Stone Tool Use Research Articles

"How handy was early hominin 'know-how'?" An experimental approach exploring efficient early stone tool use.

The appearance of early lithic industries has been associated with the gradual development of unique biomechanical and cognitive abilities in hominins, including human-like precision grasping and basic learning and/or communicating capacities. These include tools used for activities exclusively associated with hominin contexts (cutting flakes) and hammerstones utilized for behaviors shared with non-human primates (e.g., nut-cracking). However, no previous experimental research has focused on comparing the factors affecting efficiency between these two key behavioral patterns and their evolutionary implications. Here, we address this gap with an experimental design involving participants with varying tool-related experience levels (i.e., no experience, theoretical-only experience, and extensive practical knapping expertise) to monitor their success rates, biometrics, and surface electromyography (sEMG) recordings from eight important hand and forearm muscles. Our results showed that practical experience had a substantial impact on flake-cutting efficiency, allowing participants to achieve greater success rates with substantially less muscle effort. This relationship between success rates and muscle effort was not observed for the nut-cracking task. Moreover, even though practical experience did not significantly benefit nut-cracking success, experts exhibited increased rates of self-improvement in that task. Altogether, these experimental findings suggest that the ability to practice and retain tool-using knowledge played a fundamental role in the subsistence strategies and adaptability of early hominins, potentially providing the cognitive basis for conceptualizing the first intentional tool production strategies.

A new addition to the toolbox: stone tool use in blonde capuchin monkeys (Sapajus flavius).

The use of tools played a central role in human culture and evolution. Early studies with apes demonstrated the tool use; however, currently the works have focused on Platyrrhine, particularly capuchin monkeys. Blonde capuchin monkeys, Sapajus flavius, have been observed using sticks to fish for termites in the Atlantic Forest, where this species has been extensively studied. In this study, we presented the first evidence of stone tool use by the blonde capuchin monkeys, as well as the dimensions and weight of these tools. We gathered data from three areas of Caatinga dry forest where we discovered this new tool use among the species. The mean weight of the hammers was 475.7g (± 142 SD). The mean height of the anvils was 48.3cm (± 18.7 SD), while the mean surface area of the anvils was 1.2 m2 (± 0.4 SD). We identified fruits and/ornuts from three plant species-Prunus dulces, Cnidoscolus quercifolius, and Syagrus coronate-near the anvils at the study sites. Additionally, we passively observed six instances of stone tool use by blonde capuchin monkeys. Their use of stones to crack encased foods mirrored behaviors previously reported in Sapajus libidinosus, a species well known for using stone tools to exploit hard nuts. Our findings place blonde capuchin monkeys among the list of primates that utilize stones as tools, highlighting the species' adaptability in exploiting resources within the Caatinga. Long-term studies are essentials to comprehend the use pattern of stone tools (across both general and seasonal perspectives) and the influence of variables, such as fruit hardness, distance to watercourses, and fruit availability on the use of this technology by this primate.

An experimental approach on dynamic occlusal fingerprint analysis to simulate use-wear localisation and development on stone tools

Information about the use of stone tools in the past is encoded in the wear patterns left on their surface; however, post-depositional processes can modify and obstruct these traces. One aim in the field of lithic functional analysis is to develop methods to detect and quantify these traces on stone tools. The occlusal fingerprint analysis (OFA) is a well-established method in dental wear studies to virtually simulate dental occlusal (contact between teeth) stroke movements and thus locate and quantify the sequential contact between opposing tooth crowns. Reaching across disciplines, we conducted controlled experiments to test the applicability of the OFA method on stone tools to address the challenge of use-wear quantification and localisation, and therefore the identification of post-depositional wear. Our findings reveal a clear overlap between zones of experimentally produced use-wear and OFA-calculated contact areas. We demonstrate OFA as a potential method to generate models of multiscale use-wear that can be used as references on experimental tools to identify post-depositional surface modifications on stone tool artefacts.

Back(s) to basics: The concept of backing in stone tool technologies for tracing hominins' technical innovations.

The evolution of Paleolithic stone tool technologies is characterized by gradual increase in technical complexity along with changes in the composition of assemblages. In this respect, the emergence of retouched-backed tools is an important step and, for some, a proxy for "modern" behavior. However, backed tools emerge relatively early and develop together with major changes in Middle-Upper Pleistocene stone tool technologies. We provide an updated review of the emergence and development of the "backing" concept across multiple chrono-cultural contexts and discuss its relationship to both the emergence of hafting and major evolutionary steps in the ergonomics of stone tool use. Finally, we address potential mechanisms of context-specific re-invention of backing based primarily on data from the late Middle Paleolithic of Western Europe.

Tool skill impacts the archaeological evidence across technological primates

The archaeological record offers insights into our evolutionary past by revealing ancient behaviour through stone and fossil remains. Percussive foraging is suggested to be particularly relevant for the emergence of tool-use in our lineage, yet early hominin percussive behaviours remain largely understudied compared to flaked technology. Stone tool-use of extant primates allows the simultaneous investigation of their artefacts and the associated behaviours. This is important for understanding the development of tool surface modification, and crucial for interpreting damage patterns in the archaeological record. Here, we compare the behaviour and the resulting material record across stone tool-using primates. We investigate the relationship of nut-cracking technique and stone tool modification across chimpanzees, capuchins, and long-tailed macaques by conducting standardized field experiments with comparable raw materials. We show that different techniques likely emerged in response to diverse nut hardness, leading to variation in foraging success across species. Our experiments further demonstrate a correlation between techniques and the intensity of visible percussive damage on the tools. Tools used with more precision and efficiency as demonstrated by macaques, show fewer use wear traces. This suggests that some percussive techniques may be less readily identified in the archaeological record.

The Influence of Hand Dimensions on Finger Flexion during Lower Paleolithic Stone Tool Use in a Comfortable Grip

Considering the biomechanical and cognitive aspects involved in tool manipulation, hand size emerges as a critical factor. Males, on average, exhibit greater grip strength attributed to larger hand dimensions. Beyond mere physical factors, cognitive components tied to visuospatial abilities also influence stone tool use. However, the intricate relationship between hand size, grip strength, and ergonomic patterns necessitates further exploration. Here, we study the ergonomic pattern of phalanx flexion during the manipulation of Lower Paleolithic stone tools (choppers and handaxes) to understand the nuanced interplay between hand dimensions and grasping behaviors in Lower Paleolithic stone tool use. The static hand posture during the comfortable grasping of each tool is measured using a motion capture hand glove. Flexions are measured at the metacarpophalangeal joint, the proximal interphalangeal joint and the distal interphalangeal joint of each finger. Our investigation into Lower Paleolithic stone tool manipulation reveals gender-based differences in phalanx flexion, with hand dimensions showing correlation only in pooled samples. However, these associations diminish when analyzing males and females separately. This study suggests a minimal link between hand size and grasping behavior within our sample, hinting at the influence of cognitive, behavioral, and motor factors. Exploring lifestyle and psychometric profiles could provide further insights. In the context of early human technology, our results prompt considerations on the evolution of the hand-tool interaction system, linking our tool-dependent culture to our phylogenetic history.

Cooked or discarded? Experimental distinction of rabbit burnt bones and its application to the archaeological record

Leporid bones from Middle Palaeolithic assemblages may result from the contributions of various predators, including humans, or natural processes. Although the acquisition, processing, and consumption of small mammals by Neanderthal groups has been widely demonstrated, there are still some unresolved issues. Cut marks are typically the most reliable indicators of human processing of carcasses. However, animals the size of rabbits often pose a challenge in this regard, as the use of stone tools is not always necessary for their consumption, particularly for meat or marrow extraction. Consequently, the quantity of these types of marks, such as cuts or hammer-stone percussion damage, indicating human processing, may be limited. Burning is another type of bone damage that could be indicative of human action, although both intentional and accidental processes could lead to the thermal alteration of remains without necessarily linking them to consumption. Therefore, efforts to distinguish the processes resulting in bone burning are of vital importance in determining the origin of these animals in archaeological assemblages. In this work, the results of several experimental series designed to characterise the roasting and subsequent cleaning of waste on rabbit bones are presented. These results confirm most of the characteristics described in previous experimental works on burnt bones, highlighting the differential damage between bones with and without meat. The current study aims to contribute new data for characterising burned rabbit bones resulting from human actions, which can then be applied to Middle Palaeolithic assemblages with this type of thermal alteration bone modifications.

Niche expansion of capuchin monkeys to forest floor on guild‐reduced islands increases interspecific spatio‐temporal overlap

AbstractInterspecific interactions play an important role in structuring wildlife communities. On islands, which often have reduced species assemblages, species may expand their niches resulting in unusual patterns of interactions with other members of the ecological community. In this study, we compared spatio‐temporal interactions of two food competitors between a site with predators and two predator‐free islands in the Coiba archipelago, Panama. Here, capuchin monkeys (Cebus capucinus imitator) exhibit high levels of terrestriality, and some groups engage in stone tool use. This potentially leads to competition with sympatric agoutis (Dasyprocta coibae), which have overlapping diets. We used camera‐trap surveys to estimate temporal overlap between both species, distinguishing between arboreal and terrestrial activity of capuchins. We also compared detection rates and intervals between consecutive detections of both species at sites in which the monkeys use stone tools (tool‐use area) and sites in which they do not (non‐tool‐use area). We found high spatio‐temporal overlap between agouti and capuchin on the forest floor of both islands. While capuchins visited the tool‐use area four times as often as the non‐tool‐use area, agoutis avoided the tool‐use area, capture rates being 25 times as low. Waiting times were shorter for both species at the tool‐use area. These results suggest temporal overlap and spatial segregation. Niche expansions on islands thus cause unique interactions that do not occur on the mainland.Abstract in Spanish is available with online material.

Mapping nut-cracking in a new population of wild capuchin monkeys (Sapajus libidinosus) at Ubajara National Park, Brazil.

Populations of bearded capuchin monkeys (Sapajus libidinosus) vary in their tool use behaviors, with some of this divergence regarded as culturally determined. The use of stone tools, primarily to crack open encased foods, is widespread among bearded capuchins living in dry habitats (Caatinga and Cerrado). Significant diversity in targets, processed foods, material, and size of tools is observed across populations. However, so far, only a few sites have been systematically studied, and we are still distant from a representative picture of the range of variation in capuchins' culture. In this study, we did a systematic assessment of stone tool use sites in the Ubajara National Park (UNP), in the Caatinga region of Ceará, Brazil, recording and measuring stone tools, processed foods, and available lithic resources as part of an extensive comparative research, the CapCult project. We found indirect and direct evidence that capuchin monkeys at UNP customarily use hammerstones and anvils to process at least two species of palm nuts, macauba (Acrocomia aculeata) and the harder babaçu (Attalea speciosa). Most of the anvils were rock surfaces and had leftovers of only one palm nut species. The hammerstones used to process both palm nuts were not significantly different in weight, although the ones used for Ac. aculeata were longer. We found a higher frequency of nut-cracking sites in the drier lowland area of the park, reflecting differences in the density of the most common palm species, Ac. aculeata, and availability of raw stone material. The stone tool use observed in UNP is within the scope of previously reported in savannah capuchin populations. Our study widens the knowledge of stone tool-use diversity in wild capuchin monkeys, which could contribute to shaping conservation policy, including cultural traits.

Male-biased stone tool use by wild white-faced capuchins (Cebuscapucinus imitator).

Tool-using primates often show sex differences in both the frequency and efficiency of tool use. In species with sex-biased dispersal, such within-group variation likely shapes patterns of cultural transmission of tool-use traditions between groups. On the Panamanian islands of Jicarón and Coiba, a population of white-faced capuchins (Cebus capucinus imitator)-some of which engage in habitual stone tool use-provide an opportunity to test hypotheses about why such sex-biases arise. On Jicarón, we have only observed males engaging in stone tool use, whereas on Coiba, both sexes are known to use tools. Using 5 years of camera trap data, we provide evidence that this variation likely reflects a sex difference in tool use rather than a sampling artifact, and then test hypotheses about the factors driving this pattern. Differences in physical ability or risk-aversion, and competition over access to anvils do not account for the sex-differences in tool-use we observe. Our data show that adult females are physically capable of stone tool use: adult females on Coiba and juveniles on Jicarón smaller than adult females regularly engage in tool use. Females also have ample opportunity to use tools: the sexes are equally terrestrial, and competition over anvils is low. Finally, females rarely scrounge on left-over food items either during or after tool-using events, suggesting they are not being provisioned by males. Although it remains unclear why adult white-faced capuchin females on Jicarón do not use stone-tools, our results illustrate that such sex biases in socially learned behaviors can arise even in the absence of obvious physical, environmental, and social constraints. This suggests that a much more nuanced understanding of the differences in social structure, diet, and dispersal patterns are needed to explain why sex-biases in tool use arise in some populations but not in others.

Stone tools beyond traditional functions: the journey of lithics from profane to ceremonial

The production of flint tools evolved and diversified in response to the increasing and newly appearing demands of the early societies. The maintenance of this tradition coupled with the durability of stone tools resulted in the development of the lithic tool kit and the accumulation of large lithic assemblages mainly in settlements. The twentieth century witnessed the wide investigation of those assemblages through techno-typological approaches that aim at classifying and interpreting lithic assemblages and using them to reconstruct the chronological and cultural phases of given societies. The wide use of stone tools in daily-life activities i.e. hunting, gathering, farming, and food processing, enhanced the perception of lithics as functional objects that are mainly associated with secular activities. However, investigating the changing roles of stone tools over time remained partially overlooked. Apart from finely-made flint knives, the ritual functions of stone tools remain an unexplored research area. The current paper focuses on assessing the symbolic roles of the Predynastic lithics based on their use as grave goods. The results show that varied classes of tools were recruited for funerary purposes and that the evolving roles of lithics were influenced by a long process of human-nature and people-object interactions.

Stone tools beyond traditional functions: the journey of lithics from profane to ceremonial

The production of flint tools evolved and diversified in response to the increasing and newly appearing demands of the early societies. The maintenance of this tradition coupled with the durability of stone tools resulted in the development of the lithic tool kit and the accumulation of large lithic assemblages mainly in settlements. The twentieth century witnessed the wide investigation of those assemblages through techno-typological approaches that aim at classifying and interpreting lithic assemblages and using them to reconstruct the chronological and cultural phases of given societies. The wide use of stone tools in daily-life activities i.e. hunting, gathering, farming, and food processing, enhanced the perception of lithics as functional objects that are mainly associated with secular activities. However, investigating the changing roles of stone tools over time remained partially overlooked. Apart from finely-made flint knives, the ritual functions of stone tools remain an unexplored research area. The current paper focuses on assessing the symbolic roles of the Predynastic lithics based on their use as grave goods. The results show that varied classes of tools were recruited for funerary purposes and that the evolving roles of lithics were influenced by a long process of human-nature and people-object interactions.

History of Shoushan Stone Culture Neolithic Period

Fuzhous cultural roots can be traced back over 6000 years to the Neolithic period. It evolved from a barbarian land to a prominent political, economic, and cultural center over 2000 years. The region witnessed the development of various prehistoric cultures like the Keqiutou, Tanshishan, and Huangguashan cultures. These cultures left behind archaeological sites with stone tools, pottery, and other artifacts, reflecting the lives of ancient Fuzhou inhabitants and the significant influences on other regions. The Fucun site in Fuzhou, as it featured the use of stone tools made from Shoushan stone, provided valuable insights into the Neolithic Age. These tools played a crucial role in the daily lives and production activities of the ancient Fuzhou inhabitants, brought the advancement of labor tools and productivity during that era and potentially influenced the later art and culture of the region.

Influence of COVID-19 on the emergence of stone-tool use behavior in a population of common long-tailed macaques (Macaca fascicularis fascicularis) in Thailand.

Stone tool use is a rare behavior across nonhuman primates. Here we report the first population of common long-tailed macaques (Macaca fascicularis fascicularis) who customarily used stone tools to open rock oysters (Saccostrea forskali) on a small island along the Thai Gulf in Koh Ped (KPE), eastern Thailand. We observed this population several times during the past 10 years, but no stone-tool use behavior was observed until our survey during the coronavirus disease 2019 (COVID-19) pandemic in July 2022. KPE is located in Pattaya City, a hotspot for tourism in Thailand. Tourists in this area frequently provided large amounts of food for the monkeys on KPE. During the COVID-19 curfew, however, tourists were not allowed to access the island, and monkeys began to face food scarcity. During this time, we observed stone-tool use behavior for the first time on KPE. Based on our observations, the first tool manipulation was similar to stone throwing (a known precursor of stone tool use). From our observations in March 2023, we found 17 subadult/adult animals performing the behavior, 15 of 17 were males and mostly solitary while performing the behavior. The M. f. fascicularis subspecies was confirmed by distribution, morphological characteristics, and mtDNA and SRY gene sequences. Taken together, we proposed that the stone tool use behavior in the KPE common long-tailed macaques emerged due to the COVID-19 food scarcity. Since traveling is no longer restricted many tourists have started coming back to the island, and there is a high risk for this stone tool-use behavior to disappear within this population of long-tailed macaques.

Exploring the impact of mobility and selection on stone tool recycling behaviors through agent-based simulation.

Recycling behaviors are becoming increasingly recognized as important parts of the production and use of stone tools in the Paleolithic. Yet, there are still no well-defined expectations for how recycling affects the appearance of the archaeological record across landscapes. Using an agent-based model of recycling in surface contexts, this study looks how the archaeological record changes under different conditions of recycling frequency, occupational intensity, mobility, and artifact selection. The simulations also show that while an increased number of recycled artifacts across a landscape does indicate the occurrence of more scavenging and recycling behaviors generally, the location of large numbers of recycled artifacts is not necessarily where the scavenging itself happened. This is particularly true when mobility patterns mean each foraging group spend more time moving around the landscape. The results of the simulations also demonstrate that recycled artifacts are typically those that have been exposed longer in surface contexts, confirming hypothesized relationships between recycling and exposure. In addition to these findings, the recycling simulation shows how archaeological record formation due to recycling behaviors is affected by mobility strategies and selection preferences. While only a simplified model of recycling behaviors, the results of this simulations give us insight into how to better interpret recycling behaviors from the archaeological record, specifically demonstrating the importance of contextualizing the occurrence of recycled artifacts on a wider landscape-level scale.

Digital twin models of replicative ground stones: insight into simulating usage of Upper Paleolithic tools

This work presents the first attempt to create a physics-based digital twin model for predictive analysis of damage evolution during the use of ground stone tools (GSTs) in transformative tasks, encompassing the processing of raw resources for nutritional and non-alimentary purposes. The proposed methodology introduces a digital twin of the GSTs developed from 3D models generated using a photogrammetric technique based on Structure-from-Motion and Multi-View Stereo reconstruction. These models serve as the foundation for the development of the finite element (FE)-based digital twin model of the GSTs that exploits a contact formulation and the phase-field approach to simulate tool damage during pounding and grinding tasks. Defining the initial relative positions of the stones, their mechanical behaviour, and controlling the movement of the active stone in a way as close as possible to the real one, the digital twin model has been devised to evaluate how the surface damage is affected by perturbations in the loading conditions. The simulated damage is compared with the surface traces observed from experiments. The developed digital twin model aims at demonstrating its potentials for the GSTs investigations, as a supporting tool for experiments and for simulated tests on the archaeological records.

American crows that excel at tool use activate neural circuits distinct from less talented individuals

Tools enable animals to exploit and command new resources. However, the neural circuits underpinning tool use and how neural activity varies with an animal’s tool proficiency, are only known for humans and some other primates. We use 18F-fluorodeoxyglucose positron emission tomography to image the brain activity of naïve vs trained American crows (Corvus brachyrhynchos) when presented with a task requiring the use of stone tools. As in humans, talent affects the neural circuits activated by crows as they prepare to execute the task. Naïve and less proficient crows use neural circuits associated with sensory- and higher-order processing centers (the mesopallium and nidopallium), while highly proficient individuals increase activity in circuits associated with motor learning and tactile control (hippocampus, tegmentum, nucleus basorostralis, and cerebellum). Greater proficiency is found primarily in adult female crows and may reflect their need to use more cognitively complex strategies, like tool use, to obtain food.

Clovis point allometry, modularity, and integration: Exploring shape variation due to tool use with landmark-based geometric morphometrics.

Landmark-based geometric morphometrics (LGM) is most often used in archaeology to characterize and differentiate groups of artifacts, but it can be used for much more. We demonstrate LGM's power to uncover new insights by exploring stone-tool allometry, modularity, and integration using a sample of 100 western North American Clovis points. Here, allometry concerns how stone tools change in shape as their size changes through their use-lives, and modularity and integration concern how the constituent parts of a tool work together. We show that Clovis points are surprisingly complex tools. When their blades and hafts are defined technologically, rather than arbitrarily, they unambiguously exhibit allometry, and their hafts and blades are modular and highly integrated. We use these analyses to further explore questions about Clovis points, including the differences between cache and non-cache points. Finally, we use heuristic haft-size categories to examine functional constraints on the shape and size of hafts and blades. This work illustrates the importance of using accurate measurements of point components rather than estimates or proxies, which can lead to unfounded inferences. These analytical approaches and accompanying R code are easily transferable to other research questions of stone-tool use.

Newly Discovered Prehistoric Sites in the Seonath Basin, Chhattisgarh, India

Prehistoric cultures shed light on the evolution of human social organization. The development and use of stone tools are significant milestones in human evolution. Prehistoric artifacts provide evidence of early technologies and the progression of tool-making techniques. Presented paper provides a comprehensive overview of the recently identified Prehistoric sites within the Durg and Rajnandgaon districts situated in the Central Seonath Basin of Chhattisgarh. It offers detailed descriptive and contextual data regarding these newly discovered archaeological locations. The discussed sites or site complexes include Palaeolithic, microlithic and individual artifacts finding sites along the Durg-Raipur upland, Rajnandgaon upland and Eastern edge of the Mekal range in Rajnandgaon district. The occurrences vary in terms of their locations, scatters, context and tools typology.

Engraved images of the Shulgan-Tash (Kapova) cave, Bashkortostan, South Ural

The cave of Shulgan-Tash (Kapova) with wall drawings of the Upper Paleolithic is located in the mountain course of the River Belaya in the Southern Urals, nearby the village of Gadelgareevo, Burzyansky district of the Republic of Bashkortostan. In the process of more than 50 years of studying the cave sanctuary, the search for engraved images has been carried out. Two compositions with engraved images were discovered in 2008. Com-position No. 1 is located in the Main Gallery, 100 m from the entrance, in a niche on the western wall at a height of about 2 m above the floor level. It consists of the elements located on two levels. At the lower level, a number of elements are confined to the natural fracture and a chain of caverns. Parallel to the horizontal crack, five lines were drawn. The lines connect to a quadrangular shape filled with vertical and horizontal lines. Behind it, the crack merges into a chain of caverns. The upper tier consists of four oval artificial recesses. The fourth groove is located under the engraved anthropomorphic figure, between the legs. This indicates that this is a vulva-shaped symbol. The grooves are connected by deeply incised lines to the quadrangular figure and caverns of the lower tier. Lines also run from the chain of the caverns downwards. Thus, these groups of artificial and natural elements were combined into a single composition. Composition No. 2 is located in the Dome Hall, 150 m from the entrance, above the Chapel of Skulls in the western wall, nearby the colorful wall images in the shape of splashes. It was made on a 16 cm × 14 cm rock surface leveled and cleaned of calcite deposits. The composition consists of three pictorial ele-ments made in three different ways. The first element is represented by two parallel arcuate bands of comb lines of 4 cm wide and about 30 cm long made with a serrated stone tool of 4 cm wide in the soft mondmilch. Under them, with finger impressions in the mondmilch, a circle of about 6 cm in diameter was made of round dimples; rows of en-graved straight lines and zigzags were applied to the right of the circle. At present, the composition is held together by calcite incrustation and has completely hardened. The use of stone tools to create the engravings and grooves, the calcite crust inside the engraved lines, the use of the natural forms of the wall relief in the pictorial ensemble, the similarity of the quadrangular figure with the quadrangular symbols painted with ochre in the same cave, and the presence of a vulva-shaped symbol — all this indicates the Upper Paleolithic Age of these compositions.