Simone Pika

Primate Vocalization, Gesture, and the Evolution of Human Language

The performance of language is multimodal, not confined to speech. Review of monkey and ape communication demonstrates greater flexibility in the use of hands and body than for vocalization. Nonetheless, the gestural repertoire of any group of nonhuman primates is small compared with the vocabulary of any human language and thus, presumably, of the transitional form called protolanguage. We argue that it was the coupling of gestural communication with enhanced capacities for imitation that made possible the emergence of protosign to provide essential scaffolding for protospeech in the evolution of protolanguage. Similarly, we argue against a direct evolutionary path from nonhuman primate vocalization to human speech. The analysis refines aspects of the mirror system hypothesis on the role of the primate brain’s mirror system for manual action in evolution of the human language‐ready brain.

A cross-cultural study on the use of gestures: Evidence for cross-linguistic transfer?

Anecdotal reports provide evidence of so called “hybrid” gesturer whose non-verbal behavior of one language/culture becomes visible in the other. The direction of this gestural transfer seems to occur from a high to a low frequency gesture language. The purpose of this study was therefore to test systematically 1) whether gestural transfer occurs from a high frequency gesture language to a low frequency gesture language, 2) if the frequency of production of some gesture types is more likely to be transferred than others, and 3) whether gestural transfer can also occur bi-directionally. To address these questions, we investigated the use of gestures of English–Spanish bilinguals, French–English bilinguals, and English monolinguals while retelling a cartoon. Our analysis focused on the rate of gestures and the frequency of production of gesture types. There was a significant difference in the overall rate of gestures: both bilingual groups gestured more than monolingual participants. This difference was particularly salient for iconic gestures. In addition, we found that French–English bilinguals used more deictic gestures in their L2. The results suggest that knowledge of a high frequency gesture language affects the gesture rate in a low-frequency gesture language.

Gestures of apes and pre-linguistic human children: Similar or different?

The majority of studies on animal communication provide evidence that gestural signalling plays an important role in the communication of non-human primates and resembles that of pre-linguistic and just-linguistic human infants in some important ways. However, ape gestures also differ from the gestures of human infants in some important ways, and these differences might provide crucial clues for answering the question of how human language — at least in its cognitive and social-cognitive aspects — evolved from the gestural communication of our ape-like ancestors. This article provides an overview on the gestural signalling of monkeys and apes to enable a comparison with gestures in pre- or just-linguistic children. Implications for the evolution of language are discussed.

Female bonobos use copulation calls as social signals

During mating events, females of many primate species produce loud and distinct vocalizations known as ‘copulation calls’. The adaptive significance of these signals is considered to be in promoting the callers direct reproductive success. Here, we investigated copulation calling in bonobos (Pan paniscus), a species in which females produce these vocalizations during sexual interactions with partners of both sexes. Females were more likely to call when mating with males than with females. We also observed a positive relationship between the likelihood of calling and partner rank, regardless of partner sex. Sexual activity generally increased with swelling size (an indicator of reproductive state) and, during their peak swelling, females called more with male than with female partners. Female bonobos are unusual among the non-human primates in terms of their heightened socio-sexuality. Our results suggest that in this species, copulation calls have undergone an evolutionary transition from a purely reproductive to a more general social function, reflecting the intrinsic evolutionary links between vocal behaviour and social cognition.

Unpeeling the layers of language: Bonobos and chimpanzees engage in cooperative turn-taking sequences

Human language is a fundamentally cooperative enterprise, embodying fast-paced and extended social interactions. It has been suggested that it evolved as part of a larger adaptation of humans’ species-unique forms of cooperation. Although our closest living relatives, bonobos and chimpanzees, show general cooperative abilities, their communicative interactions seem to lack the cooperative nature of human conversation. Here, we revisited this claim by conducting the first systematic comparison of communicative interactions in mother-infant dyads living in two different communities of bonobos (LuiKotale, DRC; Wamba, DRC) and chimpanzees (Taï South, Côte d’Ivoire; Kanyawara, Uganda) in the wild. Focusing on the communicative function of joint-travel-initiation, we applied parameters of conversation analysis to gestural exchanges between mothers and infants. Results showed that communicative exchanges in both species resemble cooperative turn-taking sequences in human conversation. While bonobos consistently addressed the recipient via gaze before signal initiation and used so-called overlapping responses, chimpanzees engaged in more extended negotiations, involving frequent response waiting and gestural sequences. Our results thus strengthen the hypothesis that interactional intelligence paved the way to the cooperative endeavour of human language and suggest that social matrices highly impact upon communication styles.

How to Order a Beer Cultural Differences in the Use of Conventional Gestures for Numbers

It is said that conventional gestures for numbers differ by culture. Conventional gestures are thought to imply consistency of form both across and within individuals. The present study tests the consistency of finger gestures of 60 participants of three different cultures and in three different mother tongues in nine different hypothetical scenarios. The first subject of analysis is whether participants differentiate between counting and signaling. The second subject is the consistency of gestures within and between groups. The third is how participants depict the number 1. Result show that most people use the same gestures for counting and signaling. In addition, Germans and English Canadians show relatively low degrees of individual differences whereas French Canadians show relatively high degrees of individual variability. Furthermore, only the Germans use the thumb to indicate the number 1, whereas the two North American cultures use the index finger. The present data suggest that finger gestures of some cultures clearly qualify as conventional gestures whereas others do not. It is suggested that the development of conventional gestures is influenced by cultural exposure, which can even result into the loosening of conventions.

Play-solicitation gestures in chimpanzees in the wild: Flexible adjustment to social circumstances and individual matrices

Social play is a frequent behaviour in great apes and involves sophisticated forms of communicative exchange. While it is well established that great apes test and practise the majority of their gestural signals during play interactions, the influence of demographic factors and kin relationships between the interactants on the form and variability of gestures are relatively little understood. We thus carried out the first systematic study on the exchange of play-soliciting gestures in two chimpanzee (Pan troglodytes) communities of different subspecies. We examined the influence of age, sex and kin relationships of the play partners on gestural play solicitations, including object-associated and self-handicapping gestures. Our results demonstrated that the usage of (i) audible and visual gestures increased significantly with infant age, (ii) tactile gestures differed between the sexes, and (iii) audible and visual gestures were higher in interactions with conspecifics than with mothers. Object-associated and self-handicapping gestures were frequently used to initiate play with same-aged and younger play partners, respectively. Our study thus strengthens the view that gestures are mutually constructed communicative means, which are flexibly adjusted to social circumstances and individual matrices of interactants.

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. We conclude that the three most predominant perspectives on gestural acquisition—Phylogenetic Ritualization, Social Transmission via Imitation, and Ontogenetic Ritualization—do not satisfactorily explain our current findings on gestural interactions in chimpanzees in the wild. In contrast, we argue that the role of interactional experience and social exposure on gestural acquisition and communicative development has been strongly underestimated. We introduce the revised Social Negotiation Hypothesis and conclude with a brief set of empirical desiderata for instigating more research into this intriguing research domain.

The case of referential gestural signaling. Where next

Referential acts play a crucial part in our every day communication since human language is, in its essence, a referential system. Reference can be made via icons, indices and signs but also via ostensive/inferential gestural communication, in which the behavior of the actor directs the attention of the recipient to particular aspects of the environment. The earliest uses of ostensive/inferential communication can be observed in human children around the age of nine to 12 mo. However, what about comparable gestures in our closest living relatives, the nonhuman primates or other animal taxa? The present paper aims to provide a brief overview of the state of the art to encourage future research into the evolutionary origins and uses of referential gestural signaling.

Differences and similarities between the natural gestural communication of the great apes and human children

Studies of animal communication systems are essential to understand the evolution of human language. The majority of research focused on vocal communication. Recent studies however provide evidence that gestural signaling plays an important role in the communication of apes and resembles that of prelinguistic and just-linguistic human infants in some important ways. However, ape gestures also differ from the gestures of human infants in some important ways as well, and these differences might provide crucial clues for answering the question of how human language –at least in its cognitive and social-cognitive aspectsevolved from the gestural communication of our ape-like ancestors. The present manuscript summarizes and compares recent studies on the gestural signaling of the great apes (Gorilla gorilla, Pan paniscus, Pan troglodytes, Pongo pygmaeus) to enable a comparison with gestures in children. We focused on the three following aspects: 1) nature of gestures, 2) intentional use of gestures, 3) and learning of gestures. Our results show, that apes have multifaceted gestural repertoires and use their gestures intentionally. Although some group-specific gestures seem to be acquired via a social learning process, the majority of gestures are learned via individual learning. Importantly, all of the intentional produced gestures share two important characteristics that make them crucially different from human deictic and symbolic gestures: 1) they are almost invariably used in dyadic contexts, and 2) they are used exclusively for imperative purposes. Implications for these differences are discussed. One of the enduring questions of the Western intellectual traditions is how spoken language, which is thought to be unique to humans, originated and evolved. One important way to address this question is to compare speech to the systems of vocal communication evolved in other animals, especially in nonhuman primates (hereafter primates) (e.g., Marler, 1977; Seyfarth, 1987; Snowdon, 1988; Zuberbuhler, 2003). The majority of studies investigated vocal communication and revealed that call morphology and call usage seem to have only limited flexibility (Liebermann, 1998; Corballis, 2002). However, recent data provided evidence that vervet monkeys use different alarm calls in association with different predators (leading to different escape responses in receivers) and therefore raised the possibility that some nonhuman species may, like humans, use vocalizations to make reference to outside entities (Cheney & Seyfarth, 1990). But it has turned out since then that alarm calls of this type have arisen numerous times in evolution in species that also must organize different escape responses for different predators, including most prominently prairie dogs and domestic chickens (Owings & Morton, 1998). And importantly, there is currently no evidence that any species of ape has such referent specific alarm calls or any other vocalizations that appear to be referential (Cheney & Wrangham, 1987; however see Crockford & Boesch, 2003). This implies that it is highly unlikely that vervet monkey alarm calls could be the direct precursor of human language unless at some point apes used similar calls and have now lost them. Interestingly, gestural or ideographic communication systems have to some extent been mastered by human-reared great apes (e.g. Gardner, et al, 1989; Savage-Rumbaugh, et al, 1993). Though by no means ‘language’, these projects have shown intentional, referential use of numerous gestures and ideograms (Gardner, et al., 1989; Savage-Rumbaugh, 1986), accurate usage under doubleblind conditions, and understanding of human speech. These findings support the hypothesis that the evolutionary roots of language might have evolved in the visual-gestural modality (e.g., Condillac, 1971; Hewes, 1976; Armstrong et al., 1995; Dunbar, 1996; Arbib, 2002). In addition, recent studies provide evidence that gestural signaling plays an important role in the natural communication of primates and resembles that of pre-linguistic and just-linguistic human infants in some important ways (Plooij, 1978, Tomasello et al., 1985). However, ape gestures differ from the gestures of human infants in some important ways as well, and these differences might provide crucial clues for answering the question of how human language –at least in its cognitive and social-cognitive aspectsevolved from the gestural communication of our ape-like ancestors. The question thus arises: what is the nature of the gestural communication of nonhuman primates, and how do they relate to human gestures and language? The present manuscript is based on observations of the communicative signaling of the four great apes species (Gorilla gorilla, Pan paniscus, Pan troglodytes, Pongo pygmaeus). To enable a qualitative comparison with gestures in children, we focused on the three following aspects: First we investigated the nature of gestures by examining whether they are used dyadic, triadic, imperative (used to get another individual to help in attaining a goal, cf. Bates, 1976) and/or declarative (used to draw another’s attention to an object or entity merely for the sake of sharing attention, cf. Bates, 1976). Second, we investigated if apes use their gestures intentionally, focusing on the key characteristics for intentional communication in children (Piaget, 1952; Bates, 1976; Bruner, 1981), –a) means-ends dissociation and b) special sensitivity to the social context. A) Means-ends dissociation can be characterized by the flexible relation of signaling behavior and goal. An individual uses for instance a single gesture for several goals (touch for nursing and riding) or different gestures for the same goal (slap ground and bodybeat for play). b) Sensitivity to the social context: The sender performs a gesture toward a recipient for the purpose of communication. Evidence for specifically communicative intent includes the signaler’s alternation of gaze between goal and recipient (Bates, 1979; observed in wild chimpanzees, Plooij, 1978), persistence to the goal, or adjustment to audience effects (Tomasello et al., 1997). Our third goal concerned the learning of gestures by focusing on individual and group variability to distinguish between underlying social and individual learning processes. Following Tomasello and colleagues (Tomasello et al., 1994) similarities in the gestural repertoires within a group and group specific gestures would provide evidence for the existence of a social learning process, whereas individual differences that overshadow group differences (i.e., a lack of systematic group differences, idiosyncratic gestures) imply that an individual learning process is involved.