Search

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2010.02.022 Byline: L. Marechal (a), E. Genty (b), J.J. Roeder (a) Abstract: Three brown lemurs, Eulemur fulvus, and two black lemurs, Eulemur macaco, were trained to select consistently the photograph of the face of a known individual (KI: belonging to the same social group) when it was presented simultaneously with a photograph of the face of an unfamiliar individual (UI: belonging to another social group). After the learning phase, the subjects were presented with new pairs of photographs (KI versus UI: photographs that were not used in the learning phase), the same pairs presented in different associations, and finally pairs of photographs that were completely novel (50 different pairs). All the subjects selected the KI significantly more often than the UI under all conditions. Additional tests showed that the subjects preferentially selected photographs of a UI belonging to their own species versus a UI belonging to the other species. No preference was observed when the subjects were presented with two KI or with their own photograph associated with a UI. These results reveal that the face contains information allowing lemurs to discriminate familiar individuals from unfamiliar ones. Author Affiliation: (a) IPHC-DEPE, CNRS, UDS, France (b) Centre de Primatologie, Universite de Strasbourg, France Article History: Received 26 June 2009; Revised 10 September 2009; Accepted 15 February 2010 Article Note: (miscellaneous) MS. number: 09-00432R

Catalytic total oxidation is an effective technique for the treatment of industrial VOCs principally resulting from industrial processes using solvents and usually containing mono-aromatics (BTEX) and oxygenated compounds (acetone, ethanol, butanone). The aim of this work is to deposit gold nanoparticles on CoAl mixed oxide issued from layered double hydroxide (LDH) precursor by using the deposition precipitation (DP) method, which is applied with two modifications, labeled method (A) and method (B), in order to enhance the interaction of the HAuCl 4 precursor with the support. Method (A) involves the hydrolysis of the HAuCl 4 precursor after addition of the support, while in method (B), the gold precursor is hydrolyzed before adding the support. The two methods were applied using as support the CoAl mixed oxide and the LDH precursor. Samples were characterized by several physical chemical techniques and evaluated for ethanol total oxidation. Method (B) allowed the ethanol oxidation activity to be enhanced for the resulting Au/CoAlOx catalysts thanks to the high surface concentration of Co 2+ and improved reducibility at low temperature. The presence of gold permits to minimize the formation of by-products, notably, methanol, allowed for a total oxidation of ethanol at lower temperature than the corresponding support.

The Interaction Engine Hypothesis postulates that humans have a unique ability and motivation for social interaction. A crucial juncture in the ontogeny of the interaction engine could be around 2-4 years of age, but observational studies of children in natural contexts are limited. These data appear critical also for comparison with non-human primates. Here, we report on focal observations on 31 children aged 2- and 4-years old in four preschools (10 h per child). Children interact with a wide range of partners, many infrequently, but with one or two close friends. Four-year olds engage in cooperative social interactions more often than 2-year olds and fight less than 2-year olds. Conversations and playing with objects are the most frequent social interaction types in both age groups. Children engage in social interactions with peers frequently (on average 13 distinct social interactions per hour) and briefly (28 s on average) and shorter than those of great apes in comparable studies. Their social interactions feature entry and exit phases about two-thirds of the time, less frequently than great apes. The results support the Interaction Engine Hypothesis, as young children manifest a remarkable motivation and ability for fast-paced interactions with multiple partners. This article is part of the theme issue 'Revisiting the human 'interaction engine': comparative approaches to social action coordination'.

Joint commitment, the feeling of mutual obligation binding participants in a joint action, is typically conceptualized as arising by the expression and acceptance of a promise. This account limits the possibilities of investigating fledgling forms of joint commitment in actors linguistically less well-endowed than adult humans. The feeling of mutual obligation is one aspect of joint commitment (the product ), which emerges from a process of signal exchange. It is gradual rather than binary; feelings of mutual obligation can vary in strength according to how explicit commitments are perceived to be. Joint commitment processes are more complex than simple promising, in at least three ways. They are affected by prior joint actions, which create precedents and conventions that can be embodied in material arrangements of institutions. Joint commitment processes also arise as solutions to generic coordination problems related to opening up, maintaining and closing down joint actions. Finally, during joint actions, additional, specific commitments are made piecemeal. These stack up over time and persist, making it difficult for participants to disengage from joint actions. These complexifications open up new perspectives for assessing joint commitment across species. This article is part of the theme issue 'Revisiting the human 'interaction engine': comparative approaches to social action coordination'.

Human communication relies heavily on pragmatic competence. Speech utterances are often ambiguous requiring listeners to use interaction history, shared knowledge, presumed intention and other contextual variables to make inferences about a speaker's meaning. To probe the evolutionary origins of pragmatic competence we tested whether bonobos (Pan paniscus) can make inferences about the type of food available from listening to other group members' food calls. We trained two group members to either prefer blue or pink chow and demonstrated these preferences to observers. A third group member served as an untrained control. In playback experiments, we broadcast the food calls of a trained demonstrator and the untrained group member to investigate whether subjects were able to infer which coloured chow was most likely available, based on the callers' trained food preferences or lack thereof. As predicted, when hearing the untrained group member's calls, subjects did not exhibit a bias, whereas they responded with a significant foraging bias when hearing a trained group member's calls. These findings suggest that bonobos may take into account the idiosyncratic food preferences of others, although subjects probably differed in what they remembered., Competing Interests: The authors have declared that no competing interests exist.

Human joint action seems special, as it is grounded in joint commitment-a sense of mutual obligation participants feel towards each other. Comparative research with humans and non-human great apes has typically investigated joint commitment by experimentally interrupting joint actions to study subjects' resumption strategies. However, such experimental interruptions are human-induced, and thus the question remains of how great apes naturally handle interruptions. Here, we focus on naturally occurring interruptions of joint actions, grooming and play, in bonobos and chimpanzees. Similar to humans, both species frequently resumed interrupted joint actions (and the previous behaviours, like grooming the same body part region or playing the same play type) with their previous partners and at the previous location. Yet, the probability of resumption attempts was unaffected by social bonds or rank. Our data suggest that great apes experience something akin to joint commitment, for which we discuss possible evolutionary origins., (© 2021 The Authors.)

Many social animals interact jointly, but only humans experience a specific sense of obligation toward their co-participants, a joint commitment . However, joint commitment is not only a mental state but also a process that reveals itself in the coordination efforts deployed during entry and exit phases of joint action. Here, we investigated the presence and duration of such phases in N  = 1,242 natural play and grooming interactions of captive chimpanzees and bonobos. The apes frequently exchanged mutual gaze and communicative signals prior to and after engaging in joint activities with conspecifics, demonstrating entry and exit phases comparable to those of human joint activities. Although rank effects were less clear, phases in bonobos were more moderated by friendship compared to phases in chimpanzees, suggesting bonobos were more likely to reflect patterns analogous to human "face management". This suggests that joint commitment as process was already present in our last common ancestor with Pan ., Competing Interests: The authors declare no competing interests., (© 2021 The Authors.)

Joint action is central to human nature, enabling collectives to achieve goals otherwise unreachable by individuals. It is enabled by humans' capacity to understand and engage in joint commitments. Joint commitments are evidenced when partners in interrupted joint actions reengage one another. To date, there is no clear evidence whether nonhuman animals understand joint commitment, suggesting that only humans experience it. Here, we revisit this claim by interrupting bonobos engaged in social activities. Bonobos reliably resumed the activity, and the likelihood of resumption was higher for social compared to solitary activities. Furthermore, communicative efforts deployed to suspend and resume social activities varied depending on partners' social relationships and interactive roles. Our results suggest that bonobos, like humans, engage in joint commitment and have some awareness of the social consequences of breaking it., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

The question of whether animals have some sort of self-awareness is a topic of continued debate. A necessary precondition for self-awareness is the ability to visually discriminate the self from others, which has traditionally been investigated through mirror self-recognition experiments. Although great apes generally pass such experiments, interpretations of results have remained controversial. The aim of this study was to investigate how bonobos ( Pan paniscus ) respond to different types of images of themselves and others, both before and after prolonged mirror exposure. We first presented presumably mirror-naive subjects with representations of themselves in three different ways (mirror image, contingent and non-contingent video footage) as well as representations of others (video footage of known and unknown conspecifics). We found that subjects paid significantly less attention to contingent images of themselves (mirror image, video footage) than to non-contingent images of themselves and unfamiliar individuals, suggesting they perceived the non-contingent self-images as novel. We then provided subjects with three months of access to a large mirror centrally positioned in the enclosure. Following this manipulation, subjects showed significantly reduced interest in the non-contingent self-images, while interest in unknown individuals remained unchanged, suggesting that the mirror experience has led to a fuller understanding of their own self. We discuss implications of this preliminary investigation for the on-going debate on self-awareness in animals., Competing Interests: The authors declare there are no competing interests., (©2020 Shorland et al.)

Catalytic total oxidation is an effective technique for the treatment of industrial VOCs. This emission is generally accompanied by the presence of other products like CO, NO x or other VOC. In this paper, the development of catalysts for the total oxidation of CO and toluene mixture is performed. For this study, Mg 6 Al₂HT hydrotalcites precursors were synthesized by three different methods: co-precipitation, microwaves and ultrasound assisted method. Hydrotalcite precursors have been used in order to develop mixed oxides after calcination for the catalytic oxidation test. Hydrotalcite structure as well as the mixed oxides obtained after calcination was studied, by several techniques: XRD, TEM, DTA/TG, BET, N₂ sorption, H₂-TPR. The physico chemical studies revealed modification in the structural characteristics (surface area, porosity) as well as in reducibility properties of the formed mixed oxides. The nanocatalyst issued from microwaves synthesis was the most active in these studied reactions for the total oxidation of the mixture. Moreover, addition of CO on the reaction mixture allows obtaining a beneficial effect on the toluene oxidation.

A fruitful approach to investigate social learning in animals is based on paradigms involving the manipulation of artefacts. However, tool use and elaborate object manipulations are rare in natural conditions, suggesting that social learning evolved in other contexts where fitness consequences are higher, such as discriminating palatable from noxious foods, recognising predators or understanding social hierarchies. We focussed on one such context by investigating whether bonobos socially learned others' arbitrary food preferences through mere observation. To this end, we trained two demonstrators to prefer or avoid distinctly coloured food items, treated with either a sweet or bitter agent. Demonstrators then displayed their newly acquired preferences in front of naïve subjects. In subsequent choice tests, subjects generally matched their choices to the demonstrators' preferred food colours, despite having already tasted the equally palatable colour alternative. Both age and exposure to demonstrator preference had a significant positive effect on the proportion of matched choices. Moreover, in a context where errors can be costly, social learning was instant insofar as six of seven subjects used socially learned information to influence their very first food choice. We discuss these findings in light of the current debate on the evolution of social learning in animals., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Social play has a complex, cooperative nature that requires substantial coordination. This has led researchers to use social games to study cognitive abilities like shared intentionality, the skill and motivation to share goals and intentions with others during joint action. We expand this proposal by considering play as a joint action and examining how shared intentionality is achieved during human joint action. We describe how humans get into, conduct, and get out of joint actions together in an orderly way, thereby constructing the state of "togetherness" characteristic of shared intentionality. These processes play out as three main phases, the opening (where participants are ratified and joint commitments are established), the main body (where progress, ongoing commitments, and possible role reversals are coordinated), and the closing (where the intention to terminate the action is coordinated and where participants take leave of each other). We use this process in humans as a framework for examining how various animal species get into, maintain, and get out of play bouts. This comparative approach constitutes an alternative measure of those species' possession of shared intentionality. Using this framework, we review the play literature on human children and different social species of mammals and birds in search of behavioral markers of shared intentionality in the coordination of play bouts. We discuss how our approach could shed light on the evolution of the special human motivation to cooperate and share psychological states with others.

Toluene is one of the most used Volatile Organic Compounds (VOCs) in the industry despite its major health impacts. Catalytic oxidation represents an efficient remediation technique in order to reduce its emission directly at the source, but it can release by-products. To complete the classical performance assessment using dedicated analytical chemistry methods, we propose to perform an untargeted toxicological validation on two efficient catalysts. Using biological system allows integrating synergy and antagonism in toxic effects of emitted VOCs and by-products, often described in case of multi-exposure condition. Catalysts Pd/α-Al 2 O 3 and Pd/γ-Al 2 O 3 developed for the oxidation of toluene were both coupled to a Vitrocell ® Air-Liquid Interface (ALI) system, for exposure of human A549 lung cells during 1h to toluene or to catalysts exhaust before quantification of xenobiotics metabolizing enzymes. This study validated initially the Vitrocell ® as an innovative, direct and dynamic model of ALI exposure in the assessment of the performances of new catalysts, showing the presence of chemically undetected by-products. The comparison of the two catalysts showed then that fewer organic compounds metabolizing genes were induced by Pd/γ-Al 2 O 3 in comparison to Pd/α-Al 2 O 3 , suggesting that Pd/γ-Al 2 O 3 is more efficient for toluene total oxidation from a toxicological point of view., (Copyright © 2016. Published by Elsevier Inc.)

Human and nonhuman primate communication differs in various ways. In particular, humans base communicative efforts on mutual knowledge and conventions shared between interlocutors. In this study, we experimentally tested whether bonobos (Pan paniscus), a close relative to humans, are able to take into account the familiarity, i.e. the shared interaction history, when communicating with a human partner. In five experimental conditions we found that subjects took the recipients' attentional state and their own communicative effectiveness into account by adjusting signal production accordingly. More importantly, in case of communicative failure, subjects repeated previously successful signals more often with a familiar than unfamiliar recipient, with whom they had no previous interactions, and elaborated by switching to new signals more with the unfamiliar than the familiar one, similar to what has previously been found in two year-old children. We discuss these findings in relation to the human capacity to establish common ground between interlocutors, a crucial aspect of human cooperative communication.

Sexual behaviour in bonobos (Pan paniscus) functions beyond mere reproduction to mediate social interactions and relationships. In this study, we assessed the signalling behaviour in relation to four social goals of sex in this species: appeasement after conflict, tension reduction, social bonding and reproduction. Overall, sexual behaviour was strongly decoupled from its ancestral reproductive function with habitual use in the social domain, which was accompanied by a corresponding complexity in communication behaviour. We found that signalling behaviour varied systematically depending on the initiator's goals and gender. Although all gestures and vocalisations were part of the species-typical communication repertoire, they were often combined and produced flexibly. Generally, gestures and multi-modal combinations were more flexibly used to communicate a goal than vocalisations. There was no clear relation between signalling behaviour and success of sexual initiations, suggesting that communication was primarily used to indicate the signaller's intention, and not to influence a recipient's willingness to interact sexually. We discuss these findings in light of the larger question of what may have caused, in humans, the evolutionary transition from primate-like communication to language.

We comment on a recent behavioral study in which we describe a human-like beckoning gesture in 2 groups of bonobos, used in combination with sexual solicitation postures. The beckoning gesture fulfils key criteria of deixis and iconicity, in that it communicates to a distant recipient the desired travel path in relation to a specific social intention, i.e., to have sex at another location. We discuss this finding in light of the fact that, despite the documented great ape capacity and obvious communicative advantage, referential gestures are still surprisingly rare in their natural communication. We address several possibilities for this peculiar underuse and are most compelled by the notion that non-human primates are generally not very motivated to share their experiences of external objects or events with others, which removes most reasons for referential signaling.

Great apes frequently produce gestures during social interactions to communicate in flexible, goal-directed ways [1-3], a feature with considerable relevance for the ongoing debate over the evolutionary origins of human language [1, 4]. But despite this shared feature with language, there has been a lack of evidence for semantic content in ape gestures. According to one authoritative view, ape gestures thus do not have any specific referential, iconic, or deictic content, a fundamental difference versus human gestures and spoken language [1, 5] that suggests these features have a more recent origin in human evolution, perhaps caused by a fundamental transition from ape-like individual intentionality to human-like shared intentionality [6]. Here, we revisit this human uniqueness claim with a study of a previously undescribed human-like beckoning gesture in bonobos that has potentially both deictic and iconic character. We analyzed beckoning in two groups of bonobos, kept under near natural environmental and social conditions at the Lola Ya Bonobo sanctuary near Kinshasa, Democratic Republic of Congo, in terms of its linguistic content and underlying communicative intention., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

'Contest hoots' are acoustically complex vocalisations produced by adult and subadult male bonobos (Pan paniscus). These calls are often directed at specific individuals and regularly combined with gestures and other body signals. The aim of our study was to describe the multi-modal use of this call type and to clarify its communicative and social function. To this end, we observed two large groups of bonobos, which generated a sample of 585 communicative interactions initiated by 10 different males. We found that contest hooting, with or without other associated signals, was produced to challenge and provoke a social reaction in the targeted individual, usually agonistic chase. Interestingly, 'contest hoots' were sometimes also used during friendly play. In both contexts, males were highly selective in whom they targeted by preferentially choosing individuals of equal or higher social rank, suggesting that the calls functioned to assert social status. Multi-modal sequences were not more successful in eliciting reactions than contest hoots given alone, but we found a significant difference in the choice of associated gestures between playful and agonistic contexts. During friendly play, contest hoots were significantly more often combined with soft than rough gestures compared to agonistic challenges, while the calls' acoustic structure remained the same. We conclude that contest hoots indicate the signaller's intention to interact socially with important group members, while the gestures provide additional cues concerning the nature of the desired interaction.

Rosati et al. (Curr Biol 17(19):1663-1668, 2007) found in a self-control test in which choice was between a smaller, immediately delivered food and a larger, delayed food, that chimpanzees preferred the larger reward (self-control); humans, however, preferred the smaller reward (impulsivity). They attributed their results to a species difference in self-control. In Experiment 1, monkeys (long-tailed macaques) were exposed to a self-control task in two conditions: where the food was hidden under differently colored bowls and where it was visible. When these two conditions were compared, choice shifted from greater preference for the impulsive alternative in the hidden condition to greater preference for the self-control alternative in the visible condition. Additionally, in both conditions, preference shifted from self-control to impulsivity over sessions. These results were explained in terms of the reversed-contingency effect (a propensity to reach for more over less when rewards are visible) and not to a capacity for self-control. In Experiment 2, humans that demonstrated preference for more over less in choice preferred the impulsive alternative when choice to either alternative was followed by the same intertrial interval-a preference that accelerates trial rates relative to preference of the self-control alternative. When trial rates were equated so that neither choice accelerated session's end, humans demonstrated self-control. These results suggest that Rosati et al.'s demonstration of impulsivity in humans was due to participants' desire to minimize session time.

Objective: To assess the results of inlay butterfly tympanoplasty on dry perforation., Study Design: Retrospective case study., Patients: 26 patient (14 male, 12 female), mean age 38 years, ranged from 9 to 73. Mean follow up: 20 months., Surgery: Inlay cartilage butterfly tympanoplasty performed under general or local anesthesia according to the technique originally described by Eavey, with our specific modifications (use of a dermatological punch)., Results: 92.3% of perforation closure was obtained; 2 residual perforations and 1 non-epithelialisation were observed. No iatrogenic cholesteatoma was observed. The mean preoperative to post operative four-tone air bone gap improved from 27.67 to 20.1 (mean gain 7.5)., Conclusion: Inlay butterfly cartilage tympanoplasty is a safe, efficient and easy technique. This technique need more prospective evaluation, and its place among other techniques of tympanoplasty needs to be precised.

Objectives: To report the long-term sinonasal complications after endoscopic repair of anterior skull base fractures in children. This study describes mucocele formation in 6 patients treated endoscopically for posttraumatic CSF fistulae. We aim to address possible etiologic factors, specific treatments and follow-up modalities., Patients and Methods: 12 children, mean age 5.8 years (3-10), treated endoscopically at our institution between 2004 and 2010 for an anterior cranial base fracture complicated by a CSF fistula. An iatrogenic mucocele was observed in 6 cases. A retrospective review of the files of these 6 patients was carried out demonstrating demographic characteristics, presenting signs/symptoms, site of skull base defect, repair technique, timing and onset of the mucoceles, their presentation and management. A systematic CT-scan and/or MRI was carried out at 3 months, 1 year and then annually., Results: 3 patients presented after cranial trauma with persistent CSF nasal leak, and 4 with meningitis. Posttraumatic defects reached the posterior wall of the frontal sinus and the junction of ethmoid and frontal bone in 3 cases, and the cribriform plate in 3 cases. Endoscopic closure was performed in all cases, with the middle turbinate as an overlay patch. No recurrence of a CSF leak was observed. After a mean period of 16 months, a single iatrogenic mucocele was observed in 4 patients (radiological detection only), and multiple mucoceles in 2 patients. Surgical treatment was advocated in cases of proptosis, quick expansion of the mucocele leading to sinus bony wall remodelling or erosion (2 cases), and meningitis related to an erosion of the cribriform plate by the mucocele. Three mucoceles were successfully treated endoscopically, and 1 required an external approach., Conclusion: Mucocele incidence after endoscopic repair of skull base fractures in children is not insignificant (50% in our 12 patients series). Paediatric anatomical features, cranial trauma, and the transethmoidal approach may play a role in mucocele pathogenesis. Long-term clinical and radiological follow-up is therefore recommended. These mucoceles may be managed endoscopically with good outcomes., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

In previous studies we demonstrated that brown and black lemurs (Eulemur fulvus and E. macaco) showed self-control abilities under a reverse-reward contingency. They were able to significantly select the smaller quantity of food to be rewarded with the larger one and to generalize this ability when presented with two rewards that differed in quality. In the present study, previously trained subjects had to choose between graphic representations of two different quantities of food under the reverse-reward contingency. Three out of four subjects learned to associate a graphic representation of the reward with the corresponding quantity. Only one subject consistently selected the representation of the smaller quantity to be rewarded with the larger quantity of food and therefore showed abstraction as well as relative numerousness skills. Indeed, she was able to discriminate between representations of different quantities and to ordinate them. We discuss how primates mentally represent food quantities and how self-control is involved in foraging strategies.

A common paradigm used to study inhibitory control is the reverse-reward contingency task in which the subject is presented with a choice between two different quantities of food and is rewarded with the non-chosen item. Most animals have problems inhibiting their impulsive choice towards the larger quantity, and need correction procedures to master the reverse-reward task. Recent studies have nonetheless shown that rhesus macaques and white crowned mangabeys were able to master the task without correction procedures after a large number of trials were applied. We previously demonstrated that, similar to other primates tested under the reverse-reward contingency task, lemurs initially showed an impulsive bias towards the larger quantity of food. But following introduction of a large-or-none contingency, all the subjects learned to reliably select the smaller quantity in order to gain access to the larger one. Here, we assessed the possibility that, similar to rhesus macaques and mangabeys, lemurs could master the reverse-reward task, without a modified procedure, by presenting a large number of trials. One of 5 subjects was able to master the task and then generalize performance to novel food arrays., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Objective: To analyse the efficacy of CO(2) laser arytenoidectomy in the management of bilateral vocal cord paralysis in children., Methods: Retrospective series of 17 patients who underwent laser arytenoidectomy for bilateral vocal cord between 1995 and 2008 in a tertiary care institution. All patients had bilateral laryngeal paralysis, in isolation (n=5) or associated with concomitant airway conditions (n=12). All cases had anterior prolapse of the arytenoids with partial obstruction of the airway on inspiration. 12/17 patients (70.5%) were tracheotomy-dependant, 2/17 were in-extubatable, and 3/17 had severe airway limitation, effort dyspnea and poor sleep pattern. Main outcome measures were decannulation rate for patients with tracheotomy, occurrence of aspiration and quality of voice., Results: The mean age was 2.8 years old. 9/12 patients with tracheotomy (75%) were decannulated with a median delay of 2 months (2 days to 18 months). Both of the intubated patients were extubated with a median delay of 36h. One of the decannulated patients who re-presented with a residual dyspnea after the arytenoidectomy was improved by a further laser cordotomy. 2/17 patients (11.7%) had post-operative persistent aspirations (with pneumopathies in one case), 5/17 patients were dysphonic, 3 improved with speech therapy and 2 with intracordal lipoinjection., Conclusions: Laser arytenoidectomy is effective for improving the breathing in children presenting with a bilateral vocal fold paralysis associated with obstructive arytenoid prolapse. Results are good as a first-line surgery or following laryngo-tracheal surgery. Voice outcomes are satisfactory. However, aspiration is a rare complication., (Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.)

Great ape gestures have attracted considerable research interest in recent years, prompted by their flexible and intentional pattern of use; but almost all studies have focused on single gestures. Here, we report the first quantitative analysis of sequential gesture use in western gorillas (Gorilla gorilla gorilla), using data from three captive groups and one African study site. We found no evidence that gesture sequences were given for reasons of increased communicative efficiency over single gestures. Longer sequences of repeated gestures did not increase the likelihood of response, and using a sequence was seldom in reaction to communicative failure. Sequential combination of two gestures with similar meanings did not generally increase effectiveness, and sometimes reduced it. Gesture sequences were closely associated with play contexts. Markov transition analysis showed two networks of frequently co-occurring gestures, both consisting of gestures used to regulate play. One network comprised only tactile gestures, the other a mix of silent, audible and tactile gestures; apparently, these clusters resulted from gesture use in play with proximal or distal contact, respectively. No evidence was found for syntactic effects of sequential combination: meanings changed little or not at all. Semantically, many gestures overlapped massively with others in their core information (i.e. message), and gesture messages spanned relatively few functions. We suggest that the underlying semantics of gorilla gestures is highly simplified compared to that of human words. Gesture sequences allow continual adjustment of the tempo and nature of social interactions, rather than generally conveying semantically referential information or syntactic structures.

Social groups of gorillas were observed in three captive facilities and one African field site. Cases of potential gesture use, totalling 9,540, were filtered by strict criteria for intentionality, giving a corpus of 5,250 instances of intentional gesture use. This indicated a repertoire of 102 gesture types. Most repertoire differences between individuals and sites were explicable as a consequence of environmental affordances and sampling effects: overall gesture frequency was a good predictor of universality of occurrence. Only one gesture was idiosyncratic to a single individual, and was given only to humans. Indications of cultural learning were few, though not absent. Six gestures appeared to be traditions within single social groups, but overall concordance in repertoires was almost as high between as within social groups. No support was found for the ontogenetic ritualization hypothesis as the chief means of acquisition of gestures. Many gestures whose form ruled out such an origin, i.e. gestures derived from species-typical displays, were used as intentionally and almost as flexibly as gestures whose form was consistent with learning by ritualization. When using both classes of gesture, gorillas paid specific attention to the attentional state of their audience. Thus, it would be unwarranted to divide ape gestural repertoires into 'innate, species-typical, inflexible reactions' and 'individually learned, intentional, flexible communication'. We conclude that gorilla gestural communication is based on a species-typical repertoire, like those of most other mammalian species but very much larger. Gorilla gestures are not, however, inflexible signals but are employed for intentional communication to specific individuals.

In the present study we asked whether lemurs could learn to manipulate information in order to deceive a human competitive trainer. Four brown lemurs were trained to communicate about the location of a hidden reward to a cooperative trainer, who rewarded the subject if he indicated the baited bowl. Next, a competitive trainer was introduced who kept the reward for himself if the subject indicated the baited bowl. In a first experiment, sessions were randomly assigned to be with either the cooperative or competitive trainer. No subject was able to show an efficient tactic with both trainers. In a second experiment, the participation of the two trainers was randomized across the trials for each session. When trials were mixed, one subject significantly chose baited location when interacting with the cooperative trainer, and reliably increased his choices of the unbaited location when presented with the competitive trainer. As with most other primate species tested under the same paradigm, associative learning may explain deceptive pointing by lemurs in this study.

When presented a choice between two food-type arrays of equivalent size under a reverse-reward contingency, black (Eulemur macaco) and brown (Eulemur fulvus) lemurs transposed their self-control abilities, acquired in a previous experiment, to significantly select the less-desired food item in order to gain access to the more desired one. However, when presented with the choice between two different food-type arrays in which the amount of the less desired food array was larger than the more desired one, large individual differences were revealed: Some subjects established a consistent rule favoring quality or quantity, whereas others exhibited various point of trade-off. These results show that lemurs seem to manage the task considering not only food quantity but also food quality., (Copyright 2007 APA.)