Tool-use by chimpanzees (Pan t. troglodytes) in the Lopé Reserve,Gabon

During a long-term study of chimpanzees in the Lopé Reserve, Gabon, tool-use to obtain insects or their products was observed four times and on 23 other occasions tools made and used by chimpanzees were recovered. Of 144 tools used to obtain insects, 142 were made from woody material. Tools varied in dimensions and in the degree of modification (bark stripping and fraying of ends) but those used to obtain different prey species were generally similar and resembled tools described from other chimpanzee populations in central Africa. Use of a leaf “sponge” to obtain water from a hole in the branch of a tree was observed once. Four tool-use patterns shown by other chimpanzee populations appeared to be absent at Lopé as no direct or indirect evidence of their existence was obtained in ten years.     

Young children spontaneously invent wild great apes’ tool-use behaviours

The variety and complexity of human-made tools are unique in the animal kingdom. Research investigating why human tool use is special has focused on the role of social learning: while non-human great apes acquire tool-use behaviours mostly by individual (re-)inventions, modern humans use imitation and teaching to accumulate innovations over time. However, little is known about tool-use behaviours that humans can invent individually, i.e. without cultural knowledge. We presented 2- to 3.5-year-old children with 12 problem-solving tasks based on tool-use behaviours shown by great apes. Spontaneous tool use was observed in 11 tasks. Additionally, tasks which occurred more frequently in wild great apes were also solved more frequently by human children. Our results demonstrate great similarity in the spontaneous tool-use abilities of human children and great apes, indicating that the physical cognition underlying tool use shows large overlaps across the great ape species. This suggests that humans are neither born with special physical cognition skills, nor that these skills have degraded due to our species’ long reliance of social learning in the tool-use domain.     

If at first you don't succeed… Studies of ontogeny shed light on the cognitive demands of habitual tool use

Many species use tools, but the mechanisms underpinning the behaviour differ between species and even among individuals within species, depending on the variants performed. When considering tool use ‘as adaptation’, an important first step is to understand the contribution made by fixed phenotypes as compared to flexible mechanisms, for instance learning. Social learning of tool use is sometimes inferred based on variation between populations of the same species but this approach is questionable. Specifically, alternative explanations cannot be ruled out because population differences are also driven by genetic and/or environmental factors. To better understand the mechanisms underlying routine but non-universal (i.e. habitual) tool use, we suggest focusing on the ontogeny of tool use and individual variation within populations. For example, if tool-using competence emerges late during ontogeny and improves with practice or varies with exposure to social cues, then a role for learning can be inferred. Experimental studies help identify the cognitive and developmental mechanisms used when tools are used to solve problems. The mechanisms underlying the route to tool-use acquisition have important consequences for our understanding of the accumulation in technological skill complexity over the life course of an individual, across generations and over evolutionary time.     

Individual and social learning processes involved in the acquisition and generalization of tool use in macaques

Macaques can efficiently use several tools, but their capacity to discriminate the relevant physical features of a tool and the social factors contributing to their acquisition are still poorly explored. In a series of studies, we investigated macaques' ability to generalize the use of a stick as a tool to new objects having different physical features (study 1), or to new contexts, requiring them to adapt the previously learned motor strategy (study 2). We then assessed whether the observation of a skilled model might facilitate tool-use learning by naive observer monkeys (study 3). Results of study 1 and study 2 showed that monkeys trained to use a tool generalize this ability to tools of different shape and length, and learn to adapt their motor strategy to a new task. Study 3 demonstrated that observing a skilled model increases the observers' manipulations of a stick, thus facilitating the individual discovery of the relevant properties of this object as a tool. These findings support the view that in macaques, the motor system can be modified through tool use and that it has a limited capacity to adjust the learnt motor skills to a new context. Social factors, although important to facilitate the interaction with tools, are not crucial for tool-use learning.     

Sex differences in young children’s use of tools in a problem-solving task

Three-year-old children were observed in two free-play sessions and participated in a toy-retrieval task, in which only one of six tools could be used to retrieve an out-of-reach toy. Boys engaged in more object-oriented play than girls and were more likely to use tools to retrieve the toy during the baseline tool-use task. All children who did not retrieve the toy during the baseline trials did so after being given a hint, and performance on a transfer-of-training tool-use task approached ceiling levels. This suggests that the sex difference in tool use observed during the baseline phase does not reflect a difference in competency, but rather a sex difference in motivation to interact with objects. Amount of time boys, but not girls, spent in object-oriented play during the free-play sessions predicted performance on the tool-use task. The findings are interpreted in terms of evolutionary theory, consistent with the idea that boys’ and girls’ play styles evolved to prepare them for adult life in traditional environments.     

Sex differences in the stone tool-use behavior of a wild population of burmese long-tailed macaques (Macaca fascicularis aurea)

We investigated sex differences in how Burmese long-tailed macaques (Macaca fascicularis aurea) used stone tools to open shelled food items along the shores of two islands in Laemson National Park, Thailand. Over a 2-week period in December 2009, we collected scan and focal samples on macaques when they were visible along the shores and mangroves. We found females used stones more often while feeding and used smaller tools than males. Females also processed sessile oysters more than males, whereas males processed unattached foods more than females. It was unclear which sex was overall more proficient at stone tool use, but males did perform significantly better at opening unattached food items with large pounding stones. Females also struck food items more times during tool-use bouts and at a faster rate, but no significant difference was found in average tool-use bout duration. Males processed foods slightly faster within a tool-use bout, but we were unable to detect a significant difference in the rate of food processing while foraging with tools. In summary females chipped open sessile oysters with an axing technique more than males, while males used larger stones to pound open unattached shelled food more often than females. Despite using pounding more than females, males also regularly utilized the axing technique on sessile oysters. Our results are the first assessment of sex differences in macaque stone tool use, providing a basis for comparison with tool use in other primates, and to nonfunctional forms of stone use in other macaques.     

Tool use by aquatic animals

Tool-use research has focused primarily on land-based animals, with less consideration given to aquatic animals and the environmental challenges and conditions they face. Here, we review aquatic tool use and examine the contributing ecological, physiological, cognitive and social factors. Tool use among aquatic animals is rare but taxonomically diverse, occurring in fish, cephalopods, mammals, crabs, urchins and possibly gastropods. While additional research is required, the scarcity of tool use can likely be attributable to the characteristics of aquatic habitats, which are generally not conducive to tool use. Nonetheless, studying tool use by aquatic animals provides insights into the conditions that promote and inhibit tool-use behaviour across biomes. Like land-based tool users, aquatic animals tend to find tools on the substrate and use tools during foraging. However, unlike on land, tool users in water often use other animals (and their products) and water itself as a tool. Among sea otters and dolphins, the two aquatic tool users studied in greatest detail, some individuals specialize in tool use, which is vertically socially transmitted possibly because of their long dependency periods. In all, the contrasts between aquatic- and land-based tool users enlighten our understanding of the adaptive value of tool-use behaviour.     

Tool use by wild cebus monkeys at Santa Rosa National Park,Costa Rica

Although wild cebus monkeys have been observed to use tools, this behavior has been reported only rarely. No one has systematically examined tool use in wildCebus, and it is not known how prevalent tool use is in the species' natural repertoire. During 300 hr of observation on 21 wild capuchins (Cebus capucinus imitator) at Santa Rosa National Park in Costa Rica, 31 incidents of tool use, including eight different types of tool-use behavior, were observed. These observations indicate that tool use is a notable behavior pattern in this troop. Considering these incidents of tool use in conjunction with other reports on complex food-getting and preparation behavior byCebus suggests that tool use is a manifestation ofCebus' high behavioral adaptability. Since onlyCebus and the great apes (especially chimpanzees) have been observed to show such a diverse tool-use repertoire, to use tools so frequently, or to show such complex food-getting behavior in the wild, these observations also support the notion thatCebus and the great apes have followed a parallel evolutionary development of tool-using capacity.     

动物使用工具行为研究进展北大核心CSCD

使用工具曾被认为是人类独有的能力,然而,在过去的50年中,学界逐渐认识到工具的使用普遍存在于整个动物界。其中,使用工具最多的类群是哺乳类、鸟类和昆虫。动物使用工具有一定目标性,然而大多数动物仅考虑当前的目标,而非长远目标。动物使用工具的行为受到环境因素和动物自身认知能力、生理特点与进化历史的影响,并可能表现出一定的个体差异。有些动物使用工具的行为是与生俱来的,然而大部分高等动物通过试错学习获得使用工具的能力。通过模仿学习,一些使用工具的行为可以传播和演化,从而在种群中广泛分布。工具的使用是动物认知领域的核心概念之一,开展动物使用工具的研究,能够加深对动物认知能力和行为进化的理解。     

Object affordances tune observers' prior expectations about tool-use behaviors

Learning about the function and use of tools through observation requires the ability to exploit one's own knowledge derived from past experience. It also depends on the detection of low-level local cues that are rooted in the tool's perceptual properties. Best known as 'affordances', these cues generate biomechanical priors that constrain the number of possible motor acts that are likely to be performed on tools. The contribution of these biomechanical priors to the learning of tool-use behaviors is well supported. However, it is not yet clear if, and how, affordances interact with higher-order expectations that are generated from past experience--i.e. probabilistic exposure--to enable observational learning of tool use. To address this question we designed an action observation task in which participants were required to infer, under various conditions of visual uncertainty, the intentions of a demonstrator performing tool-use behaviors. Both the probability of observing the demonstrator achieving a particular tool function and the biomechanical optimality of the observed movement were varied. We demonstrate that biomechanical priors modulate the extent to which participants' predictions are influenced by probabilistically-induced prior expectations. Biomechanical and probabilistic priors have a cumulative effect when they 'converge' (in the case of a probabilistic bias assigned to optimal behaviors), or a mutually inhibitory effect when they actively 'diverge' (in the case of probabilistic bias assigned to suboptimal behaviors).     

Distribution of potential suitable hammers and transport of hammer tools and nuts by wild capuchin monkeys

Selection and transport of objects to use as tools at a distant site are considered to reflect planning. Ancestral humans transported tools and tool-making materials as well as food items. Wild chimpanzees also transport selected hammer tools and nuts to anvil sites. To date, we had no other examples of selection and transport of stone tools among wild nonhuman primates. Wild bearded capuchins (Cebus libidinosus) in Boa Vista (Piauí, Brazil) routinely crack open palm nuts and other physically well-protected foods on level surfaces (anvils) using stones (hammers) as percussive tools. Here we present indirect evidence, obtained by a transect census, that stones suitable for use as hammers are rare (study 1) and behavioral evidence of hammer transport by twelve capuchins (study 2). To crack palm nuts, adults transported heavier and harder stones than to crack other less resistant food items. These findings show that wild capuchin monkeys selectively transport stones of appropriate size and hardness to use as hammers, thus exhibiting, like chimpanzees and humans, planning in tool-use activities.     

Tool use, communicative gesture and cerebral asymmetries in the modern human brain

Determining the brain adaptations that underlie complex tool-use skills is an important component in understanding the physiological bases of human material culture. It is argued here that the ways in which humans skilfully use tools and other manipulable artefacts is possible owing to adaptations that integrate sensory-motor and cognitive processes. Data from brain-injured patients and functional neuroimaging studies suggest that the left cerebral hemisphere, particularly the left parietal cortex, of modern humans is specialized for this purpose. This brain area integrates dynamically representations that are computed in a distributed network of regions, several of which are also left-lateralized. Depending on the nature of the task, these may include conceptual knowledge about objects and their functions, the actor's goals and intentions, and interpretations of task demands. The result is the formation of a praxis representation that is appropriate for the prevailing task context. Recent evidence is presented that this network is organized similarly in the right- and left-handed individuals, and participates in the representation of both familiar tool-use skills and communicative gestures. This shared brain mechanism may reflect common origins of the human specializations for complex tool use and language.     

Tool-use and tool-making by captive, group-living orangutans (Pongo pygmaeus abelii) at an artificial termite mound

The present study examined the use and making of tools to obtain foodstuffs in artificial-mound holes by five captive, group-living Sumatran orangutans (Pongo pygmaeus abelii). Three adult orangutans frequently stripped leaves and twigs from a branch provided (tool-making), and then inserted the tool into a hole to obtain foodstuffs (tool-using). A 5-year-old female juvenile usually used the tools that adult orangutans had previously used, but rarely made tools herself. A 2-year-old male infant did not use any tools. The adult orangutans tend to leave one to several leaves at the top of the branch than to leave many leaves on the branch or to strip all leaves. It seemed likely that tools with appropriate leaves are easier to insert into holes and obtain more foodstuffs, compared with branches with many leaves or sticks without any leaves. When the orangutans were unable to insert a tool into a hole, they usually modified the tool and/or changed their tool-using technique, such as changing how they grasped the tool. These findings are discussed from the perspectives of the orangutan's behavioral flexibility regarding tool-use skills and hierarchical organization in food-processing techniques.     

The evolutionary origins and ecological context of tool use in New Caledonian crows

New Caledonian (NC) crows Corvus moneduloides are the most prolific avian tool users. In the wild, they use at least three distinct tool types to extract invertebrate prey from deadwood and vegetation, with some of their tools requiring complex manufacture, modification and/or deployment. Experiments with captive-bred, hand-raised NC crows have demonstrated that the species has a strong genetic predisposition for basic tool use and manufacture, suggesting that this behaviour is an evolved adaptation. This view is supported by recent stable-isotope analyses of the diets of wild crows, which revealed that tool use provides access to highly profitable hidden prey, with preliminary data indicating that parents preferentially feed their offspring with tool-derived food. Building on this work, our review examines the possible evolutionary origins of these birds’ remarkable tool-use behaviour. Whilst robust comparative analyses are impossible, given the phylogenetic rarity of animal tool use, our examination of a wide range of circumstantial evidence enables a first attempt at reconstructing a plausible evolutionary scenario. We suggest that a common ancestor of NC crows, originating from a (probably) non-tool-using South-East Asian or Australasian crow population, colonised New Caledonia after its last emersion several million years ago. The presence of profitable but out-of-reach food, in combination with a lack of direct competition for these resources, resulted in a vacant woodpecker-like niche. Crows may have possessed certain behavioural and/or morphological features upon their arrival that predisposed them to express tool-use rather than specialised prey-excavation behaviour, although it is possible that woodpecker-like foraging preceded tool use. Low levels of predation risk may have further facilitated tool-use behaviour, by allowing greater expenditure of time and energy on object interaction and exploration, as well as the evolution of a ‘slow’ life-history, in which prolonged juvenile development enables acquisition of complex behaviours. Intriguingly, humans may well have influenced the evolution of at least some of the species’ tool-oriented behaviours, via their possible introduction of candlenut trees together with the beetle larvae that infest them. Research on NC crows’ tool-use behaviour in its full ecological context is still in its infancy, and we expect that, as more evidence accumulates, some of our assumptions and predictions will be proved wrong. However, it is clear from our analysis of existing work, and the development of some original ideas, that the unusual evolutionary trajectory of NC crows is probably the consequence of an intricate constellation of interplaying factors.     

Tool-use to obtain honey by chimpanzees at Bulindi: new record from Uganda

Honey-gathering from bee nests has been recorded at chimpanzee (Pan troglodytes) study sites across tropical Africa. Different populations employ different strategies, ranging from simple ‘smash-and grab’ raids to use of sophisticated tool-sets, i.e., two or more types of tool used sequentially in a single task. In this paper I present evidence of tool-use, and the probable use of a tool-set, for honey-gathering by unhabituated chimpanzees at Bulindi, a forest–farm mosaic south of the Budongo Forest in Uganda. Between June and December 2007, 44 stick tools were found in association with 16 holes dug in the ground, corresponding to the period when stingless bees (Meliponula sp.) appeared in chimpanzee dung. In 11 cases the confirmed target was a Meliponula ground nest. Two potential tool types were distinguished: digging sticks encrusted with soil, and more slender and/or flexible sticks largely devoid of soil that may have functioned to probe the bees’ narrow entry tubes. Reports of chimpanzees using tools to dig for honey have been largely confined to Central Africa. Honey-digging has not previously been reported for Ugandan chimpanzees. Similarly, use of a tool-set to obtain honey has thus far been described for wild chimpanzee populations only in Central Africa. Evidence strongly suggests that Bulindi chimpanzees also use sticks in predation on carpenter bee (Xylocopa sp.) nests, perhaps as probes to locate honey or to disable adult bees. These preliminary findings from Bulindi add to our understanding of chimpanzee technological and cultural variation. However, unprotected forests at Bulindi and elsewhere in the region are currently severely threatened by commercial logging and clearance for farming. Populations with potentially unique behavioral and technological repertoires are being lost.     

An unusual instance of tool-use among wild orang-utans in tanjung puting reserve,indonesian borneo

Despite several recent orang-utan (Pongo pygmaeus) field studies in Borneo and Sumatra, tool-use has never been reported among wild orang-utan populations in contexts other than agonistic displays or nesting/covering behaviors. During a continuous 9-year study at Tanjung Puting Reserve, Central Indonesian Borneo, only one instance of wild orang-utan tool-use outside these two contexts was observed: an adult male orang-utan broke off a dead branch and used it to scratch his rear for half a minute.     

Tool-use for drinking water by immature chimpanzees of Mahale: prevalence of an unessential behavior

Use of leaves or sticks for drinking water has only rarely been observed during long-term study of wild chimpanzees (Pan troglodytes schweinfurthii) at Mahale. Recently, however, we observed 42 episodes of tool-use for drinking water (73 tools and two cases of using tool-sets) between 1999 and 2004. Interestingly, all of the performers were immature chimpanzees aged from 2 to 10 years. Immature chimpanzees sometimes observed the tool-using performance of others and subsequently reproduced the behavior, while adults usually paid no attention to the performance. This tool-use did not seem to occur out of necessity: (1) chimpanzees often used tools along streams where they could drink water without tools, (2) they used tools for drinking water from tree holes during the wet season when they could easily obtain water from many streams, and (3) the tool-using performance sometimes contained playful aspects. Between-site comparisons revealed that chimpanzees at drier habitats used tools for drinking water more frequently and in a more conventional manner. However, some variations could not be explained by ecological conditions. Such variations and the increase in this tool-use in recent years at Mahale strongly suggest that social learning plays an important role in the process of acquiring the behavior. We should note here that such behaviors that lack obvious benefits or necessity can be prevalent in a group.     

Tool use, aye-ayes, and sensorimotor intelligence

Humans, chimpanzees, capuchins and aye-ayes all display an unusually high degree of encephalization and diverse omnivorous extractive foraging. It has been suggested that the high degree of encephalization in aye-ayes may be the result of their diverse, omnivorous extractive foraging behaviors. In combination with certain forms of tool use, omnivorous extractive foraging has been hypothesized to be linked to higher levels of sensorimotor intelligence (stages 5 or 6). Although free-ranging aye-ayes have not been observed to use tools directly in the context of their extractive foraging activities, they have recently been reported to use lianas as tools in a manner that independently suggests that they may possess stage 5 or 6 sensorimotor intelligence. Although other primate species which display diverse, omnivorous extractive foraging have been tested for sensorimotor intelligence, aye-ayes have not. We report a test of captive aye-ayes' comprehension of tool use in a situation designed to simulate natural conditions. The results support the view that aye-ayes do not achieve stage 6 comprehension of tool use, but rather may use trial-and-error learning to develop tool-use behaviors. Other theories for aye-aye encephalization are considered.     

Wild Capuchins Show Male-Biased Feeding Tool Use

Relatively few studies have explored sex differences in the use of foraging tools among primates other than apes. Although male primates are thought to be more innovative, researchers have reported a female sex bias in the use of feeding tools in wild chimpanzees. We investigate here the nature and extent of sex differences in foraging tool use over 12 mo in a free-ranging group of bearded capuchins (2 males, 5 females, and 3 juveniles) living in the dry Caatinga forests of the Serra da Capivara National Park, Piaui, Brazil. These capuchins used 3 major types of feeding tools: 1) tools for probing; 2) tools for pounding/cracking; and 3) digging stones to extract tubers or roots. Adult males performed 63% (n = 134) of all events of tool use and used tools significantly more frequently than did females, although male bout lengths across all tools (57 s ± 7.9 SE) were equivalent to those of adult females (47.3 s ± 12.6 SE). Both sexes used digging and cracking tools, although at different rates, whereas adult males used sticks to probe for prey and other rewards far more than females. Differential opportunities to use tools were not apparent: >71% of tool-use events occurred on the ground, and males and females spent equal time on the ground. We suggest that sex differences in tool use may function as opportunities for male signaling of investment quality.     

‘Captivity bias’ in animal tool use and its implications for the evolution of hominin technology

Animals in captive or laboratory settings may outperform wild animals of the same species in both frequency and diversity of tool use, a phenomenon here termed ‘captivity bias’. Although speculative at this stage, a logical conclusion from this concept is that animals whose tool-use behaviour is observed solely under natural conditions may be judged cognitively or physically inferior than if they had also been tested or observed under controlled captive conditions. In turn, this situation creates a potential problem for studies of the behaviour of extinct members of the human family tree—the hominins—as hominin cognitive abilities are often judged on material evidence of tool-use behaviour left in the archaeological record. In this review, potential factors contributing to captivity bias in primates (including increased contact between individuals engaged in tool use, guidance or shaping of tool-use behaviour by other tool-users and increased free time and energy) are identified and assessed for their possible effects on the behaviour of the Late Pleistocene hominin Homo floresiensis. The captivity bias concept provides one way to uncouple hominin tool use from cognition, by considering hominins as subject to the same adaptive influences as other tool-using animals.