Avian cognition: understanding tool use

Although rooks are considered non-tool-using animals, a recent study has shown that they learn to solve a 'trap-tube' task faster than many tool-using primates, raising questions about the evolution of sophisticated physical cognition.     

Snowball construction by a feral troop of Japanese macaques (Macaca fuscata) living under seminatural conditions

Feral Japanese macaques (Macaca fuscata) living under seminatural conditions in Oregon constructed several large snowballs in their two-acre corral. This behavior did not involve the basic reward systems connected with agonistic or feeding behavior which are most commonly associated with tool-using in nonhuman primates.     

Tool use in wild spider monkeys (<Emphasis Type="Italic">Ateles geoffroyi</Emphasis>)

Tool use has been observed in a variety of primate species, including both New and Old World monkeys. However, such reports mainly address the most prodigious tool users and frequently limit discussions of tool-using behavior to a foraging framework. Here, we present observations of novel and spontaneous tool use in wild black-handed spider monkeys (Ateles geoffroyi), where female spider monkeys used detached sticks in a self-directed manner. We introduce factors to explain Ateles tool-using abilities and limitations, and encourage the synthesis of relevant research in order to gain insight into the cognitive abilities of spider monkeys and the evolution of tool-using behaviors in primates.     

Intellectual activity during formation of quantitative concepts in the lower and higher monkeys

Results of study of formation of quantitative concepts in the lower and higher monkey are presented. Various authors used different methods of study of this issue. It has been established that not only the higher primates, such as chimpanzees and orangutans, but also the lower ones—macaques, capuchins, squirrel monkeys—have the “mathematical capabilities.” The detailed study of formation of quantitative concepts in primates of different levels of phylogenesis allows disclosing mechanisms of formation of this function in human.     

Use of a tool-set by capuchin monkeys (Cebus apella)

The purpose of this study was to examine the use of a tool-set by capuchin monkeys (Cebus apella). Capuchins were presented with an apparatus designed to accommodate the use of pounding tools to crack walnuts and the use of probing tools to loosen and extract the inner meat. Three capuchins used stones and sticks sequentially for these purposes. The capuchins' behavior was similar in form and function to behavior that has been reported for chimpanzees in analogous situations. These results provide further evidence of the extensive tool-using capabilities of capuchin monkeys and are consistent with a hypothesis of cross-species continuity in the skillful use of tools by primates.     

Do woodpecker finches acquire tool-use by social learning?

Tool-use is widespread among animals, but except in primates the development of this behaviour is poorly known. Here, we report on the first experimental study to our knowledge of the mechanisms underlying the acquisition of tool-use in a bird species. The woodpecker finch Cactospiza pallida, endemic to the Galápagos Islands, is a famous textbook example of tool-use in animals. This species uses modified twigs or cactus spines to pry arthropods out of tree holes. Using nestlings and adult birds from the field, we tested experimentally whether woodpecker finches learn tool-use socially. We show that social learning is not essential for the development of tool-use: all juveniles developed tool-use regardless of whether or not they had a tool-using model. However, we found that not all adult woodpecker finches used tools in our experiments. These non-tool-using individuals also did not learn this task by observing tool-using conspecifics. Our results suggest that tool-use behaviour depends on a very specific learning disposition that involves trial-and-error learning during a sensitive phase early in ontogeny.     

Comparative analysis of the prion protein (PrP) gene in cetacean species

The partial PrP gene sequence and the deduced protein of eight cetacean species, seven of which have never been reported so far, have been determined in order to extend knowledge of sequence variability of the PrP genes in different species and to aid in speculation on cetacean susceptibility to prions. Both the nucleotide and the deduced amino acid sequences have been analysed in comparison with some of the known mammalian PrPs. Cetacean PrPs present typical features of eutherian PrPs. The PrP gene from the species of the family Delphinidae gave identical nucleic acid sequences, while differences in the PrP gene were found in Balaenopteridae and Ziphidae. The phylogenetic tree resulting from analysis of the cetacean PrP gene sequences, together with reported sequences of some ungulates, carnivores and primates, showed that the PrP gene phylogenesis mirrors the species phylogenesis. The PrP gene of cetaceans is very close to species where natural forms of TSEs are known. From an analysis of the sequences and the phylogenesis of the PrP gene, susceptibility to or occurrence of prion diseases in cetaceans can not be excluded.     

The ecology of primate material culture

Tool use in extant primates may inform our understanding of the conditions that favoured the expansion of hominin technology and material culture. The ‘method of exclusion’ has, arguably, confirmed the presence of culture in wild animal populations by excluding ecological and genetic explanations for geographical variation in behaviour. However, this method neglects ecological influences on culture, which, ironically, may be critical for understanding technology and thus material culture. We review all the current evidence for the role of ecology in shaping material culture in three habitual tool-using non-human primates: chimpanzees, orangutans and capuchin monkeys. We show that environmental opportunity, rather than necessity, is the main driver. We argue that a better understanding of primate technology requires explicit investigation of the role of ecological conditions. We propose a model in which three sets of factors, namely environment, sociality and cognition, influence invention, transmission and retention of material culture.     

Critically endangered blonde capuchins fish for termites and use new techniques to accomplish the task

We report the spontaneous modification and use of sticks to fish for termites, above the ground, in wild blonde capuchins (Cebus flavius). These critically endangered Neotropical primates inhabit remnants of the Atlantic Forest. They used two previously undescribed techniques to enhance their termite capture success: nest tapping and stick rotation. The current ecologically based explanation for tool use in wild capuchins (i.e. terrestrial habits and bipedalism) must be viewed cautiously. Instead, remarkable manual skills linked to a varied diet seem important in promoting tool use in different contexts. The repertoire of tool-using techniques employed by wild capuchins has been expanded, highlighting the behavioural versatility in this genus.     

Cognitive abilities related to tool use in the woodpecker finch, Cactospiza pallida

Woodpecker finches are famous for their spontaneous tool use behaviour in the wild. They use twigs or cactus spines to pry arthropods out of crevices and use this ability more than any other tool-using species known. We experimentally investigated the cognitive abilities related to tool use. We chose three experimental designs that have been used to test several primate species (trap tube task and modification task) and New Caledonian crows (tool length task). One of six woodpecker finches was able to solve the trap tube task, and several individuals modified tools and chose twigs of appropriate length. Most subjects mastered these new tasks quickly, but we found no evidence that they were able to assess the problems in advance. These findings resemble those obtained for primates in these tasks.     

New perspectives in primate cognitive ecology

The papers in this issue are from a symposium presented at the 71st Annual Meeting of the American Association of Physical Anthropologists held in Buffalo, New York, in April 2002. In the light of recent theoretical and methodological advances and debates in the study of cognition, this symposium addressed questions concerning primate cognitive ecology and decision-making from a variety of perspectives. These include ontogenetic patterns of brain growth and learning, paleoecology and evolution, sensory adaptations, foraging strategies, tool-using behavior, and concepts derived from the study of human cognition, such as schemata, planning, and rehearsal of activities. In this issue, data are presented on New World monkeys, Old World monkeys, apes, and humans. It is argued that the ability to make decisions based on the recognition that tertiary relationships in one context can be used to understand cause-and-effect relationships in an unrelated context may enable nonhuman primates to effectively reduce uncertainty and solve problems in changing social and ecological environments.     

Object-use in free-ranging white-faced capuchins (Cebus capucinus) in Costa Rica

Chimpanzees and capuchins demonstrate greater varieties and higher rates of tool-use when compared to other non-human primates. Although capuchins have been studied extensively in captivity, data on their tool-using behavior under free-ranging conditions are limited. This is the first long-term field research to systematically study complex object manipulation in capuchins. The aims of this research are 1) to examine the types, rates, and contexts of tool- and object-use in free-ranging capuchins and 2) to determine if free-ranging capuchins' object manipulation behavior is comparable to the behavior exhibited by captive individuals. Data on 3 troops of white-faced capuchins (Cebus capucinus) were collected from February 1995 to January 1996 at Palo Verde, Costa Rica. Data were collected using focal animal and ad libitum sampling techniques. Any observed incident of tool-use and object-use was recorded. No tool-use was observed during the 11-month study. Object-use (pound, rub, and fulcrum-use) occurred at a rate of 0.19/hr and made up less than 1% of the monkeys' time (there were no differences among the age/sex classes). The results indicate that free-ranging capuchins do not exhibit the range of tool-using behavior demonstrated by their captive counterparts. This may be the result of differential motivational responses to objects, arboreal lifestyle, absence of adequate tool material, and/or absence of food resources that require extraction involving tool-use. Am J Phys Anthropol 106:311–321, 1998. © 1998 Wiley-Liss, Inc.     

Pestle use and modification by tufted capuchins (Cebus apella)

We examined the use and modification of pestles by tufted capuchins (Cebus apella). In each of two experiments we presented 18 subjects with an apparatus that held sugarcane along with materials that the animals could use as tools. In Experiment 1 we presented the subjects with sticks, and in Experiment 2 we presented them with sticks, stones, paper towels, and food biscuits. Seven subjects used sticks as pestles to break down fiber to and squeeze sap from sugarcane in Experiment 1. Five of them modified sticks for this purpose. In Experiment 2, 10 animals used pestles and sponges, combined tools, and used pestles to mix together different kinds of food. These results provide further evidence of functional convergence for the use and modification of tools byCebus andPan and are consistent with the view that extractive foraging is associated with the tool-using and toolmaking behavior of primates.     

Pestle-pounding behavior of wild chimpanzees at Bossou,Guinea: A newly observed tool-using behavior

A new type of tool-using behavior was observed in a group of wild chimpanzees (Pan troglodytes verus) at Bossou, Guinea. The chimpanzees used the leaf-petiole of oil-palm trees (Elaeis guineensis) as a pounding tool to deepen a hole in the oil-palm crown which appeared after the chimpanzees had pulled out the central young shoots. Finally, the chimpanzees extracted and ate the apical meristem or apical bud of the oil-palm tree which is edible but inaccessible without such tool use. The motor pattern which the chimpanzees employed is similar to that used for termite-nest digging but it is more exaggerated and requires great force. The behavior is reminiscent of pestlepounding. The chimpanzees exploit substantial amounts of food with this tool-using skill, compensating for insufficient fruit foods in the primary forest. This tool-using behavior was first observed in 1990 and, to date, almost half of the group members have been confirmed to use the pestle tool. It appears that this tool-using behavior was invented recently and has since spread widely throughout the group as a habitual one.     

Pestle use and modification by tufted capuchins (Cebus apella)

We examined the use and modification of pestles by tufted capuchins (Cebus apella). In each of two experiments we presented 18 subjects with an apparatus that held sugarcane along with materials that the animals could use as tools. In Experiment 1 we presented the subjects with sticks, and in Experiment 2 we presented them with sticks, stones, paper towels, and food biscuits. Seven subjects used sticks as pestles to break down fiber to and squeeze sap from sugarcane in Experiment 1. Five of them modified sticks for this purpose. In Experiment 2, 10 animals used pestles and sponges, combined tools, and used pestles to mix together different kinds of food. These results provide further evidence of functional convergence for the use and modification of tools byCebus andPan and are consistent with the view that extractive foraging is associated with the tool-using and toolmaking behavior of primates.     

The present state in the phylogeny and ontogeny of hormone receptors

Presence of signal receivers (for food, toxic, substances, "hostile" cells etc.) is essential at all levels of phylogenesis. The first encounter of a "hormone to be" with an aspecific membrane structure ("receptor to be") could result in the formation of a lasting receptor-hormone connection if it is adventageous for the cell or organism (which contains the cell), during phylogeny. At higher levels of phylogenesis receptors (ontogenetically) develop according to the differentiation program of the cell, however reinforcement (by the hormone) is necessary in a critical (neonatal) period of receptor development. This is the hormonal imprinting. In that time the receptor could be damaged by the presence of molecules analogous to the hormone. The hormonal imprinting belongs to the perinatal recognition mechanisms of organisms. The possible mechanisms of receptor development are also discussed.     

Transport of tools and mental representation: is capuchin monkey tool behaviour a useful model of Plio-Pleistocene hominid technology?

Capuchin monkeys display greatly developed tool-using capacities, performing successfully a variety of tool-tasks. Impressed by their achievements in this respect, some investigators have suggested that capuchin tool-using behaviour could be used as a model of the tool behaviour of the first hominids. The transport of tools, a task requiring complex cognitive capabilities, is an essential ingredient in the technological behaviour of the first hominids. In this way, to qualify as another source for modelling hominid behavioural evolution, capuchins had to exhibit proficiency in the transport of tools. We investigated this problem through experiments designed to elicit the transport of objects. The results showed that the monkeys were able to transport food to be processed with the use of tools, but failed when the tools themselves had to be transported. Our hypothesis is that a limited capacity for abstract representation, together with the lack of a regulatory system ensuring that the food would not be lost and consumed by another individual during the search for and transport of the tools, were responsible for such a failure. We conclude that the tool-using behaviour of capuchins presents no functional analogy with the tool behaviour of the Plio-Pleistocene hominids, and that capuchin monkeys are a very inadequate source for modelling Plio-Pleistocene hominid's technological behaviour.     

‘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.     

制作工具在人类演化中的地位与作用

制作工具曾经被视作人类独有的行为能力,"人类"曾经据此而定义。但目前学术界将直立行走作为人类区别于其他灵长类最重要的体质与行为特征。少量其他动物种类,尤其是非人高等灵长类,也能使用工具乃至简单制作工具。如何认识制作工具在人类演化中的作用?人类制作工具的能力与其他动物有何区别?考古学是否有能力分辨人类的工具和其他灵长类的产品?本文通过对现代巴西猴群敲砸石头的行为及其产品、4300年前黑猩猩的"石制品"和早期人类石制品的比较研究,指出人类的工具与其他动物制作和使用的工具存在根本的区别;工具制作和使用对确定人类的演化方向,增强人类的适应生存能力,塑造人类的大脑与心智及行为方式,提升语言和交流能力,形成现代人类的身心和社会,至关重要,不可或缺。考古工作者一方面需要谨慎分辨、研究人类工具制作初期的产品,不使其与自然的产物和其他动作的作品相混淆,另一方面应该认识到人类工具制作在计划性、目的性、预见性、规范性和精美度上具有唯一性,有内在的智能控制、思维逻辑和规律可循。学科发展的积累和现代科技的支撑使考古学者具有多方面的利器,能够把人类工具制作的历史挖掘、复原出来,能够破译特定的石器技术和功能,进而将人类演化的历史画卷描绘得更加精细,更加完整。     

Social organization of the Milne-Edward's potto

Nocturnal prosimian primates are often seen alone during their nocturnal activities, and are therefore categorized as "solitary". Recent research has shown that these animals actually possess social networks that differ among species. Here we present new information on one of the lesser studied prosimian primates, the potto, derived from fieldwork in Cameroon that employed radiotelemetry and behavioral observations. An analysis of association patterns and home-range overlaps between animals revealed that pottos associated more frequently with conspecifics than expected for a supposedly solitary primate. Certain males and females that were seen together regularly throughout the study, but were not observed to have contact with other pottos of the opposite sex, were labeled as "pairs". These pairs were found to have higher levels of association with each other than with other conspecifics. The only affiliative and sexual behaviors observed between members of the opposite sex occurred within the pairs of pottos. Although given the secretive nature of these primates, the possibility of extrapair copulations cannot be ruled out, their relatively small testis size indicates that sperm competition is not so important for this species.