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Recent decades have seen a steady increase in studies looking at the impact of human activities on wild animals. Many describe behavioural changes that concern traits that have been considered, or have the potential to be considered, as cultural, leading to the question of whether we are witnessing cultural evolution in other animals as a direct result of our own activities. Results indicate that human activities influence animal cultural repertoires through a variety of mechanisms: they can lead to the modification and, in extreme cases, the disappearance of existing cultural traits, but they can also foster the invention of novel traditions that have themselves the potential to become cultural. These examples are often found in the domain of food acquisition, where animals modify their diet to include new resources, adopt novel foraging strategies to avoid or, in contrast, establish long-lasting relationships with humans or human products or artifacts. Understanding these new cultural patterns in relation to humans is crucial for two reasons: as wildlife is increasingly exposed to humans and their activities, studying how animal cultures are impacted and change in response to anthropogenic factors is important for conservation purposes. Second, the current resulting situation for other animals, with drastic environmental changes in a short amount of time leading to behaviour change, may reflect past ecological pressures on human cultures and hence be informative to models of cultural evolution.

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 vocalisations, that we share with other primate species—particularly great apes (Hominidae). To better understand these processes at the behavioural 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. 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 gyruspars 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 IFGtrispecifically for the accurate classification of chimpanzee calls compared to human voices. Our data therefore reveal distinct frontal mechanisms that shed light on how the human brain evolved to process non-verbal language.Author contributionsCD and LC were involved in every steps of the study including experimental design, programming, data acquisition, data analysis and redaction of the first draft of the manuscript and subsequent editing. EP helped design the model-based MRI analyses and interpret the results. TG and DG were involved in the experimental design and study planification. All authors wrote and edited the manuscript.

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 989 night-nests, 205 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 that appear to make its use disadvantageous. While further study is required to establish this behaviour as meeting the strict criteria for non-human animal culture, we support the argument that the wider use of population and group-specific behavioural 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.

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) 2021 APA, all rights reserved).

Are conspecific emotional vocalizations special? Although often investigated in non-human primates using functional magnetic resonance imaging or positron emission tomography, it remains unclear whether the listening of conspecific vocal emotions leads to similar or different cerebral activations when compared to heterospecific calls (i.e. expressed by another primate species). Using a neuroimaging technique rarely employed in monkeys so far, functional Near Infrared Spectroscopy (fNIRS), the present study investigated cortical temporal activities during exposure to both conspecific and heterospecific calls in three female adult baboons (Papio anubis). The three subjects were lightly anesthetized and passively exposed to agonistic baboon and chimpanzee (Pan troglodytes) vocalizations, as well as energy matched white noises in order to control for this low-level acoustic feature. Despite inter-individual variabilities, permutation test analyses on the extracted OxyHemoglobin signal revealed for two subjects out of three significant differences between the passive listening of baboon versus chimpanzee stimuli. Additionally, in one subject, a modulation of the left temporal cortex activity was found for the perception of baboon calls contrasted to chimpanzee vocalizations as well as for the passive listening of baboon white noises compared to chimpanzee ones. Although the lack of generalization of those findings in all three subjects prevents us to drawn any conclusion and that more subjects would be needed, the hypothesis that baboons’ cortical temporal regions may be more sensitive to the processing of conspecific sounds compared to heterospecific stimuli is not excluded. Our study highlights that fNIRS may be a promising alternative to further investigate the auditory mechanisms at play in the right and left baboons’ temporal cortices for the processing of emotional vocalizations.

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.

The intentional communication of affective states is a central part of human sociality and cognition. Although nonhuman primates (henceforth primates) also signal intentionally, there is a perceived chasm between their intentional versus affective forms of communication. Whereas primate vocalizations and facial expressions are traditionally viewed as involuntary'read-outs' of affective states, gestures are considered as products of intentional control. However, this traditional view is increasingly contentious, given recent evidence of intentional signal production of primate vocalizations and facial expressions, as well as the general void of arousal-based explanations in gesture research. In this chapter, we challenge the perceived dichotomy between affective and intentional communication in primates and propose a dimensional approach, whereby primate signals can be both affective and intentional, regardless of signal modality (tactile, audible, visible) or component (gesture, facial expression, vocalization). We argue that a dimensional approach, which incorporates both affective and intentional components, would improve our knowledge on how affective and cognitive processes have jointly shaped the evolution of primate communication.

International audience; The role emotions play in the dynamics of cultural phenomena has long been neglected. The collection of articles recently published in Emotion Review provides an important first step into this necessary endeavor. In this commentary, we discuss this contribution by emphasizing the role epistemological parsimony should play in the future of this research agenda. The cultural behavior and emotions of chimpanzees is taken as reference.

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 (The online version contains supplementary material available at 10.1007/s42761-022-00164-z.

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.

The intentional communication of affective states is a central part of human sociality and cognition. Although nonhuman primates (henceforth primates) also signal intentionally, there is a perceived chasm between their intentional versus affective forms of communication. Whereas primate vocalizations and facial expressions are traditionally viewed as involuntary 'read-outs' of affective states, gestures are considered as products of intentional control. However, this traditional view is increasingly contentious, given recent evidence of intentional signal production of primate vocalizations and facial expressions, as well as the general void of arousal-based explanations in gesture research. In this chapter, we challenge the perceived dichotomy between affective and intentional communication in primates and propose a dimensional approach, whereby primate signals can be both affective and intentional, regardless of signal modality (tactile, audible, visible) or component (gesture, facial expression, vocalization). We argue that a dimensional approach, which incorporates both affective and intentional components, would improve our knowledge on how affective and cognitive processes have jointly shaped the evolution of primate communication.

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.

International audience; 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 noninvasively 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.

18 pages, 5 figures, supplementary data https://doi.org/10.1016/j.biocon.2021.109175.-- The data supporting the findings of this study are available in the Supplementary Materials (Appendix 3–5, Table A3-A5). Raw datasets (where available) and results summary tables for each analysis of human mobility and empirical datasets are deposited in a github repository: https://github.com/rjcommand/PAN-Environment, The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness, The Canada Research Chairs program provided funding for the core writing team. Field research funding was provided by A.G. Leventis Foundation; Agence Nationale de la Recherche, [grant number ANR-18-32–0010CE-01 (JCJC PEPPER)]; Agencia Estatal de Investigaci; Agência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação (ARDITI), [grant number M1420-09-5369-FSE-000002]; Alan Peterson; ArcticNet; Arkadaşlar; Army Corp of Engineers; Artificial Reef Program; Australia's Integrated Marine Observing System (IMOS), National Collaborative; Research Infrastructure Strategy (NCRIS), University of Tasmania; Australian Institute of Marine Science; Australian Research Council, [grant number LP140100222]; Bai Xian Asia Institute; Batubay Özkan; BC Hydro Fish and Wildlife Compensation Program; Ben-Gurion University of the Negev; Bertarelli Foundation; Bertarelli Programme in Marine Science; Bilge Bahar; Bill and Melinda Gates Foundation; Biology Society of South Australia; Boston University; Burak Över; California State Assembly member Patrick O'Donnell; California State University Council on Ocean Affairs, Science & Technology; California State University Long Beach; Canada Foundation for Innovation (Major Science Initiative Fund and funding to Oceans Network Canada), [grant number MSI 30199 for ONC]; Cape Eleuthera Foundation; Centre National d'Etudes Spatiales; Centre National de la Recherche Scientifique; Charles Darwin Foundation, [grant number 2398]; Colombian Institute for the Development of Science and Technology (COLCIENCIAS), [grant number 811–2018]; Colombian Ministry of Environment and Sustainable Development, [grant number 0041–2020]; Columbia Basin Trust; Commission for Environmental Cooperation; Cornell Lab of Ornithology; Cultural practices and environmental certification of beaches, Universidad de la Costa, Colombia, [grant number INV.1106–01–002-15, 2020–21]; Department of Conservation New Zealand; Direction de l'Environnement de Polynésie Française; Disney Conservation Fund; DSI-NRF Centre of; Excellence at the FitzPatrick Institute of African Ornithology; Ecology Project International; Emin Özgür; Environment and Climate Change Canada; European Community: RTD programme - Species Support to Policies; European Community's Seventh Framework Programme; European Union; European Union's Horizon 2020 research and innovation programme, Marie Skłodowska-Curie, [grant number 798091, 794938]; Faruk Eczacıbaşı; Faruk Yalçın Zoo; Field research funding was provided by King Abdullah University of Science and Technology; Fish and Wildlife Compensation Program; Fisheries and Oceans Canada; Florida Fish and Wildlife Conservation Commission, [grant numbers FWC-12164, FWC-14026, FWC-19050]; Fondo Europeo de Desarrollo Regional; Fonds québécois de la recherche nature et technologies; Foundation Segré; Fundação para a Ciência e a Tecnologia (FCT Portugal); Galapagos National Park Directorate research, [grant number PC-41-20]; Gordon and Betty Moore Foundation, [grant number GBMF9881 and GBMF 8072]; Government of Tristan da Cunha; Habitat; Conservation Trust Foundation; Holsworth Wildlife Research Endowment; Institute of Biology of the Southern Seas, Sevastopol, Russia; Instituto de Investigación de Recursos Biológicos Alexander von Humboldt; Instituto Nacional de Pesquisas Espaciais (INPE), Brazil; Israeli Academy of Science's Adams Fellowship; King Family Trust; Labex, CORAIL, France; Liber Ero Fellowship; LIFE (European Union), [grant number LIFE16 NAT/BG/000874]; María de Maeztu Program for Units of Excellence in R&D; Ministry of Science and Innovation, FEDER, SPASIMM,; Spain, [grant number FIS2016–80067-P (AEI/FEDER, UE)]; MOE-Korea, [grant number 2020002990006]; Mohamed bin Zayed Species Conservation Fund; Montreal Space for Life; National Aeronautics and Space Administration (NASA) Earth and Space Science Fellowship Program; National Geographic Society, [grant numbers NGS-82515R-20]; National Natural Science Fund of China; National Oceanic and Atmospheric Administration; National Parks Board, Singapore; National Science and Technology Major Project of China; National Science Foundation, [grant number DEB-1832016]; Natural Environment Research Council of the UK; Natural Sciences and Engineering Research Council of Canada (NSERC), Alliance COVID-19 grant program, [grant numbers ALLRP 550721–20, RGPIN-2014-06229 (year: 2014), RGPIN-2016-05772 (year: 2016)]; Neiser Foundation; Nekton Foundation; Network of Centre of Excellence of Canada: ArcticNet; North Family Foundation; Ocean Tracking Network; Ömer Külahçıoğlu; Oregon State University; Parks Canada Agency (Lake Louise, Yoho, and Kootenay Field Unit); Pew Charitable Trusts; Porsim Kanaf partnership; President's International Fellowship Initiative for postdoctoral researchers Chinese Academy of Sciences, [grant number 2019 PB0143]; Red Sea Research Center; Regional Government of the Azores, [grant number M3.1a/F/025/2015]; Regione Toscana; Rotary Club of Rhinebeck; Save our Seas Foundation; Science & Technology (CSU COAST); Science City Davos, Naturforschende Gesellschaft Davos; Seha İşmen; Sentinelle Nord program from the Canada First Research Excellence Fund; Servizio Foreste e Fauna (Provincia Autonoma di Trento); Sigrid Rausing Trust; Simon Fraser University; Sitka Foundation; Sivil Toplum Geliştirme Merkezi Derneği; South African National Parks (SANParks); South Australian Department for Environment and Water; Southern California Tuna Club (SCTC); Spanish Ministry for the Ecological Transition and the Demographic Challenge; Spanish Ministry of Economy and Competitiveness; Spanish Ministry of Science and Innovation; State of California; Sternlicht Family Foundation; Suna Reyent; Sunshine Coast Regional Council; Tarea Vida, CEMZOC, Universidad de Oriente, Cuba, [grant number 10523, 2020]; Teck Coal; The Hamilton Waterfront Trust; The Ian Potter Foundation, Coastwest, Western Australian State NRM; The Red Sea Development Company; The Wanderlust Fund; The Whitley Fund; Trans-Anatolian Natural Gas Pipeline; Tula Foundation (Hakai Institute); University of Arizona; University of Pisa; US Fish and Wildlife Service; US Geological Survey; Valencian Regional Government; Vermont Center for Ecostudies; Victorian Fisheries Authority; VMRC Fishing License Fund; and Wildlife Warriors Worldwide, With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S

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.

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 affect can allow bridging of the debates of the unique characteristics of social learning in humans compared to other animals. We first review the two major bodies of literature in non-human 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 towards, cognitions concerning, and feelings about objects, events and people in our environment. All three thus contribute to an affective, behavioral and cognitive 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 non-verbal infants. Yet, it can also explain some of the major achievements only found in human cultures.

In recent years, research on voice processing, particularly the study of temporal voice areas (TVA), was dedicated almost exclusively to human voice. To characterize commonalities and differences regarding primate vocalization representations in the human brain, the inclusion of closely related primates, especially chimpanzees and bonobos, is needed. We hypothesized that commonalities would depend on both phylogenetic and acoustic proximity, with chimpanzees ranking the closest to Homo. Presenting human participants with four primate species vocalizations (rhesus macaques, chimpanzees, bonobos and humans) and taking into account acoustic distance or removing voxels explained solely by vocalization low-level acoustics, we observed within-TVA enhanced left and right anterior superior temporal gyrus activity for chimpanzee compared to all other species, and chimpanzee compared to human vocalizations. Our results provide evidence for a common neural basis in the TVA for the processing of phylogenetically and acoustically close vocalizations, namely those of humans and chimpanzees.

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 motor condition our results show that left-arm versus right-arm stimulations induced typical contralateral difference in hemispheric activation asymmetries in the three subjects for all three channels. For the auditory condition, we also revealed typical human-like patterns of hemispheric asymmetries in one subject for all three channels, namely (1) typical contralateral differences in hemispheric asymmetry between left-ear versus right-ear stimulations, and (2) a rightward asymmetry for stereo stimulations. 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.

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.

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., Frontiers in Neuroscience, 14, ISSN:1662-453X, ISSN:1662-4548

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.

Some East African chimpanzee (Pan troglodytes schweinfurthii) communities, such as the Sonso chimpanzees, display an unusually limited range of tool-use, but it remains unclear whether this is due to ecological and/or cultural factors. Information on ecological conditions and the diet of the Sonso chimpanzees in relation to neighbouring communities is needed. Here, we studied three adjacent communities in Budongo Forest (Sonso, Waibira, and Kamira), and the presumed core area of an undescribed community (Mwera), in the neighbouring Bugoma Forest. Through line-transects, we investigated (i) whether there were differences in food diversity and abundance between the communities’ home ranges; (ii) whether the home ranges differed in abundance of sticks and insect nests; and (iii) whether Sonso and Mwera chimpanzees differed in their diet (using faecal samples). Across communities, Sonso had the richest food availability and the lowest insect nest abundance. However, food availability in Mwera, Bugoma, was richer than Budongo communities that neighbour the Sonso territory, suggesting that there may be variation within Budongo. Data from faecal samples replicated our direct observations of food availability suggesting that Sonso chimpanzees had a broader diet than Mwera chimpanzees. This difference in foods availability may partially explain the Sonso chimpanzees’ lack of stick-tool-use, and low levels of insectivory. The tool repertoire of the other communities is currently unknown; however, we make predictions based on our ecological data. More detailed knowledge of small-scale variation in ecology within and between forest habitats may be important to advancing our understanding of the drivers of tool-use.SIGNIFICANCE STATEMENT – HIGHLIGHTED STUDENT PAPERTo advance our knowledge of the role of ecological factors in the emergence of tool use in chimpanzees, a nuanced understanding of the ecological conditions different chimpanzee communities experience is needed. We studied four Ugandan chimpanzee communities in two forests. One of these communities, Sonso, in the Budongo Forest, is well-known for its restricted range of tool types, including a total absence of stick use. Food diversity and abundance were highest, and stick tool use opportunities (abundance of sticks and insect nests) were lowest for the core-habitat of the Sonso chimpanzees in contrast to the other communities. We argue that ecological factors play a role in their unusual pattern of tool use, and make predictions about the expected types of tool use in the other communities based on their ecology. Thus, our study provides information that may help advance our understanding of how tool use arises under varied socioecological circumstances.

It has long been held that triadic interactions, or interactions between individuals that include shared perception and goals concerning an outside entity, require elaborate cognitive processes such as joint attention. With their connection to shared intentionality, triadic interactions have been a key topic of interest for developmental and evolutionary psychologists, notably when making comparisons between humans and other ape species. There is good evidence that chimpanzees and bonobos engage in triadic interactions; however, convincing evidence for orangutans are more limited and so far have been found only in the context of feeding. I engaged 11 wild-born sanctuary orangutans through the medium of a stick, allowing them to decide how to use the object and how to interact with me. The participating orangutans developed idiosyncratic ways of using the stick and engaging with me during the activity, and six of them alternated their gaze between the stick and me. When I interrupted the activity, the participating orangutans displayed more numerous and different behaviors than before the interruption to actively reengage me in the game. Much like human infants, they appeared more interested in the social interaction than in the stick. These findings confirm that triadic interactions occur in nonenculturated orangutans and are consistent with studies of other nonhuman great ape species, which also show triadic interactions, suggesting that joint attention and potentially shared intentionality may have an early origin in our evolutionary history.

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.

Language's intentional nature has been highlighted as a crucial feature distinguishing it from other communication systems. Specifically, language is often thought to depend on highly structured intentional action and mutual mindreading by a communicator and recipient. Whilst similar abilities in animals can shed light on the evolution of intentionality, they remain challenging to detect unambiguously. We revisit animal intentional communication and suggest that progress in identifying analogous capacities has been complicated by (i) the assumption that intentional (that is, voluntary) production of communicative acts requires mental-state attribution, and (ii) variation in approaches investigating communication across sensory modalities. To move forward, we argue that a framework fusing research across modalities and species is required. We structure intentional communication into a series of requirements, each of which can be operationalised, investigated empirically, and must be met for purposive, intentionally communicative acts to be demonstrated. Our unified approach helps elucidate the distribution of animal intentional communication and subsequently serves to clarify what is meant by attributions of intentional communication in animals and humans.

Animal culture has been of interest for decades but the concept remains controversial. Many researchers feel that animal behavior should not be granted the label “culture” because the latter includes more than “simple” behavioral variation. In recent years, the study of animal culture has been concerned mainly with social learning mechanisms, often claimed to be human specific, which led to the uniqueness of human culture. In addition, failure to innovate novel cultural behavior as often as humans is usually explained by psychological mechanisms presented as more parsimonious, such as conservatism or functional fixedness. However, it is unclear how cognitively complex these mechanisms are in the first place. Here, I analyze recent data obtained with wild chimpanzees (Pan troglodytes schweinfurthii) and wild-born orangutans (Pongo abelii) using the honey-trap experiment, in which individuals must devise a solution to reach inaccessible honey. I compare behavior of apes that developed a tool-based solution in the task with those that did not, and test whether conservatism and functional fixedness can explain individual variation in ape behavior. I find evidence of conservatism, with apes relying on their existing knowledge, and evidence of functional fixedness, with this knowledge potentially preventing them from innovating. However, the apes showed large intraspecific variability. I discuss the two mechanisms through a representational perspective to tackle their cognitive complexity. Understanding how conservatism and functional fixedness interact with ape cultural knowledge to limit innovation of novel tool use appears necessary to understand the full extent of ape cultures and how they compare to human cultures.

The concept of functional reference has been used to isolate potentially referential vocal signals in animal communication. However, its relatedness to the phenomenon of reference in human language has recently been brought into question. While some researchers have suggested abandoning the concept of functional reference altogether, others advocate a revision of its definition to include contextual cues that play a role in signal production and perception. Empirical and theoretical work on functional reference has also put much emphasis on how the receiver understands the referential signal. However, reference, as defined in the linguistic literature, is an action of the producer, and therefore, any definition describing reference in non-human animals must also focus on the producer. To successfully determine whether a signal is used to refer, we suggest an approach from the field of pragmatics, taking a closer look at specific situations of signal production, specifically at the factors that influence the production of a signal by an individual. We define the concept of signaller's reference to identify intentional acts of reference produced by a signaller independently of the communicative modality, and illustrate it with a case study of the hoo vocalizations produced by wild chimpanzees during travel. This novel framework introduces an intentional approach to referentiality. It may therefore permit a closer comparison of human and non-human animal referential behaviour and underlying cognitive processes, allowing us to identify what may have emerged solely in the human lineage.