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The edges of stone tools have significant technological and functional implications. The nature of these edges-their sharpness, whether they are concave or convex, and their asymmetry-reflect how they were made and how they could be used. Similarly, blunt portions of a tool's perimeter hint at how they could have been grasped or hafted and in which directions force could be applied. However, due to the difficulty in accurately measuring the complex 3D geometry of tool edges with traditional methods, their attributes are often overlooked. When they are analyzed, they have traditionally been assessed with visual qualitative categories or unreliable physical measurements. We introduce new computational 3D methods for automatically and repeatably measuring key attributes of stone tool edges. These methods allow us to automatically identify the 3D perimeter of tools, segment this perimeter according to changes in edge angles, and measure these discrete edge segments with a range of metrics. We test this new computational toolkit on a large sample of 3D models of handaxes from the later Acheulean of the southern Levant. Despite these handaxes being otherwise technologically and morphologically similar, we find marked differences in the amount of knapped outline, edge angle, and the concavity of their edges. We find many handaxes possess blunt portions of perimeter, suitable for grasping, and some handaxes even possess more than one discrete sharp edge. Among our sample, sites with longer occupations and more diverse toolkits possessed handaxes with more diverse edges. Above all, this paper offers new methods for computing the complex 3D geometry of stone tool edges that could be applied to any number of artifact types. These methods are fully automated, allowing the analysis and visualization of entire assemblages.

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We present new evidence for the emergence of biface shaping from Kokiselei 6 in the Kokiselei Site Complex (KS) in West Turkana, Kenya. This rich and well-preserved new site presents an opportunity to investigate the earliest development of biface shaping. The emergence of biface shaping in lithic technology is often used as evidence for increased and/or novel cognitive abilities that contrast prior hominins' flaking capacities. Yet, recent research reveals a story of gradual change over time in a variety of different flaking and shaping strategies. Here, we present preliminary excavation and lithic data from Kokiselei 6 that will be critical for future investigations of biface shaping emergence at KS. Kokiselei preserves the oldest known Acheulean lithic assemblage, Kokiselei 4 (1.76 Ma), as well as several older sites. Geochronological research shows that Kokiselei 6 stratigraphically underlies Kokiselei 4 and is the oldest site in the complex at 1.8 Ma. The Kokiselei 6 excavation yielded thousands of piece-plotted lithic artifacts and faunal remains. Preliminary analysis of the lithics (n = 3856) indicates a prevalence of bifacial flaking strategies alongside minimal evidence for rough biface shaping. We argue that the flaking strategies observed from bifacial cores share similar operations and abilities as those involved in the production of the roughly shaped bifaces at the site. This preliminary evidence supports existing arguments that biface shaping emerged gradually out of variability in bifacial core reduction, ultimately leading to the systematic production of bifaces characteristic of the Acheulean. Future work teasing apart the processes of technological change at KS more broadly will be critical for understanding the emergence of biface shaping. These new data add to a growing narrative that opposes long-held assumptions about hominin cognitive evolution that suggest Acheulean technology required new, and more complex, cognitive abilities and gestures.

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Some areas in Western Europe indicate hiatuses in human occupations, which cannot be systematically attributed to taphonomic factors and poor site preservation. The site of la Noira in the center of France records two occupation phases with a significant time gap. The older one is dated to around 700 ka (stratum a) with an Acheulean assemblage, among the earliest in Western Europe, and the upper phase of the sequence (stratum c) is dated to ca. 450 ka. Humans left the area at around 670 ka, at the beginning of the marine isotope stage (MIS) 16 glacial stage, when cold conditions became too severe. No sites between 650 and 450 ka have yet been discovered in the center region despite systematic surveys over the past three decades. The archaeological evidence indicates that populations returned to the area, at the end of MIS 12 or the beginning of the long interglacial MIS 11. Here, we use technological behaviors common to the two levels of la Noira-strata a and c to evaluate their differences. Compared to other key European sequences, this site can be used to address the evolution of the behavioral strategies in Europe between MIS 17 and 11. We formulate two hypotheses concerning the human settlement of this area: (1) local behavioral evolution over time of populations occasionally occupying the region when the climate was favorable or (2) dispersal and arrival of new populations from other areas. The results focus on (1) changes in land-use patterns with the extension of the territory used by hominins in the upper level, (2) the introduction of new core technologies, including some evidence of early Levallois debitage, and (3) more intensive shaping of bifaces and bifacial tools. Results attest that the la Noira archaeological assemblages record similar regional behavioral evolution as observed at a larger scale in Europe.

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Archaeologists are currently producing huge numbers of digitized photographs to record and preserve artefact finds. These images are used to identify and categorize artefacts and reason about connections between artefacts and perform outreach to the public. However, finding specific types of images within collections remains a major challenge. Often, the metadata associated with images is sparse or is inconsistent. This makes keyword-based exploratory search difficult, leaving researchers to rely on serendipity and slowing down the research process. We present an image-based retrieval system that addresses this problem for biface artefacts. In order to identify artefact characteristics that need to be captured by image features, we conducted a contextual inquiry study with experts in bifaces. We then devised several descriptors for matching images of bifaces with similar artefacts. We evaluated the performance of these descriptors using measures that specifically look at the differences between the sets of images returned by the search system using different descriptors. Through this nuanced approach, we have provided a comprehensive analysis of the strengths and weaknesses of the different descriptors and identified implications for design in the search systems for archaeology.

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Explaining late Middle Palaeolithic industrial variability remains a topic of great interest for researchers focusing on aspects of Neanderthal behavioural complexity and the so-called Middle-to-Upper Paleolithic 'transition.' Several sites in southwestern France figure prominently in these discussions, including the eponymous site of Le Moustier (Dordogne, France), one of the 'key' sequences used in larger anthropological models. Here we present a re-assessment of this important site based on a technological and taphonomic re-evaluation of previously studied collections combined with an analysis of unpublished archaeological material, which includes both lithic and faunal components. Our study produces a very different interpretation of the 'classic' Le Moustier sequence, challenging previous cultural attributions in a way that significantly impacts current debates surrounding the proposed Mousterian of Acheulean Tradition (MTA)--Châtelperronian affiliation. This new interpretation highlights independent changes in lithic technology and subsistence strategies that were previously undetected as well as a novel aspect of Neanderthal raw material use. Finally, we discuss how this new vision has important ramifications for broader issues connected to the definition of late Mousterian techno-complexes, such as the MTA, and the identification of relationships between technology, subsistence, and mobility strategies.

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