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

Cooperative but Dependent-Functional Breed Selection in Dogs Influences Human-Directed Gazing in a Difficult Object-Manipulation Task

It is still largely unknown to what extent domestication, ancestry, or recent functional selection are responsible for the behavioral differences in whether dogs look back to a human when presented with a difficult task. Here, we tested whether this ubiquitous human-related response of companion dogs would appear differently in subjects that were selected for either cooperative or independent work tasks. We tested N = 71 dogs from 18 cooperative and 18 independent breeds. Subjects learned in a five-trial warming-up phase that they could easily obtain the reward from a container. In trial six, the reward became impossible to take out from the locked container. When the task was easy, both breed groups behaved similarly, and their readiness to approach the container did not differ between the last 'solvable' and the subsequent 'unsolvable' trial. Task focus, looking at the container, touching the container for the first time, or interacting with the container with a paw or nose did not differ between the breed groups, indicating that their persistence in problem solving was similar. However, in the 'unsolvable' trial, cooperative dogs alternated their gaze more often between the container and the humans than the independent dogs did. The frequency of looking back was also higher in cooperative dogs than in the independent breeds. These are the first empirical results that suggest, in a balanced, representative sample of breeds, that the selection for different levels of cooperativity in working dogs could also affect their human-dependent behavior in a generic problem-solving situation.

Synchronous citizen science with dogs

Citizen science approaches have grown in popularity over the years, partly due to their ability to reach a wider audience and produce more generalizable samples. In dogs, these studies, though, have been limited in their controls over materials or experimental protocols, with guardians typically reporting results without researcher supervision. Over two studies, we explored and validated a synchronous citizen science approach. We had dog guardians act as experimenters while being supervised by a researcher over Zoom. In study 1, we demonstrated that synchronous citizen science produced equivalent levels of performance to in-lab designs in a choice task. Consistent with past in-lab research, dogs selected a treat (vs. an empty plate) in a two-alternative forced-choice task. In study 2, we showed that Zoom methods are also appropriate for studies utilizing looking time measures. We explored dogs' looking behaviors when a bag of treats was placed in an unreachable location, and dogs' guardians were either attentive or inattentive while dogs attempted to retrieve the treats. Consistent with past work, dogs in the attentive condition looked at their guardian for longer periods and had a shorter latency to first look than dogs in the inattentive condition. Overall, we have demonstrated that synchronous citizen science studies with dogs are feasible and produce valid results consistent with those found in a typical lab setting.

Free-ranging dogs match a human's preference in a foraging task

Social learning is a mechanism used by many species to efficiently gain information about their environment. Although many animals live in an environment where members of other species are present, little is known about interspecific social learning. Domesticated and urbanized species provide the opportunity to investigate whether nonhuman animals can learn from heterospecifics such as humans, who are integral parts of their social landscape. Although domestic dogs Canis familiaris have been intensively researched for their ability to learn from humans, most studies have focused on dogs living as pets. However, free-ranging dogs represent the majority of the world's dog population, they live alongside humans, scavenge on human refuse, and are subject to natural and sexual selection. Thus, free-ranging dogs with extensive exposure to humans and their artifacts provide the opportunity to investigate interspecific social learning in a naturalistic setting, where learning from humans might be a benefit for them. Here we tested individual free-ranging dogs in a between-subject design: Dogs in the control group could spontaneously choose between two novel and differently patterned food-delivering boxes. In the experimental group, instead, dogs could first observe an unfamiliar human approaching and eating from 1 of the 2 boxes. We provide the first evidence that free-ranging dogs match the choice of an unfamiliar human. These results show that at least simple forms of interspecific social learning might be involved in dogs' success in living alongside humans in a complex urbanized environment.

Street-wise dog testing: Feasibility and reliability of a behavioural test battery for free-ranging dogs in their natural habitat

Behavioural scientists are increasingly recognizing the need to conduct experiments in the wild to achieve a comprehensive understanding of their species' behaviour. For domestic dogs (Canis familiaris), such progress has been slow. While the life in human households is often regarded as dogs' natural habitat, this classification disregards most of the global dog population. The value of experimentally testing free-ranging dogs' cognition and behaviour is increasingly being recognized, but no comprehensive test batteries have been conducted on those populations so far, leaving the feasibility and reliability of such endeavours unknown. This study is the starting point to fill this gap by pioneering and validating an elaborate behavioural test battery on street-living dogs. Therein, six common temperament tests (human-/conspecific-directed sociability, neophobia, tractability) and dog-human communication paradigms (pointing, inaccessible object) were adapted to the street conditions. We evaluated the feasibility of the test battery, the coding reliability of the measures, and investigated their temporal consistency in a retest of the same individuals six weeks later (test-retest reliability). The test battery proved feasible with most dogs participating in all subtests, and it showed satisfactory inter- and intra-rater reliability (0.84 and 0.93 respectively), providing evidence that complex behavioural tests can be conducted even in highly variable street conditions. Retesting revealed that some behaviours could be captured reliably across time, especially when the subtest was particularly engaging (e.g., human approach, point following). In contrast, the low retest reliability for subtests relying on sustained novelty and behaviours that were highly susceptible to disturbances (e.g., gazing) reflects the difficulties of street dog testing, including standardisation in disturbance-prone environments, ecology-dependent adaptation of methods, and intrinsic differences between pet and free-ranging dogs. With some adaptations, this test battery can be valuable in investigating cognition and behavioural profiles in such an understudied population as free-ranging dogs.

Are domesticated animals dumber than their wild relatives? A comprehensive review on the domestication effects on animal cognitive performance

Animal domestication leads to diverse behavioral, physiological, and neurocognitive changes in domesticated species compared to their wild relatives. However, the widely held belief that domesticated species are inherently less "intelligent" (i.e., have lower cognitive performance) than their wild counterparts requires further investigation. To investigate potential cognitive disparities, we undertook a thorough review of 88 studies comparing the cognitive performance of domesticated and wild animals. Approximately 30% of these studies showed superior cognitive abilities in wild animals, while another 30% highlighted superior cognitive abilities in domesticated animals. The remaining 40% of studies found similar cognitive performance between the two groups. Therefore, the question regarding the presumed intelligence of wild animals and the diminished cognitive ability of domesticated animals remains unresolved. We discuss important factors/limitations for interpreting past and future research, including environmental influences, diverse objectives of domestication (such as breed development), developmental windows, and methodological issues impacting cognitive comparisons. Rather than perceiving these limitations as constraints, future researchers should embrace them as opportunities to expand our understanding of the complex relationship between domestication and animal cognition.

Function predicts how people treat their dogs in a global sample

Dogs have an extraordinary relationship with humans. We understand, communicate, and cooperate remarkably with our dogs. But almost all we know about dog-human bonds, dog behaviour, and dog cognition is limited to Western, Educated, Industrialized, Rich, Democratic (WEIRD) societies. WEIRD dogs are kept for a variety of functions, and these can influence their relationship with their owner, as well as their behaviour and performance in problem-solving tasks. But are such associations representative worldwide? Here we address this by collecting data on the function and perception of dogs in 124 globally distributed societies using the eHRAF cross-cultural database. We hypothesize that keeping dogs for multiple purposes and/or employing dogs for highly cooperative or high investment functions (e.g., herding, guarding of herds, hunting) will lead to closer dog-human bonds: increased primary caregiving (or positive care), decreased negative treatment, and attributing personhood to dogs. Our results show that indeed, the number of functions associates positively with close dog-human interactions. Further, we find increased odds of positive care in societies that use herding dogs (an effect not replicated for hunting), and increased odds of dog personhood in cultures that keep dogs for hunting. Unexpectedly, we see a substantial decrease of dog negative treatment in societies that use watchdogs. Overall, our study shows the mechanistic link between function and the characteristics of dog-human bonds in a global sample. These results are a first step towards challenging the notion that all dogs are the same, and open questions about how function and associated cultural correlates could fuel departures from the 'typical' behaviour and social-cognitive skills we commonly associate with our canine friends.

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.

Secure base effect in former shelter dogs and other family dogs: Strangers do not provide security in a problem-solving task

Domestic dogs display behavioural patterns towards their owners that fulfil the four criteria of attachment. As such, they use their owners as a secure base, exploring the environment and manipulating objects more when accompanied by their owners than when alone. Although there are some indications that owners serve as a better secure base than other human beings, the evidence regarding a strong owner-stranger differentiation in a manipulative context is not straightforward. In the present study, we conducted two experiments in which pet dogs were tested in an object-manipulation task in the presence of the owner and of a stranger, varying how the human partner would behave (i.e. remaining silent or encouraging the dog, Experiment 1), and when alone (Experiment 2). Further, to gain a better insight into the mechanisms behind a potential owner-stranger differentiation, we investigated the effect of dogs' previous life history (i.e. having lived in a shelter or having lived in the same household since puppyhood). Overall, we found that strangers do not provide a secure base effect and that former shelter dogs show a stronger owner-stranger differentiation than other family dogs. As former shelter dogs show more behavioural signs correlated with anxiety towards the novel environment and the stranger, we concluded that having been re-homed does not necessarily affect the likelihood of forming a secure bond with the new owner but might have an impact on how dogs interact with novel stimuli, including unfamiliar humans. These results confirm the owner's unique role in providing security to their dogs and have practical implications for the bond formation in pet dogs with a past in a shelter.

A review of the unsolvable task in dog communication and cognition: comparing different methodologies

Communication between dogs and humans is a topic of growing interest, and the "unsolvable task" is a common method used to measure human-directed communication. In this task, dogs learn how to solve a problem to obtain a reward. After a fixed number of trials, the reward becomes impossible to access, arguably leading to communicative attempts from the dog. Although useful to observe dogs' communicative behaviors in a fairly naturalistic situation, the methodology varies among studies regarding apparatus, number of trials, and other factors. The proxies used, for instance, gaze duration or frequency of gaze alternation, also vary, and there are discrepancies and a debate regarding what the task actually measures. Therefore, in this study, we reviewed the usage of the unsolvable task in canids of the genus Canis, searching Web of Science and Scopus for the terms "dog*", "Canis", "dingo*", "wolf" or "wolves" in the title and "unsolvable task" or "impossible task" in the topic. We included thirty-five studies in this review and discussed their different methodologies and proxies, such as different apparatuses, number of solvable trials, and different interpretations of "looking back", pointing out how they can affect results and hinder comparisons. Lastly, we used current data to propose strategies to homogenize the use of this important paradigm, with an ethogram of possible behaviors and their interpretation and a predefined set of methodological aspects for future research.

Social position indirectly influences the traits yellow-bellied marmots use to solve problems

Animals adapt to changing environments by behaving flexibly when solving problems. Traits, such as sex and age, and specifically behavioral traits like persistence-the amount of time spent attempting to solve a problem, are positively associated with successful problem-solving. However, individuals face social pressures, such as aggression, which may directly alter an individual's behavior or interact with sex or age, when they attempt to problem-solve. We examined the direct and indirect effects of social position and individual behavioral traits on solving a novel puzzle box in facultatively social yellow-bellied marmots (Marmota flaviventer), using both generalized linear mixed models and confirmatory path analysis. We found strong support that marmots who used a diversity of behaviors were more successful problem-solvers and weak support that those who received more aggression were less successful. Additionally, marmots who received more aggression were less behaviorally diverse, less behaviorally selective and less persistent while trying to open the puzzle box. Thus, we show that aggression indirectly decreases problem-solving success by acting on the behavioral traits that an individual uses. We conclude that specific social relationships, including the type of interaction and whether they are recipients or initiators, influences the ways in which an individual interacts with cognitive tests and should be considered in analysis of individual problem-solving.

Neophobia in 10 ungulate species-a comparative approach

ABSTRACT

Neophobia (the fearful reaction to novel stimuli or situations) has a crucial effect on individual fitness and can vary within and across species. However, the factors predicting this variation are still unclear. In this study, we assessed whether individual characteristics (rank, social integration, sex) and species socio-ecological characteristics (dietary breadth, group size, domestication) predicted variation in neophobia. For this purpose, we conducted behavioral observations and experimental tests on 78 captive individuals belonging to 10 different ungulate species-an ideal taxon to study inter-specific variation in neophobia given their variety in socio-ecological characteristics. Individuals were tested in their social groups by providing them with familiar food, half of which had been positioned close to a novel object. We monitored the individual latency to approach and eat food and the proportion of time spent in its proximity. Using a phylogenetic approach and social network analyses, we showed that across ungulate species neophobia was higher in socially more integrated individuals, as compared to less integrated ones. In contrast, rank and sex did not predict inter-individual differences in neophobia. Moreover, species differed in their levels of neophobia, with Barbary sheep being on average less neophobic than all the other study species. As group size in Barbary sheep was larger than in all the other study species, these results support the hypothesis that larger group size predicts lower levels of neophobia, and confirm ungulates as a highly promising taxon to study animal behavior and cognition with a comparative perspective.

SIGNIFICANCE STATEMENT

In several species, individuals may respond fearfully to novel stimuli, therefore reducing the risks they may face. However, it is yet unclear if certain individuals or species respond more fearfully to novelty. Here, we provided food to 78 individual ungulates with different characteristics (e.g., sex, rank, social integration, group size, domestication, dietary breadth) in different controlled conditions (e.g., when food was close to novel or to familiar objects). Across species, we found that socially integrated individuals responded more fearfully in all species. Moreover, being in larger groups decreased the probability of fearfully responding to novelty.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00265-021-03041-0.

The development of problem-solving abilities in a population of candidate detection dogs (Canis familiaris)

Both ontogenetic and phylogenetic factors have shaped dogs' cognitive capabilities, resulting in a heightened social sensitivity at the apparent cost of non-social problem-solving abilities. Research has suggested that training history and life experience can influence problem-solving abilities in dogs. However, the ontogenetic development of problem-solving abilities in dogs has been less explored. We tested a population of candidate detection dogs of various ages across the first year of development on four well-established problem-solving tasks targeting different cognitive domains (i.e., cylinder, A-not-B barrier, delayed search, and spatial transposition tasks). We examined developmental effects by comparing cognitive task performance across three age groups. Age-related improvements for all four cognitive measures indicate developmental increases in processes related to inhibitory control, attention, and spatial cognition between 3 and 12 months of age. Additionally, we found some relationships between cognitive measures and detection dog performance measures, though effects were not as robust. We discuss the results in the context of canine cognitive development and corresponding effects of phylogeny and ontogeny, as well as potential applications to working dog training and selection.