Idiosyncratic gesture use in a mother-infant dyad in chimpanzees (Pan troglodytes schweinfurthii) in the wild.

One promising method to tackle the question, "In which modality did language evolve?" is by studying the ontogenetic trajectory of signals in human's closest living relatives, including chimpanzees (Pan troglodytes). Concerning gestures, current debates centre on four different hypotheses: "phylogenetic ritualization", "social transmission through imitation", "ontogenetic ritualization", and "social negotiation". These differ in their predictions regarding idiosyncratic gestures, making such occurrences a crucial area of investigation.

Bodies at play: the role of intercorporeality and bodily affordances in coordinating social play in chimpanzees in the wild.

The comparative approach is a crucial method to gain a better understanding of the behavior of living human and nonhuman animals to then draw informed inferences about the behavior of extinct ancestors. One focus has been on disentangling the puzzle of language evolution. Traditionally, studies have predominantly focused on intentionally produced signals in communicative interactions.

Intentional gestural communication amongst red-capped mangabeys (Cercocebus torquatus).

Apes, human's closest living relatives, are renowned for their intentional and highly flexible use of gestural communication. In stark contrast, evidence for flexible and intentional gestural communication in monkeys is scarce. Here, we investigated the intentionality and flexibility of spontaneous gesture use in red-capped mangabeys (Cercocebus torquatus).

Application of insects to wounds of self and others by chimpanzees in the wild.

Self-medication refers to the process by which a host suppresses or prevents the deleterious effects of parasitism and other causes of illness via behavioural means. It has been observed across multiple animal taxa (e.g.

Lethal coalitionary attacks of chimpanzees (Pan troglodytes troglodytes) on gorillas (Gorilla gorilla gorilla) in the wild.

Intraspecies violence, including lethal interactions, is a relatively common phenomenon in mammals. Contrarily, interspecies violence has mainly been investigated in the context of predation and received most research attention in carnivores. Here, we provide the first information of two lethal coalitionary attacks of chimpanzees (Pan troglodytes troglodytes) on another hominid species, western lowland gorillas (Gorilla gorilla gorilla), that occur sympatrically in the Loango National Park in Gabon.

Home range size in central chimpanzees (Pan troglodytes troglodytes) from Loango National Park, Gabon.

Ranging behavior has been studied extensively in eastern (Pan troglodytes schweinfurthii) and western (P. t. verus) chimpanzees, but relatively little is known regarding home ranges of the other two subspecies (P.

Intercommunity interactions and killings in central chimpanzees (Pan troglodytes troglodytes) from Loango National Park, Gabon.

Intercommunity competition in chimpanzees (Pan troglodytes) has been widely studied in eastern (P. t. schweinfurthii) and western (P.

Hunting of mammals by central chimpanzees (Pan troglodytes troglodytes) in the Loango National Park, Gabon.

The predation and consumption of animals are common behaviours in chimpanzees across tropical Africa. To date, however, relatively little is known concerning the hunting behaviour of central chimpanzees (Pan troglodytes troglodytes). Here, we provide the first direct observations of hunting behaviour by individuals of the newly habituated Rekambo community in the Loango National Park, Gabon.

Ravens parallel great apes in physical and social cognitive skills.

Human children show unique cognitive skills for dealing with the social world but their cognitive performance is paralleled by great apes in many tasks dealing with the physical world. Recent studies suggested that members of a songbird family-corvids-also evolved complex cognitive skills but a detailed understanding of the full scope of their cognition was, until now, not existent. Furthermore, relatively little is known about their cognitive development.

Old and New Approaches to Animal Cognition: There Is Not "One Cognition".

Using the comparative approach, researchers draw inferences about the evolution of cognition. Psychologists have postulated several hypotheses to explain why certain species are cognitively more flexible than others, and these hypotheses assume that certain cognitive skills are linked together to create a generally "smart" species. However, empirical findings suggest that several animal species are highly specialized, showing exceptional skills in single cognitive domains while performing poorly in others.

Author Correction: Chimpanzee ethnography reveals unexpected cultural diversity.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Chimpanzee ethnography reveals unexpected cultural diversity.

Human ethnographic knowledge covers hundreds of societies, whereas chimpanzee ethnography encompasses at most 15 communities. Using termite fishing as a window into the richness of chimpanzee cultural diversity, we address a potential sampling bias with 39 additional communities across Africa. Previously, termite fishing was known from eight locations with two distinguishable techniques observed in only two communities.

Gorillas' (Gorilla g. gorilla) knowledge of conspecifics' affordances: intraspecific social tool use for food acquisition.

The use of tools, long thought to be uniquely human, has now been observed in other animal taxa including several species of birds, non-primate mammals as well as some non-human primate species. Chimpanzees, one of humankind's closest living relatives, exceed all other non-human animal species as they have been reported to use an exceptionally large toolkit. However, relatively little is known about the tool-use skills of the other great ape species.

Social relationships and greetings in wild chimpanzees (Pan troglodytes): use of signal combinations.

Signals of submission, so-called 'greetings', represent an important tool for the regulation of social life in primates. In chimpanzees, vocalizations and gestures are commonly employed to communicate greetings, however, the topic of signal complexity (i.e.

Wild chimpanzees (Pan troglodytes troglodytes) exploit tortoises (Kinixys erosa) via percussive technology.

Chimpanzees (Pan troglodytes), one of humankinds' closest living relatives, are known to hunt and consume the meat of various animal taxa. Although some researchers have presented indirect evidence that chimpanzees may also prey on tortoises, until now, direct observations of this behaviour did not exist. Here, we provide systematic descriptions of the first observations of chimpanzee predation on tortoises (Kinixys erosa).

Joint attention skills in wild Arabian babblers ( Turdoides squamiceps): a consequence of cooperative breeding?

Human cooperation strongly relies on the ability of interlocutors to coordinate each other's attentional state: joint attention. One predominant hypothesis postulates that this hallmark of the unique cognitive system of humans evolved due to the combination of an ape-like cognitive system and the prosocial motives that facilitate cooperative breeding. Here, we tested this hypothesis by investigating communicative interactions of a cooperatively breeding bird species, the Arabian babbler ( Turdoides squamiceps).

How many fingers am I holding up? The answer depends on children's language background.

Monolingual English-speaking preschool children tend to process number gestures as unanalyzed wholes rather than use the one-to-one (finger-to-quantity) correspondence. By school age, however, children can use the one-to-one correspondence. The purpose of the present studies was to test whether children learn one-to-one correspondence through exposure to a variety of finger configurations to convey a single quantity.

The ontogeny of intentional communication in chimpanzees in the wild.

The onset of intentional communication in children's first year of life represents a major milestone in human cognitive development. Similarly, it is well established that our closest living relatives, the great apes, communicate with signals characterized by at least first-order intentionality. Despite the well-documented influence of developmental experiences on socio-cognitive abilities in apes, the developmental trajectory of intentional signal use as well as effects of social exposure remain poorly understood under naturalistic conditions.

Taking turns: bridging the gap between human and animal communication.

Language, humans' most distinctive trait, still remains a 'mystery' for evolutionary theory. It is underpinned by a universal infrastructure-cooperative turn-taking-which has been suggested as an ancient mechanism bridging the existing gap between the articulate human species and their inarticulate primate cousins. However, we know remarkably little about turn-taking systems of non-human animals, and methodological confounds have often prevented meaningful cross-species comparisons.

Captive chimpanzees' manual laterality in tool use context: Influence of communication and of sociodemographic factors.

Understanding variations of apes' laterality between activities is a central issue when investigating the evolutionary origins of human hemispheric specialization of manual functions and language. We assessed laterality of 39 chimpanzees in a non-communication action similar to termite fishing that we compared with data on five frequent conspecific-directed gestures involving a tool previously exploited in the same subjects. We evaluated, first, population-level manual laterality for tool-use in non-communication actions; second, the influence of sociodemographic factors (age, sex, group, and hierarchy) on manual laterality in both non-communication actions and gestures.

Gestural acquisition in great apes: the Social Negotiation Hypothesis.

Scientific interest in the acquisition of gestural signalling dates back to the heroic figure of Charles Darwin. More than a hundred years later, we still know relatively little about the underlying evolutionary and developmental pathways involved. Here, we shed new light on this topic by providing the first systematic, quantitative comparison of gestural development in two different chimpanzee (Pan troglodytes verus and Pan troglodytes schweinfurthii) subspecies and communities living in their natural environments.

A multifactorial investigation of captive gorillas' intraspecific gestural laterality.

Multifactorial investigations of intraspecific laterality of primates' gestural communication aim to shed light on factors that underlie the evolutionary origins of human handedness and language. This study assesses gorillas' intraspecific gestural laterality considering the effect of various factors related to gestural characteristics, interactional context and sociodemographic characteristics of signaller and recipient. Our question was: which factors influence gorillas' gestural laterality? We studied laterality in three captive groups of gorillas (N = 35) focusing on their most frequent gesture types (N = 16).

Captive gorillas' manual laterality: The impact of gestures, manipulators and interaction specificity.

Relationships between humans' manual laterality in non-communicative and communicative functions are still poorly understood. Recently, studies showed that chimpanzees' manual laterality is influenced by functional, interactional and individual factors and their mutual intertwinement. However, what about manual laterality in species living in stable social groups? We tackled this question by studying three groups of captive gorillas (N=35) and analysed their most frequent manual signals: three manipulators and 16 gesture types.

Intraspecific gestural laterality in chimpanzees and gorillas and the impact of social propensities.

A relevant approach to address the mechanisms underlying the emergence of the right-handedness/left-hemisphere language specialization of humans is to investigate both proximal and distal causes of language lateralization through the study of non-human primates' gestural laterality. We carried out the first systematic, quantitative comparison of within-subjects' and between-species' laterality by focusing on the laterality of intraspecific gestures of chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla) living in six different captive groups. We addressed the following two questions: (1) Do chimpanzees and gorillas exhibit stable direction of laterality when producing different types of gestures at the individual level? If yes, is it related to the strength of laterality? (2) Is there a species difference in gestural laterality at the population level? If yes, which factors could explain this difference? During 1356 observation hours, we recorded 42335 cases of dyadic gesture use in the six groups totalling 39 chimpanzees and 35 gorillas.