earlier and Middle Stone Ages. From the late 1960s, many researchers abandoned the term in favor of sinking the Fauresmith within the Later Acheulean. More recently, however, some have supported the idea of the Fauresmith as the earliest Middle Stone Age, whereas other researchers continue to use the term to refer to a transitional technological development. In this article, we evaluate the status of the Fauresmith. We do this by describing a newly excavated assemblage from Canteen Kopje in the Northern Cape Province of South Africa and by comparing it with other assemblages published as Fauresmith. Although there is substantial variability across these assemblages, we present data to show that the relevant assemblages show the consistency of a regional technology that is indeed transitional between the Earlier and Middle Stone Ages. It includes prepared cores, blades, and very reduced numbers of large cutting tools compared with the Acheulean, and it often includes convergent flakes and retouched points. We argue that the Fauresmith, along with parallel developments both within and beyond Africa, is a term worth retaining to identify the slow process of decline of Acheulean technology in favor of a lighter toolkit, which includes varying degrees of more advanced core reduction strategies, larger numbers of formal tools, and hafting. Such developments are associated with populations linked to the development of Homo sapiens in Africa from ca. 600 to 160 ka.

Black obsidian procurement strategies and circulation along the northern coast of the Santa Cruz Province (Argentine Patagonia): human mobility and interaction

In this article, we examine the strategies behind the acquisition and reduction of black obsidian found in rock shelters and shell middens from the north coast of the Santa Cruz Province, in Argentine Patagonia. Geochemical analyses performed on black obsidian artifacts from this area posit the long-distance circulation of this raw material given its source at Pampa del Asador, located approximately 400 km to the west. In a previous article, we suggested that evidence for the initial knapping of obsidian pebbles, added to the identification of artifacts with high cortex percentage, implied that obtaining pieces of said raw material would have been based on pebble morphologies. Here we expand on this proposal, contending that this was the case at least for Late Holocene occupational contexts.
 During the Middle Holocene an exceptionally low representation of very small-sized debris without cortical reserve was observed; cores and tools were not registered. Knapping activities related to intermediate technical steps in the framework of core reduction and blank production were evidenced, including small and very small flakes as well as bifacial preforms. We inferred that obsidian pieces probably entered into these Middle Holocene sites as part of personal toolkits, cores and bifacial artifacts without cortex, within the framework of exploratory incursions into the area.
 For the Late Holocene occupations, taking into consideration the presence of obsidian pebbles, of similar dimensions to those registered at the source itself, we suggest that their procurement would have occurred through various mechanisms, such as the establishment and strengthening of social relations within the context of mobility circuits that would have linked the coast to the interior, among other factors.

Preliminary design and analysis of Liquid Fuel Molten Salt Reactor using multi-physics code GeN-Foam

In this study, a hypothetical fast spectrum Liquid Fuel Molten Salt Reactor (LFMSR) core is modeled using the multiphysics C++ code GeN-Foam (General Nuclear Foam). GeN-Foam is based on OpenFOAM, a C++ open-source library for solution of continuum mechanics problems. The code utilizes a unified fine/coarse mesh approach, modeling different physics such as neutron kinetics, thermal-hydraulics based on porous fluid equations, and structural thermal-mechanics. A steady state analysis of a simplified two-dimensional (2D) LFMSR model has been performed assuming rotational symmetry to cross verify the code with the commercial ANSYS Computational Fluid Dynamics (CFD) code Fluent. The calculations showed very good agreement between the two codes allowing progression to a three-dimensional (3D) model simulation. A coupled neutron kinetics and CFD steady state analysis of a right-cylindrical 3D LFMSR core has been performed modeling one quarter of the core while using symmetry boundaries to reduce the computational time. Mixed uranium and plutonium chloride fuel has been selected in this preliminary study. Both 2D and 3D simulations showed appearance of recirculation zones within the right-cylinder core. These zones can be a challenge for LFMSR control and materials. A new hyperboloid design is proposed to remove recirculation zones, which is based on eight symmetrical loops. An Unprotected Loss of Flow accident (ULOF), in which the pump head is instantaneously reduced to zero, has been selected to demonstrate the safety characteristics of the reactor in one of the most challenging possible situations for LFMSR. The obtained results (e.g., reduced total precursors concentration at the core inlet and reduction of the core nominal power following the transient) confirm that GeN-Foam is capable of performing coupled LFMSR transient analysis and can be used for design analysis and optimization. Although the current design needs further assessment and development, it shows encouraging performance under ULOF conditions paving the way to the next step in the optimization process.

Re-evaluating the Gravettian technocomplex in Iberia: The 497C lithic assemblage from Cova Gran de Santa Linya (Southeastern Pyrenees)

Traditionally, fossil directors have been key elements for the characterization of chrono-cultural series over time. Current research on lithic technology demonstrate extensive and growing variability within technocomplexes, particularly in the Upper Paleolithic, making more complex the previously established chrono-cultural organization.In this article we analyze the lithic technology of level 497C from Cova Gran de Santa Linya, dated to 26.220 ± 220 BP (31260–30580 cal BP). Chronometric data indicates the assemblage is located between MIS 3 and MIS 2, likely placing it within the Gravettian tradition. The level 497C constitutes one of the few archaeological sites in NE Iberia for this period and allows identifying technical traits in core reduction methods, stone tools manufacture and site composition.Reduction strategies through prismatic cores were used to obtain distinct sequences of blades and bladelets. The assemblage of retouched artifacts is mainly composed by “fond commun”, pieces with abrupt retouch, and burins (mostly on oblique truncation). Backed tools, which were common during this period, are notably rare, as are Gravette points and Noailles burins, classic indicators that are not represented here. Nevertheless, a group of partially retouched macro-flakes forms a little-known category of instruments that can provide remarkable information regarding the technical behaviors of human groups.The technological features seen in level 497C may be consistent with the Gravettian technocomplex. However, we suggest the integration of technical-organizational indicators to assist the contextualization of the diversity of responses and technological decisions identified in technocomplexes. In this sense, the characteristics of this assemblage offer keys for evaluating archaeological sequences without fossil directors, thereby expanding our understanding of technological variability in this period in Iberia.

Another Look at Expedient Technologies, Sedentism, and the Bow and Arrow

The transition from the dart to the arrow, and the commensurate changes in lithic technology is poorly understood in the American Southwest. This transition has often been linked to shifts in sedentism and the increasing use of expedient flake tools. However, the relationship between the use of bifacial and core reduction strategies are conditioned by a variety of factors, and not primarily in response to the use of the bow-and-arrow, or simply sedentism. We, therefore, evaluate a series of potential factors which can be used to understand the variability exhibited in the use of biface and flake technologies.

A 1.4-million-year-old bone handaxe from Konso, Ethiopia, shows advanced tool technology in the early Acheulean

In the past decade, the early Acheulean before 1 Mya has been a focus of active research. Acheulean lithic assemblages have been shown to extend back to ∼1.75 Mya, and considerable advances in core reduction technologies are seen by 1.5 to 1.4 Mya. Here we report a bifacially flaked bone fragment (maximum dimension ∼13 cm) of a hippopotamus femur from the ∼1.4 Mya sediments of the Konso Formation in southern Ethiopia. The large number of flake scars and their distribution pattern, together with the high frequency of cone fractures, indicate anthropogenic flaking into handaxe-like form. Use-wear analyses show quasi-continuous alternate microflake scars, wear polish, edge rounding, and striae patches along an ∼5-cm-long edge toward the handaxe tip. The striae run predominantly oblique to the edge, with some perpendicular, on both the cortical and inner faces. The combined evidence is consistent with the use of this bone artifact in longitudinal motions, such as in cutting and/or sawing. This bone handaxe is the oldest known extensively flaked example from the Early Pleistocene. Despite scarcity of well-shaped bone tools, its presence at Konso shows that sophisticated flaking was practiced by ∼1.4 Mya, not only on a range of lithic materials, but also occasionally on bone, thus expanding the documented technological repertoire of African Early Pleistocene Homo.

Intra-assemblage variation in the macro-blade assemblage from the 1963 excavation at Shuidonggou locality 1, northern China, in the context of regional variation.

The emergence of the Upper Paleolithic and regional variability in early Upper Paleolithic industries are prominent topics in Paleolithic archaeology, with special relevance to the dispersal and differentiation of early modern human cultures across Eurasia. The so-called Initial Upper Paleolithic (IUP) has been considered a key element in the emergence of the Upper Paleolithic in northern Asia. Here, we examine the intra-assemblage variation in the collection from the 1963 excavation at Shuidonggou locality 1, a major IUP site in northern China. We combine technological and quantitative attribute analyses to investigate the variety of core reduction sequences and tool manufacture behaviors at the site. A range of core reduction sequences have been documented at Shuidonggou locality 1, including both simple core reduction and prepared core reduction yielding laminar (blade-like) products. The simple core reduction component may due to mixed non-IUP assemblages from different archaeological layers. Among the laminar core reduction sequences, the main strategy involves asymmetrical exploitation of the broad face of core blank, producing blades and elongate flakes, and resembling a recurrent Levallois blade method sensu lato. We compare Shuidonggou laminar blank production with that of IUP assemblages in the Siberian Altai, northern Mongolia, and the Transbaikal region. The comparison demonstrates a general consistency to the basic blank production in IUP assemblages across northern Asia, with some regional variation. The results suggest a multi-directional model of diffusion of the IUP in northeast Asia.

Rethinking the Desirability of Quartz for the Manufacture of Standardized Retouched Flakes: An Example From Weereewaa (Lake George), South-eastern Australia

ABSTRACT Quartz is regularly held to be of lower quality than fine-grained siliceous (FGS) material and often correlated with lower levels of retouch. This paper examines the “desirability” of quartz as a raw material for the production of backed artefacts in a landscape which also contains fine-grained siliceous material. Quartz, chert and silcrete backed artefact manufacturing strategies and morphologies are compared to examine whether technological choices differ by raw material. Quartz and chert are found to display high degrees of similarity in terms of core reduction technology, flake selection and backed artefact morphology. This alignment challenges perceptions regarding the desirability of quartz for the manufacture of small, standardized retouched flakes.

Newly discovered Upper Paleolithic sites from the Tsagaan Turuut river valley, Mongolia

In this article, we report artefacts found at the valley of Tsagaan Turuut River in the Khangai Mountain ranges in Central Mongolia. The artefacts were identified based upon core morphology, tool types and retouch. Regarding the core reduction techniques, single striking platform and single reduction platform cores are dominant. Although the tools on flake blanks predominant, tools such as points and knives with massive blades also occur. Side scraper, point, borer, combination tool, and borers are types that are less represented within the collection. This tool collection is highly similar to several IUP and EUP sites (Chikhen-2; Tolbor-4, 15 and 16) in Mongolia in terms of its reduction techniques and tool morphology. On a larger scale, it is similar to those of Early Upper Paleolithic sites in Trans-Baikal and Altai Mountains in Russia and North China.

The Last Glacial Maximum Microblades from Kashiwadai 1 in Hokkaido, Japan

ABSTRACT Although microliths are regarded as small standardized tools for complex composite technology, it is still not fully understood whether this schematic understanding developed in Old World prehistory can apply to the Late Pleistocene microblades in northeastern Asia. Here, referring to the definition of the Old World microliths, we explore the morphometric traits of the Late Pleistocene microblades in northeast Asia through an examination of the laminar blank production technology from the Last Glacial Maximum (LGM) microblade assemblage recovered from the Kashiwadai 1 site in Hokkaido, northern Japan. Metric and nonmetric data obtained from numerous laminar blanks reveal that microblades are comparable to bladelets without backing, as defined in the Old World records. The core reduction sequence reconstructed from the refitted specimen reveals that microblades are produced from blade core gradually reduced by careful core preparations, best labeled as the integrated laminar technology conceptually related to post-LGM bifacial microblade core technologies.

Randomized core reduction for discrete ill-posed problem

In this paper, we apply randomized algorithms to approximate the total least squares (TLS) solution of the problem Ax≈b in the large-scale discrete ill-posed problems. A regularization technique, based on the multiplicative randomization and the subspace iteration, is proposed to obtain the approximate core problem. In the error analysis, we provide upper bounds for the errors of the solution and the residual of the randomized core reduction. Illustrative numerical examples and comparisons are presented.

Diachronic Variation in Microlith Production Systems During the Late Pleistocene, Algeria

The Iberomaurusian lithic industries in the Maghreb are known for their microlithization characteristics beginning ca. 25 ka cal BP. The analyses of the Iberomaurusian lithic assemblages in Algeria have mostly focused on typological and stylistic issues. These are good for distinguishing the various archaeological entities encountered in the region but inadequate for understanding the techno-economic behaviors that these industries supported. A technological approach to analysis allows for the recognition of the choices made by the knappers throughout the core reduction processes, the blank production, the transformation of blanks into tools, and the debitage methods and techniques. It has proven useful for understanding not only lithic production process but also the roles that lithic tools played in various subsistence economies. Hence, this paper uses a technological approach to reanalyze the lithic assemblages from Tamar Hat, Rassel, and Columnata. The lithic industries of these three sites are characterized by the tendency toward microlithization as attested by the presence of small chipped stone artifacts on diminutive blanks. The results suggest that the hunter-gatherer populations of the Maghreb produced microliths using a wide range of technological options during the Late Pleistocene. The study also reveals diachronic changes in the production modalities of the microliths. These changes are likely related to variations in hunting strategies in different ecological niches and as adaptive strategies to various paleoclimatic events of the Late Pleistocene.

Changes in Core Reduction Models on Upper Paleolithic Sites in the Northwest Caucasus

The article presents an analysis of the changes in core reduction models at different stages of the Upper Paleolithic in the Northwest Caucasus. The broad chronological framework of this study (40 thousand - 12 thousand years ago) makes it possible to trace the changes in the preferred models for the use of cores. The correlation of the change dynamics in the main core reduction models along with a change in the metric and morphological features of the chips allowed the author to trace the development of stone knepping technology throughout the entire Upper Paleolithic era in the Northwest Caucasus. Methods. The work is based on an analysis of core morphology. All the cores from the collections were divided into several categories: core-shaped pieces, prismatic cores, edge-faceted cores, karenoid cores, and residual core fragments. Upon analyzing the morphology, the author takes into account the number of cleavage systems and their relative position. Based on the analysis of core morphology, the author determined the main reduction models. The identification of core reduction models is correlated with a change in the metric features of preformed chips. The author's analysis of core morphology revealed a number of trends. 1. There was a shift from the knepping technology, which includes two reduction models (knepping from prismatic and edge-faceted cores in the Early Upper Paleolithic (layer 1C of the Mezmay Cave), and in the first stage of the Late Upper Paleolithic) to primary splitting of prismatic cores in the late period of the Late Upper Paleolithic and in the Epipaleolithic. 2. The change in core reduction models was accompanied by a change in the metric features of the plate chips (an increase in the average value of the chip width and a decrease in the average value of the relative chip thickness).

Ushbulak—A New Stratified Upper Paleolithic Site in Northeastern Kazakhstan

We present the findings of excavations at the stratified site of Ushbulak, discovered during a joint Russian-Kazakhstan research project in 20I6. The site is located in the Shilikty Valley, northeastern Kazakhstan, at the junction of routes connecting southwestern Central Asia, southern Siberia, and northern China. On the basis of stratigraphy, chronology, and technological evidence, we identify three technological complexes, relating to the Metal Ages (stratum I), Final Upper Paleolithic (strata 2-4), and Initial Upper Paleolithic (strata 5.2-7). Focusing on the principal markers of the Initial Upper Paleolithic in the region, we conclude that finds from strata 5.2-7 belong to the southern Siberian-Mongolian variant of the Initial Upper Paleolithic, as evidenced by the uni- and bidirectional parallel volumetric blade core reduction, tool types, and absolute chronology. The tool kit includes mostly endscrapers, heavily retouched blades, and truncated-facetted or notched implements. Particularly diagnostic types include waisted blade, blade with a ventrally retouched distal edge, beveled point, backed blade, stemmed implement with a sharp tip, stemmed endscraper, and burin-core. Two AMS-dates from stratum 6 date this layer to ca 36,I80 ± 730 and 4I,II0 ± 302 BP. The closest known parallels to the industry of the lower strata of Ushbulak are finds from horizon UP2 of Kara-Bom in the Russian Altai. Our results suggest that Ushbulak strata 5.2-7 correlate with the Initial Upper Paleolithic industries of the Altai (Denisova Cave), northern China (Luotoshi), and Mongolia (Tolbor-4 and -2I).

Learner-driven innovation in the stone tool technology of early Homo sapiens.

Current perspectives of stone tool technology tend to emphasize homogeneity in tool forms and core reduction strategies across time and space. This homogeneity is understood to represent shared cultural traditions that are passed down through the generations. This represents a top-down perspective on how and why stone tools are manufactured that largely restricts technological agency to experts, adults and teachers. However, just as bottom-up processes driven by children and youth influence technological innovation today, they are likely to have played a role in the past. This paper considers evidence from the archaeological record of early Homo sapiens' lithic technology in Africa that may attest to our long history of bottom-up social learning processes and learner-driven innovation. This evidence includes the role of emulative social learning in generating assemblages with diverse reduction strategies, a high degree of technological fragmentation across southern Africa during some time periods, and technological convergence through the Pleistocene. Counter to some perspectives on the uniqueness of our species, our ability to learn independently, to 'break the rules' and to play, as opposed to conforming to top-down influences, may also account for our technological success.

New discoveries from the early Late Pleistocene Lingjing site (Xuchang)

The applicability of the three stage Paleolithic sequence (Lower, Middle, Upper) in eastern Asia that is used in the western Old World has long been a debated issue. The crux of the discussion is whether a distinct “Middle Paleolithic” (“MP”) is present in the eastern Asian record, especially north China. Recently, the artifacts from the Lingjing site (2005–2016), in northern China, have been argued to be potential representative of a “Chinese Middle Paleolithic” (“CMP”). In this paper, we introduce a thorough analysis on a newly discovered lithic assemblage from the 2017 excavation of the Lingjing site. We found that simple free-hand hard hammer percussion is the dominant core reduction strategy with only a very small frequency of atypical, bi-conical discoidal cores. When considering other contemporary sites in northern China (e.g., Xujiayao and Banjingzi), Lingjing belongs to a small tool tradition that is widespread throughout northern China. The Lingjing artifacts do display some obvious differences in core reduction and lithic retouching techniques from those typical of the Lower/Early Paleolithic (or Mode 1) assemblage pre-40 ka in the Chinese Paleolithic. The diversity of characteristics of lithic technology from Lingjing and other contemporary sites in north China show the complexity of the Chinese Early Paleolithic, rather than a simple monotonous stone tool tradition.

3D visual technology applied for the reconstruction of a Paleolithic workshop

Archaeological investigations at the Paleolithic Piovesello open-air site in Italy have brought to light a small lithic workshop composed of 123 artefacts (Structure I). In order to remedy to the destructive nature of the excavation, we developed a conservative protocol based on a three-dimensional reconstruction of the heap, enabling us to restore information lost during the removals of the flakes. A 3D model of the structure and its close context was produced for each artefact through laser scanning, and then it was spatially positioned after the creation of a relative coordinate system using Structure from Motion with Agisoft Photoscan and by rectifying 24 photographs documenting different SI removal stages, performed by the software QGIS. Images provide X, Y coordinates of the findings located at the base of SI; for the Z coordinate is used the quote recorded during excavation. To reconstruct the formation process of the structure, we investigated its stratigraphy and performed the analysis according to different technological and morphometrical parameters, as core reduction stages, dimensional classes, presence of direct connections like refittings. Once Structure I has been interpreted like a primary workshop formed during knapping activities, it was possible to cross different data and to recognize six depositional stages, in which the alternation of large-size core shaping products, management flakes and fine full- production artefacts is visible.