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This review highlights the scientific advances concerning the origins of human right‐handedness and language (speech and gestures). The comparative approach we adopted provides evidence that research on human and non‐human animals’ behavioural asymmetries helps understand the processes that lead to the strong human left‐hemisphere specialisation. We review four major non‐mutually exclusive environmental factors that are likely to have shaped the evolution of human and non‐human primates’ manual asymmetry: socioecological lifestyle, postural characteristics, task‐level complexity and tool use. We hypothesise the following scenario for the evolutionary origins of human right‐handedness: the right‐direction of modern humans’ manual laterality would have emerged from our ecological (terrestrial) and social (multilevel system) lifestyle; then, it would have been strengthened by the gradual adoption of the bipedal stance associated with bipedal locomotion, and the increasing level of complexity of our daily tasks including bimanual coordinated actions and tool use. Although hemispheric functional lateralisation has been shaped through evolution, reports indicate that many factors and their mutual intertwinement can modulate human and non‐human primates’ manual laterality throughout their life cycle: genetic and environmental factors, mainly individual sociodemographic characteristics (e.g., age, sex and rank), behavioural characteristics (e.g., gesture per se and gestural sensory modality) and context‐related characteristics (e.g., emotional context and position of target). These environmental (evolutionary and life cycle) factors could also have influenced primates’ manual asymmetry indirectly through epigenetic modifications. All these findings led us to propose the hypothesis of a multicausal origin of human right‐handedness.     

Patterns of lateralized hand use in an arboreal primate, Simias concolor

Studies of hand use in nonhuman primates suggest that several species exhibit hand preferences for a variety of tasks. The majority of studies, however, focus on the lateralized hand use of captive nonhuman primate populations. Although captive settings offer a more controlled environment for assessing hand preferences, studies of wild populations provide important insights into how handedness is affected by natural environmental conditions and thus potential insights into the evolution of handedness. To investigate handedness in a population of wild nonhuman primates, we studied patterns of lateralized hand use during feeding in four simakobu monkeys (Simias concolor), an arboreal species inhabiting the Mentawai Islands, Indonesia. Our data show that individual variation in hand preferences for feeding existed among our study animals. In addition, each simakobu expressed a significant hand preference for supporting itself on a branch during feeding, an uncoordinated bimanual task. This bias was most prevalent when the branch used for support was a main branch rather than a terminal branch. When both hands were employed in a coordinated bimanual feeding activity (bimanual manipulation), only two subjects showed a significant bias for feeding. Our data suggest that these individuals are more likely to express significant hand preferences when feeding from stable, rather than precarious, positions within the canopy.     

Laterality in hand use across four tool-use behaviors among the wild chimpanzees of Bossou, Guinea, West Africa

Population-level right handedness is a human universal, whose evolutionary origins are the source of considerable empirical and theoretical debate. Although our closest neighbor, the chimpanzee, shows some evidence for population-level handedness in captivity, there is little evidence from the wild. Tool-use measures of hand use in chimpanzees have yielded a great deal of variation in directionality and strength in hand preference, which still remains largely unexplored and unexplained. Data on five measures of hand use across four tool-use skills--ant-dipping, algae-scooping, pestle-pounding and nut-cracking--among the wild chimpanzees of Bossou, Guinea, West Africa, are presented here. This study aims to explore age- and sex-class effects, as well as the influence of task motor, cognitive and haptic demands, on the strength and directionality of hand preference within and across all five measures of hand use. Although there was no age- or sex-class effect on the directionality of hand preference, immature 相似文献   

Influence of the task on hand preference: individual differences among gorillas (Gorilla gorilla gorilla)

The degree of task complexity and bimanual complementarity have been proposed as factors affecting lateralization strength in humans. However, a large number of studies have demonstrated group-level lateral hand bias for different manual activities in numerous non-human primate species. However, no study has tested the effects that a variety of tasks may have in inducing differences in hand preference. Here, we aim to test if 3 adult gorillas exhibited a greater hand preference bias performing 4 tasks of varying complexity: grasping small versus large foods, proto-tool use task and tool use task involving greater visuospatial requirements. We found that (1) the complexity of the task does not necessarily induce a right-handed bias and (2) a subject can be right-handed for a complex task and left-handed for another one. These results, complemented by many publications on hand preference in non-human primates, reveal a great variability in hand preference, which makes it very difficult to deduce any details of hominin handedness with artefacts.     

Tool behavior and the origins of laterality

The cerebral cortex of modern humans is exceptional in that it is characterized by certain functional asymmetries for which no clear homologue is known in the non-human primates. These asymmetries consist at least in part in the presence in the left cerebral hemisphere of certain mechanisms which mediate language as well as skilled manual activity. Right-handedness is the most obvious overt manifestation of this cerebral asymmetry. It is argued in this paper that the lateralized representation of these mechanisms is an evolutionary consequence of the requirement for asymmetric employment of the forelimbs in the making and using of tools during hominid evolution. The adaptiveness of such an asymmetric arrangement is shown to follow from a few assumptions pertaining to brain organization and evolution. The colateralization of language mechanisms in modern humans to the left hemisphere is held to be a consequence of the coupling of these linguistic mechanisms to the motoric mechanisms already lateralized to the left hemisphere at an earlier point in hominid evolution. Finally, it is argued that this explanation of the evolution of laterality is more parsimonious in relation to known facts about human evolution than competing hypotheses.     

Does the Complexity of the Task Influence Manual Laterality in De Brazza’s Monkeys (Cercopithecus neglectus)?

We assessed the manual preferences of 12 De Brazza's monkeys ( Cercopithecus neglectus ) in spontaneous feeding situations and in two different coordinated bimanual tasks that were not visually guided. We recorded the hand used by each subject for 22 spontaneous activities, hand and digits use while extracting peanut butter from a hollow tube (tube task) and the hand used to extract candies from hanging plastic balls (ball task). Spontaneous activities revealed individual manual preferences but no population-level biases. For both experimental tasks, all subjects were lateralized in their hand use. We found a left bias at the group level for the tube task, but no group-level asymmetry for the ball task. Experimental tasks induced greater strength of laterality than did spontaneous activities. Although the size of our sample did not allow us to draw any conclusions concerning manual preference at the population level, this study stresses the importance of coordinated bimanual tasks to reveal manual laterality in non-human primates.     

Detection of early secretory antigenic target-6 antibody for diagnosis of tuberculosis in non-human primates

Tuberculosis is one of the most economically devastating, zoonotic infections of captive non-human primates. The limitations of the tuberculin skin test, which is currently used to diagnose tuberculosis in living non-human primates, make it necessary to find new, simple, and economical diagnostic methods. We describe use of an enzyme-linked immunoassay to detect IgG antibodies against early secretory antigenic target (ESAT)-6, a small protein secreted by virulent tubercle bacilli, in paired (pre- and post-outbreak) sera from 57 non-human primates involved in an outbreak of Mycobacterium bovis infection in a research colony. Of 25 animals with tuberculosis lesions at necropsy, 22 (88%) had high serum levels of the ESAT-6 antibody. The ESAT-6 antibody was found in 16% (5/32) of post-outbreak sera from animals in which tuberculosis could not be confirmed at necropsy. The strong association between the ESAT-6 antibody and tuberculosis in non-human primates documented in this study, together with the robustness of the serologic assay, make the ESAT-6 ELISA a valuable tool for diagnosis of tuberculosis in captive non-human primates.     

Human handedness: an ethological perspective

Human handedness is thought to be unique and universal. Critical examination of primary sources challenges both of these conclusions. Data on laterality of function in apes, humankind’s closest living relations, indicates hand preference and task specialization, but not yet handedness, as crucial studies remain to be done. Ethnographic data across cultures reveal more variance than is usually acknowledged, but existing findings are based on minimal and limited data. Ethological studies of spontaneous behavior in every day life are needed for both human and non-human primates.     

Directional asymmetry in the forelimb of Macaca mulatta

Asymmetry was investigated in the forelimbs of 150 rhesus monkey (Macaca mulatta) skeletons using measurements of right and left humerii, radii, ulnae, second metacarpals, and femora. Seven of the ten forelimb dimensions were larger on the right than on the left side. Paired t-tests revealed that the mean of the right side was significantly larger than that for the left for two measurements of the ulna and two of the humerus. No measurement was significantly larger on the left than on the right side. These results indicate a small but significant asymmetry in the forelimb bones of rhesus monkeys and, as is the case for humans, the direction of asymmetry favors the right side. Our findings are consistent with an interpretation of hypertrophy of certain muscles and opens the question of whether rhesus monkeys preferentially use their right forelimbs for manipulative tasks that require manual dexterity, as is the case for humans. These forelimb skeletal asymmetries are discussed in light of the recent literature on cortical asymmetry and handedness in nonhuman primates.     

Hierarchical grouping analysis and skeletal materials

The technique of hierarchical grouping analysis is examined with respect to its use as a tool in grouping skeletal remains, utilizing both continuous and certain types of discontinuous anthropometric variables. The method is found to be useful when tested with Amerind skeletal materials at the micro-evolutionary level, and as a technique for sexual differentiation within human and non-human primate populations. The application of this form of cluster analysis to dental data is examined.     

Cortical activations in humans grasp-related areas depend on hand used and handedness

Background

In non-human primates grasp-related sensorimotor transformations are accomplished in a circuit involving the anterior intraparietal sulcus (area AIP) and both the ventral and the dorsal sectors of the premotor cortex (vPMC and dPMC, respectively). Although a human homologue of such a circuit has been identified whether activity within this circuit varies depending on handedness has yet to be investigated.

Methodology/Principal Findings

We used functional magnetic resonance imaging (fMRI) to explicitly test how handedness modulates activity within human grasping-related brain areas. Right- and left-handers subjects were requested to reach towards and grasp an object with either the right or the left hand using a precision grip while scanned. A kinematic study was conducted with similar procedures as a behavioral counterpart for the fMRI experiment. Results from a factorial design revealed significant activity within the right dPMC, the right cerebellum and AIP bilaterally. The pattern of activity within these areas mirrored the results found for the behavioral study.

Conclusion/Significance

Data are discussed in terms of an handedness-independent role for the right dPMC in monitoring hand shaping, the need for bilateral AIP activity for the performance of precision grip movements which varies depending on handedness and the involvement of the cerebellum in terms of its connections with AIP. These results provide the first compelling evidence of specific grasping related neural activity depending on handedness.     

Perspectives on object manipulation and action grammar for percussive actions in primates

The skill of object manipulation is a common feature of primates including humans, although there are species-typical patterns of manipulation. Object manipulation can be used as a comparative scale of cognitive development, focusing on its complexity. Nut cracking in chimpanzees has the highest hierarchical complexity of tool use reported in non-human primates. An analysis of the patterns of object manipulation in naive chimpanzees after nut-cracking demonstrations revealed the cause of difficulties in learning nut-cracking behaviour. Various types of behaviours exhibited within a nut-cracking context can be examined in terms of the application of problem-solving strategies, focusing on their basis in causal understanding or insightful intentionality. Captive chimpanzees also exhibit complex forms of combinatory manipulation, which is the precursor of tool use. A new notation system of object manipulation was invented to assess grammatical rules in manipulative actions. The notation system of action grammar enabled direct comparisons to be made between primates including humans in a variety of object-manipulation tasks, including percussive-tool use.     

Bipedal tool use strengthens chimpanzee hand preferences

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.     

Sex and asymmetry in humans: what is the role of developmental instability?

Because asymmetric individuals are less attractive and may suffer from reduced fitness, bilateral asymmetry is widely believed to affect human sexual selection. Its evolutionary significance is based on the presumed relationship with developmental instability (DI). Yet, relationships between DI and bilateral asymmetry are often weak and possibly confounded by asymmetric mechanical loadings because of handedness. We related asymmetry in hands and faces to degrees of handedness and sexual behaviour in 100 humans. Handedness correlated to levels of asymmetry, thereby likely invalidating the use of asymmetry to estimate DI. For facial asymmetry, applying existing theoretical models refuted a link between asymmetry and DI. Explicit statistical modelling at the level of DI confirmed the absence of a link between DI and aspects of sexual behaviour. Nevertheless, asymmetries in both hands and face correlated significantly with sexual behaviour. We conclude that bilateral asymmetry per se, rather than its presumed link with DI, more likely relates to measures of human sexual behaviour. Because lateralization of behaviour appears widespread, evaluating the role of DI in evolution and ecology relies on a very critical selection of traits whose asymmetry can reliably reflect DI.     

Are right- and left-handedness relevant as general categories in a non-industrialized country?

Whether right- and left-handedness are defined as a function of individual tasks or represent general categories across tasks has been long debated. However, the literature on handedness primarily concerns industrialized societies in which manual work has been extensively automated, and the majority of individuals in those countries do not use their arms and hands intensively for highly specialized tasks on an everyday basis. Thus, the question remains whether results from those countries regarding handedness are transferable to countries where the majority of individuals are still exploiting their lateralized skills. Here, we sampled 506 individuals from 143 locations on the islands of Flores and Adonara, Indonesia, to assess their hand preference for and hand performance on several tasks in order to evaluate, in a non-industrialized country, the level of manual specialization and the relevance of right- or left-handedness as general categories. Generalized-declared handedness was consistent with task-declared handedness across 10 specific tasks and with a measure of strength and a measure of skilfulness, suggesting that general handedness is a valid concept. This hand specialization for tasks is discussed in the context of intense and daily tool use in this agricultural society.     

Lateralized tool use in wild New Caledonian crows

Many vertebrate species exhibit sensory and motor asymmetries. Laterality studies of tool use have focused on primates, where hemispheric asymmetries, manifested behaviourally in hand preferences, are thought to be associated with complex motor tasks. Here we report strong individual lateralization for tool use in birds. New Caledonian crows, Corvus moneduloides, hold stick tools with their bills while foraging, often with the nonworking end laterally positioned on one side of the head and the working end possibly positioned in the binocular field. We observed four wild crows to determine whether tools were consistently held on one side. All crows showed a significant preference (two right, two left). This preference was independent of any asymmetry in tool manufacture and held for artificial holes similarly accessible for tools held on either side. This is the first demonstration of lateralized tool use in a nonprimate. In addition, all 173 tools used unilaterally were held only on a crow's preferred side. Such pronounced individual laterality for tool use in natural conditions has previously been reported only in humans and chimpanzees.     

Bone Growth Dynamics of the Facial Skeleton and Mandible in <Emphasis Type="Italic">Gorilla gorilla</Emphasis> and <Emphasis Type="Italic">Pan troglodytes</Emphasis>

Adult craniofacial morphology results from complex processes that involve growth by bone modelling and interactions of skeletal components to keep a functional and structural balance. Previous analyses of growth dynamics in humans revealed critical changes during late ontogeny explaining particular morphological features in our species. Data on bone modelling patterns from other primate species could help us to determine whether postnatal changes in the growth dynamics of the craniofacial complex are human specific or are shared with other primates. However, characterizations of bone modelling patterns through ontogeny in non-human hominids are scarce and restricted to isolated data on facial and mandibular regions. In the present study, we analyse the bone modelling patterns in an ontogenetic series of Pan and Gorilla to infer the growth dynamics of their craniofacial complex during postnatal development. Our results show that both Pan troglodytes and Gorilla gorilla are characterized by species-specific bone modelling patterns indicative of a mainly forward growth direction during postnatal development. Both species show minor but consistent ontogenetic changes in the distribution of bone modelling fields in specific regions of the face and mandible, in contrast to other regions which show more constant bone modelling patterns. In addition, we carry out a preliminary integrative study merging histological and geometric morphometric data. Both approaches yield highly complementary data, each analysis providing details on specific growth dynamics unavailable to the other. Moreover, geometric morphometric data show that ontogenetic variation in the modelling pattern of the mandibular ramus may be linked to sexual dimorphism.     

非人灵长类声音通讯的研究进展

声音通讯是非人灵长类研究一个重要的研究领域,有助于了解非人灵长类的社会行为、个体关系、行为进化和社会演化等,甚至对探究人类语言起源和进化等方面也具有十分重要的意义。本文通过对非人灵长类声音通讯的研究内容、影响因素和研究方法等进行了梳理,探讨非人灵长类声音通讯研究的前景和展望,旨在进一步推动国内非人灵长类声音通讯研究的深入,同时为相关研究提供借鉴和参考。     

The neural origins and implications of imitation, mirror neurons and tool use

Several recent studies report how laboratory-raised, non-human primates exposed to tool use can exhibit intelligent behaviors, such as imitation and reference vocal control, that are never seen in their wild counterparts. Tool-use training appears to forge a novel cortico-cortical connection that underlies this boost in capacity, which normally exists only as latent potential in lower primates. Although tool-use training is patently non-naturalistic, its marked effects on brain organization and behavior could shed light on the evolution of higher intelligence in humans.