Submarine volcanic activity and giant amygdale formation along the Panama island arc as a precursor to 6000-year-old agate exploitation on Pedro González Island

An extensive deposit of agate occurs in Pedro González Island in the Gulf of Panama. Previous archaeological research showed that the agate was exploited between 6200 and 5600 cal BP to make stone tools found at the oldest known Preceramic human settlement in the Pearl Island archipelago. We constrain here the origin and geological context of the agate through a geological and geochemical study of the island. We show that it includes primary volcanic breccias, lavas, and tuffaceous marine deposits with sedimentary conglomerates and debris flow deposits, which we define as the Pedro González Formation. This formation records submarine to subaerial volcanic activity along an island arc during the Oligo-Miocene, confirming previous regional models that favour progressive emergence of the isthmus in the early Miocene. The igneous rocks have an extreme tholeiitic character that is interpreted to reflect magmatic cessation in eastern Panama during the early Miocene. The agate is hosted in andesitic lavas in unusually large amygdales up to 20–40 cm in diameter, as well as small amygdales (0.1–1.0 cm) in a bimodal distribution, and in veins. The large size of the agates made them suitable for tool manufacture. Field evidence suggests that the formation of large amygdales resulted from subaqueous lava–sediment interaction, in which water released from unconsolidated tuffaceous deposits at the base of lava flows rose through the lavas, coalesced, and accumulated below the chilled lava top, with subsequent hydrothermal mineralization. These amygdales could therefore be regarded as an unusual result of combined peperitic and hydrothermal processes.

Design Space Constraints and the Cultural Taxonomy of European Final Palaeolithic Large Tanged Points: A Comparison of Typological, Landmark-Based and Whole-Outline Geometric Morphometric Approaches

The identification of material culture variability remains an important goal in archaeology, as such variability is commonly coupled with interpretations of cultural transmission and adaptation. While most archaeological cultures are defined on the basis of typology and research tradition, cultural evolutionary reasoning combined with computer-aided methods such as geometric morphometrics (GMM) can shed new light on the validity of many such entrenched groupings, especially in regard to European Upper Palaeolithic projectile points and their classification. Little methodological consistency, however, makes it difficult to compare the conclusions of such studies. Here, we present an effort towards a benchmarked, case-transferrable toolkit that comparatively explores relevant techniques centred on outline-based GMM. First, we re-analyse two previously conducted landmark-based analyses of stone artefacts using our whole-outline approach, demonstrating that outlines can offer an efficient and reliable alternative. We then show how a careful application of clustering algorithms to GMM outline data is able to successfully discriminate between distinctive tool shapes and suggest that such data can also be used to infer cultural evolutionary histories matching already observed typo-chronological patterns. Building on this baseline work, we apply the same methods to a dataset of large tanged points from the European Final Palaeolithic (ca. 15,000–11,000 cal BP). Exploratively comparing the structure of design space within and between the datasets analysed here, our results indicate that Final Palaeolithic tanged point shapes do not fall into meaningful regional or cultural evolutionary groupings but exhibit an internal outline variance comparable to spatiotemporally much closer confined artefact groups of post-Palaeolithic age. We discuss these contrasting results in relation to the architecture of lithic tool design spaces and technological differences in blank production and tool manufacture.

The Thermal Error Estimation of the Machine Tool Spindle Based on Machine Learning

Thermal error is one of the main sources of machining error of machine tools. Being a key component of the machine tool, the spindle will generate a lot of heat in the machining process and thereby result in a thermal error of itself. Real-time measurement of thermal error will interrupt the machining process. Therefore, this paper presents a machine learning model to estimate the thermal error of the spindle from its feature temperature points. The authors adopt random forests and Gaussian process regression to model the thermal error of the spindle and Pearson correlation coefficients to select the feature temperature points. The result shows that random forests collocating with Pearson correlation coefficients is an efficient and accurate method for the thermal error modeling of the spindle. Its accuracy reaches to 90.49% based on only four feature temperature points—two points at the bearings and two points at the inner housing—and the spindle speed. If the accuracy requirement is not very onerous, one can select just the temperature points of the bearings, because the installation of temperature sensors at these positions is acceptable for the spindle or machine tool manufacture, while the other positions may interfere with the cooling pipeline of the spindle.

Economy and status of Neolithic to Early Bronze age sites in the Southern Caucasus during the 6th‐3rd mill. BCE: The evidence from ground stone tools

In the Southern Caucasus, the evolution of the Neolithic to Bronze age (6th-3rd millenia BCE) economies is often investigated through the prism of adaptation to constrasted landscapes and environments (arid plain, high moutains, subtropical western coasts) and strategies of natural resource exploitation. This overview of the main technological and functional characteristics of ground stone tools from about 20 sites in the Kura Valley (Georgia, Azerbaijan) contributes to the discussion surrounding these questions. After an overview of the evolution of the grinding equipment and stone tool manufacture within a long term perspective, from the Late Neoliothic to the Early Bronze Age, several issues are adressed. The composition of the macrolithic toolkit is a key issue when discussing the importance of agriculture versus pastoralism in the economy of these populations, which evolved in different regional and environmental contexts. Its management also contributes to our understanding of the degree of sedentarity versus mobility of the populations. Finally, we discuss how the technical evolution of the macrolithic toolkit reflects the principal global changes occurring during this long period of time (neolithisation, emergence of metallurgy, and the mining phenomenon) and their cultural meaning. Our initial results underline the significance of some implements as cultural markers, and also contribute to defining the common cultural background and regional specificities within the South Caucasus region.

Palaeolithic toolmaking and the evolution of cognition and language

This paper reviews in short the current research on the hypothesis of coevolution between Palaeolithic stone tool manufacture on one side, and cognition and specifically language on the other. Of particular interest are behavioral and neuroimaging studies.

Selection preferences for animal species used in bone-tool-manufacturing strategies in KwaZulu-Natal, South Africa

Animal symbolism is a prominent feature of many human societies globally. In some cases, these symbolic attributes manifest in the technological domain, influencing the decision to use the bones of certain animals and not others for tool manufacture. In southern Africa, animals feature prominently in the cosmogenic narratives of both hunter-gatherer and Bantu-speaking farmer groups. Whenever these two culturally distinct groups came into contact with each other there would be an assimilation of cosmogenic concepts of power and the adoption of certain symbolically important animals. In this paper, we report on which animals were selected to make bone tools during the first millennium AD contact period in KwaZulu-Natal Province, South Africa, and explore the extent to which this selection may have been influenced by the symbolic associations of specific animals. Our results show selective targeting of specific animals for tool manufacture at some sites, with a narrowing of the range of selected species during the first millennium AD contact period. Certain antelope tribes, such as Aepycerotini, Cephalophini and Antilopini, appear to have been deliberately avoided, thus arguing against opportunistic selection. Nor does the range of selected animals appear to show any obvious mechanical considerations, as has been noted in similar studies. We highlight the potential of ZooMS for understanding the dynamics of animal symbolism in the past.

First Evidence of Chimpanzee Extractive Tool Use in Cantanhez, Guinea-Bissau: Cross-Community Variation in Honey Dipping

Wild chimpanzee tool use is highly diverse and, in many cases, exhibits cultural variation: tool-use behaviours and techniques differ between communities and are passed down generations through social learning. Honey dipping – the use of sticks or leaves to extract honey from hives – has been identified across the whole species’ range. Nonetheless, there seems to be marked variation in honey dipping at a species level, with most descriptions originating from central Africa, and involving the use of complex tool sets, or even multifunctional tools. In West Africa, while honey consumption is common, in most cases tools are not used. We document, for the first time, the use of honey dipping tools in unhabituated chimpanzee (Pan troglodytes verus) communities at Cantanhez National Park (CNP), Guinea-Bissau. Over a 23-month period we employed a combination of direct (camera traps, n = 1944 camera trap days) and indirect (1000km of reconnaissance walks, collection of abandoned tools) methods to study four neighbouring communities in central CNP. Fluid dipping tools were found in three of the four communities; here we analyse 204 individual stick tools from the 70 tool-use ateliers found. In addition to documenting individual tool dimensions and raw materials, we adopt methods from primate archaeology to describe the typology of different tools based on use-wear patterns. We describe differences in tools used for different honey types, between communities, and tools and tool kits that show an unexpected degree of complexity. Our data also suggest the use of tool sets, i.e., tools with different functions used sequentially toward the same goal; as well as possible multifunction tools (pounding and dipping), never before described for western chimpanzees. Our study fills gaps in our knowledge of the wild chimpanzee cultural repertoire and highlights how chimpanzee tool manufacture and use can vary even at local scales.