Variation in pedagogy affects overimitation in children and adolescents.

Children are strong imitators, which sometimes leads to overimitation of causally unnecessary actions. Here, we tested whether learning from a peer decreases this tendency. First, 65 7- to 10-year-old children performed the Hook task (i.e., retrieve a reward from a jar with tools) with child or adult demonstrators. The overimitation rate was lower after watching a peer versus an adult. Second, we tested whether experiencing peer-to-peer learning versus adult-driven learning (i.e., Montessori or traditional pedagogy) affected overimitation. Here, 66 4- to 18-year-old children and adolescents performed the Hook task with adult demonstrators only. Montessori-schooled children had a lower propensity to overimitate. These findings emphasize the importance of the teaching model across the school years. Whereas peer models favor selective imitation, adult models encourage overimitation.

In search of animal normativity: a framework for studying social norms in non-human animals.

Social norms - rules governing which behaviours are deemed appropriate or inappropriate within a given community - are typically taken to be uniquely human. Recently, this position has been challenged by a number of philosophers, cognitive scientists, and ethologists, who have suggested that social norms may also be found in certain non-human animal communities. Such claims have elicited considerable scepticism from norm cognition researchers, who doubt that any non-human animals possess the psychological capacities necessary for normative cognition. However, there is little agreement among these researchers about what these psychological prerequisites are. This makes empirical study of animal social norms difficult, since it is not clear what we are looking for and thus what should count as behavioural evidence for the presence (or absence) of social norms in animals. To break this impasse, we offer an approach that moves beyond contested psychological criteria for social norms. This approach is inspired by the animal culture research program, which has made a similar shift away from heavily psychological definitions of 'culture' to become organised around a cluster of more empirically tractable concepts of culture. Here, we propose an analogous set of constructs built around the core notion of a normative regularity, which we define as a socially maintained pattern of behavioural conformity within a community. We suggest methods for studying potential normative regularities in wild and captive primates. We also discuss the broader scientific and philosophical implications of this research program with respect to questions of human uniqueness, animal welfare and conservation.

Habitual ground nesting in the Bugoma Forest chimpanzees (Pan troglodytes schweinfurthii), Uganda.

We report the presence of habitual ground nesting in a newly studied East African chimpanzee (Pan troglodytes schweinfurthii) population in the Bugoma Central Forest Reserve, Uganda. Across a 2-year period, we encountered 891 night nests, 189 of which were classified as ground nests, a rate of ~21%. We find no preliminary evidence of socio-ecological factors that would promote its use and highlight local factors, such as high incidence of forest disturbance due to poaching and logging, which appear to make its use disadvantageous. While further study is required to establish whether this behavior meets the strict criteria for nonhuman animal culture, we support the argument that the wider use of population and group-specific behavioral repertoires in flagship species, such as chimpanzees, offers a tool to promote the urgent conservation action needed to protect threatened ecosystems, including the Bugoma forest.

Frontal mechanisms underlying primate calls recognition by humans.

Introduction: The ability to process verbal language seems unique to humans and relies not only on semantics but on other forms of communication such as affective vocalizations, that we share with other primate species-particularly great apes (Hominidae). Methods: To better understand these processes at the behavioral and brain level, we asked human participants to categorize vocalizations of four primate species including human, great apes (chimpanzee and bonobo), and monkey (rhesus macaque) during MRI acquisition. Results: Classification was above chance level for all species but bonobo vocalizations. Imaging analyses were computed using a participant-specific, trial-by-trial fitted probability categorization value in a model-based style of data analysis. Model-based analyses revealed the implication of the bilateral orbitofrontal cortex and inferior frontal gyrus pars triangularis (IFGtri) respectively correlating and anti-correlating with the fitted probability of accurate species classification. Further conjunction analyses revealed enhanced activity in a sub-area of the left IFGtri specifically for the accurate classification of chimpanzee calls compared to human voices. Discussion: Our data-that are controlled for acoustic variability between species-therefore reveal distinct frontal mechanisms that shed light on how the human brain evolved to process vocal signals.

Decay rates of arboreal and terrestrial nests of Eastern chimpanzees (Pan troglodytes schweinfurthii) in the Bugoma Central Forest Reserve, Uganda: Implications for population size estimates.

Chimpanzees were once thought to sleep primarily in the trees, but recent studies indicate that some populations also construct terrestrial night nests. This behavior has relevance not only to understanding the behavioral diversity of Pan troglodytes, but also to the conservation of the species, given that nest encounter rates are often used to estimate great ape population densities. A proper estimate of decay rates for ground nests is necessary for converting the encounter rate of nests to the density of weaned chimpanzees. Here we present the results of the first systematic comparative study between the decay rates of arboreal and terrestrial chimpanzee nests, from the Bugoma Central Forest Reserve in western Uganda. We followed the decay of 56 ground and 51 tree nests in eight nest groups between April 2020 and October 2021. For 15 of the ground and 19 of the tree nests, we collected detailed information on the condition of the nests every two weeks; we checked the remaining 73 nests only twice. On average, ground nests lasted 238 days versus 276 days for tree nests (p = 0.05). Of the 107 total nests surveyed, 51% of tree and 64% of ground nests had disappeared after six months. Based on our results, we propose a modification of the formula used to convert nest density into chimpanzee density. Our results highlight the importance of taking into account potential differences in decay rates between ground versus tree nests, which will likely influence our understanding of the distribution of ground nesting behavior in chimpanzee across tropical Africa, as well as our estimations of the densities of ground nesting populations.

A multicomponent approach to studying cultural propensities during foraging in the wild.

Determining the cultural propensities or cultural behaviours of a species during foraging entails an investigation of underlying drivers and motivations. In this article, we propose a multicomponent approach involving behaviour, ecology, and physiology to accelerate the study of cultural propensities in the wild. We propose as the first component the use of field experiments that simulate natural contexts, such as foraging behaviours and tool use opportunities, to explore social learning and cultural tendencies in a variety of species. To further accelerate this component, we discuss and advocate for the use of modern machine learning video analysis tools. In conjunction, we examine non-invasive methods to measure ecological influences on foraging such as phenology, fruit availability, dietary intake; and physiological influences such as stress, protein balance, energetics, and metabolism. We feature non-invasive urine sampling to investigate urea, creatinine, ketone bodies, the thyroid hormone triiodothyronine (T3), cortisol and connecting peptides of insulin. To conclude, we highlight the benefits of combining ecological and physiological conditions with behavioural field experiments. This can be done across wild species, and provides the framework needed to test ecological hypotheses related to cultural behaviour.

Cerebral Activity in Female Baboons (Papio anubis) During the Perception of Conspecific and Heterospecific Agonistic Vocalizations: a Functional Near Infrared Spectroscopy Study.

The "voice areas" in the superior temporal cortex have been identified in both humans and non-human primates as selective to conspecific vocalizations only (i.e., expressed by members of our own species), suggesting its old evolutionary roots across the primate lineage. With respect to non-human primate species, it remains unclear whether the listening of vocal emotions from conspecifics leads to similar or different cerebral activations when compared to heterospecific calls (i.e., expressed by another primate species) triggered by the same emotion. Using a neuroimaging technique rarely employed in monkeys so far, functional Near Infrared Spectroscopy, the present study investigated in three lightly anesthetized female baboons (Papio anubis), temporal cortex activities during exposure to agonistic vocalizations from conspecifics and from other primates (chimpanzees-Pan troglodytes), and energy matched white noises in order to control for this low-level acoustic feature. Permutation test analyses on the extracted OxyHemoglobin signal revealed great inter-individual differences on how conspecific and heterospecific vocal stimuli were processed in baboon brains with a cortical response recorded either in the right or the left temporal cortex. No difference was found between emotional vocalizations and their energy-matched white noises. Despite the phylogenetic gap between Homo sapiens and African monkeys, modern humans and baboons both showed a highly heterogeneous brain process for the perception of vocal and emotional stimuli. The results of this study do not exclude that old evolutionary mechanisms for vocal emotional processing may be shared and inherited from our common ancestor. Supplementary Information: The online version contains supplementary material available at 10.1007/s42761-022-00164-z.

The ABC of social learning: Affect, behavior, and cognition.

Debates concerning social learning in the behavioral and the developmental cognitive sciences have largely ignored the literature on social influence in the affective sciences despite having arguably the same object of study. We argue that this is a mistake and that no complete model of social learning can exclude an affective aspect. In addition, we argue that including affect can advance the somewhat stagnant debates concerning the unique characteristics of social learning in humans compared to other animals. We first review the two major bodies of literature in nonhuman animals and human development, highlighting the fact that the former has adopted a behavioral approach while the latter has adopted a cognitive approach, leading to irreconcilable differences. We then introduce a novel framework, affective social learning (ASL), that studies the way we learn about value(s). We show that all three approaches are complementary and focus, respectively, on behavior toward; cognitions concerning; and feelings about objects, events, and people in our environment. All three thus contribute to an affective, behavioral, and cognitive (ABC) story of knowledge transmission: the ABC of social learning. In particular, ASL can provide the backbone of an integrative approach to social learning. We argue that this novel perspective on social learning can allow both evolutionary continuity and ontogenetic development by lowering the cognitive thresholds that appear often too complex for other species and nonverbal infants. Yet, it can also explain some of the major achievements only found in human cultures. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Carry-over effects of tool functionality and previous unsuccessfulness increase overimitation in children.

Children 'overimitate' causally irrelevant actions in experiments where both irrelevant and relevant actions involve a single common tool. This study design may make it harder for children to recognize the irrelevant actions, as the perceived functionality of the tool during the demonstration of the relevant action may be carried over to the irrelevant action, potentially increasing overimitation. Moreover, little is known how overimitation is affected by the demonstrator's expressed emotions and the child's prior success with the task. Here, 131 nine- to ten-year-old French and German children first engaged in a tool-based task, being successful or unsuccessful, and then watched an adult demonstrating the solution involving one irrelevant and one relevant action before smiling or remaining neutral. These actions were performed with the same tool or with two separate tools, testing potential carry-over effects of the functionality of the relevant action on the irrelevant action. We show that overimitation was higher when the same tool was used for both actions and when children were previously unsuccessful, but was not affected by the demonstrator's displayed emotion. Our results suggest that future overimitation research should account for the number of tools used in a demonstration and participants' previous task experience.

Validating the use of functional Near-Infrared Spectroscopy in monkeys: The case of brain activation lateralization in Papio anubis.

Hemispheric asymmetries have long been seen as characterizing the human brain; yet, an increasing number of reports suggest the presence of such brain asymmetries in our closest primate relatives. However, most available data in non-human primates have so far been acquired as part of neurostructural approaches such as MRI, while comparative data in humans are often dynamically acquired as part of neurofunctional studies. In the present exploratory study in baboons (Papio anubis), we tested whether brain lateralization could be recorded non-invasively using a functional Near-Infrared Spectroscopy (fNIRS) device in two contexts: motor and auditory passive stimulations. Under light propofol anaesthesia monitoring, three adult female baboons were exposed to a series of (1) left- versus right-arm passive movement stimulations; and (2) left- versus right-ear versus stereo auditory stimulations while recording fNIRS signals in the related brain areas (i.e., motor central sulcus and superior temporal cortices respectively). For the sensorimotor condition our results show that left-arm versus right-arm stimulations induced typical contralateral difference in hemispheric activation asymmetries in the three subjects. For the auditory condition, we also revealed typical human-like patterns of hemispheric asymmetries in one subject, namely a leftward lateralization for right ear stimulations for all three channels. Overall, our findings support the use of fNIRS to investigate brain processing in non-human primates from a functional perspective, opening the way for the development of non-invasive procedures in non-human primate brain research.

Selecting between iron-rich and clay-rich soils: a geophagy field experiment with black-and-white colobus monkeys in the Budongo Forest Reserve, Uganda.

Geophagy, the intentional consumption of soil, has been observed in humans and numerous other animal species. Geophagy has been posited to be adaptive, i.e., consumed soil protects against gastrointestinal distress and/or supplements micronutrients. We conducted a field experiment in the Budongo Forest, Uganda, to investigate geophagic behaviors, including soil preference, the quantity of soil eaten, and competition for access to preferred soils. We placed pairs of artificial tree stumps at two existing geophagy sites. One stump contained soil from the surrounding area, Sonso, that could supplement bioavailable iron. The other stump contained soil from a neighboring community, Waibira, that was richer in clay minerals, which could provide protection from plant secondary compounds. We monitored activity and engagement with the stumps for 10 days using camera traps. After 5 days, we reversed the type of soil that was in the stumps at both sites (i.e., a crossover design). Only Colobus guereza (black-and-white colobus monkeys) interacted with the stumps. These monkeys used visual and olfactory cues to select between the two soils and exclusively ate the clay-rich soil, consuming 9.67 kg of soil over 4.33 h. Our findings lend the greatest plausibility to the protection hypothesis. Additionally, monkeys competed for access to the stumps, and 13% of the videos captured aggression, including pushing, excluding, and chasing other individuals from the experimental stumps. Nine episodes of vigilance and flight behavior were also observed. Given that intentionally ingested soil is a valuable resource that may confer health benefits, geophagy sites should be conserved and protected.

A cognitive approach to cumulative technological culture is useful and necessary but only if it also applies to other species.

The debate on cumulative technological culture (CTC) is dominated by social-learning discussions, at the expense of other cognitive processes, leading to flawed circular arguments. I welcome the authors' approach to decouple CTC from social-learning processes without minimizing their impact. Yet, this model will only be informative to understand the evolution of CTC if tested in other cultural species.

Human Discrimination and Categorization of Emotions in Voices: A Functional Near-Infrared Spectroscopy (fNIRS) Study.

Functional Near-Infrared spectroscopy (fNIRS) is a neuroimaging tool that has been recently used in a variety of cognitive paradigms. Yet, it remains unclear whether fNIRS is suitable to study complex cognitive processes such as categorization or discrimination. Previously, functional imaging has suggested a role of both inferior frontal cortices in attentive decoding and cognitive evaluation of emotional cues in human vocalizations. Here, we extended paradigms used in functional magnetic resonance imaging (fMRI) to investigate the suitability of fNIRS to study frontal lateralization of human emotion vocalization processing during explicit and implicit categorization and discrimination using mini-blocks and event-related stimuli. Participants heard speech-like but semantically meaningless pseudowords spoken in various tones and evaluated them based on their emotional or linguistic content. Behaviorally, participants were faster to discriminate than to categorize; and processed the linguistic faster than the emotional content of stimuli. Interactions between condition (emotion/word), task (discrimination/categorization) and emotion content (anger, fear, neutral) influenced accuracy and reaction time. At the brain level, we found a modulation of the Oxy-Hb changes in IFG depending on condition, task, emotion and hemisphere (right or left), highlighting the involvement of the right hemisphere to process fear stimuli, and of both hemispheres to treat anger stimuli. Our results show that fNIRS is suitable to study vocal emotion evaluation, fostering its application to complex cognitive paradigms.

Spontaneous categorization of tools based on observation in children and chimpanzees.

The acquisition of the concept of 'tool' remains intriguing from both developmental and comparative perspectives. Our current model of tool use development in children is based on humans' supposedly unique ability to adopt a teleological stance: the understanding of a demonstrator's goal-based intentions when using a tool. It is however unclear how children and chimpanzees, our closest relatives, combine their knowledge of different objects whose function is to act on other parts of the environment, and assign them to a single category of 'tools'. Here, we used a function-based approach to address this question. We exposed 7 to 11-year-old children and adult chimpanzees to a Matching-to-Function (MTF) task to explore whether they would sort tools and non-tools separately after demonstration of their function by an experimenter. MTF is a variant of Matching-to-Sample where the sample and the target are from the same category/kind rather than identical. Around 40% of children paired objects according to their function in the MTF task, with only one child younger than 8 years doing so. Moreover, when verbally questioned, these children offered a function-based answer to explain their choices. One of six chimpanzees also successfully paired objects according to function. Children and at least one chimpanzee can thus spontaneously sort tools into functional categories based on observing a demonstrator. The success of a single chimpanzee in our task suggests that teleological reasoning might already have been present in our last common ancestor but also shows that human children more readily conceptualize tools in a spontaneous fashion.

Multimodal communication and language origins: integrating gestures and vocalizations.

The presence of divergent and independent research traditions in the gestural and vocal domains of primate communication has resulted in major discrepancies in the definition and operationalization of cognitive concepts. However, in recent years, accumulating evidence from behavioural and neurobiological research has shown that both human and non-human primate communication is inherently multimodal. It is therefore timely to integrate the study of gestural and vocal communication. Herein, we review evidence demonstrating that there is no clear difference between primate gestures and vocalizations in the extent to which they show evidence for the presence of key language properties: intentionality, reference, iconicity and turn-taking. We also find high overlap in the neurobiological mechanisms producing primate gestures and vocalizations, as well as in ontogenetic flexibility. These findings confirm that human language had multimodal origins. Nonetheless, we note that in great apes, gestures seem to fulfil a carrying (i.e. predominantly informative) role in close-range communication, whereas the opposite holds for face-to-face interactions of humans. This suggests an evolutionary shift in the carrying role from the gestural to the vocal stream, and we explore this transition in the carrying modality. Finally, we suggest that future studies should focus on the links between complex communication, sociality and cooperative tendency to strengthen the study of language origins.

Group Membership Influences More Social Identification Than Social Learning or Overimitation in Children.

Group membership is a strong driver of everyday life in humans, influencing similarity judgments, trust choices, and learning processes. However, its ontogenetic development remains to be understood. This study investigated how group membership, age, sex, and identification with a team influenced 39- to 60-month-old children (N = 94) in a series of similarity, trust, and learning tasks. Group membership had the most influence on similarity and trust tasks, strongly biasing choices toward in-groups. In contrast, prior experience and identification with the team were the most important factors in the learning tasks. Finally, overimitation occurred most when the children's team, but not the opposite, displayed meaningless actions. Future work must investigate how these cognitive abilities combine during development to facilitate cultural processes.

Wild chimpanzees select tool material based on efficiency and knowledge.

Some animals have basic culture, but to date there is not much evidence that cultural traits evolve as part of a cumulative process as seen in humans. This may be due to limits in animal physical cognition, such as an inability to compare the efficiency of a novel behavioural innovation with an already existing tradition. We investigated this possibility with a study on a natural tool innovation in wild chimpanzees: moss-sponging, which recently emerged in some individuals to extract mineral-rich liquids at a natural clay-pit. The behaviour probably arose as a variant of leaf-sponging, a tool technique seen in all studied chimpanzee communities. We found that moss-sponges not only absorbed more liquid but were manufactured and used more rapidly than leaf-sponges, suggesting a functional improvement. To investigate whether chimpanzees understood the advantage of moss- over leaf-sponges, we experimentally offered small amounts of rainwater in an artificial cavity of a portable log, together with both sponge materials, moss and leaves. We found that established moss-spongers (having used both leaves and moss to make sponges) preferred moss to prepare a sponge to access the rainwater, whereas leaf-spongers (never observed using moss) preferred leaves. Survey data finally demonstrated that moss was common in forest areas near clay-pits but nearly absent in other forest areas, suggesting that natural moss-sponging was at least partly constrained by ecology. Together, these results suggest that chimpanzees perceive functional improvements in tool quality, a crucial prerequisite for cumulative culture.

Chimpanzee quiet hoo variants differ according to context.

In comparative studies of evolution of communication, the function and use of animal quiet calls have typically been understudied, despite that these signals are presumably under selection like other vocalizations, such as alarm calls. Here, we examine vocalization diversification of chimpanzee quiet 'hoos' produced in three contexts-travel, rest and alert-and potential pressures promoting diversification. Previous playback and observational studies have suggested that the overarching function of chimpanzee hoos is to stay in contact with others, particularly bond partners. We conducted an acoustic analysis of hoos using audio recordings from wild chimpanzees (Pan troglodytes schweinfurthii) of Budongo Forest, Uganda. We identified three acoustically distinguishable, context-specific hoo variants. Each call variant requires specific responses from receivers to avoid breaking up the social unit. We propose that callers may achieve coordination by using acoustically distinguishable calls, advertising their own behavioural intentions. We conclude that natural selection has acted towards acoustically diversifying an inconspicuous, quiet vocalization, the chimpanzee hoo. This evolutionary process may have been favoured by the fact that signallers and recipients share the same goal, to maintain social cohesion, particularly among those who regularly cooperate, suggesting that call diversification has been favoured by the demands of cooperative activities.