Cooperative problem solving in a social carnivore

Evidence for socially influenced and potentially actively coordinated cooperation by bumblebees

Cooperation is common in animals, yet the specific mechanisms driving collaborative behaviour in different species remain unclear. We investigated the proximate mechanisms underlying the cooperative behaviour of bumblebees in two different tasks, where bees had to simultaneously push a block in an arena or a door at the end of a tunnel for access to reward. In both tasks, when their partner's entry into the arena/tunnel was delayed, bees took longer to first push the block/door compared with control bees that learned to push alone. In the tunnel task, just before gaining access to reward, bees were more likely to face towards their partner than expected by chance or compared with controls. These results show that bumblebees' cooperative behaviour is not simply a by-product of individual efforts but is socially influenced. We discuss how bees' turning behaviours, e.g. turning around before first reaching the door when their partner was delayed and turning back towards the door in response to seeing their partner heading towards the door, suggest the potential for active coordination. However, because these behaviours could also be interpreted as combined responses to social and secondary reinforcement cues, future studies are needed to help clarify whether bumblebees truly use active coordination.

Social-ecological predictors of spotted hyena navigation through a shared landscape

Human-wildlife interactions are increasing in severity due to climate change and proliferating urbanization. Regions where human infrastructure and activity are rapidly densifying or newly appearing constitute novel environments in which wildlife must learn to coexist with people, thereby serving as ideal case studies with which to infer future human-wildlife interactions in shared landscapes. As a widely reviled and behaviorally plastic apex predator, the spotted hyena (Crocuta crocuta) is a model species for understanding how large carnivores navigate these human-caused 'landscapes of fear' in a changing world. Using high-resolution GPS collar data, we applied resource selection functions and step selection functions to assess spotted hyena landscape navigation and fine-scale movement decisions in relation to social-ecological features in a rapidly developing region comprising two protected areas: Lake Nakuru National Park and Soysambu Conservancy, Kenya. We then used camera trap imagery and Barrier Behavior Analysis (BaBA) to further examine hyena interactions with barriers. Our results show that environmental factors, linear infrastructure, human-carnivore conflict hotspots, and human tolerance were all important predictors for landscape-scale resource selection by hyenas, while human experience elements were less important for fine-scale hyena movement decisions. Hyena selection for these characteristics also changed seasonally and across land management types. Camera traps documented an exceptionally high number of individual spotted hyenas (234) approaching the national park fence at 16 sites during the study period, and BaBA results suggested that hyenas perceive protected area boundaries' semi-permeable electric fences as risky but may cross them out of necessity. Our findings highlight that the ability of carnivores to flexibly respond within human-caused landscapes of fear may be expressed differently depending on context, scale, and climatic factors. These results also point to the need to incorporate societal factors into multiscale analyses of wildlife movement to effectively plan for human-wildlife coexistence.

The proximate regulation of prosocial behaviour: towards a conceptual framework for comparative research

Humans and many other animal species act in ways that benefit others. Such prosocial behaviour has been studied extensively across a range of disciplines over the last decades, but findings to date have led to conflicting conclusions about prosociality across and even within species. Here, we present a conceptual framework to study the proximate regulation of prosocial behaviour in humans, non-human primates and potentially other animals. We build on psychological definitions of prosociality and spell out three key features that need to be in place for behaviour to count as prosocial: benefitting others, intentionality, and voluntariness. We then apply this framework to review observational and experimental studies on sharing behaviour and targeted helping in human children and non-human primates. We show that behaviours that are usually subsumed under the same terminology (e.g. helping) can differ substantially across and within species and that some of them do not fulfil our criteria for prosociality. Our framework allows for precise mapping of prosocial behaviours when retrospectively evaluating studies and offers guidelines for future comparative work.

Some dogs can find the payoff-dominant outcome in the Assurance game

Studies on coordination often present animals with the choice of either cooperating or remaining inactive; however, in nature, animals may also choose to act alone. This can be modeled with the Assurance game, an economic game that has recently been used to explore decision-making in primates. We investigated whether dyads of pet dogs coordinate in the Assurance game. Pairs were presented with two alternatives: they could individually solve an apparatus baited with a low-value reward (Hare) or they could coordinate to solve a cooperative apparatus baited with a high-value reward for each dog (Stag). All individuals matched their partner's choices, but after controlling for side bias, only four out of eleven dyads consistently coordinated on the payoff-dominant strategy (Stag-Stag). Thus, some dogs are capable of finding coordinated outcomes, as do primates, at least when their partner's actions are visible and coordination results in the biggest payoff for both individuals.

A cooperation experiment with white-handed gibbons (Hylobates lar)

Cooperative behaviors among individuals of numerous species play a crucial role in social interactions. There is a special interest in investigating the occurrence of cooperation among apes because this knowledge could also shed light on evolutionary processes and help us understand the origin and development of cooperation in humans and primates in general. Gibbons are phylogenetically intermediate between the great apes and monkeys, and therefore represent a unique opportunity for comparisons. The aim of the present study was to discover whether or not white-handed gibbons (Hylobates lar) show cooperative behaviors. In order to test for the respective behaviors, the gibbons were presented with a commonly used experimental cooperative rope-pulling task. The gibbons in this study did not exhibit cooperative behaviors during the problem-solving task. However, prior training procedures could not be fully completed, hence this project constitutes only the onset of exploring cooperative behaviors in gibbons. Additional behavioral observations revealed that the gibbons spent significantly more time "out of arm's reach to everyone", suggesting that they are less often involved in social interactions, than other, more cooperative primates.

Cooperation increases bottlenose dolphins' (Tursiops truncatus) social affiliation

Dolphins live in a fission-fusion society, where strong social bonds and alliances can last for decades. However, the mechanism that allows dolphins to form such strong social bonds is still unclear. Here, we hypothesized the existence of a positive feedback mechanism in which social affiliation promotes dolphins' cooperation, which in turn promotes their social affiliation. To test it, we stimulated the cooperation of the 11 dolphins studied by providing a cooperative enrichment tool based on a rope-pulling task to access a resource. Then we measured the social affiliation [simple ratio index (SRI)] of each possible pair of dolphins and evaluated whether it increased after cooperation. We also evaluated whether, before cooperation, pairs that cooperated had a higher SRI than those that did not cooperate. Our findings showed that the 11 cooperating pairs had significantly stronger social affiliation before cooperation than the 15 non-cooperating pairs. Furthermore, cooperating pairs significantly increased their social affiliation after cooperation, while non-cooperating pairs did not. As a result, our findings provide support to our hypothesis, and suggest that the previous social affiliation between dolphins facilitates cooperation, which in turn promotes their social affiliation.

Does tolerance allow bonobos to outperform chimpanzees on a cooperative task? A conceptual replication of Hare et al., 2007

Across various taxa, social tolerance is thought to facilitate cooperation, and many species are treated as having species-specific patterns of social tolerance. Yet studies that assess wild and captive bonobos and chimpanzees result in contrasting findings. By replicating a cornerstone experimental study on tolerance and cooperation in bonobos and chimpanzees (Hare et al. 2007 Cur. Biol. 17, 619-623 (doi:10.1016/j.cub.2007.02.040)), we aim to further our understanding of current discrepant findings. We tested bonobos and chimpanzees housed at the same facility in a co-feeding and cooperation task. Food was placed on dishes located on both ends or in the middle of a platform. In the co-feeding task, the tray was simply made available to the ape duos, whereas in the cooperation task the apes had to simultaneously pull at both ends of a rope attached to the platform to retrieve the food. By contrast to the published findings, bonobos and chimpanzees co-fed to a similar degree, indicating a similar level of tolerance. However, bonobos cooperated more than chimpanzees when the food was monopolizable, which replicates the original study. Our findings call into question the interpretation that at the species level bonobos cooperate to a higher degree because they are inherently more tolerant.

The current state of carnivore cognition

The field of animal cognition has advanced rapidly in the last 25 years. Through careful and creative studies of animals in captivity and in the wild, we have gained critical insights into the evolution of intelligence, the cognitive capacities of a diverse array of taxa, and the importance of ecological and social environments, as well as individual variation, in the expression of cognitive abilities. The field of animal cognition, however, is still being influenced by some historical tendencies. For example, primates and birds are still the majority of study species in the field of animal cognition. Studies of diverse taxa improve the generalizability of our results, are critical for testing evolutionary hypotheses, and open new paths for understanding cognition in species with vastly different morphologies. In this paper, we review the current state of knowledge of cognition in mammalian carnivores. We discuss the advantages of studying cognition in Carnivorans and the immense progress that has been made across many cognitive domains in both lab and field studies of carnivores. We also discuss the current constraints that are associated with studying carnivores. Finally, we explore new directions for future research in studies of carnivore cognition.

Yawning informs behavioural state changing in wild spotted hyaenas

Abstract

Yawning is a complex behaviour linked to several physiological (e.g. drowsiness, arousal, thermoregulation) and social phenomena (e.g. yawn contagion). Being yawning an evolutionary well-conserved, fixed action pattern widespread in vertebrates, it is a valuable candidate to test hypotheses on its potential functions across the different taxa. The spotted hyaena (Crocuta crocuta), the most social and cooperative species of the Hyaenidae family, is a good model to test hypotheses on yawning correlates and significances. Through an accurate sequential analysis performed on a group of wild hyaenas, we found that yawning mainly occurred during an imminent behavioural state changing in both juveniles and adults and that seeing others’ yawn elicited a mirror response in the receiver, thus demonstrating that yawn contagion is present in this species. These results taken together suggest that yawning is linked to a behavioural state change of the yawner and that such change is caught by the observers that engage in a motor resonance phenomenon, yawn contagion, possibly effective in anticipating yawners’ motor actions. Although additional data are necessary to verify whether yawn contagion translates into subsequent motor convergence and alignment, our data suggest that both spontaneous and contagious yawning can be fundamental building blocks on the basis of animal synchronisation in highly social and cooperative species.

Significant statement

Yawning is pervasive in many animal species, including humans. It is considered as a polyfunctional cue that has a role in regulating social interactions. While several studies focussed on yawning functions in primates, a little amount of effort was devoted to exploring this behaviour in social carnivores. We monitored a group of wild spotted hyaenas (Crocuta crocuta), which is one of the most cooperative carnivore species. In both immature and adult subjects, we found that a subject frequently changed its behavioural state after spontaneously yawning and that seeing others’ yawn elicited a mirror response in the observer. Although additional data are necessary to verify whether yawn contagion translates into subsequent motor convergence and alignment, our data suggest that both spontaneous and contagious yawning can be fundamental building blocks on the basis of animal synchronisation in highly social and cooperative species.

Teamwork Makes the String Work: A Pilot Test of the Loose String Task with African Crested Porcupines (Hystrix cristata)

Comparative researchers have heavily focused their studies of social cognition on species that live in large social groups, while neglecting other potential predictors of social cognition. African crested porcupines (Hystrix cristata) are relatively rare among mammals in that they are cooperative breeders that pair for life. Little is known about their social cognition, but they are good candidates for exploring cooperative behavior due to the need to coordinate behavior to cooperatively raise young. Cooperation, as defined in this study, is the process by which two or more participants perform independent actions on an object to obtain a reward for all parties. Humans are thought to outperform all other species in the frequency and magnitude of cooperative behaviors. Yet, only by studying a variety of species can researchers fully understand the likely selection pressures for cooperation, such as cooperative breeding. Here, we pilot tested the feasibility of the popular loose-string task with a mated pair of African crested porcupines, a task that required the porcupines to cooperatively pull ropes to access an out of reach platform baited with food rewards. Other species presented with this task were able to work together to receive rewards but did not always demonstrate understanding of the role of their partner. The porcupines achieved success but did not appear to coordinate their actions or solicit behavior from their partner. Thus, similar to other species, they may achieve success in this task without taking their partner’s role into account. This study demonstrates that the loose string task can be used to assess cooperation in porcupines. However, further experiments are needed to assess the porcupine’s understanding of their partner’s role under this paradigm.

The Joint Log-Lift Task: A Social Foraging Paradigm

Behavioural cooperation is under intense research. Yet, popular experimental paradigms often employ artificial tasks, require training, or do not permit partner choice, possibly limiting their biological relevance. We developed the joint log-lift task, a social foraging paradigm in which animals have to jointly lift a log to each obtain a food reward. The task relies on an obligate strategy, meaning that the only way to benefit is to work jointly. We hypothesised that (1) animals learn to spontaneously solve the task, and that (2) kin and (3) more sociable individuals would engage more often together in the task and achieve greater success than non-kin and less sociable individuals, respectively. We presented the task to 8 groups of juvenile domestic pigs (Sus scrofa domesticus) in their home pen for 30 min daily. Over the course of 9 days, the pigs showed evidence of learning by progressively switching from individual to joint behaviours, leading to 68% (62 out of 91 pigs) spontaneously solving the task. Success was influenced by sociability, but not kinship. There were large differences in success among dyads, hinting at the possible role of social dynamics and inter-individual differences in the ability and/or motivation to solve the task. The joint log-lift task allows researchers to investigate spontaneous cooperative tendencies of individuals, dyads and groups in the home environment through ad libitum engagement with the apparatus. This ecologically relevant paradigm opens the way to investigate social foraging experimentally at large scale, by giving animals free choice about when and with whom to work jointly.

Cooperating elephants mitigate competition until the stakes get too high

Cooperation is ubiquitous in the animal kingdom as it aims to maximize benefits through joint action. Selection, however, may also favor competitive behaviors that could violate cooperation. How animals mitigate competition is hotly debated, with particular interest in primates and little attention paid thus far to nonprimates. Using a loose-string pulling apparatus, we explored cooperative and competitive behavior, as well as mitigation of the latter, in semi-wild Asian elephants (Elephas maximus). Our results showed that elephants first maintained a very high cooperation rate (average = 80.8% across 45 sessions). Elephants applied “block,” “fight back,” “leave,” “move side,” and “submission” as mitigation strategies and adjusted these strategies according to their affiliation and rank difference with competition initiators. They usually applied a “fight back” mitigation strategy as a sanction when competition initiators were low ranking or when they had a close affiliation, but were submissive if the initiators were high ranking or when they were not closely affiliated. However, when the food reward was limited, the costly competitive behaviors (“monopoly” and “fight”) increased significantly, leading to a rapid breakdown in cooperation. The instability of elephant cooperation as a result of benefit reduction mirrors that of human society, suggesting that similar fundamental principles may underlie the evolution of cooperation across species.

This study shows that in a task requiring coordinated pulling, elephants compete for access to food but work to mitigate competition in order to maintain cooperation. If the cost of competition becomes too high, however, cooperation breaks down entirely. This behavior mirrors that seen in humans and other great apes, suggesting that certain cooperative mechanisms are not unique to primates.

Exploring the Cognitive Capacities of Japanese Macaques in a Cooperation Game

Simple Summary

Experiments using animal models are often conducted to explore the cognitive capacities of different species and to shed light upon the evolution of behavior and the mind that shapes it. Investigating the cognitions and motivations involved in cooperation is one such area that has attracted attention in recent years. As experiments examining these abilities in natural settings are underrepresented in the literature, our study was conducted in a setting closely resembling the natural environment of the study species so as to retain the social factors that help shape these behaviors. In our experiments, Japanese macaques needed to work together to simultaneously pull two loops in order to release food rewards onto a central platform. Over the course of the experiment, the macaques in our study came to make fewer attempts at the cooperative task when no potential partner was present. Furthermore, following an unequal division of the rewards, macaques receiving lesser rewards were more likely to express stress-related and aggressive behavior. Together, these results suggest that the Japanese macaques in our study understood the importance of having a partner in the cooperative task, paid attention to the relative value of the reward they received from the task and became distressed if their reward was inferior to that of another.

Abstract

Cooperation occurs amongst individuals embedded in a social environment. Consequently, cooperative interactions involve a variety of persistent social influences such as the dynamics of partner choice and reward division. To test for the effects of such dynamics, we conducted cooperation experiments in a captive population of Japanese macaques (Macaca fuscata, N = 164) using a modified version of the loose-string paradigm in an open-experiment design. We show that in addition to becoming more proficient cooperators over the course of the experiments, some of the macaques showed sensitivity to the presence of potential partners and adjusted their behavior accordingly. Furthermore, following an unequal reward division, individuals receiving a lesser reward were more likely to display aggressive and stress-related behaviors. Our experiments demonstrate that Japanese macaques have some understanding of the contingencies involved in cooperation as well as a sensitivity to the subsequent reward division suggestive of an aversion to inequity.

Cognitive enrichment device provides evidence for intersexual differences in collaborative actions in Indo-Pacific bottlenose dolphins (Tursiops aduncus)

Social living, long lifespan and advanced cognitive skills provided favourable conditions for the development of pro-social behaviours and cooperative activities in cetacean. Dolphins have been observed to collaborate for various purposes, finding food, finding mates or raising and teaching younger individuals. This study investigated the potential impact of demographic factors (sex and age), social factors (relatedness and group size), and individual experience in a cooperative problem solving task. A cognitive enrichment device was tested with 22 dolphins in 11 group settings. The device consisted of a tube, containing ice and fish, sealed by two caps with rope handles and designed to be operated by pairs of dolphins. The investigation focused on the differences in trial outcome (success rate of cooperative opening of the device) and on cooperative play (dolphin pairs engaging in synchronous swim with the device). From the five potential factors, sex showed the highest impact. Cooperative openings were more than four times more frequent in males than in females (75% vs 17%, respectively), and cooperative play was exclusively displayed by adult males. Given the strong correlation between cooperative opening and cooperative play, we argue the two behaviours can be regarded as parts of a cooperative action chain. This study provides the first evidence for intersexual differences in collaborative actions in dolphins under systematic testing conditions.

Problem Solving in Animals: Proposal for an Ontogenetic Perspective

Problem solving, the act of overcoming an obstacle to obtain an incentive, has been studied in a wide variety of taxa, and is often based on simple strategies such as trial-and-error learning, instead of higher-order cognitive processes, such as insight. There are large variations in problem solving abilities between species, populations and individuals, and this variation could arise due to differences in development, and other intrinsic (genetic, neuroendocrine and aging) and extrinsic (environmental) factors. However, experimental studies investigating the ontogeny of problem solving are lacking. Here, we provide a comprehensive review of problem solving from an ontogenetic perspective. The focus is to highlight aspects of problem solving that have been overlooked in the current literature, and highlight why developmental influences of problem-solving ability are particularly important avenues for future investigation. We argue that the ultimate outcome of solving a problem is underpinned by interacting cognitive, physiological and behavioural components, all of which are affected by ontogenetic factors. We emphasise that, due to the large number of confounding ontogenetic influences, an individual-centric approach is important for a full understanding of the development of problem solving.

Evidence that bottlenose dolphins can communicate with vocal signals to solve a cooperative task

Cooperation experiments have long been used to explore the cognition underlying animals' coordination towards a shared goal. While the ability to understand the need for a partner in a cooperative task has been demonstrated in a number of species, there has been far less focus on cooperation experiments that address the role of communication. In humans, cooperative efforts can be enhanced by physical synchrony, and coordination problems can be solved using spoken language. Indeed, human children adapt to complex coordination problems by communicating with vocal signals. Here, we investigate whether bottlenose dolphins can use vocal signals to coordinate their behaviour in a cooperative button-pressing task. The two dolphin dyads used in this study were significantly more likely to cooperate successfully when they used whistles prior to pressing their buttons, with whistling leading to shorter button press intervals and more successful trials. Whistle timing was important as the dolphins were significantly more likely to succeed if they pushed their buttons together after the last whistle, rather than pushing independently of whistle production. Bottlenose dolphins are well known for cooperating extensively in the wild, and while it remains to be seen how wild dolphins use communication to coordinate cooperation, our results reveal that at least some dolphins are capable of using vocal signals to facilitate the successful execution of coordinated, cooperative actions.

Kea, Nestor notabilis, achieve cooperation in dyads, triads, and tetrads when dominants show restraint

Animal cooperation in the wild often involves multiple individuals that must tolerate each other in close proximity. However, most cooperation experiments in the lab are done with two animals, that are often also physically separated. Such experiments are useful for answering some pertinent questions, for example about the understanding of the role of the partner and strategies of partner control, but say little about factors determining successful cooperation with multiple partners in group settings. We explored the influence of dominance, rank distance, tolerance, affiliation, and coordination by testing kea parrots with a box requiring two, three, or four chains to be pulled simultaneously to access food rewards. The reward could be divided unevenly, but not monopolized completely. Eventually dyadic, triadic, and tetradic cooperation tasks were solved, showing that non-human animals are capable of tetradic cooperation in an experimental setup. Starting with two chains, we found that in a dyad monopolization of the box by the highest-ranking bird was the largest obstacle preventing successful cooperation. High-ranking birds learned to restrain themselves from monopolizing the box during a single session in which monopolization was hindered by the presence of a large number of birds. Thereafter, restraint by dominants remained the strongest factor determining success in the first trial in dyadic, triadic, and tetradic setups. The probability of success increased with the degree of restraint shown by all dominant subjects present. Previous experience with the task contributed to success in subsequent sessions, while increasing rank distance reduced success notably in the four-chain setup.

Neuronal correlates of strategic cooperation in monkeys

We recorded neural activity in male monkeys playing a variant of the game 'chicken' in which they made decisions to cooperate or not cooperate to obtain rewards of different sizes. Neurons in the middle superior temporal sulcus (mSTS)-previously implicated in social perception-signaled strategic information, including payoffs, intentions of the other player, reward outcomes and predictions about the other player. Moreover, a subpopulation of mSTS neurons selectively signaled cooperatively obtained rewards. Neurons in the anterior cingulate gyrus, previously implicated in vicarious reinforcement and empathy, carried less information about strategic variables, especially cooperative reward. Strategic signals were not reducible to perceptual information about the other player or motor contingencies. These findings suggest that the capacity to compute models of other agents has deep roots in the strategic social behavior of primates and that the anterior cingulate gyrus and the mSTS support these computations.

Cooperative responding in rats: II. Performance on fixed-ratio schedules of mutual reinforcement

Coordinated responses of 5 dyads of rats were investigated under fixed-ratio (FR) schedules of mutual water reinforcement. Coordinated responding was defined as 2 consecutive lever-presses, 1 from each of 2 rats, occurring <.5 s apart. In the FR schedules, each coordinated episode was defined as 1 response in the FR sequence. The size of FR schedules was parametrically manipulated assuming the values of FR 1, 6, 12, 18, 24, 30, 50, and 9, in this order. Each FR remained in effect until responding reached stability. Under all conditions, pairs of rats received access to water simultaneously (mutual reinforcement). Rates and proportions of coordinated responding showed a bitonic inverted U-shaped function of ratio size. Postreinforcement pauses increased systematically as the interreinforcement interval increased. Local rates and proportions increased as a function of response location within ratios. Results of a control condition with relaxed temporal constraints for mutual reinforcement showed decreases in rates and proportion of coordinated responses, suggesting that the coordinated responses were controlled by the mutual reinforcement contingencies. The present experiment showed that coordinated responding is quantitatively affected by 3 properties of FR schedules: response requirement, reinforcement rates, and proximity to reinforcement.

What matters for cooperation? The importance of social relationship over cognition

Cooperation is vital for the survival of many species and has been extensively researched at the ultimate level however, there is a considerable degree of variation within a given species in the extent of cooperative behaviours exhibited. Possible factors that have been discussed to contribute to this variation are the social relationship between the cooperating individuals, but also non-social factors such as inhibitory control. Investigating the performance of wolves, a highly cooperative species, in three experimental cooperative tasks; a coordination (string-pulling) task, a prosocial task and an inequity aversion task, we found that the social relationship between the partners had the largest effects on all tasks, while non-social factors (inhibition, learning speed, causal understanding and persistence) had rather unpredicted, or no effects. The results support the potential importance of relational factors, rather than motivation and cognitive abilities, in driving cooperative interactions.

Indirect genetic effects allow escape from the inefficient equilibrium in a coordination game

Social interactions involving coordination between individuals are subject to an "evolutionary trap." Once a suboptimal strategy has evolved, mutants playing an alternative strategy are counterselected because they fail to coordinate with the majority. This creates a detrimental situation from which evolution cannot escape, preventing the evolution of efficient collective behaviors. Here, we study this problem using evolutionary robotics simulations. We first confirm the existence of an evolutionary trap in a simple setting. We then, however, reveal that evolution can solve this problem in a more realistic setting where individuals need to coordinate with one another. In this setting, simulated robots evolve an ability to adapt plastically their behavior to one another, as this improves the efficiency of their interaction. This ability has an unintended evolutionary consequence: a genetic mutation affecting one individual's behavior also indirectly alters their partner's behavior because the two individuals influence one another. As a consequence of this indirect genetic effect, pairs of partners can virtually change strategy together with a single mutation, and the evolutionary barrier between alternative strategies disappears. This finding reveals a general principle that could play a role in nature to smoothen the transition to efficient collective behaviors in all games with multiple equilibriums.

How animals collaborate: Underlying proximate mechanisms

Collaboration or social interactions in which two or more individuals coordinate their behavior to produce outcomes from which both individuals benefit are common in nature. Individuals from many species hunt together, defend their territory, and form coalitions in intragroup competition. However, we still know very little about the proximate mechanisms underlying these behaviors. Recent theories of human cognitive evolution have emphasized the role collaboration may have played in the selection of socio-cognitive skills. It has been argued that the capacity to form shared goals and joint intentions with others, is what allows humans to collaborate so flexibly and efficiently. Although there is no evidence that nonhuman animals are capable of shared intentionality, there is conceivably a wide range of proximate mechanisms that support forms of, potentially flexible, collaboration in other species. We review the experimental literature with the aim of evaluating what we know about how other species achieve collaboration; with a particular focus on chimpanzees. We structure the review with a new categorization of collaborative behavior that focuses on whether individuals intentionally coordinate actions with others. We conclude that for a wider comparative perspective we need more data from other species but the findings so far suggest that chimpanzees, and possibly other great apes, are capable of understanding the causal role of a partner in collaboration. This article is categorized under: Cognitive Biology > Evolutionary Roots of Cognition Psychology > Comparative Psychology.

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. While the majority of tools described are inanimate objects, the use of social tools has received relatively little attention. Here we provide the first evidence of naturally occurring spontaneous exploitative behaviour of a conspecific as a social tool for food acquisition in non-human animals. We observed gorillas in captivity utilising a conspecific as a ladder to gain access to unreachable food. We discuss our findings in the light of other studies on social tool use and suggest the need for more nuanced interpretations of gorillas’ cognitive skills.

Testing use of a potential cognitive enrichment device by an Indo-Pacific bottlenose dolphin (Tursiops aduncus)

Cognitive enrichment aims to provide animals with opportunities to use their cognitive skills and to promote behaviors associated with positive wellbeing. Cooperation in mammals has been recorded during various behavioral contexts such as hunting, mating, playing, and parental care. Coordinated activity, often with some level of problem-solving action included, is required during cooperation. To investigate dolphins' ability for collaborative problem-solving, an enrichment device was introduced to two adult male Indo-Pacific bottlenose dolphins (Tursiops aduncus). The device contained fish and ice and was designed to be opened by simultaneously pulling on both ends. After repeated presentation, it became apparent that only one dolphin had active interest in the device. To facilitate opportunities for problem-solving by this individual, an alternative collaborator, a human partner, was provided. Still, both dolphins had access to the device throughout the entire experiment. After the first opening, the same dolphin was highly successful in collaborating with the human in both joined (93%) and delayed (100%) partner conditions. The device provided a novel opportunity for the dolphin to use his cognitive skills. Even though only one dolphin participated actively, both dolphins showed varying degrees of interest to the device throughout the study. Both dolphins spent an average of 48% and 16% of their time, respectively, with the device, which resulted in a significant decrease in their other two most frequently observed behaviors: swimming and poolside observation. As a novel cognitive challenge, the device may be considered as a type of cognitive enrichment.

Chimpanzees (Pan troglodytes) tolerate some degree of inequity while cooperating but refuse to donate effort for nothing

In cooperative hunting, a carcass cannot be divided equally, and hunts may be unsuccessful. We studied how chimpanzees respond to these two variables, working for unequal rewards and no rewards, which have been rarely included in experimental cooperative tasks. We presented chimpanzees with a task requiring three chimpanzees to work together and varied the reward structure in two separate experiments. In Experiment 1, two individuals received more rewards than the third, making the outcome unequal. We wanted to know if cooperation would continue or break down, and what mechanisms might maintain performance. Experiment 2 used equal rewards, but this time one or more locations were left unbaited on a proportion of trials. Thus, there was a chance of individuals working to receive nothing. In Experiment 1, the chimpanzees worked at a high rate, tolerating the unequal outcomes, with rank appearing to determine who got access to the higher-value locations. However, equal outcomes (used as a control) enhanced cooperative performance, most likely through motivational processes rather than the absence of inequity aversion. In Experiment 2, performance dropped off dramatically when the chimpanzees were not rewarded on every trial. Their strategy was irrational as donating effort would have led to more rewards in the long run for each individual. Our results lead to a hierarchy of performances by condition with equity > inequity > donating effort. Chimpanzees therefore tolerate mild inequity, but cannot tolerate receiving nothing when others are rewarded.

Bonobo personality predicts friendship

In bonobos, strong bonds have been documented between unrelated females and between mothers and their adult sons, which can have important fitness benefits. Often age, sex or kinship similarity have been used to explain social bond strength variation. Recent studies in other species also stress the importance of personality, but this relationship remains to be investigated in bonobos. We used behavioral observations on 39 adult and adolescent bonobos housed in 5 European zoos to study the role of personality similarity in dyadic relationship quality. Dimension reduction analyses on individual and dyadic behavioral scores revealed multidimensional personality (Sociability, Openness, Boldness, Activity) and relationship quality components (value, compatibility). We show that, aside from relatedness and sex combination of the dyad, relationship quality is also associated with personality similarity of both partners. While similarity in Sociability resulted in higher relationship values, lower relationship compatibility was found between bonobos with similar Activity scores. The results of this study expand our understanding of the mechanisms underlying social bond formation in anthropoid apes. In addition, we suggest that future studies in closely related species like chimpanzees should implement identical methods for assessing bond strength to shed further light on the evolution of this phenomenon.

Cooperation in bottlenose dolphins: bidirectional coordination in a rope-pulling task

In comparison with terrestrial animals, such as primates, there is limited empirical evidence for cooperative behavior in marine mammals under experimental conditions. In this study, we used a cooperative rope-pulling task to investigate how bottlenose dolphins (Tursiops truncatus) coordinate their behavior with a partner. Dolphins successfully learned and were able to perform the task, even when one subject started after the other. In the no-delay condition (i.e., both subjects sent at the same time), one pair of dolphins showed coordinated behaviors. When pairs were successful in solving the task in the delay condition (i.e., one individual sent later than the other), the initiators (i.e., first individual sent) were likely to wait for the follower to arrive, and the follower was likely to swim faster when the initiator did not wait and started pulling the rope alone. These coordinated behaviors might help resolve the given cooperative task. Our results suggest that bottlenose dolphins learn to coordinate their behaviors via trial and error and recognize the necessity of performing simultaneous actions with a partner to successfully accomplish cooperative tasks. In addition, both partners showed behavioral changes over many trials of no-delay and delay conditions, suggesting that bidirectional coordination occurred in the cooperative task.

In what sense are dogs special? Canine cognition in comparative context

The great increase in the study of dog cognition in the current century has yielded insights into canine cognition in a variety of domains. In this review, we seek to place our enhanced understanding of canine cognition into context. We argue that in order to assess dog cognition, we need to regard dogs from three different perspectives: phylogenetically, as carnivoran and specifically a canid; ecologically, as social, cursorial hunters; and anthropogenically, as a domestic animal. A principled understanding of canine cognition should therefore involve comparing dogs' cognition with that of other carnivorans, other social hunters, and other domestic animals. This paper contrasts dog cognition with what is known about cognition in species that fit into these three categories, with a particular emphasis on wolves, cats, spotted hyenas, chimpanzees, dolphins, horses, and pigeons. We cover sensory cognition, physical cognition, spatial cognition, social cognition, and self-awareness. Although the comparisons are incomplete, because of the limited range of studies of some of the other relevant species, we conclude that dog cognition is influenced by the membership of all three of these groups, and taking all three groups into account, dog cognition does not look exceptional.

A task-experienced partner does not help dogs be as successful as wolves in a cooperative string-pulling task

Although theories of domestication have suggested that dogs evolved a greater capacity for tolerant and cooperative behaviour compared to their wild wolf cousins, the differences between wolves’ and free-ranging dogs’ social ecology, with wolves relying more on conspecific cooperation than dogs, would rather predict the opposite. In a cooperative task involving joint action on a rope to pull a tray forward, wolves systematically outperformed dogs. The dogs’ failure appeared largely due to tolerance issues, i.e. one partner avoiding interacting with the apparatus, when the other was engaged with it, rather than cognitive limitations. To verify this, in the current study we trained the dominant partner to become an ‘expert’ on the task thereby potentially enhancing their understanding that they ‘needed the partner to succeed’. Indeed both the duration of co-action on the apparatus and the success rate of dyads composed of an expert and an inexperienced dog was higher than dyads composed of two inexperienced partners. Nevertheless the dogs’ performance was substantially poorer than that of wolf dyads with equivalent experience, highlighting that despite the facilitating effect of the ‘expert’, cooperation on this task did not come easily to dogs. For both dogs and wolves, cooperation was facilitated by the closeness of the affiliative bond between individuals, but opposite rank effects emerged. Dogs further apart in rank were more successful co-operators, whereas in wolves, animals closer in rank had a higher cooperative success. The results further highlight the importance of the different socio-ecologies of wolves and dogs in understanding their behaviour.

Bottlenose dolphins can understand their partner's role in a cooperative task

In recent decades, a number of studies have examined whether various non-human animals understand their partner's role in cooperative situations. Yet the relatively tolerant timing requirements of these tasks make it theoretically possible for animals to succeed by using simple behavioural strategies rather than by jointly intended coordination. Here we investigated whether bottlenose dolphins could understand a cooperative partner's role by testing whether they could learn a button-pressing task requiring precise behavioural synchronization. Specifically, members of cooperative dyads were required to swim across a lagoon and each press their own underwater button simultaneously (within a 1 s time window), whether sent together or with a delay between partners of 1–20 s. We found that dolphins were able to work together with extreme precision even when they had to wait for their partner, and that their coordination improved over the course of the study, with the time between button presses in the latter trials averaging 370 ms. These findings show that bottlenose dolphins can learn to understand their partner's role in a cooperative situation, and suggest that the behavioural synchronization evident in wild dolphins' synchronous movement and coordinated alliance displays may be a generalized cognitive ability that can also be used to solve novel cooperative tasks.

Associations between glucocorticoids and sociality across a continuum of vertebrate social behavior

The causes and consequences of individual differences in animal behavior and stress physiology are increasingly studied in wild animals, yet the possibility that stress physiology underlies individual variation in social behavior has received less attention. In this review, we bring together these study areas and focus on understanding how the activity of the vertebrate neuroendocrine stress axis (HPA-axis) may underlie individual differences in social behavior in wild animals. We first describe a continuum of vertebrate social behaviors spanning from initial social tendencies (proactive behavior) to social behavior occurring in reproductive contexts (parental care, sexual pair-bonding) and lastly to social behavior occurring in nonreproductive contexts (nonsexual bonding, group-level cooperation). We then perform a qualitative review of existing literature to address the correlative and causal association between measures of HPA-axis activity (glucocorticoid levels or GCs) and each of these types of social behavior. As expected, elevated HPA-axis activity can inhibit social behavior associated with initial social tendencies (approaching conspecifics) and reproduction. However, elevated HPA-axis activity may also enhance more elaborate social behavior outside of reproductive contexts, such as alloparental care behavior. In addition, the effect of GCs on social behavior can depend upon the sociality of the stressor (cause of increase in GCs) and the severity of stress (extent of increase in GCs). Our review shows that the while the associations between stress responses and sociality are diverse, the role of HPA-axis activity behind social behavior may shift toward more facilitating and less inhibiting in more social species, providing insight into how stress physiology and social systems may co-evolve.

To free, or not to free: Social reinforcement effects in the social release paradigm with rats

The present research measured social reinforcement in rats, using a social-release procedure in which lever presses permitted 10-s access to a familiar social partner. The work requirements for reinforcement increased systematically according to progressive-ratio (PR) schedules. Social and food reinforcement value were compared across blocks of sessions (Experiment 1) and concurrently within the same sessions (Experiment 2). To assess motivational effects, response and reinforcer rates for both reinforcer types were studied under food restriction, social restriction, and combined food and social restriction. Responding was maintained by both reinforcers, albeit at substantially higher levels for food than for social access. Responding for social access decreased to low levels under extinction conditions, demonstrating functional control by the social-reinforcement contingency. Sensitivity to social restriction was seen in some conditions in Experiment 2, in which social reinforcers were earned earlier in the session (at lower food prices) under social restriction than under the other deprivation conditions. Altogether, results are consistent with a social reinforcement conceptualization, and demonstrate an important role for social contact in social release behavior. The study demonstrates a promising set of methods for analyzing and quantifying social reinforcement.

Comparing physical and social cognitive skills in macaque species with different degrees of social tolerance

Contemporary evolutionary theories propose that living in groups drives the selection of enhanced cognitive skills to face competition and facilitate cooperation between individuals. Being able to coordinate both in space and time with others and make strategic decisions are essential skills for cooperating within groups. Social tolerance and an egalitarian social structure have been proposed as one specific driver of cooperation. Therefore, social tolerance is predicted to be associated with enhanced cognitive skills that underpin communication and coordination. Social tolerance should also be associated with enhanced inhibition, which is crucial for suppressing automatic responses and permitting delayed gratification in cooperative contexts. We tested the performance of four closely related non-human primate species (genus Macaca) characterized by different degrees of social tolerance on a large battery of cognitive tasks covering physical and social cognition, and on an inhibitory control task. All species performed at a comparable level on the physical cognition tasks but the more tolerant species outperformed the less tolerant species at a social cognition task relevant to cooperation and in the inhibitory control task. These findings support the hypothesis that social tolerance is associated with the evolution of sophisticated cognitive skills relevant for cooperative social living.

Importance of a species' socioecology: Wolves outperform dogs in a conspecific cooperation task

A number of domestication hypotheses suggest that dogs have acquired a more tolerant temperament than wolves, promoting cooperative interactions with humans and conspecifics. This selection process has been proposed to resemble the one responsible for our own greater cooperative inclinations in comparison with our closest living relatives. However, the socioecology of wolves and dogs, with the former relying more heavily on cooperative activities, predicts that at least with conspecifics, wolves should cooperate better than dogs. Here we tested similarly raised wolves and dogs in a cooperative string-pulling task with conspecifics and found that wolves outperformed dogs, despite comparable levels of interest in the task. Whereas wolves coordinated their actions so as to simultaneously pull the rope ends, leading to success, dogs pulled the ropes in alternate moments, thereby never succeeding. Indeed in dog dyads it was also less likely that both members simultaneously engaged in other manipulative behaviors on the apparatus. Different conflict-management strategies are likely responsible for these results, with dogs' avoidance of potential competition over the apparatus constraining their capacity to coordinate actions. Wolves, in contrast, did not hesitate to manipulate the ropes simultaneously, and once cooperation was initiated, rapidly learned to coordinate in more complex conditions as well. Social dynamics (rank and affiliation) played a key role in success rates. Results call those domestication hypotheses that suggest dogs evolved greater cooperative inclinations into question, and rather support the idea that dogs' and wolves' different social ecologies played a role in affecting their capacity for conspecific cooperation and communication.

Cooperative problem solving in giant otters (Pteronura brasiliensis) and Asian small-clawed otters (Aonyx cinerea)

Cooperative problem solving has gained a lot of attention over the past two decades, but the range of species studied is still small. This limits the possibility of understanding the evolution of the socio-cognitive underpinnings of cooperation. Lutrinae show significant variations in socio-ecology, but their cognitive abilities are not well studied. In the first experimental study of otter social cognition, we presented two species—giant otters and Asian small-clawed otters—with a cooperative problem-solving task. The loose string task requires two individuals to simultaneously pull on either end of a rope in order to access food. This task has been used with a larger number of species (for the most part primates and birds) and thus allows for wider cross-species comparison. We found no differences in performance between species. Both giant otters and Asian small-clawed otters were able to solve the task successfully when the coordination requirements were minimal. However, when the temporal coordination demands were increased, performance decreased either due to a lack of understanding of the role of a partner or due to difficulty inhibiting action. In conclusion, two species of otters show some ability to cooperate, quite similar to most other species presented with the same task. However, to draw further conclusions and more nuanced comparisons between the two otter species, further studies with varied methodologies will be necessary.

Big cats as a model system for the study of the evolution of intelligence

Currently, carnivores, and felids in particular, are vastly underrepresented in cognitive literature, despite being an ideal model system for tests of social and ecological intelligence hypotheses. Within Felidae, big cats (Panthera) are uniquely suited to studies investigating the evolutionary links between social, ecological, and cognitive complexity. Intelligence likely did not evolve in a unitary way but instead evolved as the result of mutually reinforcing feedback loops within the physical and social environments. The domain-specific social intelligence hypothesis proposes that social complexity drives only the evolution of cognitive abilities adapted only to social domains. The domain-general hypothesis proposes that the unique demands of social life serve as a bootstrap for the evolution of superior general cognition. Big cats are one of the few systems in which we can directly address conflicting predictions of the domain-general and domain-specific hypothesis by comparing cognition among closely related species that face roughly equivalent ecological complexity but vary considerably in social complexity.

The psychology of cooperation: Insights from chimpanzees and children

Across all cultures, humans engage in cooperative activities that can be as simple as preparing a meal or sharing food with others and as complex as playing in an orchestra or donating to charity. Although intraspecific cooperation exists among many other animal species, only humans engage in such a wide array of cooperative interaction and participate in large-scale cooperation that extends beyond kin and even includes strangers.

Primate empathy: three factors and their combinations for empathy-related phenomena

Empathy as a research topic is receiving increasing attention, although there seems some confusion on the definition of empathy across different fields. Frans de Waal (de Waal FBM. Putting the altruism back into altruism: the evolution of empathy. Annu Rev Psychol 2008, 59:279-300. doi:10.1146/annurev.psych.59.103006.093625) used empathy as an umbrella term and proposed a comprehensive model for the evolution of empathy with some of its basic elements in nonhuman animals. In de Waal's model, empathy consists of several layers distinguished by required cognitive levels; the perception-action mechanism plays the core role for connecting ourself and others. Then, human-like empathy such as perspective-taking develops in outer layers according to cognitive sophistication, leading to prosocial acts such as targeted helping. I agree that animals demonstrate many empathy-related phenomena; however, the species differences and the level of cognitive sophistication of the phenomena might be interpreted in another way than this simple linearly developing model. Our recent studies with chimpanzees showed that their perspective-taking ability does not necessarily lead to proactive helping behavior. Herein, as a springboard for further studies, I reorganize the empathy-related phenomena by proposing a combination model instead of the linear development model. This combination model is composed of three organizing factors: matching with others, understanding of others, and prosociality. With these three factors and their combinations, most empathy-related matters can be categorized and mapped to appropriate context; this may be a good first step to discuss the evolution of empathy in relation to the neural connections in human and nonhuman animal brains. I would like to propose further comparative studies, especially from the viewpoint of Homo-Pan (chimpanzee and bonobo) comparison. WIREs Cogn Sci 2017, 8:e1431. doi: 10.1002/wcs.1431 For further resources related to this article, please visit the WIREs website.

Kea cooperate better with sharing affiliates

Controlled studies that focus on intraspecific cooperation tasks have revealed striking similarities, but also differences, in abilities across taxa as diverse as primates, fish, and birds. Such comparisons may provide insight into the specific socio-ecological selection pressures that led to the evolution of cooperation. Unfortunately, however, compared to primates data on birds remain relatively scarce. We tested a New Zealand psittaciform, the kea, in a dyadic cooperation task using the loose-string design. During trials our subjects were in separate compartments, but obtained a common reward that could be divided multiple ways, allowing the examination of reward division effects. Ten individuals were tested twice in 44 combinations of partners. Dyads with a high affiliation score attempted to cooperate more often and were also more often successful in doing so. Furthermore, dyads that shared rewards more equally seemed to be more likely to attempt cooperation in the next trial. Like other bird and some monkey species, but unlike, for example, chimpanzees, kea did not spontaneously show understanding of either the role of the partner or the mechanism behind the cooperation task. This may point to true disparities between species, but may also be due to differences in task design and/or the amount of exposure to similar tasks and individual skills of the subjects.