Comparing wolves and dogs: current status and implications for human 'self-domestication'.

Based on claims that dogs are less aggressive and show more sophisticated socio-cognitive skills compared with wolves, dog domestication has been invoked to support the idea that humans underwent a similar 'self-domestication' process. Here, we review studies on wolf-dog differences and conclude that results do not support such claims: dogs do not show increased socio-cognitive skills and they are not less aggressive than wolves. Rather, compared with wolves, dogs seek to avoid conflicts, specifically with higher ranking conspecifics and humans, and might have an increased inclination to follow rules, making them amenable social partners. These conclusions challenge the suitability of dog domestication as a model for human social evolution and suggest that dogs need to be acknowledged as animals adapted to a specific socio-ecological niche as well as being shaped by human selection for specific traits.

Adult, intensively socialized wolves show features of attachment behaviour to their handler.

Dogs' attachment towards humans might be the core of their social skillset, yet the origins of their ability to build such a bond are still unclear. Here we show that adult, hand-reared wolves, similarly to dogs, form individualized relationship with their handler. During separation from their handler, wolves, much like family dogs, showed signs of higher-level stress and contact seeking behaviour, compared to when an unfamiliar person left them. They also used their handler as a secure base, suggesting that the ability to form interspecific social bonds could have been present already in the common ancestor of dogs and wolves. We propose that their capacity to form at least some features of attachment with humans may stem from the ability to form social bond with pack members. This might have been then re-directed to humans during early domestication, providing the basis for the evolution of other socio-cognitive abilities in dogs.

Wolves and dogs recruit human partners in the cooperative string-pulling task.

In comparison to non-human animals, humans are highly flexible in cooperative tasks, which may be a result of their ability to understand a partner's role in such interactions. Here, we tested if wolves and dogs could flexibly adjust their behaviour according to whether they needed a partner to solve a cooperative loose string-pulling paradigm. First, we presented animals with a delay condition where a human partner was released after the subject so that the animal had to delay pulling the string to enable coordinated pulling with the human partner. Subsequently, we investigated whether subjects would recruit a partner depending on whether they could operate the apparatus alone, or help from a partner was required. Both wolves and dogs successfully waited in the delay condition in 88% of the trials. Experimental subjects were also successful in recruiting a partner, which occurred significantly more often in the cooperation trials than in the solo pulling condition. No species differences were found in either experiment. These results suggest that both wolves and dogs have some understanding of whether a social partner is needed to accomplish a task, which enables behavioural coordination and cooperation.

Anthropogenic food resources sustain wolves in conflict scenarios of Western Iran.

The feeding ecology of gray wolves has been investigated extensively worldwide. Despite previous studies on food habits of wolves in Asia and Iran, none has focused on the diet of the species in a scenario of depleted of wild prey and with recent records of attacks on humans. Here, we combined telemetry methods and scat analysis to study the diet of wolves in areas of Hamadan province, Iran, where medium to large wild prey is almost absent. Between October 2015 and March 2017, we studied the feeding behavior (by identifying feeding sites through clusters of GPS locations) of three wolves fitted with GPS collars, belonging to different wolf packs. We also collected and analyzed 110 wolf scats during the same period within the same areas. Overall, we investigated 850 clusters of GPS locations in the field, and identified 312 feeding sites. Most feeding clusters were linked to dumpsites and poultry farms around villages. We found 142 and 170 events of predatory (kill sites) and scavenging behavior, respectively. Prey composition based on kill sites was comprised of 74.6% livestock, 19.7% lagomorphs, 3.5% dogs, 1.4% red fox, and 0.7% golden jackal. Similarly, prey composition based on scavenging clusters was comprised of 79.9% livestock, 10.6% red fox, and 9.4% golden jackal. Scat analysis, however, indicated that livestock (34.3%), garbage (23.7%), poultry (16.0%), and European hare (15.4%) were the most frequent food items. We discuss the role of anthropogenic food sources in a context where agonistic wolf-human encounters occur recurrently, and suggest management guidelines regarding illegal dumping of animal carcasses and garbage dumpsites, in order to minimize wolf-human negative interactions.

The role of life experience in affecting persistence: A comparative study between free-ranging dogs, pet dogs and captive pack dogs.

Persistence in object manipulation has been consistently associated with problem-solving success and it is known to be affected, at the individual level, by life experience. Differences in life experiences are particularly poorly studied in the problem-solving context and mainly refer to the comparison between wild and captive animals. Dogs represent interesting study subjects, since dog populations differ widely in their life experiences. In this comparative study we investigated subjects' persistence when presenting a novel object containing food that could not be accessed (impossible task) to three dog populations with very diverse life experiences: free-ranging village dogs (in Morocco), pet dogs (in Vienna) and captive pack living dogs (Wolf Science Center-WSC). We found that pet dogs and captive dogs (WSC) were more manipulative and persistent than free-ranging dogs. The low persistence of free ranging-dogs is unlikely the effect of a lack of exposure to objects, since they are confronted with many human' artefacts in their environment daily. Instead, we suggest that the higher persistence of captive dogs and pet dogs in comparison to free-ranging dogs might be due to their increased experience of human-mediated object interaction. This provides subjects with a socially guided experience in manipulating and interacting with objects increasing their motivation to engage in such tasks.

Dogs and wolves do not differ in their inhibitory control abilities in a non-social test battery.

Being able to inhibit certain behaviours is of clear advantage in various situations. In particular, it has been suggested that inhibitory control plays a role in problem-solving and cooperation. Interspecific differences in the capacity for inhibitory control have been attributed to social and ecological factors, while one additional factor, namely domestication, has received only little attention so far. Dogs are an interesting species to test the effects of socio-ecological factors and also the influence of domestication on inhibitory control abilities. While dogs might have been selected for enhanced inhibition skills during domestication, the predictions derived from their socio-ecological background are reversed. Wolves are cooperative hunters and breeders, while dogs predominately scavenge and raise their young alone, accordingly, it would be predicted that dogs show impaired inhibitory control abilities since they no longer rely on these coordinated actions. To test these hypotheses, we assessed inhibitory control abilities in dogs and wolves raised and kept under similar conditions. Moreover, considering the problem of context-specificity in inhibitory control measures, we employed a multiple-test-approach. In line with previous studies, we found that the single inhibition tests did not correlate with each other. Using an exploratory approach, we found three components that explained the variation of behaviours across tests: motivation, flexibility, and perseveration. Interestingly, these inhibition components did not differ between dogs and wolves, which contradicts the predictions based on their socio-ecological backgrounds but also suggests that at least in tasks with minimal human influence, domestication did not affect dogs' inhibitory control abilities, thus raising questions in regard to the selection processes that might have affected inhibitory control abilities during the course of domestication.

Food preferences of similarly raised and kept captive dogs and wolves.

Food preferences may be driven by a species' ecology. Closely related species such as dogs and wolves may have evolved preferences for different foods owing to their differing foraging styles. Wolves have been shown to be more persistent in problem-solving experiments and more risk-prone in a foraging task. A possible element affecting these (and other) results is a potential wolf-dog difference in food preferences. To address this possibility, we tested similarly raised and kept dogs and wolves in two different food choice tasks, a classic two-choice task and a multiple-choice paradigm. We predicted that if dogs have adapted to a more opportunistic, scavenging foraging style, they would show a weaker preference for meat over starch rich foods (such as kibble) and be less affected by hunger than wolves. Alternatively, given the recentness of the new niche dogs have created, we predicted no substantial differences between dogs' and wolves' food preferences. We found that our subjects did not differ in their preference for meat over kibble in either paradigm. However, wolves' (but not dogs') choice patterns were affected by satiation, with wolves being less "selective" when hungry. Furthermore, when fed before testing, wolves were more selective than dogs. These differences were more noticeable in the multiple-choice paradigm than the two-choice task, suggesting that the former, novel paradigm may be more sensitive and better capable of evaluating food preferences in a diverse range of species. Overall, we found that the distinct differences in wolves' and dogs' ecology and foraging styles do not appear to have affected their food preferences and thus, differences in food preferences are unlikely to have influenced results of previous experiments demonstrating wolf-dog differences in cognitive skills.

Wolf (Canis lupus) hybrids highlight the importance of human-directed play behavior during domestication of dogs (Canis familiaris).

The domestication of animals and plants offers an exceptional opportunity to study evolutionary adaptations. In particular, domesticated animals display several behavioral alterations, including increased sociability and decreased fearfulness and aggression, when compared with their wild ancestors. However, studies quantifying simultaneous changes in multiple behaviors during domestication are lacking. Moreover, the role of human-directed play behavior has been largely neglected when studying the domestication process. Here we address these issues by examining behavioral changes during the domestication of the dog (Canis familiaris) from the gray wolf (Canis lupus) using a standardized behavioral test applied to wolf hybrids and several dog breeds. Contrary to expectations, our study provides little support for collective behavioral alterations. Specifically, although we found that wolf hybrids were less playful and overall more fearful than dogs, we did not detect any differences in sociability or aggression between wolf hybrids and dog breeds. Instead, our results suggest that behavioral alterations during domestication do not necessarily occur in concert and point to an important, but previously overlooked, role of selection on play behavior directed at humans during the domestication of dogs. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

A new approach to understanding canine social cognition.

Domestic dogs have become well known for their socio-cognitive successes, so what does it mean when domestic dogs fail to cooperate? A new study by Marshall-Pescini, Schwarz, Kostelnik, Virányi, and Range (PNAS, 114(44) 11793-11798, 2017) highlights the importance of considering socioecological context, learning, and relationship quality when evaluating the social cognition of dogs and wolves.

Post-conflict opponent affiliation reduces victim re-aggression in a family group of captive arctic wolves (Canis lupus arctos).

Post-conflict affiliative interactions have been widely investigated in primates but not extensively in other species. Using the Post Conflict-Matched Control (PC-MC) comparison method, this study investigated the patterns of post-conflict opponent affiliation (POA) of a captive family group of 19 arctic wolves (Canis lupus arctos), investigating the correlation with various factors. We found that POAs occurred mainly in the non-feeding context and more often when the victim was dominant and the aggressor subordinate. Furthermore, POAs were more likely to have been initiated by the victim than the aggressor. Victims' stress related behaviours occurred more in PC than MC periods, and more after high vs. low intensity aggressions but they were not more likely to occur after conflicts between wolves with a stronger social bond and POAs did not reduce their rate of occurrence. Our results showed that re-aggression was twice less frequent when a friendly interaction occurred between the aggressor and the victim, and consistent with this, victims engaged in POAs more often than the aggressor. Overall, our results support the hypothesis that POAs in wolves may have been selected for as a mechanism to avoid conflict escalation, which could lead to social disruption and hence jeopardize cooperative activities. The high relatedness among individuals in the pack and the greater dependence of all members on cooperation in breeding and hunting may reduce the importance of 'relationship quality' as a mediating factor of POAs, although dominance relationships, which are directly linked to the risks of further conflicts, do play an important role.

Cross-jurisdictional management of a trophy-hunted species.

Gray wolves (Canis lupus) are managed for competing uses in the Greater Yellowstone Ecosystem (GYE). Tourism benefits Yellowstone National Park (YNP) visitors while trophy hunting benefits hunters outside of the park. We investigate the policy scope of gray wolf management across jurisdictional boundaries by incorporating three foundations of the behavioral ecology of wolves: refuge-seeking behavior, optimal foraging group size and territoriality. Tradeoffs between and within consumptive and non-consumptive human benefits and wolf population fitness and life history indicators are quantified as a set of elasticities, providing clear implications to resource managers. Our approach highlights that hunting intensity affects the provision of consumptive and non-consumptive human benefits across jurisdictional boundaries and ought to be managed accordingly. We also show that population levels are an incomplete indicator of species fitness, which may depend on how hunting policies impact underlying group ecology. Our findings suggest traditional optimization approaches to wildlife management may lead to suboptimal policy recommendations when the boundaries on the natural system are oversimplified. Highlighting the human element of wildlife management, we show that understanding tourist and hunter responses to wildlife population abundances is critical to balancing provision of consumptive and non-consumptive human uses.

Numerical assessment in the wild: insights from social carnivores.

Playback experiments have proved to be a useful tool to investigate the extent to which wild animals understand numerical concepts and the factors that play into their decisions to respond to different numbers of vocalizing conspecifics. In particular, playback experiments have broadened our understanding of the cognitive abilities of historically understudied species that are challenging to test in the traditional laboratory, such as members of the Order Carnivora. Additionally, playback experiments allow us to assess the importance of numerical information versus other ecologically important variables when animals are making adaptive decisions in their natural habitats. Here, we begin by reviewing what we know about quantity discrimination in carnivores from studies conducted in captivity. We then review a series of playback experiments conducted with wild social carnivores, including African lions, spotted hyenas and wolves, which demonstrate that these animals can assess the number of conspecifics calling and respond based on numerical advantage. We discuss how the wild studies complement those conducted in captivity and allow us to gain insights into why wild animals may not always respond based solely on differences in quantity. We then consider the key roles that individual discrimination and cross-modal recognition play in the ability of animals to assess the number of conspecifics vocalizing nearby. Finally, we explore new directions for future research in this area, highlighting in particular the need for further work on the cognitive basis of numerical assessment skills and experimental paradigms that can be effective in both captive and wild settings.This article is part of a discussion meeting issue 'The origins of numerical abilities'.

In-group defense, out-group aggression, and coordination failures in intergroup conflict.

Intergroup conflict persists when and because individuals make costly contributions to their group's fighting capacity, but how groups organize contributions into effective collective action remains poorly understood. Here we distinguish between contributions aimed at subordinating out-groups (out-group aggression) from those aimed at defending the in-group against possible out-group aggression (in-group defense). We conducted two experiments in which three-person aggressor groups confronted three-person defender groups in a multiround contest game (n = 276; 92 aggressor-defender contests). Individuals received an endowment from which they could contribute to their group's fighting capacity. Contributions were always wasted, but when the aggressor group's fighting capacity exceeded that of the defender group, the aggressor group acquired the defender group's remaining resources (otherwise, individuals on both sides were left with the remainders of their endowment). In-group defense appeared stronger and better coordinated than out-group aggression, and defender groups survived roughly 70% of the attacks. This low success rate for aggressor groups mirrored that of group-hunting predators such as wolves and chimpanzees (n = 1,382 cases), hostile takeovers in industry (n = 1,637 cases), and interstate conflicts (n = 2,586). Furthermore, whereas peer punishment increased out-group aggression more than in-group defense without affecting success rates (Exp. 1), sequential (vs. simultaneous) decision-making increased coordination of collective action for out-group aggression, doubling the aggressor's success rate (Exp. 2). The relatively high success rate of in-group defense suggests evolutionary and cultural pressures may have favored capacities for cooperation and coordination when the group goal is to defend, rather than to expand, dominate, and exploit.

Play Behavior in Wolves: Using the '50:50' Rule to Test for Egalitarian Play Styles.

Social play is known as a cooperative interaction between individuals involving multiple mechanisms. However, the extent to which the equality of individuals' play styles affects the interaction has not been studied in many species. Dyadic play between wolf puppies, as well as between puppies and adults, was studied to investigate both self-handicapping and offensive behaviors to determine the extent to which wolves engage in play styles where one individual does not dominate the play. Our results did not support the hypothesized '50:50' rule, which suggests that more advantaged individuals should show higher rates of self-handicapping behaviors in order to facilitate play with others. Adult wolves performed significantly less self-handicapping behaviors than their puppy partners, and they performed significantly more offensive behaviors than their puppy partners. While the '50:50' rule was not supported at any time during our study period, dyads consisting of two puppies had significantly more equal play than dyads consisting of one puppy and one adult. These results suggest that wolf puppies are more likely to play on equal terms with similarly-aged play partners, while the dominance status of the partners dictates offensive and self-handicapping behaviors between animals of different ages.

Sociability and gazing toward humans in dogs and wolves: Simple behaviors with broad implications.

Sociability, defined as the tendency to approach and interact with unfamiliar people, has been found to modulate some communicative responses in domestic dogs, including gaze behavior toward the human face. The objective of this study was to compare sociability and gaze behavior in pet domestic dogs and in human-socialized captive wolves in order to identify the relative influence of domestication and learning in the development of the dog-human bond. In Experiment 1, we assessed the approach behavior and social tendencies of dogs and wolves to a familiar and an unfamiliar person. In Experiment 2, we compared the animal's duration of gaze toward a person's face in the presence of food, which the animals could see but not access. Dogs showed higher levels of interspecific sociability than wolves in all conditions, including those where attention was unavailable. In addition, dogs gazed longer at the person's face than wolves in the presence of out-of-reach food. The potential contributions of domestication, associative learning, and experiences during ontogeny to prosocial behavior toward humans are discussed.

When dogs look back: inhibition of independent problem-solving behaviour in domestic dogs (Canis lupus familiaris) compared with wolves (Canis lupus).

Domestic dogs have been recognized for their social sensitivity and aptitude in human-guided tasks. For example, prior studies have demonstrated that dogs look to humans when confronted with an unsolvable task; an action often interpreted as soliciting necessary help. Conversely, wolves persist on such tasks. While dogs' 'looking back' behaviour has been used as an example of socio-cognitive advancement, an alternative explanation is that pet dogs show less persistence on independent tasks more generally. In this study, pet dogs, shelter dogs and wolves were given up to three opportunities to open a solvable puzzle box: when subjects were with a neutral human caretaker, alone and when encouraged by the human. Wolves were more persistent and more successful on this task than dogs, with 80% average success rate for wolves versus a 5% average success rate for dogs in both the human-in and alone conditions. Dogs showed increased contact with the puzzle box during the encouragement condition, but only a moderate increase in problem-solving success. Social sensitivity appears to play an important role in pet and shelter dogs' willingness to engage in problem-solving behaviour, which could suggest generalized dependence on, or deference to, human action.

A method to assess relative preference for training and environmental enrichment in captive wolves (Canis lupus and Canis lupus arctos).

It is currently debated as to whether or not positive reinforcement training is enriching to captive animals. Although both husbandry training and environmental enrichment (EE) have been found to benefit animal welfare in captivity, to date, no systematic investigation has compared an animal's preference for performing a trained behavior to engaging freely with a stimuli provided as EE. In the current paper, we used four captive wolves to (1) test the efficacy of a paired-stimulus preference assessment to determine preference for engaging in a trained behavior as a choice; and to (2) use a paired-stimulus preference assessment to determine whether or not individuals prefer to engage in a previously trained behavior versus a previously encountered EE stimuli. Of the four subjects tested, visual inspection of the graphs revealed that two of the subjects preferred trained behavior stimuli and two of the subjects preferred EE stimuli; only one of the wolves had a statically higher preference for an EE stimulus over a trained behavior. We believe that letting the animals choose between these two events is the first step in answering the question of whether or not is training enriching, however more research needs to be done and suggestions for future research is discussed.

Testing the myth: tolerant dogs and aggressive wolves.

Cooperation is thought to be highly dependent on tolerance. For example, it has been suggested that dog-human cooperation has been enabled by selecting dogs for increased tolerance and reduced aggression during the course of domestication ('emotional reactivity hypothesis'). However, based on observations of social interactions among members of captive packs, a few dog-wolf comparisons found contradictory results. In this study, we compared intraspecies aggression and tolerance of dogs and wolves raised and kept under identical conditions by investigating their agonistic behaviours and cofeeding during pair-wise food competition tests, a situation that has been directly linked to cooperation. We found that in wolves, dominant and subordinate members of the dyads monopolized the food and showed agonistic behaviours to a similar extent, whereas in dogs these behaviours were privileges of the high-ranking individuals. The fact that subordinate dogs rarely challenged their higher-ranking partners suggests a steeper dominance hierarchy in dogs than in wolves. Finally, wolves as well as dogs showed only rare and weak aggression towards each other. Therefore, we suggest that wolves are sufficiently tolerant to enable wolf-wolf cooperation, which in turn might have been the basis for the evolution of dog-human cooperation (canine cooperation hypothesis).