Could woodworking have influenced variation in the form of Acheulean handaxes?

The relationship between tool form and function is fundamental to hominin behaviour and evolution. Acheulean handaxes are known for their general consistency across more than a million years and three continents, albeit with some variation in size and shape. However, the influence of this variation on cutting has only rarely been studied, mostly in either butchery or generalized cutting tasks. Yet evidence indicates that handaxes were used for woodworking by at least 1.5 mya. Here, we experimentally tested whether woodworking could have exerted selective pressures on handaxe form. Additionally, these data were compared with a previous experiment that tested flakes during woodworking. For handaxes, no significant relationships were detected in woodworking efficiency. Accordingly, woodworking likely did not exert strong selective pressures on handaxe variability. However, the effectiveness shown by handaxes further demonstrates the functional flexibility of this technology, which is likely a factor contributing to their use over broad temporal, geographical and ecological spans. When comparing handaxes with flakes, only the smallest flakes were found to be significantly less efficient than handaxes. Therefore, the functional demands of woodworking were likely influencing hominin technological decisions about flake morphology, or the selection of flakes for woodworking, more than they were handaxe morphology.     

Investigating interrelationships between Lower Palaeolithic stone tool effectiveness and tool user biometric variation: implications for technological and evolutionary changes

Lower Palaeolithic hominins are thought to have been dependent upon stone tools during the acquisition and processing of food resources. Hence, it is hypothesized that the evolutionary advantages provided by efficient stone tool use may have selected for anatomical changes observed in the hand during this period. Similarly, hominin manipulative capabilities are suggested to have been of consequence to Lower Palaeolithic technological choices and tool use capabilities. The extent and character of these relationships are not, however, fully understood and it is not known whether these hypothesized co-evolutionary and co-dependent relationships are consistent across varying technological and task-type conditions. Here, six key biometric parameters of the hand are investigated in terms of their statistical relationship with cutting efficiency using both flakes and handaxes over extended periods of use and in multiple types of cutting task. Results indicate that (1) both handaxe and flake cutting efficiencies are significantly related with biometric variation of individual tool users, (2) relationships between biometric parameters and efficiency are consistent across extended durations but vary dependent upon task-type conditions, (3) manipulative strength is the most significant biometric trait in terms of predicting flake efficiency, while (4) hand size is the strongest predictor of handaxe cutting efficiency. These results demonstrate the long-term impact that stone tool use likely had on the evolution of hominin biometric variation during the Lower Palaeolithic, while also highlighting the variable influence of different tool use contexts. Most notably, results indicate that the onset of the Acheulean may have been dependent, a priori, upon hand dimensions that are close to the modern human range, and that prior to the appearance of this anatomy, handaxe use would have been an impractical (i.e. inefficient) tool use behaviour compared to the use of flakes.     

Acheulean variation and selection: does handaxe symmetry fit neutral expectations?

It has been suggested that the property of symmetry observed in Acheulean handaxes was selected for functional, adaptive or social and aesthetic reasons. However, selectionist accounts of variation may be contrasted with the approach taken by population geneticists to molecular variation. Population geneticists always first assume a neutral pattern of variation for molecular data, and only look to non-neutral (e.g., selective) scenarios for pattern and variation in the face of strong evidence against this null model of neutral expectation. Here, using a combination of cultural transmission theory, morphometrics, and the principles of population genetics, (null) neutral expectations for Acheulean handaxe symmetry are tested. The results of the analyses are inconsistent with a null hypothesis of neutral expectation for patterns of handaxe symmetry variation. Rather, the results imply that the property of symmetry in Acheulean handaxes was subject to selection for functional, adaptive or social reasons.     

Biometric variables predict stone tool functional performance more effectively than tool‐form attributes: a case study in handaxe loading capabilities

Both the form of a stone tool and the anatomy of the individual using it have potential to influence its cutting performance. To date, however, the selective pressures acting on stone‐tool form and hominin biometric/biomechanical attributes have been investigated in isolation and their relative influence on performance have never been compared directly. This paper examines the influence of both tool‐form attributes and biometric variation on the functional performance of Acheulean handaxes. Specifically, it investigates the impact of 13 tool attributes and eight biometric traits on the working forces applied through the edge of 457 replica tools. The relative contribution of tool‐form and biometric attributes to handaxe loading levels were examined statistically. Results identify that both tool‐form attributes and biometric traits are significantly related to loading; however, tool–user biometric variation has a substantially greater impact relative to tool‐form attributes. This difference was demonstrated by up to a factor of 10. These results bear directly on the co‐evolutionary relationships of stone tools and hominin anatomy, and the comparative strength of selective pressure acting on each. They also underline why handaxe forms may have been free to vary in form across time and space without necessarily incurring critical impacts on their functional capabilities.     

Investigating experimental knapping damage on an antler hammer: a pilot-study using high-resolution imaging and analytical techniques

Organic (bone, antler, wood) knapping tools were undoubtedly a component of early human tool kits since the Lower Palaeolithic. Previous studies have identified pitting and the occasional presence of embedded flint flakes as important features for recognizing archaeological bone and antler percussors. However, no systematic protocol of analysis has been suggested for the study of this rare archaeological material. Here we present qualitative and quantitative results of a preliminary analysis of an experimental knapping hammer, using a novel combination of microscopy (focus variation optical microscope and scanning electron microscope), micro-CT scanning and energy dispersive X-ray spectroscopy. These imaging and analytical techniques are used to characterize use-damage from the manufacture of handaxes. This paper highlights the strengths and weakness of each technique. Use-wear on the working area included attritional bone loss, micro-striations and compaction of the outer layer of the antler matrix from repeated hitting of the beam against the sharp edge of the handaxe during knapping. Embedded flint flakes were also identified in the pits and grooves. This combination of high-resolution imaging techniques is applicable to fragile archaeological specimens, including those encrusted by sediment or encased in matrix.     

Introducing a new experimental design for controlled studies of flake formation: results for exterior platform angle,platform depth,angle of blow,velocity, and force

Potential variables that underlie variation in flake size, and in some instances shape, are investigated in a newly designed experiment. This new design, which utilizes glass cores molded to a specific shape, results in flakes that are identical to archaeological ones. Variation in exterior platform angle, platform depth and angle of blow all directly affect flake size, and in the case of exterior platform angle, flake shape as well (in spite of constant core surface morphology). In treating velocity and force independently, neither is found to affect flake size or shape. These results have implications for understanding different strategies that flintknappers may employ to control the size of their flake products.     

Edge Angle as a Variably Influential Factor in Flake Cutting Efficiency: An Experimental Investigation of Its Relationship with Tool Size and Loading

Simple flake cutting tools were utilized across broad chronological and geographical ranges during prehistory. Fundamental to their functional utility is the presence of a relatively acute working edge. The acuteness of this ‘edge angle’ is widely hypothesized to be a primary determinant of cutting efficiency and, subsequently, of potential consequence to prehistoric peoples. However, the influence of the cutting edge angle in flake tools on the ability (efficiency) of tool users to cut through objects has not been empirically investigated under explicitly stated experimental conditions. Moreover, no consideration has been given to whether this relationship is dependent upon the size of the tool. Here, the influence that edge angle exerts on human stone tool users is examined experimentally in terms of efficiency during a cutting task, while also considering the relationship between edge angle, loading (i.e., the force applied) and overall flake size. The results demonstrate that there is a highly significant relationship between more acute working edges and increased cutting efficiency in the smallest flake tools tested. Above a certain flake‐size threshold, however, the working edge angle has no influence on cutting efficiency because larger flakes appear to facilitate the application of greater working loads by tool users. These results have important implications for potential flake selection criteria by prehistoric peoples, especially in relation to utility, function and the changing effects of edge angle through a sequence of retouch.     

The Paleolithic of Central Asia

The Lower Paleolithic of Central Asia is represented by several sealed and more or less firmly dated Lower–Middle Pleistocene cave and open-air sites in the southeastern part and by more numerous surface occurrences throughout the region. The assemblages assigned to the Lower Paleolithic form two rather distinct groups, one remarkable for well-made handaxes and the other characterized by cores and flakes with no handaxes. The distribution map of pebble industries and industries with handaxes shows that while the latter originate from the western regions of Central Asia, the former are concentrated in the eastern part of the area. The Middle Paleolithic assemblages of Central Asia do not form a single technocomplex. Their variability in time is difficult to assess, but variation in space is obvious. Very few Upper Paleolithic sites in this region are known. At the same time, their stone industries are very diverse and most of them differ sharply from each other and from sites in adjacent regions.     

Technology based evolution? A biometric test of the effects of handsize versus tool form on efficiency in an experimental cutting task

The use of stone cutting tools opened a novel adaptive niche for hominins. Hence, it has been hypothesised that biomechanical adaptations evolved to maximise efficiency when using such tools. Here, we test experimentally whether biometric variation influences the efficiency of simple cutting tools (n = 60 participants). Grip strength and handsize were measured in each participant. 30 participants used flint flakes, while the other 30 used small (unhafted) steel blades. Variations in basic parameters of tool form (length, width, thickness, cutting edge length) were recorded for the 30 flint flakes. It was ensured that mean handsize and strength in each participant group were not significantly different to investigate the effect of tool variation. The experimental task required cutting through a 10 mm-diameter hessian rope. Cutting efficiency was measured using both ‘Number of cutting strokes required’ and ‘Total time taken’. Results show that both efficiency measures were significantly correlated with handsize using all 60 participants. However, no significant differences were found between the flake and blade groups in terms of mean efficiency. Nor was any significant relationship found between tool form parameters and efficiency in the flint flake group. We stress that our results do not imply that tool form has no impact on tool efficiency, but rather that – all other things being equal – biometric variation has a statistically significant influence on efficiency variation when using simple cutting tools. These results demonstrate that biomechanical parameters related directly to efficiency of use, may plausibly have been subject to selection in the earliest stone tool-using hominins.     

Morphometric Assessment of the Appendicular Skeleton in the New Kingdom and Napatan Components from Tombos in Upper Nubia

Due to its critical location on the Nile River controlling trade from the south, Tombos is an important ancient site to explore the interaction between Egyptians and Nubians. To assess population continuity at Tombos through sociopolitical transitions, the appendicular skeleton of people from the New Kingdom and Napatan periods was examined. Using morphometric and statistical analyses, body proportions on the upper and lower limbs were studied on each element through size (i.e. length, breadth, and width) and shape (bone's measurements with size removed). The Napatan component (when Nubia ruled Egypt) was consistently larger in size than the earlier New Kingdom component (when Egypt ruled Nubia), with little variation in shape. More variability in both size and shape was observed in males. When compared with other Nubians (C‐group and Kerma) and Egyptians (Middle and New Kingdom), the Tombos Napatan sample (males and females) was generally larger, whereas the Tombos New Kingdom sample was generally smaller than other Nubians and similar in size to Egyptians. Some of the variability between the Tombos samples may be the result of gene flow, or rather changes in migration to the area through time and sociopolitics. However, the numerous differences in size with few in shape provide more support for an environmental explanation since size is more susceptible to nutritional stress, disease, and physical activity. These results show that the people of Tombos underwent biological alterations during these major sociopolitical changes from Egyptian rule over Nubia during the New Kingdom to Nubia ruling Egypt during the Napatan period. This study also demonstrates that morphometric analyses of multiple bones and measurements are an important supplement to other bioarchaeological analyses to provide a broader of view of physical changes that occur over time. Copyright © 2014 John Wiley & Sons, Ltd.     

Why are some handaxes symmetrical? Testing the influence of handaxe morphology on butchery effectiveness

The morphology of Acheulean handaxes continues to be a subject of debate amongst Lower Palaeolithic archaeologists, with some arguing that many handaxes are over-engineered for a subsistence function alone. This study aims to provide an empirical foundation for these debates by testing the relationship between a range of morphological variables, including symmetry, and the effectiveness of handaxes for butchery. Sixty handaxes were used to butcher 30 fallow deer by both a professional and a non-professional butcher. Regression analysis on the resultant data set indicates that while frontal symmetry may explain a small amount of variance in the effectiveness of handaxes for butchery, a large percentage of variance remains unexplained by symmetry or any of the other morphological variables under consideration.     

A geometric morphometric relationship predicts stone flake shape and size variability

The archaeological record represents a window onto the complex relationship between stone artefact variance and hominin behaviour. Differences in the shapes and sizes of stone flakes—the most abundant remains of past behaviours for much of human evolutionary history—may be underpinned by variation in a range of different environmental and behavioural factors. Controlled flake production experiments have drawn inferences between flake platform preparation behaviours, which have thus far been approximated by linear measurements, and different aspects of overall stone flake variability (Dibble and Rezek J Archaeol Sci 36:1945–1954, 2009; Lin et al. Am Antiq 724–745, 2013; Magnani et al. J Archaeol Sci 46:37–49, 2014; Rezek et al. J Archaeol Sci 38:1346–1359, 2011). However, when the results are applied to archaeological assemblages, there remains a substantial amount of unexplained variability. It is unclear whether this disparity between explanatory models and archaeological data is a result of measurement error on certain key variables, whether traditional analyses are somehow a general limiting factor, or whether there are additional flake shape and size drivers that remain unaccounted for. To try and circumvent these issues, here, we describe a shape analysis approach to assessing stone flake variability including a newly developed three-dimensional geometric morphometric method (‘3DGM’). We use 3DGM to demonstrate that a relationship between platform and flake body governs flake shape and size variability. Contingently, we show that by using this 3DGM approach, we can use flake platform attributes to both (1) make fairly accurate stone flake size predictions and (2) make relatively detailed predictions of stone flake shape. Whether conscious or instinctive, an understanding of this geometric relationship would have been critical to past knappers effectively controlling the production of desired stone flakes. However, despite being able to holistically and accurately incorporate three-dimensional flake variance into our analyses, the behavioural drivers of this variance remain elusive.     

A 3D morphometric analysis of surface geometry in Levallois cores: patterns of stability and variability across regions and their implications

Levallois cores and products were manufactured by hominin populations distributed across wide regions of Africa and Eurasia. Levallois technology remains an important focus for research in Palaeolithic archaeology, yet quantitative morphological comparisons of Levallois core morphology from different regions remain rare. Here, utilizing Levallois cores from Africa, the Near East, Europe, and the Indian subcontinent, patterns of morphological variability in the shape of the Levallois flaking surface and core outline (margin) shape were examined for patterns of variability and stability across regions using 3D geometric morphometrics. The multivariate statistical shape analyses undertaken revealed a clear pattern: that is, the greatest levels of shape variability in Levallois cores is evident in the form of their outline (planform) shape. Conversely, the geometrical relationship between the margin of the Levallois cores and their topological surface morphology was relatively uniform. This pattern of variability was evident in terms of variation both across regions and between cores from the same locality. These results indicate that the outline form of such cores was a less important variable than the geometric/topological properties of the surface morphology and, in particular, the relationship between the margin of the core and those variables. These results have implications for why it has been reported that replicating such cores in modern experiments is a particularly difficult task. The specific interrelationship between the geometric properties of the core and the core margin provide further evidence that Levallois core technology would be unlikely to emerge from the context of opportunistic migrating platform reduction strategies (such as those seen in many Mode 1 industries). If, as is widely suggested, Levallois cores were deliberate products in Pleistocene contexts, these results also hint that relatively sophisticated means of social transmission (i.e. teaching) may have been required to sustain their production over time and space.     

Late-Occurring Handaxes in Korea: Their Homogeneity and Variability

Bifacially worked tools, which are formally categorized as handaxes, are increasingly found in Korea (present-day South Korea). By reviewing recently updated literature, this paper argues that Korean handaxes are unlikely to be true Acheulean handaxes from west of the Movius Line (ML), only partly sharing morphological affinities. A growing body of archaeological data in Korea provides an opportunity for a close examination of the enduring questions, although it does not offer straightforward answers. Korean handaxes show juxtaposed features; variables do not consistently match the pro and cons of affinity of the handaxes from west of the ML. The partial overlap of shapes with the specimens from the neighboring region and from west of the ML is not evidence for cultural transmission of tradition; therefore, the historical lineage across time and space ought to be reconsidered.     

Shape Reproducibility and architectural symmetry during the Chalcolithic period in the southern Levant

Architecture reflects social aspects of past communities. Structure attributes such as shape, size, building material and decoration, provide valuable information beyond their immediate structural function. However, while attributes such as size can be measured and therefore objectively compared between structures, the comparison of shape between structures is based on subjective observations. In the current study we use two quantification methods for analyzing prehistoric shape-based architectural data: (1) we developed a new method, Shape Reproducibility (SR), based on objective computerized procedure for analyzing the similarity and difference between shapes of ancient buildings; and (2) we use Continuous Symmetry Measure (CSM), a method which was originally developed for analyzing flint artifacts and ceramic vessels to objectively compare between shape symmetry. Applying these methods to settlement data of the Chalcolithic period enables quantification of the level of architectural similarity within and between different sites and their comparison to architectural data of later periods, such as the Early Bronze Age II urban center at Arad. Our CSM results suggest that the symmetry of architecture does not increase through time. Our SR findings demonstrate that in the main cultural Chalcolithic entity, the Ghassulian, the architecture of different sites could not be distinguished from one site to the other. In addition, we demonstrate that the architecture of the Chalcolithic sites in the Golan Heights is homogeneous and significantly differs from other Chalcolithic sites, while Ghassulian intra-site variability is higher. In comparison with Arad, however, this variability is relatively low and limited. These results suggest that status differentiation or hierarchical social organization cannot be indicated from Ghassulian architecture.     

The application and misapplication of mass analysis in lithic debitage studies

The technique of debitage mass analysis based upon size grades of debitage populations is shown to be prone to errors when making interpretations about the kind of tool produced or the kind of lithic reduction technology used. Significant sources of error may originate from differences in individual flintknapping styles and techniques, raw material size and shape variants, and mixing of debitage from more than one reduction episode. These sources of error render debitage Mass Analysis ineffective for determining the kind of stone tool reduction activities practiced at excavated sites. Mass Analysis may be effective for determining artifact reduction sequences if it is used on debitage from a single reduction episode or part of a reduction episode. However, it is shown that Mass Analysis when used for assessing reduction sequence information, must also control for the effects of raw material variability, assemblage mixing, and flintknapping styles.     

Taphonomic identification of cut marks made with lithic handaxes: an experimental study

Recent experimental studies have developed new diagnostic criteria to differentiate between trampling and cut marks. Within cut marks, these diagnostic criteria have been useful to differentiate between marks made with simple and retouched flakes. The present study expands the application of these criteria using a multivariate analysis to discriminate marks created with handaxes from those made with stone tool flakes. A discriminant analysis resulted in a selection of specific variables, which can successfully differentiate cut marks made with handaxes from those created with retouched flakes in more than 80% of occasions. The utility of this analogical taphonomic signature created by handaxes is discussed in the light of their potential value as butchering tools.     

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

We 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.