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It has long been suggested that object play facilitates the development and evolution of tool use, through enhanced perception of an object's properties and potential for manipulation. However, ecologically relevant support for this claim is scant. We examined whether a form of culturally maintained object play, named stone handling, characterized by high interindividual variation in its behavioural expression, promotes the acquisition and further expression of stone-tool use in a nonhuman primate species. We conducted a series of field experiments in a free-ranging group of Balinese longtailed macaques, Macaca fascicularis , to test whether the stone-handling profiles of different individuals predicted their ability to solve a foraging task, whose solution required the functional and action-specific use of stones as tools. Frequentist network-based diffusion analysis, Bayesian multilevel regression modelling and descriptions of individuals' learning trajectories showed that the solutions to different foraging tasks required varying reliance on social and asocial learning strategies. Our results suggest that certain stone-handling profiles may increase an individual's likelihood of expressing stone-tool use. However, other trait- and state-dependent variables may also contribute to explaining individual differences in the development and expression of stone-tool use. The behavioural idiosyncrasies associated with stone handling in longtailed macaques may serve as an exaptive reservoir for the possible emergence of stone-tool use. To our knowledge, this is the first study to experimentally evaluate the role of stone-directed play in the acquisition of stone-tool use. • We examined whether object play influences the expression of tool use in macaques. • Stone handling in macaques promoted stone-tool use acquisition and expression. • Stone-handling profiles helped solve foraging tasks involving stones as tools. • Object play may serve as a potential precursor to tool use. • Social influences contributed to acquiring puzzle box solutions. [ABSTRACT FROM AUTHOR]

• We tested generalization of child planning from structured tasks to free play. • Adaptive tool-use child planners gather visual information earlier during free play. • Visually-guided planning was positively correlated across different free-play tasks. • The development of visually-guided planning is domain-general. Visually guided planning is fundamental for manual actions on objects. Multi-step planning—when only the requirements for the initial action are directly visible in the scene—necessitates initial visual guidance to optimize the subsequent actions. We found that 3- to 5-year-old children (n = 23) who exhibited visually guided, multi-step planning in a structured tool-use task (hammering down a peg) also demonstrated visually guided planning during unstructured free play while interlocking Duplo bricks and Squigz pieces. Children who exhibited visually guided planning in the hammering task also spent more time looking at the to-be-grasped free-play object and at their construction during reach and transport compared with children who did not demonstrate multi-step planning in the hammering task. Moreover, visually guided planning in the Duplo and Squigz tasks was positively correlated, indicating that planning generalizes across contexts. Findings show that visually guided planning in young children generalizes across different manual actions on objects, including structured tool use and unstructured free play. [ABSTRACT FROM AUTHOR]

• We identified two distinct cognitive and neural pathways for mechanical VS. digital technology. • Mechanical tools engage the action brain; digital tools activate the conceptual and social brain. • Digital tools are anthropomorphized more than mechanical tools in behavioral studies. • Task-based connectivity shows distinct networks for processing mechanical VS. digital tools. Technology pervades every aspect of our lives, making it crucial to investigate how the human mind deals with it. Here we examine the cognitive and neural foundations of technological cognition. In the first fMRI experiment, participants viewed videos depicting the use of mechanical tools (e.g. , a screwdriver) and digital tools (e.g. , a smartphone) compared to simple object movements. Results revealed a key dissociation: mechanical tools extensively activated the dorsal and ventro-dorsal visual streams, which are motor- and action-oriented brain systems. Conversely, digital tools largely engaged the ventral visual stream, associated with conceptual and social cognition. A second behavioral experiment showed a pronounced tendency to anthropomorphize digital tools. A third experiment involving a priming task confirmed that digital tools activate the social brain. The discovery of two different neurocognitive systems for mechanical versus digital technology offers new insights into human-technology interaction and its implications for the evolution of the human mind. [ABSTRACT FROM AUTHOR]

• Complexity of play predicts infants' capacity to solve means-end problems. • This link does not depend on whether the problem involves the use of tools. • We compared tool and non-tool means-end problem-solving of similar difficulty. Tool use is primarily, but not exclusively, present in species with otherwise advanced cognitive traits. However, the interaction between such traits and conspecific inter-individual variation in the presence, complexity, or intensity of tool use is far from being established. We addressed this matter among human infants, seeking factors that relate to differences in tool use. We examined, both correlationally and experimentally, whether the propensity to engage in object combinations predicts performance in means–end problem-solving tasks involving or not involving the use of a tool. We tested 71 infants aged 15, 18, 21, and 24 months, dividing them into two subgroups: one exposed to an adult demonstrating object–object combinations (i.e., "prompting" infants to combine objects together) and another with comparable social exposure but where the adult demonstrated single-object manipulations. We found a correlation between the combined level of spontaneous and prompted object combinations and problem-solving performance regardless of the involvement of tools in the problem. However, we did not find differences in tool-use performance between the two demonstration subgroups. The correlational analysis suggests that complexity of play, as measured by the frequency of combining objects, is linked to infants' problem-solving skills rather than being specifically associated with tool use, as previously suggested in the literature. [ABSTRACT FROM AUTHOR]

• We tested how conventional and design cues impact young children's object function judgments. • When asked to identify what an object was 'for', 4- to 5-year-olds were influenced by conventional but not design cues. • Both conventional and design cues influenced 6- to 8-year-olds' function judgments. • The effect of both cues was less salient when malfunctions were presented. • Conventional and design cues appear to be similarly important in function conceptualization. This study investigated the individual influences of conventionality and designer's intent on function judgments of possibly malfunctioning artifacts. Children aged 4 and 5 years and 6 to 8 years were presented with stories about an artifact with two equally plausible functions, one labeled as either conventional or designed. Subsequently, a character attempted to use the artifact for the cued function, which resulted in either malfunction or successful use. The children's task was to identify the real function of the artifact. When the use attempt succeeded, 4- and 5-year-olds preferred conventional functions to the alternative (but did not show a clear preference between design functions and the alternative), and 6- to 8-year-olds preferred conventional and designed functions to the alternative. In case of malfunction, children's choices were at chance, where the effect of either conventional or design cues was less salient. This contrasts with a baseline condition where children avoided the malfunctioning alternatives. Presenting additional cues about an artifact's function can affect function judgments in cases of malfunction. [ABSTRACT FROM AUTHOR]

The relative importance of individual and social learning in acquiring complex technological skills in animals is debated, especially the influence of processes allowing high copying fidelity (namely, imitation and teaching). We investigated how immature wild chimpanzees, Pan troglodytes troglodytes , acquired the technique for extracting underground honey. This technique is interesting because (1) adults perform exploration, pounding and perforation in nonrandom but highly flexible action sequences to locate underground bee nests, (2) they have individual preferences for how to perforate the ground and (3) the nests are deeply buried and concealed, making success difficult to achieve. We analysed the behaviour of 16 immatures recorded by camera traps at 50 sites, and tested the influence of individual attributes (namely, age and sex) and maternal behaviour; we also tested whether mothers provided learning opportunities for their offspring. We found that, as they aged, immatures of both sexes progressively matched adults' behaviour in action sequences and observed their social models more continuously. Immature males used the most common grip type used by adults for perforating (namely, the coordinated use of hands and feet) progressively more as they aged, but no effect of maternal preferences was detected. Thus, the adult technique was probably acquired via a combination of physical maturation (i.e. increased body strength and motor coordination) and observational learning, although individual learning could not be completely ruled out. Finally, the proportion of time mothers spent inactive at bee nest sites was high when they were accompanied by young daughters and decreased as daughters aged, while the opposite pattern was found for sons. Mothers may thus stimulate learning by immatures by adjusting their behaviour according to their offspring's sex and age. Overall, we showed that immature chimpanzees acquired this complex tool use behaviour via a combination of social and nonsocial learning processes, including potential maternal stimulation. Highlights • Immature chimpanzees acquired action sequences for honey extraction as they aged. • With age, immatures used the grip type involving hands and feet more to perforate. • One immature male learned the grip type unique to his mother. • Mothers provided learning opportunities to offspring according to their age and sex. [ABSTRACT FROM AUTHOR]

Abstract The controlled semantic cognition framework proposes that the ventral anterior temporal lobes (vATL) in the left and right hemisphere function as an integrated hub region supporting transmodal semantic representations. The clinical evidence for the transmodal function of vATL is largely based on studies of semantic dementia patients with severe anomia, who also show impaired performance on nonverbal tasks that involve the retrieval of knowledge about objects and their prototypical use, such as the production of tool use pantomimes. Yet, evidence from patients with apraxia and functional neuroimaging studies in healthy adults does not implicate vATL in pantomime production. We, therefore, compared semantic retrieval of object-action associations for overt verb and pantomime production from picture and word stimuli. Our results show that, independent of stimulus modality, the retrieval of object-action associations for verb, but not pantomime, production is related to activity in bilateral vATL. Bilateral vATL activation was also observed for meaningless verbal responses that did not require the retrieval of object-action associations. Taken together, our results suggest that bilateral vATL is not engaged in the retrieval of object-action associations per se, but rather supports semantic representations that are functionally specialized for language. These findings have implications for the semantic cognition framework and our understanding of the dependence of conceptual knowledge on language. Highlights • Investigates engagement of transmodal semantic hub for nonverbal behaviour. • Compares behaviour and brain activation underlying verb and pantomime production. • Semantic control network activated for verb and pantomime production. • Semantic hub only engaged during verb but not pantomime production. • Results suggests that semantic hub is specialized for language. [ABSTRACT FROM AUTHOR]

To become skilled artifact users, children must learn the actions and functions associated with artifacts. We investigated preschoolers’ ability to fast map an action, function and name associated with a novel artifact, and retain the new mapping long term following brief incidental exposure to the artifact being used. In Experiment 1, 3- and 5-year-olds ( N  = 144) were tested 1 week after two exposures to a novel action, function, and name. Participants performed well on comprehension tests of all three kinds of information. In Experiment 2, 3-year-olds ( N  = 100) were exposed to these three kinds of information only once. Retention of the action–artifact link was above chance levels, whereas retention of function and the name was not. Finally, in Experiment 3, 4-year-olds ( N  = 128) performed well on an action production task 1 week after brief exposure. In contrast, their performance on a name production task immediately after exposure was poor. Our data suggest that preschoolers can retain function information about a novel artifact from minimal exposure, similar to their ability to learn an artifact name. Crucially, their ability to remember action–artifact mappings is markedly better than their ability to remember functions and names. [ABSTRACT FROM AUTHOR]

Cultural diversity among social groups has recently been documented in multiple animal species. Investigations of the origin and spread of diverse behaviour at group level in wild-ranging animals have added valuable information on social learning mechanisms under natural conditions. Behavioural diversity has been especially informative in the case of dispersal, where the transfer of individuals between groups leads to a sudden exposure to unfamiliar behaviour. Little is known, however, about the underlying costs and benefits of cultural transmission in animals and humans alike, as efficiency of cultural variants is often difficult to measure. The chimpanzees, Pan troglodytes , of the Taï National Park in Ivory Coast are known to exhibit a number of cultural differences between social groups, including hammer selection for nut cracking. This provides the unique opportunity to quantify the efficiency of cultural variants. We compared foraging speed and number of hits applied during nut-cracking events between three neighbouring chimpanzee groups. Our results showed significant differences in nut-cracking efficiency, caused by hammer material selection and differences in the applied power of impact per nut. Persistent behavioural coherence within the respective groups implies that immigrants adjust their behaviour to local nut-cracking techniques, even when individual foraging success might be compromised. This suggests that the benefit of belonging to a social group might outweigh the benefits of maximizing individual foraging efficiency. The differences in nut-cracking efficiency between chimpanzee groups add to the ever-growing body of cultural variants in wild chimpanzees and expand our knowledge of the importance of group belonging and conformity in wild chimpanzees. [ABSTRACT FROM AUTHOR]

Chimpanzees' natural propensity to explore and play with objects is likely to be an important precursor of tool use. Manipulating objects provides individuals with pivotal perceptual-motor experience when interacting with the material world, which may then pave the way for subsequent tool use. In this study, we were interested in the influence of social models on the developmental patterns of object manipulation in young chimpanzees, Pan troglodytes schweinfurthii , of the Sonso community of Budongo Forest, Uganda. This community is interesting because of its limited tool repertoire, with no records of stick-based foraging in over 20 years of continuous observations. Using cross-sectional data, we found evidence for social learning in that young individuals preferentially played with and explored materials manipulated by their mothers. We also found that object manipulation rates decreased with age, whereas the goal directedness of these manipulations increased. Specifically, stick manipulations gradually decreased with age, which culminated in complete disregard of sticks around the age of 10 years, a pattern not found for other tool materials, which were all used throughout adulthood. Overall, young chimpanzees initially explored and played unselectively with any object found in the environment before becoming increasingly influenced by their mothers' goal-directed object manipulations. [ABSTRACT FROM AUTHOR]

Spontaneous tool innovation to solve physical problems is difficult for young children. In three studies, we explored the effect of prior experience with tools on tool innovation in children aged 4–7 years ( N = 299). We also gave children an experience more consistent with that experienced by corvids in similar studies to enable fairer cross-species comparisons. Children who had the opportunity to use a premade target tool in the task context during a warm-up phase were significantly more likely to innovate a tool to solve the problem on the test trial compared with children who had no such warm-up experience. Older children benefited from either using or merely seeing a premade target tool prior to a test trial requiring innovation. Younger children were helped by using a premade target tool. Seeing the tool helped younger children in some conditions. We conclude that spontaneous innovation of tools to solve physical problems is difficult for children. However, children from 4 years of age can innovate the means to solve the problem when they have had experience with the solution (visual or haptic exploration). Directions for future research are discussed. [ABSTRACT FROM AUTHOR]

Across two studies, we explored cultural differences in children’s imitation and transmission of inefficient actions. Chinese American and Caucasian American preschoolers ( N = 115) viewed either one or three models using two inefficient tools to perform two different tasks. In the video, when the model(s) performed the task, only the inefficient tool was available; thus, their choice to use that tool could be considered rational. Next, children were invited to complete the task with either the inefficient tool or an efficient alternative. Whereas the two cultural groups imitated a single model at similar rates, Chinese American children imitated significantly more than Caucasian American children after viewing a consensus. Similar results were found when exploring differences in information transmission. The Chinese American children were significantly more likely than their Caucasian American peers to instruct using an inefficient tool when they had initially viewed a consensus demonstrate it. We discuss these findings with respect to differences in children’s use of social versus task-specific cues for learning and teaching. [ABSTRACT FROM AUTHOR]

Overimitation is defined as the imitation of a series of actions, including causally irrelevant ones. Although previous studies have indicated that children’s overimitation tends to be flexible, there is no research directly comparing overimitation occurrences due to types of irrelevant actions such as the target of irrelevant action or tool use. To identify the boundary of overimitation—that is, the point at which it occurs or not—Study 1 focused on the target of causally irrelevant tool-using actions. Specifically, the study examined the demonstration of irrelevant actions toward a main apparatus, a disconnected apparatus, or an actor’s own body, followed by the demonstration of causally relevant actions, to 2-, 3-, and 5-year-old children ( N = 59). Results indicated that children overimitated actions toward the apparatuses more than they did the actions toward an actor’s body. These results showed that overimitation was affected by the target, the apparatus, or the actor’s own body. Study 2 investigated the effect of tool use toward the disconnected apparatus or an actor’s body based on the findings in Study 1. Concretely, Study 2 added two actions without tool use (e.g., action toward an actor’s own body without tool use and action toward an apparatus without tool use) to Study 1’s actions for comparison. The results of this study showed that children overimitated the action toward the apparatus and the action with the tool more than the action toward an actor’s own body and the action without the tool. Taken together, these findings suggest that two factors are involved in the occurrence of overimitation: the target of the action (i.e., the apparatus) and the use of a tool. The current findings provide suggestions for considering important aspects of overimitation that are worthy of more attention. [ABSTRACT FROM AUTHOR]

Tool use in animals can be costly as foraging tools need to be actively searched for or manufactured. Consequently, some habitually tool-using species keep their tools safe and ‘recycle’ them for further use. We tested the Indonesian Goffin's cockatoo, a parrot with the capacity but no apparent adaptive specialization for tool use to investigate how tool safekeeping can arise innovatively. In this case, we further intended to test whether and how such safekeeping changes in different feeding contexts. We demonstrate that, in a set-up allowing for tool losses, the birds quickly started to keep their tools safe in between tool-using events. They used different individual strategies, suggesting that the behaviour was a product of innovation rather than inherited predispositions. The frequency of safekeeping improved over time indicating individual learning. Furthermore, the birds flexibly adjusted their performance depending on different contexts: paralleling previous results in the habitually tool-using New Caledonian crow, Corvus moneduloides , the cockatoos saved their tools more often when the foraging site was elevated and when the food item was easy rather than difficult to process. Furthermore, when feeding at heights, the birds tended to use a different safekeeping mode than when the foraging site was low. [ABSTRACT FROM AUTHOR]

• Pantomime production is at the crossroad between tool use and communication. • We investigated the role of social cognitive processes in pantomime production. • We collected kinematic data while participants performed tool-use pantomimes. • We found that social cognitive processes had a minor role in pantomime production. • Social cognitive processes might be far from necessary for pantomime production. Pantomime production is commonly interpreted as reflecting tool-use-related cognitive processes. Yet, in everyday life, pantomime deserves a communication function and the exaggeration of amplitude found during pantomime compared to real tool use may reflect the individual's attempt to communicate the intended gesture. Therefore, the question arises about whether pantomime is a communicative behavior that is nevertheless supported only by non-social cognitive processes. We contribute to answering this question by using kinematic analyses. Participants performed the pantomime of using a saw or a hammer from visual presentation in three conditions: Free (no specific instructions), Self (focus on the real tool-use action), and Others (focus on the communicative dimension). Finally, they used the tool with the corresponding object (Actual condition). Participants' social cognition were assessed using gold standard questionnaires. Our results indicated that the manipulation of instructions had a minor effect on the exaggeration of amplitude during pantomime. We reported a link between the social cognition score and the amplitude in the Others condition for the hammer, which suggests that social cognitive processes could take part in pantomime production in some conditions. Nevertheless, this result does not alter our conclusion that social cognitive processes might be far from necessary for pantomime production. [ABSTRACT FROM AUTHOR]

Tool use by nonhuman animals has received much research attention in the last couple of decades. Nevertheless, research has focused mostly on vertebrates, particularly primates and corvids, even though tool use has also been documented in insects. One of the best documented examples involves ants using debris (e.g. sand grains, mud, leaf fragments) to collect and transport liquid food to their nest. However, little is known about the factors that determine the selection of materials to be used as tools. We investigated tool selection in two species of Aphaenogaster ants by giving them the choice between different kinds of potential tools (natural and artificial objects). Ant workers showed a clear preference for certain materials to be used as tool objects. Tool selection was also shaped by familiarity with the material as ants developed a preference for artificial tools with a good soaking capacity that cannot be found in their natural environment. Our results indicate that ants of this genus have evolved unique foraging strategies and show plasticity in their behaviour. [ABSTRACT FROM AUTHOR]

How infants observe a goal-directed instrumental action provides a unique window into their understanding of others’ behavior. In this study, we investigated eye-gaze patterns while infants observed events in which an actor used a tool on an object. Comparisons among 4-, 7-, 10-, and 12-month-old infants and adults reveal changes in infants’ looking patterns with age; following an initial face bias, infants’ scan path eventually shows a dynamic integration of both the actor’s face and the objects on which they act. This shift may mark a transition in infants’ understanding of the critical components of tool-use events and their understanding of others’ behavior. [ABSTRACT FROM AUTHOR]

Labial striations on the anterior teeth have been documented in numerous European pre-Neandertal and Neandertal fossils and serve as evidence for handedness. OH-65, dated at 1.8 mya, shows a concentration of oblique striations on, especially, the left I 1 and right I 1 , I 2 and C 1 , which signal that it was right-handed. From these patterns we contend that OH-65 was habitually using the right hand, over the left, in manipulating objects during some kind of oral processing. In living humans right-handedness is generally correlated with brain lateralization, although the strength of the association is questioned by some. We propose that as more specimens are found, right-handedness, as seen in living Homo , will most probably be typical of these early hominins. [ABSTRACT FROM AUTHOR]

Scale errors offer a unique context in which to examine the interdependencies between language and action. Here, we manipulated the presence of labels in a tool-based paradigm previously shown to elicit high rates of scale errors. We predicted that labels would increase children’s scale errors with tools by directing attention to shape, function, and category membership. Children between the ages of 2 and 3 years were introduced to an apparatus and shown how to produce its function using a tool (e.g., scooping a toy fish from an aquarium using a net). In each of two test trials, children were asked to choose between two novel tools to complete the same task: one that was a large non-functional version of the tool presented in training and one novel functional object (different in shape). A total of four tool–apparatus sets were tested. The results indicated that without labels, scale errors decreased over the two test trials. In contrast, when labels were present, scale errors remained high in the second test trial. We interpret these findings as evidence that linguistic cues can influence children’s action-based errors with tools. [ABSTRACT FROM AUTHOR]

Our aim is general: we want to illustrate how much can be gleaned from mechanical measurement in the field. We ask how mechanics may constrain foraging and feeding on both plants and animals, and how various aspects of mechanical behavior could affect the feeding choices that primates make. Here, we present novel methods for the measurement of the material properties and also the employment of tried and tested methods in novel settings. This review demonstrates how mechanical investigation methods can quantify the environmental factors affecting primate locomotion to and from food, which makes up a large part of a primate's daily energy budget. We indicate that, despite the accumulation of much data on the material properties of primate foods, the introduction of new methods is allowing researchers to pursue new avenues of research and change paradigms in primate feeding ecology. Field methods are presented that could aid in the understanding of the extra-oral processing of foodstuffs by primates and enrich further studies into cognition and culture surrounding these types of behavior. We conclude that the use of in-field measurements and a greater understanding of the physics of primate environments are vital and exciting themes integral to the continued understanding of primate evolution and biology. [ABSTRACT FROM AUTHOR]

The traditional definitions of tool use typically operationalize the functionality of an object and the effect of its use on the environment and, typically, do not account for the dynamic relation among the body, task and environment that result in actions with a tool. This omission severely restricts the utility of these definitions for comparisons of tool use behaviour across individuals, populations and species. To address this issue, we propose an embodied theory of tool use based on the premise that a tool transforms the body-only system into the body-plus-tool system. It (1) explains the development of a tool use behaviour in terms of constraints on the development of tool use movements imposed by different features of the body, task and environment, (2) measures the dexterity of an actor in terms of the spatiotemporal organization of tool use movements that optimize at least one composite performance outcome variable and (3) measures the complexity in the use of a tool in terms of the control of the biomechanical degrees of freedom of the body-plus-tool system. Such an embodied theory of tool use is applicable across species, tasks and environments. [ABSTRACT FROM AUTHOR]

Tool-assisted percussion is an ancient feature of human technology. Tool-assisted percussion is not uniquely human; chimpanzees, Pan troglodytes , longtailed macaques, Macaca fascicularis aurea, and capuchin monkeys ( Sapajus spp.) use stone tools to crack open encased foods. The knowledge of how these nonhuman primates use percussion tools helps us to understand how extinct hominins might have used percussion tools. Wild bearded capuchin monkeys, Sapajus libidinosus, crack palm nuts of different species by placing them on rock outcroppings, boulders and logs (anvils) and striking them with stone hammers. In the present study, we examined whether and how these monkeys modulate the kinematic parameters of individual strikes and the organization of successive strikes to accommodate the physical properties of a nut. To this end, we observed seven monkeys as they cracked two species of nuts that differ in their structure and resistance to fracture. They cracked the less resistant tucum ( Astrocaryum spp.) nut by striking it repeatedly with moderate force (that is, by not exceeding a threshold) and modulating the kinematic parameters of each strike on the basis of the condition of the nut (that is, the development of a fracture) following the preceding strike. In contrast, they cracked the more resistant piaçava ( Orbignya spp.) nut by striking it with the maximum force that they could generate without modulating the kinematic parameters of their strikes until that nut cracked. These results demonstrate that the task-specific temporal organization of percussive movements necessary for knapping stones is within the capability of extant nonhuman primates. [ABSTRACT FROM AUTHOR]

A significant body of work has demonstrated children’s imitative abilities when learning novel actions. Although some research has examined the role of cultural background in children’s imitation of inefficient actions, to our knowledge no research has explored how culture and conformity interact when engaging in imitation. In Study 1, 87 Caucasian American and Chinese American preschoolers were presented with either one model or three models performing an inefficient action. Whereas there were no cultural differences in imitation in the Single Model condition, Chinese Americans were significantly more likely to copy the model’s preference for an inefficient tool in the Consensus condition. Children’s tool choice was associated with their justification for their choice as well as their memory for the model’s action. Study 2 explored the impact of immigration status on the cultural differences in children’s tool choice by including 16 first-generation Caucasian American children. When comparing the findings with the rates from Study 1, both groups of Caucasian American preschoolers imitated at rates significantly lower than the Chinese American preschoolers. We suggest that the tool choices of Caucasian American children relate to a tendency to engage in a perceptually driven mode of learning, whereas the choices of the Chinese American children reflect a greater likelihood to use a socially driven mode. [ABSTRACT FROM AUTHOR]

Investigating cognitively complex behaviours in their natural ecological context provides essential insights into the adaptive value of animal cognition. In this study, we investigated the selection of hammers used for cracking Coula nuts by wild chimpanzees, Pan troglodytes verus , in the Taï National Park, Côte d'Ivoire, taking account of the availability of potential tools at the site and time of tool selection. Using GLMMs and focal follows of five adult females, we estimated the probability of an object being selected as a hammer according to its physical properties, transport distance and the location of the anvil on the ground or in trees. We found that chimpanzees took account of several variables at the same time (multidimensionality) when selecting nut-cracking tools and that their selection for hammer weight was adjusted to the state/value of other variables (conditionality). In particular, chimpanzees (1) preferred stones over wooden clubs and hard woods over soft woods; (2) selected heavy stones, but relatively lighter wooden hammers; (3) selected increasingly heavier hammers the closer they were to the anvil; and (4) selected lighter hammers when they were going to crack nuts on a tree. The latter two results represent instances of conditional tool selection based on the next steps in an operational sequence (transport and/or use of the tool in a stable or unstable location) and suggest that chimpanzees anticipated future events when they chose a tool. This large set of conditional rules suggests a high level of cognitive sophistication in a tool use task. Our results represent a compelling example of how powerful cognitive skills allow the optimization of an ecologically relevant foraging activity, supporting a food extraction hypothesis for the evolution of complex cognition in our closest relatives. [ABSTRACT FROM AUTHOR]

A capacity for constructing new tools, or using old tools in new ways, to solve novel problems is a core feature of what it means to be human. Yet current evidence suggests that young children are surprisingly poor at innovating tools. However, all studies of tool innovation to date have been conducted with children from comparatively privileged Western backgrounds. This raises questions as to whether or not previously documented tool innovation failure is culturally and economically specific. In the current study, thus, we explored the innovation capacities of children from Westernized urban backgrounds and from remote communities of South African Bushmen. Consistent with past research, we found tool innovation to occur at extremely low rates and that cultural background had no bearing on this. The current study is the first to empirically test tool innovation in children from non-Western backgrounds, with our data being consistent with the view that despite its key role in human evolution, a capacity for innovation in tool making remains remarkably undeveloped during early childhood. [ABSTRACT FROM AUTHOR]

Abstract: Usewear analysis is now well established as a powerful means by which to identify the function of stone tools excavated from archaeological sites. However, one of the main issues for usewear analysts is still to provide quantified analyses and interpretations. Several attempts have yielded promising results but have not, as of yet, been widely applied and usewear analyses are still mainly performed using either Scanning Electron Microscopy (SEM) or Optical Light Microscopy (OLM). The systematic comparison of micrographs from both types of microscope presented here enables us to discuss the advantages and disadvantages of each system. Furthermore, it shows beginners or experts using only one type of microscope that these techniques are complementary and should be considered as such. It also represents a significant basis for developing the implementation of quantitative methods for usewear analysis with SEM and OLM. [Copyright &y& Elsevier]

Abstract: Insectivory is hypothesized to be an important source of macronutrients, minerals, and vitamins for chimpanzees (Pan troglodytes), yet nutritional data based on actual intake are lacking. Drawing on observations from 2008 to 2010 and recently published nutritional assays, we determined the energy, macronutrient and mineral yields for termite-fishing (Macrotermes), ant-dipping (Dorylus), and ant-fishing (Camponotus) by the Kasekela chimpanzees of Gombe National Park, Tanzania. We also estimated the yields from consumption of weaver ants (Oecophylla) and termite alates (Macrotermes and Pseudacanthotermes). On days when chimpanzees were observed to prey on insects, the time spent in insectivorous behavior ranged from <1 min to over 4 h. After excluding partial bouts and those of <1 min duration, ant-dipping bouts were of significantly shorter duration than the other two forms of tool-assisted insectivory but provided the highest mass intake rate. Termite-fishing bouts were of significantly longer duration than ant-dipping and had a lower mass intake rate, but provided higher mean and maximum mass yields. Ant-fishing bouts were comparable to termite-fishing bouts in duration but had significantly lower mass intake rates. Mean and maximum all-day yields from termite-fishing and ant-dipping contributed to or met estimated recommended intake (ERI) values for a broad array of minerals. The mean and maximum all-day yields of other insects consistently contributed to the ERI only for manganese. All forms of insectivory provided small but probably non-trivial amounts of fat and protein. We conclude that different forms of insectivory have the potential to address different nutritional needs for Kasekela chimpanzees. Other than honeybees, insects have received little attention as potential foods for hominins. Our results suggest that ants and (on a seasonal basis) termites would have been viable sources of fat, high-quality protein and minerals for extinct hominins employing Pan-like subsistence technology in East African woodlands. [Copyright &y& Elsevier]

Abstract: The role of invertebrates in the evolution of human diet has been under-studied by comparison with vertebrates and plants. This persists despite substantial knowledge of the importance of the ‘other faunivory’, especially insect-eating, in the daily lives of non-human primates and traditional human societies, especially hunters and gatherers. Most primates concentrate on two phyla, Mollusca and Arthropoda, but of the latter's classes, insects (especially five orders: Coleoptera, Hymenoptera, Isoptera, Lepidoptera, Orthoptera) are paramount. An insect product, bees' honey, is particularly important, and its collection shows a reversal of the usual sexual division of labor. Human entomophagy involves advanced technology (fire, containers) and sometimes domestication. Insectivory provides comparable calorific and nutritional benefits to carnivory, but with different costs. Much insectivory in hominoids entails elementary technology used in extractive foraging, such as termite fishing by chimpanzees. Elucidating insectivory in the fossil and paleontological record is challenging, but at least nine avenues are available: remains, lithics, residues, DNA, coprolites, dental microwear, stable isotopes, osteology, and depictions. All are in play, but some have been more successful so far than others. [Copyright &y& Elsevier]

Abstract: Damage to the superior and/or inferior parietal lobules (SPL, IPL) (Sirigu et al., 1996) or cerebellum (Grealy and Lee, 2011) can selectively disrupt motor imagery, motivating the hypothesis that these regions participate in predictive (i.e., feedforward) control. If so, then the SPL, IPL, and cerebellum should show greater activity as the demands on feedforward control increase from visually-guided execution (closed-loop) to execution without visual feedback (open-loop) to motor imagery. Using fMRI and a Fitts' reciprocal aiming task with tools directed at targets in far space, we found that the SPL and cerebellum exhibited greater activity during closed-loop control. Conversely, open-loop and imagery conditions were associated with increased activity within the IPL and prefrontal areas. These results are consistent with a superior-to-inferior gradient in the representation of feedback-to-feedforward control within the posterior parietal cortex. Additionally, the anterior SPL displayed greater activity when aiming movements were performed with a stick vs. laser pointer. This may suggest that it is involved in the remapping of far into near (reachable) space (Maravita and Iriki, 2004), or in distalization of the end-effector from hand to stick (Arbib et al., 2009). [Copyright &y& Elsevier]

Humans and chimpanzees both exhibit a diverse set of tool use skills which suggests selection for tool manufacture and use occurred in the common ancestors of the two species. Our group has previously reported phenotypic and genetic associations between tool use skill and gray matter covariation, as quantified by source-based morphometry (SBM), in chimpanzees. As a follow up study, here we evaluated repeatability in heritability in SBM components and their phenotypic association with tool use skill in two genetically independent chimpanzee cohorts. Within the two independent cohorts of chimpanzees, we identified 8 and 16 SBM components, respectively. Significant heritability was evident for multiple SBM components within both cohorts. Further, phenotypic associations between tool use performance and the SBM components were largely consistent between the two cohorts; the most consistent finding being an association between tool use performance and an SBM component including the posterior superior temporal sulcus (STS) and superior temporal gyrus (STG), and the interior and superior parietal regions (p < 0.05). These findings indicate that the STS, STG, and parietal cortices are phenotypically and genetically implicated in chimpanzee tool use abilities. [ABSTRACT FROM AUTHOR]

Surfactants are commonly used in detergents, soaps and agrichemical products. After use, the residual surfactants can be dispersed into environmental compartments, directly or indirectly affecting aquatic and terrestrial organisms. Ants are one of the few insects that are able to make and use tools when foraging for liquid food. However, this unique behavior of ants may be greatly affected by environmental pollutants. Here, we hypothesized that surfactants have adversarial impacts on ant foraging behavior, and tested this hypothesis by investigating the effect of TWEEN 80 (a common nonionic surfactant) on the tool use behavior of black imported fire ants (Solenopsis richteri) when foraging for liquid food (sugar water). Natural pine needles and man-made sponges were provided as tools for ants. The results revealed increasing surfactant concentration induced ants to deposit more tools and caused a higher drowning rate of ants. S. richteri tended to deposit more pine needles and tools of smaller size when exposed to surfactant. Interactions between tool type and surfactant concentration showed significant effects on tool deposition and drowning rate of ants. Addition of surfactant into sugar water increased the drowning rate and reduced the foraging activity and food collection of ant workers, suggesting that surfactant in liquid food can affect the foraging efficiency of ants. However, availability of tools reduced drowning rate and increased sugar water collected compared to without tools. Our results demonstrated that ants can adjust their tool use strategies to manage the foraging risk caused by environmental surfactant, such as increasing the amount and selecting appropriate size of the tools and assembling tools of different structures. Therefore, long-term exposure to surfactants may alter foraging behavior of ants and contribute to evolve new foraging strategy. [Display omitted] • Surfactant in liquid food caused a higher drowning rate of Solenopsis richteri and induced ants to deposit more tools. • S. richteri deposited more pine needles and tools of smaller size with a higher drowning risk. • The effect of tool type and tool size on deposited tools by S. richteri is associated with the surfactant concentration. • Increasing surfactant concentration reduced the foraging activity and food collection of ant workers. [ABSTRACT FROM AUTHOR]

Primate studies have recently identified the dorsal stream as constituting multiple dissociable pathways associated with a range of specialized cognitive functions. To elucidate the nature and number of dorsal pathways in the human brain, the current study utilized in vivo probabilistic tractography to map the structural connectivity associated with subdivisions of the left supramarginal gyrus (SMG). The left SMG is a prominent region within the dorsal stream, which has recently been parcellated into five structurally-distinct regions which possess a dorsal-ventral (and rostral-caudal) organisation, postulated to reflect areas of functional specialisation. The connectivity patterns reveal a dissociation of the arcuate fasciculus into at least two segregated pathways connecting frontal-parietal-temporal regions. Specifically, the connectivity of the inferior SMG, implicated as an acoustic-motor speech interface, is carried by an inner/ventro-dorsal arc of fibres, whilst the pathways of the posterior superior SMG, implicated in object use and cognitive control, forms a parallel outer/dorso-dorsal crescent. [ABSTRACT FROM AUTHOR]

Highlights: [•] We dissect children’s observational learning of complex actions. [•] We use naturalistic video displays within a ‘Ghost’ control. [•] Witnessing mechanical information does not equate to witnessing a full display. [•] Witnessing displays focused on action styles does not lead to their imitation. [Copyright &y& Elsevier]

Highlights: [•] fMRI was used to determine brain activation in understanding tool manipulation. [•] Ventral but not dorsal areas were important for understanding incorrect tool use. [•] Ventral stream areas may code the functional relevance of action affordances. [Copyright &y& Elsevier]

Abstract: In this fMRI study we investigate neural processes related to the action observation network using a complex perceptual-motor task in pilots and non-pilots. The task involved landing a glider (using aileron, elevator, rudder, and dive brake) as close to a target as possible, passively observing a replay of one''s own previous trial, passively observing a replay of an expert''s trial, and a baseline do nothing condition. The objective of this study is to investigate two types of motor simulation processes used during observation of action: imitation based motor simulation and error-feedback based motor simulation. It has been proposed that the computational neurocircuitry of the cortex is well suited for unsupervised imitation based learning, whereas, the cerebellum is well suited for error-feedback based learning. Consistent with predictions, pilots (to a greater extent than non-pilots) showed significant differential activity when observing an expert landing the glider in brain regions involved with imitation based motor simulation (including premotor cortex PMC, inferior frontal gyrus IFG, anterior insula, parietal cortex, superior temporal gyrus, and middle temporal MT area) than when observing one''s own previous trial which showed significant differential activity in the cerebellum (only for pilots) thought to be concerned with error-feedback based motor simulation. While there was some differential brain activity for pilots in regions involved with both Execution and Observation of the flying task (potential Mirror System sites including IFG, PMC, superior parietal lobule) the majority was adjacent to these areas (Observation Only Sites) (predominantly in PMC, IFG, and inferior parietal loblule). These regions showing greater activity for observation than for action may be involved with processes related to motor-based representational transforms that are not necessary when actually carrying out the task. [Copyright &y& Elsevier]

Abstract: This study investigated cognitive processes underlying tool use and knowledge transfer in 24-month-olds (N =123). Following a demonstration, participants chose a tool to reach a reward in a training transfer paradigm. Differing from previous research, various aspects considered to be relevant for children’s performance were integrated within the same study design, and performance was examined on a trial-by-trial basis. More specifically, we analyzed how the following aspects affected toddlers’ learning and transfer performance: causal information, degree of conflict between perceptually salient and functionally relevant information, and feedback information. Children with access to causal information outperformed children without corresponding information during the training and transfer phases. Perceptual conflict had a negative impact on transfer performance. However, children were quickly able to correct their choices based on feedback. Results are discussed in the light of recent accounts on tool use understanding. [Copyright &y& Elsevier]

Abstract: Impaired tool related action in ideomotor apraxia is normally ascribed to loss of sensorimotor memories for habitual actions (engrams), but this account has not been tested against a hypothesis of a general deficit in representation of hand-object spatial relationships. Rapid reaching for familiar tools was compared with reaching for abstract objects in apraxic patients (N =9) and in a control group with right hemisphere posterior stroke. The apraxic patients alone showed an impairment in rotating the wrist to correctly grasp an inverted tool but not when inverting the hand to avoid a barrier and grasp an abstract object, and the severity of the impairment in tool reaching correlated with pantomime of tool-use. A second experiment with two apraxic patients tested whether barrier avoidance was simply less spatially demanding than reaching for a tool. However, the patient with damage limited to the inferior parietal lobe still showed a selective problem for tools. These results demonstrate that some apraxic patients are selectively impaired in their interaction with familiar tools, and this cannot be explained by the demands of the task on postural or spatial representation. However, traditional engram theory cannot account for associated problems with imitation of novel actions nor the absence of any correlated deficit in recognition of the methods of grasp of common tools. A revised theory is presented which follows the dorsal and ventral streams model (Milner & Goodale, 2008) and proposes preservation of motor control by the dorsal stream but impaired modulating input to it from the conceptual systems of the left temporal lobe. [Copyright &y& Elsevier]

Geographical variation in behaviour may be best explained in terms of culture if ecological and genetic explanations can be excluded. However, ecological conditions and genetic predispositions may in turn also affect cultural processes. We examined the influence of environmental factors on foraging tool use among chimpanzees at the Seringbara study site in the Nimba Mountains, Guinea, where nut cracking and termite fishing are absent, but ant dipping is present. We tested two ecological hypotheses to explain foraging tool use prevalence. The opportunity hypothesis states that encounter rates with nuts, insects or tools explain tool use patterns. We measured the density and distribution of nut trees, nuts, army ants, termites and potential tools in relation to the chimpanzees'' ranging patterns. The necessity hypothesis states that tool use is a response to scarcity of preferred foods (i.e. ripe fruit). We measured the temporal availability of nuts, army ants and termites in relation to preferred food sources. Our findings support the opportunity hypothesis: nut trees and Macrotermes mounds were rare and peripheral to the chimpanzees'' range, whereas army ants were abundant and widespread. The necessity hypothesis did not explain tool-assisted insectivory, as both army ants and termites were available during ripe fruit scarcity, yet neither ant dipping nor termite fishing functioned as fallback strategies. Nuts were absent at times of fruit scarcity and were not available as fallback foods. Our findings highlight the importance of considering environmental conditions in explaining foraging tool use by wild chimpanzees and emphasize the interplay between environment and culture. [Copyright &y& Elsevier]

Abstract: Despite a growing interest in the question of tool-use development in infants, no study so far has systematically investigated how learning to use a tool to retrieve an out-of-reach object progresses with age. This was the first aim of this study, in which 60 infants, aged 14, 16, 18, 20, and 22months, were presented with an attractive toy and a rake-like tool. There were five conditions of spatial relationships between the toy and the tool, going from the toy and tool being connected to there being a large spatial gap between them. A second aim of the study was to evaluate at what age infants who spontaneously fail the task can learn this complex skill by being given a demonstration from an adult. Results show that even some of the youngest infants could spontaneously retrieve the toy when it was presented inside and touching the top part of the tool. In contrast, in conditions with a spatial gap, the first spontaneous successes were observed at 18months, suggesting that a true understanding of the use of the tool has not been fully acquired before that age. Interestingly, it is also at 18months that infants began to benefit from the demonstration in the conditions with a spatial gap. The developmental steps for tool use observed here are discussed in terms of changes in infants’ ability to attend to more than one item in the environment. The work provides insight into the progressive understanding of tool use during infancy and into how observational learning improves with age. [Copyright &y& Elsevier]

To determine whether tool use varied in relation to food availability in bearded capuchin monkeys, we recorded anvil and stone hammer use in two sympatric wild groups, one of which was provisioned daily, and assessed climatic variables and availability of fruits, invertebrates and palm nuts. Capuchins used tools to crack open encased fruits, mostly palm nuts, throughout the year. Significant differences between wet and dry seasons were found in rainfall, abundance of invertebrates and palm nuts, but not in fruit abundance. Catulè nuts were more abundant in the dry season. We tested the predictions of the necessity hypothesis (according to which tool use is maintained by sustenance needs during resource scarcity) and of the opportunity hypothesis (according to which tool use is maintained by repeated exposure to appropriate ecological conditions, such as preferred food resources necessitating the use of tools). Our findings support only the opportunity hypothesis. The rate of tool use was not affected by provisioning, and the monthly rate of tool use was not correlated with the availability of fruits and invertebrates. Conversely, all capuchins cracked food items other than palm nuts (e.g. cashew nuts) when available, and adult males cracked nuts more in the dry season when catulè nuts (the most common and exploited nut) are especially abundant. Hence, in our field site capuchins use tools opportunistically. [ABSTRACT FROM AUTHOR]

Abstract: Much attention has been paid to geographic variation in chimpanzee behavior, but few studies have applied quantitative techniques to explain this variation. Here, we apply methods typically utilized in macroecology to explain variation in the putative cultural traits of chimpanzees. We analyzed published data containing 39 behavioral traits from nine chimpanzee communities. We used a canonical correspondence analysis to examine the relative importance of environmental characteristics and geography, which may be a proxy for inter-community gene flow and/or social transmission, for explaining geographic variation in chimpanzee behavior. We found that geography, and longitude in particular, was the best predictor of behavioral variation. Chimpanzee communities in close longitudinal proximity to each other exhibit similar behavioral repertoires, independent of local ecological factors. No ecological variables were significantly related to behavioral variation. These results support the idea that inter-community dispersal patterns have played a major role in structuring behavioral variation. We cannot be certain whether behavioral variation has a genetic basis, is the result of innovation and diffusion, or a combination of the two. [Copyright &y& Elsevier]

The use and manufacture of tools has been considered to be cognitively demanding and thus a possible evolutionary driving factor of intelligence. Animal tool use provides the opportunity to investigate whether the use of tools evolved in conjunction with enhanced physical cognitive abilities. However, success in physical tasks may simply reflect enhanced general learning abilities and not cognitive adaptations to tool use. To distinguish between these possibilities, we compared general learning and physical cognitive abilities between the tool-using woodpecker finch, Cactospiza pallida, and its close relative, the small tree finch, Camarhynchus parvulus. Since not all woodpecker finches use tools, we also compared tool-using and nontool-using individuals, predicting that domain-specific experience should lead tool-using woodpecker finches to outperform nontool-users in a task that is similar to their natural tool use. Contrary to our predictions, woodpecker finches did not outperform small tree finches in either of the physical tasks and excelled in only one of the general learning tasks, and tool-using woodpecker finches did not outperform nontool-using woodpecker finches in the physical task closely resembling tool use. Our results provide no evidence that tool use in woodpecker finches has evolved in conjunction with enhanced physical cognition or that domain-specific experience hones domain-specific skills. This is an important contribution to a growing body of evidence indicating that animal tool use, even that which seems complex, does not necessitate specialized cognitive adaptations. [ABSTRACT FROM AUTHOR]

Abstract: When planning grasping actions, right-handers show left-lateralized responses in the anterior intraparietal sulcus (aIPS) and ventral premotor cortex (vPMC), two areas that are also implicated in sensorimotor control of grasp. We investigated whether a similar cerebral asymmetry is evident in strongly left-handed individuals. Fourteen participants were trained to grasp an object appearing in a variety of orientations with their left and right hands and with a novel mechanical tool (operated with either hand). BOLD fMRI data were then acquired while they decided prospectively whether an over- or under-hand grip would be most comfortable for grasping the same stimulus set while remaining still. Behavioral performances were equivalent to those recorded previously in right-handers and indicated reliance on effector-specific internal representations. In left-handers, however, grip selection decisions for both sides (left, right) and effectors (hand, tool) were associated with bilateral increases in activity within aIPS and vPMC. A direct comparison between left- and right-handers did reveal equivalent increases in left vPMC regardless of hand dominance. By contrast, aIPS and right vPMC activity were dependent on handedness, showing greater activity in the motor-dominant hemisphere. Though showing bilateral increases in both left- and right-handers, greater increases in the motor dominant hemisphere were also detected in the caudal IPS (cIPS), superior parietal lobule (SPL) and dorsal premotor cortex (dPMC). These findings provide further evidence that regions involved in the sensorimotor control of grasp also participate in grasp planning, and that for certain areas hand dominance is a predictor of the cerebral organization of motor cognitive functions. [Copyright &y& Elsevier]

Are wild bearded capuchin monkeys selective about where they place nuts on anvils, specifically the anvil pits, during nut cracking? In the present study, we examined (1) whether capuchins’ preferences for particular pits are influenced by the effectiveness of the pit in cracking the nut and/or by the stability of the nut during striking, (2) how capuchins detect the affordances of novel pits and (3) the influence of social context on their selections. Anvil pits varied in horizontal dimension (small, medium and large) in experiment 1 and in depth (shallow, medium and deep) in experiment 2. In both experiments, three different pits were simultaneously presented, each on one anvil. We coded the capuchins’ actions with the nut in each pit, and recorded the outcome of each strike. In both experiments, capuchins preferred the most effective pit, but not the most stabilizing pit, based on the number of first strikes, total strikes and nuts cracked. Their choice also reflected where the preceding individual had last struck. The capuchins explored the pits indirectly, placing nuts in them and striking nuts with a stone. The preference for pits was weaker than the preference for nuts and stones shown previously with the same monkeys. Our findings suggest that detecting affordances of pits through indirect action is less precise than through direct action, and that social context may also influence selection. We show that field experiments can demonstrate embodied cognition in species-typical activities in natural environments. [Copyright &y& Elsevier]

Chimpanzees, Pan troglodytes, are the most sophisticated tool-users among all nonhuman primates. From an evolutionary perspective, it is therefore puzzling that the tool use behaviour of their closest living primate relative, the bonobo, Pan paniscus, has been described as particularly poor. However, only a small number of bonobo groups have been studied in the wild and only over comparably short periods. Here, we show that captive bonobos and chimpanzees are equally diverse tool-users in most contexts. Our observations illustrate that tool use in bonobos can be highly complex and no different from what has been described for chimpanzees. The only major difference in the chimpanzee and bonobo data was that bonobos of all age–sex classes used tools in a play context, a possible manifestation of their neotenous nature. We also found that female bonobos displayed a larger range of tool use behaviours than males, a pattern previously described for chimpanzees but not for other great apes. Our results are consistent with the hypothesis that the female-biased tool use evolved prior to the split between bonobos and chimpanzees. [ABSTRACT FROM AUTHOR]

Studies on advanced forms of tool use in birds have mainly been concentrated on corvids. In this study, captive kea, a neophilic New Zealand parrot species, produced different orders of spatial object relationships in a tube-lifting/object-inserting paradigm. Hence, we found that kea, which are neither natural tool users nor nest builders, could readily solve a second-order tool use task. They also learned to produce highly complicated means–means–end sequences in a short period of time. [ABSTRACT FROM AUTHOR]

Abstract: Tool use engages a left hemispheric network including frontal, temporal and parietal regions. Patients with left brain lesions (LBD patients) exhibit deficits when demonstrating use of a single tool (apraxia). When attempting to use a tool, some apraxic patients show errors in the preceding grasping movement. Forty-two LBD patients and 18 healthy controls grasped individual tools and demonstrated their typical use. For patients with a tool use impairment (22), lesion analysis revealed a large area of overlap in the left hemisphere, mainly in the supramarginal gyrus (SMG). For patients with erroneous grasping (12), the lesion overlay showed overlaps in the left frontal and parietal cortices, especially in the inferior frontal gyrus (IFG) and the angular gyrus (ANG). However, contrasting lesions associated with impaired grasping versus tool use impairments reveal little overlap, limited to the inferior parietal cortex. Presumably the left IFG is involved in selection processes in the context of tool use, such as choosing a functional or non-functional grasping movement depending on the task and the online information about the tool''s structure and orientation. The ANG might provide this grasp related information, which is relevant for the specific action. The contribution of the SMG to tool use involves more general principals, such as integrating online and learned tool use information into the action plan for the use movement. [Copyright &y& Elsevier]

Wild bearded capuchin monkeys, Cebus libidinosus, use stone tools to crack palm nuts to obtain the kernel. In five experiments, we gave 10 monkeys from one wild group of bearded capuchins a choice of two nuts differing in resistance and size and/or two manufactured stones of the same shape, volume and composition but different mass. Monkeys consistently selected the nut that was easier to crack and the heavier stone. When choosing between two stones differing in mass by a ratio of 1.3:1, monkeys frequently touched the stones or tapped them with their fingers or with a nut. They showed these behaviours more frequently before making their first selection of a stone than afterward. These results suggest that capuchins discriminate between nuts and between stones, selecting materials that allow them to crack nuts with fewer strikes, and generate exploratory behaviours to discriminate stones of varying mass. In the final experiment, humans effectively discriminated the mass of stones using the same tapping and handling behaviours as capuchins. Capuchins explore objects in ways that allow them to perceive invariant properties (e.g. mass) of objects, enabling selection of objects for specific uses. We predict that species that use tools will generate behaviours that reveal invariant properties of objects such as mass; species that do not use tools are less likely to explore objects in this way. The precision with which individuals can judge invariant properties may differ considerably, and this also should predict prevalence of tool use across species. [Copyright &y& Elsevier]

Abstract: The degree to which non-human primate behavior is lateralized, at either individual or population levels, remains controversial. We investigated the relationship between hand preference and posture during tool use in chimpanzees (Pan troglodytes) during bipedal tool use. We experimentally induced tool use in a supported bipedal posture, an unsupported bipedal posture, and a seated posture. Neither bipedal tool use nor these supported conditions have been previously evaluated in apes. The hypotheses tested were 1) bipedal posture will increase the strength of hand preference, and 2) a bipedal stance, without the use of one hand for support, will elicit a right hand preference. Results supported the first, but not the second hypothesis: bipedalism induced the subjects to become more lateralized, but not in any particular direction. Instead, it appears that subtle pre-existing lateral biases, to either the right or left, were emphasized with increasing postural demands. This result has interesting implications for theories of the evolution of tool use and bipedalism, as the combination of bipedalism and tool use may have helped drive extreme lateralization in modern humans, but cannot alone account for the preponderance of right-handedness. [Copyright &y& Elsevier]

Wild bearded capuchins, Cebus libidinosus, in Fazenda Boa Vista, Brazil crack tough palm nuts using hammer stones. We analysed the contribution of intrinsic factors (body weight, behaviour), size of the nuts and the anvil surface (flat or pit) to the efficiency of cracking. We provided capuchins with local palm nuts and a single hammer stone at an anvil. From video we scored the capuchins'' position and actions with the nut prior to each strike, and outcomes of each strike. The most efficient capuchin opened 15 nuts per 100 strikes (6.6 strikes per nut). The least efficient capuchin that succeeded in opening a nut opened 1.32 nuts per 100 strikes (more than 75 strikes per nut). Body weight and diameter of the nut best predicted whether a capuchin would crack a nut on a given strike. All the capuchins consistently placed nuts into pits. To provide an independent analysis of the effect of placing the nut into a pit, we filmed an adult human cracking nuts on the same anvil using the same stone. The human displaced the nut on proportionally fewer strikes when he placed it into a pit rather than on a flat surface. Thus the capuchins placed the nut in a more effective location on the anvil to crack it. Nut cracking as practised by bearded capuchins is a striking example of a plastic behaviour where costs and benefits vary enormously across individuals, and where efficiency requires years to attain. [Copyright &y& Elsevier]