Bipolar Reduction Research Articles

Lithic tool provisioning in the western Aztec provinces: A view from Calixtlahuaca

AbstractWe describe an analysis of the flaked stone tools recovered from households in the Postclassic central Mexican city of Calixtlahuaca (a.d.1130–1530). Most artifacts are obsidian and represent the blade-core technology, but biface and bipolar artifacts are also represented. Even though household residents were involved in limited biface and bipolar reduction, it appears that the city did not have any resident blade producers. This finding is at odds with the views of many archaeologists, who tend to associate craft production with the emergence of complex Mesoamerican urban centers. We examine the technologies from temporally distinct Calixtlahuacan household assemblages. We discuss why the quantity and quality artifacts associated with blade production are not consistent with resident blade making in the city. Finally, we examine four models for blade provisioning: (1) whole-blade trade, (2) processed-blade trade, (3) long-distance itinerant craftsmen, and (4) local, hinterland-based craftsmen. Evaluating how the Calixtlahuacans got their flaked stone tools has important implications for the comparative understanding of the organization and scale of economic provisioning systems in Postclassic central Mexico. This analysis supports new inferences about the nature of commercial networks that supplied the Toluca Valley prior to the arrival of the Spanish in the sixteenth century.

Non-Ceramic Site of Shamanka 8 on the Southern Coast of Baikal Lake

Purpose. The southern coast of lake Baikal is a territory known in Siberian archaeology for its Kitoi cemeteries. Besides burials of the Shaman capes there are some Neolithic and Bronze age complexes at Circum–Baikal railway. In 2012 it the first non-ceramic site was discovered in South Baikal, which was named Shamanka 8. This paper presents the assemblage of this complex and discusses its chronological and cultural features.Results. The Shamanka 8 site is located on the top of the third hill of the Shaman cape. The cultural layer lies under the Holocene Optimum sediments. The site stratigraphic structure is characterized by compression. There is no bone fragments and ceramic. For lithic knapping, mainly local raw material (quartz) were used. The quartz assemblage has such features as poor formal standardization, high degree of flake fragmentation, cores with the orientation of fracture plane relative to the longitudinal axis, bipolar reduction. All of these specifics are explained by uneven fracture characteristics and bad workability of quartz, as well as its breakage patterns. Some artifacts, including single non-quartz tool, suggest that there may be a connection between the Shamanka 8 site and the industries of the Final Paleolithic sites in the Northern Baikal region and the Irkutsk region. Quartz small knife (?), carinated end-scraper and tubular core have analogies in the 2nd cultural layer of the Kurla II site, dated by 13.5 uncal kya. Similarly dated quartz components of Nirikan I and flint tool-kit of Verkholenskaya Gora I include other cultural link types.Conclusion. The similarity in the morphology of some tools with Final Paleolithic counterparts and stratigraphic position of finds allow us to assume the Final Sartan age of the Shamanka 8 site and dates it to the Bølling – Allerød warming. However, in the absence of direct radiocarbon dating, an Early Holocene/Early Neolithic attribution of the site is also possible. Further studies may help resolve this issue.

Quantum trajectories and the nuclear optical model

In the context of nuclear scattering, we use the bipolar reduction of the Schrödinger equation to examine the effects of optical model absorption on incoming and outgoing scattering waves. We compare the exact solutions for these waves, obtained using a bipolar quantum trajectory-based formalism, with their approximate WKB counterparts. Aside from reducing the magnitudes of the incoming and outgoing waves, absorption smooths the variation of the potential at the turning point, reducing reflection in this region. This brings the incoming exact solution and WKB approximation into closer agreement, but tends to worsen the agreement between the outgoing solutions. Inside the turning point, the WKB approximation overestimates the inward decaying solution. The exact solution also possesses an outward going component, solely due to reflection, with no WKB counterpart.

Milky Quartz Bipolar Reduction and Lithic Miniaturization: Experimental Results and Archaeological Implications

Milky Quartz Bipolar Reduction and Lithic Miniaturization: Experimental Results and Archaeological Implications

Archaic Period Lithic Technology, Sedentism, and Subsistence in Northern Belize: What Can Debitage at Caye Coco and Fred Smith Tell Us?

Despite the abundance of lithic debitage at preceramic sites in the Maya Lowlands, these data have rarely been studied in detail. We analyzed the chipped chert debitage from Caye Coco and Fred Smith, two Archaic period sites in the Freshwater Creek drainage of northern Belize, to evaluate strategies of lithic raw material procurement, stone tool production, and tool use. The technological and use-wear analyses of the debitage demonstrate that the sites’ inhabitants procured most of their tool stone from the Northern Belize Chert-bearing Zone (NBCZ) and relied on hard-hammer percussion to produce flakes for use as expedient tools and some crude bifaces and unifaces. Although similar patterns of raw material procurement and tool production are demonstrated at both sites, some differences exist, including bipolar reduction at Caye Coco. Based on use-wear analysis, the debitage at the island site of Caye Coco was primarily used for working wood, shell, and hard contact materials and for digging soil. On the shore at Fred Smith, most use-wear is consistent with working wood, plants, and hard contact materials, as well as digging soil. For both sites, analyses suggest the increasing importance of a horticultural subsistence strategy with reduced mobility and reliance on some cultigens that were locally produced.

Autonomic reflex effect of the inferior turbinate outfracture or bipolar cauterization inferior turbinate reduction surgery

Autonomic reflex effect of the inferior turbinate outfracture or bipolar cauterization inferior turbinate reduction surgery

Deriving original nodule size of lithic reduction sets from cortical curvature: An application to monitor stone artifact transport from bipolar reduction

Stone tools represent the largest source of information about past human behaviors on the planet. Much of the information about stone tools remains untranslated because we have little understanding about what the variation in artifact form means. One component of stone tool production that has less ambiguity is the reductive nature of the technology. Models of reduction rely on the ability to predict patterns of the rate of mass lost during artifact production. However, these patterns can vary quite substantially due to a variety of factors, one of which is variation in the original size of stone nodules prior to reduction. Here we report on a novel method to estimate the original size of stone nodules based on measurement of the curvature of residual cortex on flake and core products. Using experimental quartz bipolar reduction sets, we demonstrate the suitability of the approach, even when reduction intensity is high. Computer simulation with the experimental sets is then used to demonstrate the method’s utility for supporting archaeological inferences about land use and mobility from the analysis of bipolar assemblages. The bipolar flaking method is a technique that was used widely across the 3 million years of paleolithic tool production, yet analytically has received less attention that other modes of reduction. Methods developed here will help to expand understanding for this analytically challenging technological context.

Exploring the Influence of Predation Risks on Oldowan Tool Use in South Africa

ABSTRACT Newly described Oldowan stone tools from Swartkrans Member 1 Lower Bank have highlighted important differences in raw material use and knapping methods when compared to Sterkfontein Member 5 East. This variability has been correlated to contrasting habitats surrounding these caves and the presence of carnivores, suggesting that ecological factors may have influenced tool manufacturing in the Early Pleistocene. However, the strength of behavioral ecological interpretations rests upon the identification of adaptive advantages in employing specific reduction strategies. Knapping experiments are used to compare the flaking efficiency of bipolar and freehand reduction, which measures the rate at which these methods convert core mass into cutting edge length. Results suggest that bipolar knapping is an efficient means of producing useable flakes, and its use at Swartkrans potentially reflects adaptations to limiting predation risks.

Lithic perspectives on the Late Upper Palaeolithic in the French Pyrenees

This work deals with Late Upper Palaeolithic (Azilian and Laborian) lithic industries in the French Pyrenees. Assemblages are compared at an interregional level in order to contextualize and clarify this period. Since its discovery at the end of the 19th century, the Azilian was characterized by its specific lithic industry (backed points), osseous artefacts (harpoons) and artistic remains (painted pebbles). However, new discoveries have shed new light on our understanding the Azilian. Six lithic assemblages were examined in this study: Rhodes II (Ariège), Troubat (Hautes-Pyrénées), La Tourasse (Haute-Garonne), Le Poeymaü (Pyrénées-Atlantiques), Gouërris (Haute-Garonne) and Pagès (Lot), allowing us to investigate the evolution of the Azilian and Laborian technocomplexes and to comparatively evaluate this process at the scale of Western Europe. The beginning of the Azilian in the Pyrenees differs from what is observed in the northern Aquitain Basin; the Magdalenian seems to persist until 14 200 cal. BP, while the Early Azilian is only observed in the Basque Country. However, during the recent phase some common traits are identified at a larger scale (France, Pyrenees, Cantabria), most notably a technological simplification. Still, the Pyrenean Azilian (between 14 200 and 12 500 cal. BP) preserves its regional lithic signature, defined by the presence of double backed points, small scrapers and the use of bipolar reduction on an anvil. The Laborian, sporadically present in the Pyrenees, may indicate a later technical reinvestment, characterized by a more regular and straight production of lamino-lamellar blanks, which is a trend that appears to be observed in the whole Western Europe around 12 500 cal. BP.

Regional Variability in Lithic Miniaturization and the Organization of Technology in Late Glacial Southern Africa (~18-11 kcal BP)

Abstract Miniaturized stone tools made by controlled fracture are reported from nearly every continent where archaeologists have systematically looked for them. While similarities in technology are acknowledged between regions, few detailed inter-regional comparative studies have been conducted. Our paper addresses this gap, presenting results of a comparative lithic technological study between Klipfonteinrand and Sehonghong – two large rock shelters in southern Africa. Both sites contain Late Glacial (~18-11 kcal BP) lithic assemblages, though they are located in regions with different geologies, climates and environments. Results demonstrate that lithic miniaturization manifests differently in these different regions. Both assemblages provide evidence for small blade production, though key differences exist in terms of the specific technological composition of this evidence, the raw materials selected, the role played by bipolar reduction and the manner in which lithic reduction was organized. Patterned variability of this nature demonstrates that humans deployed miniaturized technologies strategically in relation to local conditions.

Assessing raw material’s role in bipolar and freehand miniaturized flake shape, technological structure, and fragmentation rates

This paper concludes a long-term experimental study to examine the role of bipolar and freehand reduction as strategies for lithic miniaturization on milky quartz and flint. The experiments provide clear quantifiable guidelines for identifying bipolar reduction in archeological assemblages. They suggest that with bipolar reduction—a straightforward and time-efficient strategy to learn—toolmakers could easily surpass the cutting edge/mass efficiency levels of more derived lithic reduction strategies such as pressure blade production. Here we compared the efficiency and technological attributes on the experiment’s milky quartz and flint flakes. The results show few practically significant differences between the two flake samples. The strongest differences are in the flakes’ ventral surface and platform features. Otherwise, we concur with previous experimental studies that show certain types of milky quartz behave in essentially the same way as other brittle materials such as flint. Our results aid the identification of bipolar reduction with a focus on cores and flakes. They contribute to a growing body of literature showing the importance of simple, but not simplistic, technological strategies in prehistoric human decision-making.

Bipolar Reduction and Behavioral Variability During the Mid-Late Holocene at Eagle's Nest, Mount Sinai Harbor, New York

ABSTRACTRecent syntheses for the Long Island Sound region argue for long-term cultural continuity amongst Holocene coastal hunter-gatherers. These notions derive primarily from studies of quartz lithic assemblages, which archaeologists argue show structural stasis over time. The remaining variability is explained with a ‘distance to source' model in which near-coastal sites tend to show a lack of quartz conservation while interior sites show quartz recycling. Under this model, technological strategies traditionally associated with raw material conservation (e.g., bipolar reduction) should not occur at near-coastal sites. We test the ‘distance to source’ model by reexamining a quartz lithic assemblage from Eagle's Nest-Long Island's richest Holocene coastal hunter-gatherer site. We find conclusive evidence for bipolar reduction in the site's “block/shatter” materials. Toolmakers used bipolar reduction to conserve raw material. Toolmakers also used anvils and bipolar reduction to open quartz cobbles, to stabilize freehand cores, to efficiently access cutting edges, and possibly to create crushed coarse quartz temper for pottery production. Our results point to previously unrecognized aspects of behavioral variability in the Eagle's Nest lithic assemblage and to possible revision of the ‘distance to source’ model. Similar variability may be present at other North American sites with quartz “block/shatter” material.

Milky Quartz Bipolar Reduction and Lithic Miniaturization: Experimental Results and Archaeological Implications

ABSTRACTWe present experimental data examining the energetics and identification of axial bipolar reduction in contexts of lithic miniaturization on milky quartz. These experiments answer two specific questions. First, does bipolar reduction provide any benefits over freehand reduction? Second, can axial bipolar reduction be distinguished from freehand reduction? Our data show that bipolar reduction requires significantly less time to reduce a percentage unit of core mass and to produce a millimeter of cutting edge on milky quartz than freehand reduction. Milky quartz bipolar reduction surpasses even the cutting edge production efficiency of obsidian pressure blades. We outline a series of quantitative criteria for identifying bipolar cores and flakes. Our results show that bipolar cores and flakes can be distinguished from those produced using freehand reduction by quantifying platform crushing, distal flake rebound scars, bulb shearing, as well as axial, bipolar, and splintered flake terminations. Our results challenge the widely held perceptions about the wastefulness of bipolar reduction and provide clear guidelines for identifying this reduction strategy in archaeological milky quartz assemblages.

Computational modelling of the thermoelectric properties of p-type Zintl compound CaMg2Bi2

We develop a model based on first principles calculations and experimental data for the thermoelectric properties of p-type CaMg2Bi2. The thermoelectric performance was assessed and optimized based on the model. The model predicts bipolar reduction of ZT at high temperatures (e.g. > 800 K). This indicates the thermoelectric performance of the material can be further optimized by tuning the carrier concentration beyond the bipolar regime.

Quantifying and Comparing Bipolar Versus Freehand Flake Morphologies, Production Currencies, and Reduction Energetics During Lithic Miniaturization

ABSTRACTRecognized by archaeologists for over a century, and practiced by hominins in nearly every archaeological context in which flaked stone is used, bipolar technology involves the coordination of at least three components (hammer, anvil, and core). Archaeologists are increasingly aware of the variability within bipolar reduction, such that it can hardly be considered a single unified reduction strategy. Our experiments investigate the role of axial bipolar reduction versus freehand reduction as strategies for lithic miniaturization on flint. The results provide clear, probabilistic, and quantifiable methods for identifying bipolar reduction in archaeological assemblages. They also show the time and energetic benefits of bipolar reduction over freehand reduction in contexts involving small, elongated flake production. Our results have wide applicability for interpreting archaeological assemblages across Africa, Europe, North America, and Australia.

New ages from Sehonghong rock shelter: Implications for the late Pleistocene occupation of highland Lesotho

Sehonghong rock shelter is situated in the eastern Lesotho highlands, a climatically extreme region of southern Africa. The site is one of a handful in southern Africa that preserves human occupations before, during, and after the Last Glacial Maximum (LGM). The site's long and well-preserved sequence makes it relevant to addressing questions of human mobility, subsistence, and technology in relation to broader environmental change. Here we present a Bayesian-modelled radiocarbon chronology for the LGM and terminal Pleistocene occupations at Sehonghong. Our model incorporates previously published radiocarbon dates and new accelerator mass spectrometry ages. We also present archaeological evidence to test the hypothesis that Sehonghong was occupied in a series of punctuated events, and that some of these occupations were more intensive than others. Previous chronological and archaeological data were insufficient for testing these hypotheses. The new dates and archaeological data confirm that the site was occupied intensively in the early LGM and immediately thereafter. The site was otherwise occupied sporadically. We find that greater site occupation density is not always correlated with intensified use of local resources as measured by increased bipolar reduction and fish consumption. The new dates further confirm that Sehonghong contains some of the oldest evidence for systematic freshwater fishing in southern Africa. The availability of fish, a high fat protein source, probably stimulated human occupation, however sporadic, of such montane environments during cooler and drier periods. These findings suggest behavioural variability in response to shifting mobility and subsistence strategies. Our brief discussion informs upon hunter-gatherer occupation of southern African montane environments more broadly and human behavioural variability during the LGM.

Lithic miniaturization in Late Pleistocene southern Africa

Lithic miniaturization refers to the systematic production and use of small tools made from small cores. Archaeologists typically associate the production of miniature toolkits with small retouched tools or ‘microliths’. Yet, ethnographic accounts and archaeological data show that miniature toolkits also comprised small unretouched flakes and bladelets. Because it proliferates during the Late Pleistocene and is associated with the Later Stone Age in Africa, archaeologists associate lithic miniaturization with ‘modern human behavior’. However, toolkit miniaturization is no more consistent a feature of Late Pleistocene assemblages than bone point production, rock art, or engraved ochre. Lithic miniaturization was one of many strategic options our Pleistocene ancestors employed. The paper reports a miniaturized lithic assemblage marked by the systematic production of small unretouched flakes and bladelets from small cores (<5g) during the Late Pleistocene (c. 14–12ka calBP) at Ntloana Tšoana rock shelter in Lesotho. This assemblage was made on a range of locally available rock types using freehand and bipolar reduction. Analogous lithic assemblages are reported from elsewhere in southern Africa suggesting that unretouched miniaturized toolkits were widespread. The process of systematic unretouched small tool production could be ancient, but the extent of these processes remain unknown. Using appropriate terminology combined with contextual approaches to defining and quantifying lithic miniaturization while demonstrating the intent to miniaturize toolkits provide initial solutions to this problem.

Imported obsidian at Caution Bay, south coast of Papua New Guinea: cessation of long distance procurement c. 1,900 cal BP

Until now, the evidence for imported obsidian along the south coast of Papua New Guinea has been limited to eleven excavated sites all dating after c. 2,000 cal. BP. Here we present new archaeological evidence for the sourcing and importation of 4,689 obsidian artefacts from 30 excavated sites at Caution Bay. pXRF analysis of a sample of the artefacts revealed that all but one came from a source on West Fergusson Island some 670 km away. During Lapita (here beginning c. 2,950 cal. BP) and post-Lapita times, the proportion of sites with obsidian artefacts was high, and remained so for a thousand years before suddenly ceasing c. 1,900 cal. BP. Technological analyses of obsidian artefacts from Bogi 1 and ABKL—the richest obsidian sites at Caution Bay—indicate intense unipolar and bipolar reduction and the occasional recycling of unipolar flakes into bipolar cores during both Lapita and post-Lapita times. We suggest that this is a result of the importation of obsidian to Caution Bay through down-the-line exchange.

Assemblage variability and bifacial points in the lowermost Sibudan layers at Sibudu, South Africa

Building on the important work of Lyn Wadley at Sibudu, archeologists from the University of Tubingen have excavated the upper stratigraphic units of the Middle Stone Age (MSA) sequence down to the Howiesons Poort (HP). Here, we present the main results from lithic analyses of the lowest part of the Sibudan sequence to assess its overall variability and taxonomic status. Based on the new findings, we also discuss the implications for archeological systematics and the cultural evolution of modern humans in MIS 3 from a more general perspective. The Sibudan deposits encompass over 20 archeological horizons that span a 1.2-m-thick, well-stratified sequence whose base and top have been dated to ∼58 ka (MIS 3). In contrast to the upper stratigraphic units, the lower Sibudan assemblages that we analyzed here show much higher use of local sandstone, quartz, and quartzite. These older units are characterized by frequent use of expedient core reduction methods, bipolar reduction of locally available quartz and quartzite, less retouch of blanks, and lower find densities. Tongati and Ndwedwe tools, which feature abundantly in the upper part of the Sibudan sequence, are entirely absent, as are unifacial points. Instead, notched and denticulated tools are common. Surprisingly, knappers manufactured small bifacial points, mainly made from quartz, by means of alternating shaping in the course of the oldest occupations. The results highlight the great diversity of human technological behavior over even short periods during the MSA, raising important questions about the mechanisms of behavioral change, cultural taxonomy, appropriate scales of lithic analyses, and the relationship between the HP and the Sibudan. Our findings further erode the old idea that bifacial technology in southern Africa is limited to the Still Bay. Research is increasingly showing that bifacial points come and go in different forms and contexts of African Late Pleistocene technology, impeding their use as chrono-cultural markers.

The Lithic Assemblages of Xiaochangliang, Nihewan Basin: Implications for Early Pleistocene Hominin Behaviour in North China.

Xiaochangliang (XCL), located in the Nihewan Basin of North China, is a key archaeological locality for understanding the behavioural evolution of early humans. XCL dates to ca. 1.36 Ma, making it one of the earliest sites in Northeast Asia. Although XCL represents the first excavation of an Early Pleistocene site in the Nihewan Basin, identified and excavated in the 1970’s, the lithic assemblages have never been published in full detail. Here we describe the lithic assemblages from XCL, providing information on stone tool reduction techniques and the influence of raw materials on artefact manufacture. The XCL hominins used both bipolar and freehand reduction techniques to manufacture small flakes, some of which show retouch. Bipolar reduction methods at XCL were used more frequently than previously recognized. Comparison of XCL with other Early Pleistocene sites in the Nihewan Basin indicates the variable use of bipolar and freehand reduction methods, thereby indicating a flexible approach in the utilization of raw materials. The stone tools from XCL and the Nihewan sites are classifiable as Mode I lithic assemblages, readily distinguished from bifacial industries manufactured by hominins in Eastern Asia by ca. 800 ka.