鸦科鸟类认知研究回顾

动物认知能力高低及认知在动物中的进化是动物研究领域面对的难题之一。鸦科鸟类在工具使用、情景记忆、抑制控制等方面有着与类人猿媲美的优异表现。本文对过去三四十年间主要的鸦科鸟类认知研究进行了分类与汇总,并将上述认知研究划分为一般认知、物理认知、社会认知等三类。一般认知能力或者称为认知基础,是指具有普遍性的能力因素,是在解决不同问题时都能表现出来的相同的心理特质;物理认知指个体对自然规律的认知,主要包括客体永久性、数能力、工具的使用等;社会认知主要指个体对其他个体的心理状态、行为动机和意向作出推测与判断的过程。本文介绍了上述三类认知能力的主要研究范式,旨在为国内动物认知研究提供理论依据。目前的研究更多地集中于鸦属的鸟类,对于鸦科中其他鸟类或是雀形目中其他鸟类的认知研究尚不充足。此外,鸦科鸟类的社会性、分布范围、觅食策略等生态因素具有显著差异,在后续的研究中,我们应该关注生态因素对鸦科鸟类认知能力的影响,或是结合鸦科鸟类的生境及习性设计出更加合理的研究范式。     

动物发声学习研究进展

发声学习在人类语言形成中起着重要作用。非人类动物中,鸟类最早被发现具有发声学习能力。近年来在少数哺乳动物中也发现了这种现象,人们希望通过对不同动物类群发声学习的比较研究来揭示人类语言的起源。同时,由于鸟类和哺乳类的发声学习能够简化和缩短声信号的遗传过程,更快引起发声行为的进化,对其配偶选择、生态适应等具有重要意义,因此,发声学习也是行为生态学和进化生物学长期以来的研究热点。本文概述了鸟类和哺乳类发声学习的研究进展;归纳总结了动物发声学习的起源和维持机制;在分析研究现状的基础上,提出了未来的研究重点;旨在提高人们对动物发声学习研究进展的认知,以期对未来的研究提供帮助。     

鸟类的认知行为（1）

很多动物与人类一样拥有非凡的"聪明才智"。虽然鸟类与人类的亲缘关系较远,但却与人类共享许多认知特征。研究鸟类的认知行为,有助于理解动物具有什么样的能力,并更好地理解"智慧"的运作和演化。本文从工具使用、心理时间旅行、因果推理、类别认知、语言能力及认知特征演化方面,综述了鸟类认知行为研究的最新成果,探讨了认知演化的可能原因。     

鸟类的认知行为（2）

很多动物与人类一样拥有非凡的"聪明才智"。虽然鸟类与人类的亲缘关系较远,但却与人类共享许多认知特征。研究鸟类的认知行为,有助于理解动物具有什么样的能力,并更好地理解"智慧"的运作和演化。本文从工具使用、心理时间旅行、因果推理、类别认知、语言能力及认知特征演化方面,综述了鸟类认知行为研究的最新成果,探讨了认知演化的可能原因。     

动物的文化行为

动物的文化行为(cultural behaviour)是指通过非遗传的方法把信息从一个世代传给另一世代的行为。文化行为与进化过程不同,进化过程必须借助于自然选择才能发生,而文化行为是不遗传的。可见,动物适应其生存环境可以通过体质的进化(遗传进化),也可以通过学习特定的技能(不遗传)。学会的技能不能借助于遗传传递给后代,但却可以通过印记     

肠道微生物与认知功能

近年来大量研究表明肠道微生物的改变与认知行为之间存在明显的相关性。通过无菌动物、细菌感染以及益生菌或抗生素干预等方式改变宿主的肠道菌群,可以调节宿主的认知行为,包括学习和记忆能力。应激和饮食结构的变化也会改变宿主的肠道微生物,进而影响宿主行为。同时在胃肠道疾病和某些非肠道疾病状态下也会伴随着宿主认知行为的改变。本研究将重点讨论在人类和动物研究中发现的肠道微生物多样性的改变如何影响大脑功能和认知行为。     

文化的起源——动物文化的普遍性与人类文化的独特性

在很长一段时间里文化被认为是人类文明的产物.该文提供了许多关于动物文化现象的证据,并且提供了动物创新和社会学习能力的观察与实证研究的结果,用以说明文化在动物中存在的可能性.然而,人类文化与动物文化存在着明显差异,造成这种结果的原因可能主要是两者认知能力的差异:人类特殊的认知模式--文化认知造就了人类复杂的文化体系.     

基于贮食行为的鸟类社会认知研究进展

贮食是动物应对环境变化和不可预测性而进化出的有效生存对策,认知则是当前鸟类学研究的热点问题之一。目前鸟类贮食行为中的认知研究多集中在空间认知,而社会认知研究相对滞后。对于贮食物种而言,储藏食物被盗现象非常普遍,为了避免被盗食,贮食者不仅要有发达的空间认知能力去记忆贮食地点,同时还需要极强的社会认知能力处理与盗食者的关系,可见社会认知在鸟类的贮食行为中扮演着重要角色。本文将从鸟类贮食的社会关系认知以及社会地位认知两个方面,对鸟类贮食行为中的社会认知研究进行综述,以期为后续鸟类社会认知研究提供借鉴和参考。     

动物界的爱因斯坦

一只野生猩猩准确地抓住延伸到河边的树藤,然后用树枝做成的长矛来刺捕河中的鱼,最近在印度尼西亚婆罗洲发生的这匪夷所思的一幕,有幸被科学家发现,并用相机捕捉了那精彩的瞬间。动物会制造和使用工具,是不是太奇妙了,即便它们的作品如同爱因斯坦的小板凳一样简单和粗糙。长时间以来,工具的制造和使用一度被认为是人类区别于其他动物的特征,然而,随着科学家的一系列发现,高傲的人类逐渐意识到,这种高级认知能力或许也存在于动物界。     

人类脑容量的演变及其影响因素

人类脑容量演变的趋势总体为"两头缓慢,中间迅速"的S型曲线式发展,人类脑容量的迅速扩张起始于"能人"时期,而经"智人"后,其发展渐趋平缓。脑容量的扩增在一定程度上促进了人类智力和认知能力的提升,其演变受到了包括基因和行为等多种因素的共同调节,诸如基因进化、工具的制造和使用、劳动、语言文字的形成、食性的转变等,这些都对人类脑容量的演变起到了至关重要的推动作用。     

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.     

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.     

Tool-use training in a species of rodent: the emergence of an optimal motor strategy and functional understanding

Background

Tool use is defined as the manipulation of an inanimate object to change the position or form of a separate object. The expansion of cognitive niches and tool-use capabilities probably stimulated each other in hominid evolution. To understand the causes of cognitive expansion in humans, we need to know the behavioral and neural basis of tool use. Although a wide range of animals exhibit tool use in nature, most studies have focused on primates and birds on behavioral or psychological levels and did not directly address questions of which neural modifications contributed to the emergence of tool use. To investigate such questions, an animal model suitable for cellular and molecular manipulations is needed.

Methodology/Principal Findings

We demonstrated for the first time that rodents can be trained to use tools. Through a step-by-step training procedure, we trained degus (Octodon degus) to use a rake-like tool with their forelimbs to retrieve otherwise out-of-reach rewards. Eventually, they mastered effective use of the tool, moving it in an elegant trajectory. After the degus were well trained, probe tests that examined whether they showed functional understanding of the tool were performed. Degus did not hesitate to use tools of different size, colors, and shapes, but were reluctant to use the tool with a raised nonfunctional blade. Thus, degus understood the functional and physical properties of the tool after extensive training.

Conclusions/Significance

Our findings suggest that tool use is not a specific faculty resulting from higher intelligence, but is a specific combination of more general cognitive faculties. Studying the brains and behaviors of trained rodents can provide insights into how higher cognitive functions might be broken down into more general faculties, and also what cellular and molecular mechanisms are involved in the emergence of such cognitive functions.     

Social Network Analysis Shows Direct Evidence for Social Transmission of Tool Use in Wild Chimpanzees

Social network analysis methods have made it possible to test whether novel behaviors in animals spread through individual or social learning. To date, however, social network analysis of wild populations has been limited to static models that cannot precisely reflect the dynamics of learning, for instance, the impact of multiple observations across time. Here, we present a novel dynamic version of network analysis that is capable of capturing temporal aspects of acquisition—that is, how successive observations by an individual influence its acquisition of the novel behavior. We apply this model to studying the spread of two novel tool-use variants, “moss-sponging” and “leaf-sponge re-use,” in the Sonso chimpanzee community of Budongo Forest, Uganda. Chimpanzees are widely considered the most “cultural” of all animal species, with 39 behaviors suspected as socially acquired, most of them in the domain of tool-use. The cultural hypothesis is supported by experimental data from captive chimpanzees and a range of observational data. However, for wild groups, there is still no direct experimental evidence for social learning, nor has there been any direct observation of social diffusion of behavioral innovations. Here, we tested both a static and a dynamic network model and found strong evidence that diffusion patterns of moss-sponging, but not leaf-sponge re-use, were significantly better explained by social than individual learning. The most conservative estimate of social transmission accounted for 85% of observed events, with an estimated 15-fold increase in learning rate for each time a novice observed an informed individual moss-sponging. We conclude that group-specific behavioral variants in wild chimpanzees can be socially learned, adding to the evidence that this prerequisite for culture originated in a common ancestor of great apes and humans, long before the advent of modern humans.     

‘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.     

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).     

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.     

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.     

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.     

Setting tool use within the context of animal construction behaviour

Tool use and manufacture are given prominence by their rarity and suggested relation to human lineage. Here, we question the view that tool use is rare because cognitive abilities act as an evolutionary constraint and suggest that tools are actually seldom very useful compared with anatomical adaptations. Furthermore, we argue that focussing on animal tool use primarily in terms of human evolution can lead to important insights regarding the ecological and cognitive abilities of non-human tool users being overlooked. We argue that such oversight can best be avoided by examining tools within the wider context of construction behaviours by animals (such as nest building and trap construction).