We describe the individual and combined use of vocalizations and gestures in wild chimpanzees. The rate of gesturing peaked in infancy and, with the exception of the alpha male, decreased again in ...older age groups, while vocal signals showed the opposite pattern. Although gesture-vocal combinations were relatively rare, they were consistently found in all age groups, especially during affiliative and agonistic interactions. Within behavioural contexts rank (excluding alpha-rank) had no effect on the rate of male chimpanzees' use of vocal or gestural signals and only a small effect on their use of combination signals. The alpha male was an outlier, however, both as a prolific user of gestures and recipient of high levels of vocal and gesture-vocal signals. Persistence in signal use varied with signal type: chimpanzees persisted in use of gestures and gesture-vocal combinations after failure, but where their vocal signals failed they tended to add gestural signals to produce gesture-vocal combinations. Overall, chimpanzees employed signals with a sensitivity to the public/private nature of information, by adjusting their use of signal types according to social context and by taking into account potential out-of-sight audiences. We discuss these findings in relation to the various socio-ecological challenges that chimpanzees are exposed to in their natural forest habitats and the current discussion of multimodal communication in great apes.
Animals that maintain cooperative relationships show gains in longevity and offspring survival. However, little is known about the cognitive or hormonal mechanisms involved in cooperation. Indeed, ...there is little support for a main hypothesis that non-human animals have the cognitive capacities required for bookkeeping of cooperative exchanges. We tested an alternative hypothesis that cooperative relationships are facilitated by an endocrinological mechanism involving oxytocin, a hormone required for bonding in parental and sexual relationships across mammals. We measured urinary oxytocin after single bouts of grooming in wild chimpanzees. Oxytocin levels were higher after grooming with bond partners compared with non-bond partners or after no grooming, regardless of genetic relatedness or sexual interest. We ruled out other possible confounds, such as grooming duration, grooming direction or sampling regime issues, indicating that changes in oxytocin levels were mediated by social bond strength. Oxytocin, which is thought to act directly on neural reward and social memory systems, is likely to play a key role in keeping track of social interactions with multiple individuals over time. The evolutionary linkage of an ancestral hormonal system with complex social cognition may be the primary mechanism through which long-term cooperative relationships develop between both kin and non-kin in mammals.
Fine-scale knowledge of the changes in composition and function of the human gut microbiome compared that of our closest relatives is critical for understanding the evolutionary processes underlying ...its developmental trajectory. To infer taxonomic and functional changes in the gut microbiome across hominids at different timescales, we perform high-resolution metagenomic-based analyzes of the fecal microbiome from over two hundred samples including diverse human populations, as well as wild-living chimpanzees, bonobos, and gorillas. We find human-associated taxa depleted within non-human apes and patterns of host-specific gut microbiota, suggesting the widespread acquisition of novel microbial clades along the evolutionary divergence of hosts. In contrast, we reveal multiple lines of evidence for a pervasive loss of diversity in human populations in correlation with a high Human Development Index, including evolutionarily conserved clades. Similarly, patterns of co-phylogeny between microbes and hosts are found to be disrupted in humans. Together with identifying individual microbial taxa and functional adaptations that correlate to host phylogeny, these findings offer insights into specific candidates playing a role in the diverging trajectories of the gut microbiome of hominids. We find that repeated horizontal gene transfer and gene loss, as well as the adaptation to transient microaerobic conditions appear to have played a role in the evolution of the human gut microbiome.
Abstract Stereotypies are repetitive and relatively invariant patterns of behavior, which are observed in a wide range of species in captivity. Stereotypic behavior occurs when environmental demands ...produce a physiological response that, if sustained for an extended period, exceeds the natural physiological regulatory capacity of the organism, particularly in situations that include unpredictability and uncontrollability. One hypothesis is that stereotypic behavior functions to cope with stressful environments, but the existing evidence is contradictory. To address the coping hypothesis of stereotypies, we triggered physiological reactions in 22 horses affected by stereotypic behavior (crib-biters) and 21 non-crib-biters (controls), using an ACTH challenge test. Following administration of an ACTH injection, we measured saliva cortisol every 30 min and heart rate (HR) continuously for a period of 3 h. We did not find any differences in HR or HR variability between the two groups, but crib-biters (Group CB) had significantly higher cortisol responses than controls (Group C; mean ± SD: CB, 5.84 ± 2.62 ng/ml, C, 4.76 ± 3.04 ng/ml). Moreover, crib-biters that did not perform the stereotypic behavior during the 3-hour test period (Group B) had significantly higher cortisol levels than controls, which was not the case of crib-biters showing stereotypic behavior (Group A) (B, 6.44 ± 2.38 ng/ml A, 5.58 ± 2.69 ng/ml). Our results suggest that crib-biting is a coping strategy that helps stereotypic individuals to reduce cortisol levels caused by stressful situations. We conclude that preventing stereotypic horses from crib-biting could be an inappropriate strategy to control this abnormal behavior, as it prevents individuals from coping with situations that they perceive as stressful.
Previous research has shown that a considerable number of primates can remember the location and fruiting state of individual trees in their home range. This enables them to relocate fruit or predict ...whether previously encountered fruit has ripened. Recent studies, however, suggest that the ability of primates to cognitively map fruit-bearing trees is limited. In this study, we investigated an alternative and arguably simpler, more efficient strategy, the use of synchrony, a botanical characteristic of a large number of fruit species. Synchronous fruiting would allow the prediction of the fruiting state of a large number of trees without having to first check the trees. We studied whether rainforest primates, grey-cheeked mangabeys in the Kibale National Park, Uganda, used synchrony in fruit emergence to find fruit. We analysed the movements of adult males towards
Uvariopsis congensis
food trees, a strongly synchronous fruiting species with different local patterns of synchrony. Monkeys approached within crown distance, entered and inspected significantly more
Uvariopsis
trees when the percentage of trees with ripe fruit was high compared to when it was low. Since the effect was also found for empty trees, the monkeys likely followed a synchrony-based inspection strategy. We found no indication that the monkeys generalised this strategy to all
Uvariopsis
trees within their home range. Instead, they attended to fruiting peaks in local areas within the home range and adjusted their inspective behaviour accordingly revealing that non-human primates use botanical knowledge in a flexible way.
Monkeys of the Taï Forest McGraw, William Scott; Zuberbühler, K. (Klaus); Noë, Ronald
05/2007, Letnik:
v.Series Number 51
eBook, Book
A great deal has been written about primates; however few volumes have focused on an entire community of sympatric monkeys at a single site. Drawing upon diverse sets of data, the authors provide a ...multi-thematic case study of the entire monkey community of the Taï forest (Ivory Coast). Much of the book explores how the seven monkey species have adapted to hunting pressures from chimpanzees, leopards, crowned eagles and humans. Other themes covered include feeding ecology, social behaviour, positional behaviour and habitat use, vocal communication and conservation. Colour photographs of all species are provided, showing the major behavioural characteristics of each, as little is known about these West African monkeys. This scientifically important volume will be of interest to a broad audience including primatologists, functional anatomists, psychologists, and behavioural ecologists.
•The function of crib-biting (CB) behaviour is poorly understood.•We compared the performance of CB versus control (C) horses in frustrating tasks.•CB horses had lower salivary cortisol values ...compared to other horses.•CB horses were also less likely to display behaviours indicating frustration.•Our results suggest that CB is a coping strategy serving to reduce stress.
Stereotypies are common in captive animals, but it remains unclear if they are pathological by-products of captive conditions or if they have an adaptive function. Here, we address this question using crib-biting, a common type of stereotypic behaviour in domestic horses, thought to result from stressful or frustrating environments. Since chronic stress is known to affect learning abilities via dopaminergic modulation in the basal ganglia, we predicted that stereotypic horses would underperform in learning tasks compared to healthy control animals, in line with the pathological by-product hypothesis. We exposed 19 crib-biters and 18 control horses in six spatial tasks, and collected behavioural and physiological data (heart rate, heart rate variability and salivary cortisol) to assess learning performance and stress levels. We found that, during the learning phase, 10 of 19 crib-biters showed stereotypic behaviour. Surprisingly, crib-biters that displayed the stereotypic behaviour (Group A) had lower salivary cortisol values compared to crib-biters that did not display the stereotypic behaviour (Group B) or control horses (Group C), after the first part of the experiment. In addition, a smaller proportion of horses in Group A displayed behaviours indicating frustration during one of the test compared to Group B. Moreover, we found no difference between the three groups in their learning performance nor in their heart rate or heart rate variability measures. Our results therefore suggest that crib-biting has an adaptive function and can help horses to reduce stress and frustration during learning tasks, which then enables them to show normal learning performance.
Animal semantic communication has received considerable theoretical and empirical attention because of its relevance to human language. Advances have been made by studies of alarm-call behaviour in ...nonhumans. In monkeys, for example, there is evidence that recipients have a fairly sophisticated understanding of a call's meaning; that is, the predator type usually associated with a certain alarm call. Little is known, however, about the mental mechanisms that drive call production in nonhuman primates. In some nonprimate species, it has been found that signallers do not respond to a predator's physical features but instead seem to respond to its relative threat or direction of attack. In these species, therefore, alarm calls do not denote different predator categories but simply reflect different types or levels of danger. Because different predator categories typically impose different types and degrees of threat it is entirely possible that nonhuman primates also respond to threat rather than a predator's category. This study examined how wild Diana monkeys, Cercopithecus diana, of the Taı̈ forest, Ivory Coast, label predation events. By altering playback stimuli and the position of a concealed speaker, I investigated whether Diana monkeys respond with acoustically different alarm calls depending on a predator's (1) distance (close versus far), (2) elevation (above versus below), or (3) category (eagle versus leopard). Analysis of male and female alarm-call behaviour showed that Diana monkeys consistently responded to predator category regardless of immediate threat or direction of attack. Data further suggested that, in addition to predator category, monkeys’ alarm calls might also convey information about the predator's distance.
West African Diana monkeys (Cercopithecus diana) and Campbell's monkeys (Cercopithecus campbelli) frequently form mixed-species associations. Males of both species produce acoustically distinct alarm ...calls to crowned eagles (Stephanoaetus coronatus) and leopards (Panthera pardus), two of their main predators. Field playback experiments were conducted to investigate whether Diana monkeys respond to Campbell's alarm calls and whether they understand the calls' semantic content. Diana monkeys responded to playback of Campbell's leopard or eagle alarm calls as though the original predator were present. In a second experiment, Diana monkeys were primed with either Campbell's eagle or leopard alarm calls and then subsequently probed with the vocalizations of a crowned eagle or a leopard. Results showed that monkeys used the semantic information conveyed by the Campbell's alarm calls to predict the presence of a predator. The data are consistent with the hypothesis that non-human primates are able to use acoustic signals of diverse origin as labels for underlying mental representations.
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