Estimating the heritability of cognitive traits across dog breeds reveals highly heritable inhibitory control and communication factors

An overview of the literature on assistance dogs using text mining and topic analysis

It is said that dogs are human's best friend. On occasion, dogs can be raised and trained to provide additional specific benefits to humans suffering from a range of physical or mental conditions, working as assistance dogs. In this article, we employed innovative techniques to review the vast and constantly expanding literature on the subject, which covers a multitude of aspects. The 450 articles obtained through keyword search on Scopus were initially described in terms of year of publication, geographical context and publication destination, and were subsequently analysed through automated text mining to detect the most important words contained within them. Lastly, a generative model of topic analysis (Latent Dirichlet Allocation-LDA) described the content of the collection of documents, dividing it into the appropriate number of topics. The results yielded interesting insights across all domains, demonstrating the potential of automated text mining and topic analysis as a useful tool to support the researchers in dealing with complex and time-consuming subjects' reviews, integrating the work done with traditional reviewing methods.

Age-related effects on a hierarchical structure of canine cognition

The current study investigates whether there are statistically independent age-related influences on the canine cognitive structure and how individual factors moderate cognitive aging on both cross-sectional and longitudinal samples. A battery of seven tasks was administered to 129 pet dogs, on which exploratory and confirmatory factor analyses were employed to unveil the correlational structure underlying individual differences in cognitive performance. The best-fitting model featured a hierarchical structure with two first-order cognitive domains (individual problem solving, learning) and a second-order common factor. These higher order factors exhibited consistency over a period of at least 2.5 years. External validation linked the common factor positively to discrimination and reversal learning performance, exploration, neophilia, activity/excitability, and training level while negatively to cognitive dysfunction symptoms, suggesting that it is a good candidate for a general cognitive factor (canine g). Structural equation models identified three distinct age-related influences, operating on associative learning, on memory, and on canine g. Health status moderated the negative age-canine g relationship, with a stronger association observed in dogs with poorer health status, and no relationship for dogs in good health. On a longitudinal sample (N = 99), we showed that the direction and magnitude of change in canine g over up to 3 years is affected by various interactions between the dogs' age, communication score, baseline performance, and time elapsed since the baseline measurement. These findings underscore the presence of a general cognitive factor in dogs and reveal intriguing parallels between human and canine aging, affirming the translational value of dogs in cognition and aging research.

Exploring breed differences in discrimination, reversal learning, and resistance to extinction in the domestic dog (Canis familiaris)

Learning is crucial for shaping domestic dogs' behaviour through life experiences, yet not all breeds exhibit the same learning aptitude towards a particular task. The current study's objective was to identify differences in behaviour and learning performance across and within five breed clades and elucidate the underlying factors contributing into these variations. Dogs (n = 111) from five breed clades (UK Rural, Retrievers, Asian Spitz, European Mastiff, and New World) participated in a virtual learning task with their owners. Owners completed validated questionnaires of Impulsivity and Reward Responsiveness. The learning task comprised of reinforcing an arbitrary behaviour (hand-touch) through multiple sessions of Acquisition (reinforcing the hand-touch), Discrimination (reinforcing the hand-touch on one of two hands) and Reversal Learning (reinforcing the hand-touch on the opposite hand), followed by a single session of Extinction (hand-touch not reinforced). Results showed notable differences across the studied breed clades in certain learning and behavioural components. However, the observed disparities may not be entirely attributed to inherent cognitive differences among the breed clades but rather potentially influenced by contextual factors such as the human-dog communication dynamics associated with breeds' cooperativity. Furthermore, breed clades differed in the contributing factors predicting individual learning performances, which could highlight the potential effect of breeds' historical function.

Longitudinal evidence for the emergence of multiple intelligences in assistance dog puppies

Cognitive test batteries suggest that adult dogs have different types of cognitive abilities that vary independently. In the current study, we tested puppies repeatedly over a crucial period of development to explore the timing and rate at which these different cognitive skills develop. Service dog puppies (n = 113), raised using two different socialization strategies, were either tested longitudinally (n =91) or at a single time point (n = 22). Subjects tested longitudinally participated in the battery every two weeks during and just beyond their final period of rapid brain growth (from approximately 8-20 weeks of age). Control puppies only participated in the test battery once, which allowed us to evaluate the impact of repeated testing. In support of the multiple intelligences hypothesis (MIH), cognitive skills emerged at different points across the testing period, not simultaneously. Maturational patterns also varied between cognitive skills, with puppies showing adult-like performance on some tasks only weeks after a skill emerged, while never achieving adult performance in others. Differences in rearing strategy did not lead to differences in developmental patterns while, in some cases, repeated testing did. Overall, our findings provide strong support for the MIH by demonstrating differentiated development across the cognitive abilities tested.

Basal plasma oxytocin & fecal cortisol concentrations are highly heritable and associated with individual differences in behavior & cognition in dog puppies

Oxytocin and cortisol are hormones that can influence cognition and behavior, but the relationships between endogenous concentrations and individual differences in cognitive and behavioral phenotypes remain poorly understood. Across mammals, oxytocin has important roles in diverse social behaviors, and in dogs, it has been implicated in human-oriented behaviors such as social gaze and point-following. Cortisol, an end-product of the hypothalamic-pituitary-adrenal (HPA) axis, is often studied in relation to temperament and emotional reactivity, but it is also known to modulate executive functions. In this study, we measured basal fecal cortisol (n = 247) and plasma oxytocin (n = 249) in dog puppies from a pedigreed population (Canine Companions ®). We collected cognitive and behavioral data from these subjects (n = 247), including measures of human-oriented social cognition, memory, inhibitory control, perceptual discriminations, and temperament. Oxytocin concentrations were estimated to be very highly heritable (h2 = 0.90-0.99) and cortisol concentrations were estimated to be moderately-highly heritable (h2 = 0.43-0.47). Bayesian mixed models controlling for relatedness revealed that oxytocin concentrations were positively associated with spatial working memory and displayed a negative quadratic relationship with behavioral laterality, but no credible associations were seen for social measures. Cortisol concentrations exhibited a negative linear relationship with performance on an inhibitory control task and a negative quadratic relationship with bold behavioral reactions to a novel object. Collectively, our results suggest that individual differences in oxytocin and cortisol concentrations are under strong genetic control in dogs and are associated with phenotypic variation in aspects of temperament, behavioral laterality, and executive function.

Behavioural differences and similarities between dog breeds: proposing an ecologically valid approach for canine behavioural research

The behaviour of dogs holds great relevance for not only scientists from fundamental and applied research areas, but also due to the widespread roles of dogs in our societies as companions and working animals; their behaviour is also an important factor in animal and human welfare. A large proportion of dogs currently under human supervision belong to one of roughly 400 recognised breeds. Dog breeds can be characterised by distinctive, predictable and reproducible features, including some of their behavioural traits. To the scientist, the comparative analysis of the behaviour of dog breeds provides an opportunity for investigating an array of intriguing phenomena within an easily accessible model organism created from natural and human-driven evolutionary processes. There are many ways to design and conduct breed-related behavioural investigations, but such endeavours should always be based around biologically relevant research questions and lead to ecologically valid conclusions. In this review, we surveyed recent research efforts that included dog behaviour-related comparisons and applied a critical evaluation according to their methods of breed choice and the subsequent research design. Our aim was to assess whether these two fundamentally important components of experimental design provide a solid basis to reach valid conclusions. Based on 97 publications that fulfilled our selection criteria, we identified three primary methods used by researchers to select breeds for their investigations: (i) convenience sampling; (ii) hypothesis-driven, ancestry-based sampling; and (iii) hypothesis-driven, functional sampling. By using the SWOT (Strengths, Weaknesses, Opportunities, Threats) evaluation system, we highlight each of these techniques' merits and shortcomings. We identify when particular methods may be inherently unable to produce biologically meaningful results due to a mismatch between breed choice and the initial research goals. We hope that our evaluation will help researchers adopt best practices in experimental design regarding future dog breed comparisons.

Associations between memory performance and Bifidobacterium pseudolongum abundance in the canine gut microbiome

Memory has been identified as the least heritable cognitive trait in canines, suggesting a significant influence of non-genetic factors. We observed a trend that overall memory scores (OMS) improve with age in a cohort of 27 young dogs, but considerable plasticity exists. Employing linear discriminant analysis of gut microbiome data from dogs exhibiting low and high OMS, a single bacterial species, Bifidobacterium pseudolongum, was identified and confirmed to be correlated with elevated OMS. Subsequent analysis using a random forest regression model revealed that sex, litter, and breed identity had minimal predictive importance. Age had some predictive value but failed to achieve statistical significance in this dataset. In sharp contrast, the abundance of 17 bacterial taxa in the microbiome showed a stronger predictive capacity for memory performance. Our findings provide insights into microbiome underpinnings of mammalian cognitive functions and suggest avenues for developing psychobiotics to enhance canine memory and learning.

A preliminary analysis of the effect of individual differences on cognitive performance in young companion dogs

Many factors influence cognitive performance in dogs, including breed, temperament, rearing history, and training. Studies in working dog populations have demonstrated age-related improvements in cognitive task performance across the first years of development. However, the effect of certain factors, such as age, sex, and temperament, on cognitive performance in puppies has yet to be evaluated in a more diverse population of companion dogs. In this study, companion dogs under 12 months of age were tested once on two tasks purported to measure aspects of executive function: the delayed-search task (DST) and the detour reversal task (DRT). Owners also filled out the Canine Behavioral Assessment and Research Questionnaire (C-BARQ) to evaluate how temperament influenced task performance. Contrary to prior research, performance did not improve with age on either task. However, the lack of age effects was likely the result of small sample sizes and individual differences across other factors influencing performance. Specifically, temperament differences as measured by the C-BARQ subscales for nonsocial fear and excitability predicted task performance on the DST, but the effect of temperament on task performance differed between males and females. Excitability also predicted performance on the DRT, but the effect depended on the age of the dog. In addition, no correlations were observed between task measures, indicating a lack of construct validity. Overall, these findings provide a preliminary analysis of factors that appear to influence cognitive task performance in young companion dogs and highlight suggestions for future research evaluating the impact of individual differences on cognitive performance.

Inhibitory control in teleost fish: a methodological and conceptual review

Inhibitory control (IC) plays a central role in behaviour control allowing an individual to resist external lures and internal predispositions. While IC has been consistently investigated in humans, other mammals, and birds, research has only recently begun to explore IC in other vertebrates. This review examines current literature on teleost fish, focusing on both methodological and conceptual aspects. I describe the main paradigms adopted to study IC in fish, identifying well-established tasks that fit various research applications and highlighting their advantages and limitations. In the conceptual analysis, I identify two well-developed lines of research with fish examining IC. The first line focuses on a comparative approach aimed to describe IC at the level of species and to understand the evolution of interspecific differences in relation to ecological specialisation, brain size, and factors affecting cognitive performance. Findings suggest several similarities between fish and previously studied vertebrates. The second line of research focuses on intraspecific variability of IC. Available results indicate substantial variation in fish IC related to sex, personality, genetic, age, and phenotypic plasticity, aligning with what is observed with other vertebrates. Overall, this review suggests that although data on teleosts are still scarce compared to mammals, the contribution of this group to IC research is already substantial and can further increase in various disciplines including comparative psychology, cognitive ecology, and neurosciences, and even in applied fields such as psychiatry research.

Transposons in the Williams-Beuren Syndrome Critical Region are Associated with Social Behavior in Assistance Dogs

A strong signature of selection in the domestic dog genome is found in a five-megabase region of chromosome six in which four structural variants derived from transposons have previously been associated with human-oriented social behavior, such as attentional bias to social stimuli and social interest in strangers. To explore these genetic associations in more phenotypic detail-as well as their role in training success in a specialized assistance dog program-we genotyped 1001 assistance dogs from Canine Companions for Independence®, including both successful graduates and dogs released from the training program for behaviors incompatible with their working role. We collected phenotypes on each dog using puppy-raiser questionnaires, trainer questionnaires, and both cognitive and behavioral tests. Using Bayesian mixed models, we found strong associations (95% credibility intervals excluding zero) between genotypes and certain behavioral measures, including separation-related problems, aggression when challenged or corrected, and reactivity to other dogs. Furthermore, we found moderate differences in the genotypes of dogs who graduated versus those who did not; insertions in GTF2I showed the strongest association with training success (β = 0.23, CI95% = - 0.04, 0.49), translating to an odds-ratio of 1.25 for one insertion. Our results provide insight into the role of each of these four transposons in canine sociability and may inform breeding and training practices for working dog organizations. Furthermore, the observed importance of the gene GTF2I supports the emerging consensus that variation in GTF2I genotypes and expression have important consequences for social behavior broadly.

Genetic and context-specific effects on individual inhibitory control performance in the guppy (Poecilia reticulata)

Among-individual variation in cognitive traits, widely assumed to have evolved under adaptive processes, is increasingly being demonstrated across animal taxa. As variation among individuals is required for natural selection, characterizing individual differences and their heritability is important to understand how cognitive traits evolve. Here, we use a quantitative genetic study of wild-type guppies repeatedly exposed to a 'detour task' to test for genetic variance in the cognitive trait of inhibitory control. We also test for genotype-by-environment interactions (GxE) by testing related fish under alternative experimental treatments (transparent vs. semi-transparent barrier in the detour-task). We find among-individual variation in detour task performance, consistent with differences in inhibitory control. However, analysis of GxE reveals that heritable factors only contribute to performance variation in one treatment. This suggests that the adaptive evolutionary potential of inhibitory control (and/or other latent variables contributing to task performance) may be highly sensitive to environmental conditions. The presence of GxE also implies that the plastic response of detour task performance to treatment environment is genetically variable. Our results are consistent with a scenario where variation in individual inhibitory control stems from complex interactions between heritable and plastic components.

Modulation of dog-owner relationship and dog social and cognitive behavior by owner temperament and dog breed group

As companion dogs spend most of their lives with humans, the human-dog relationship and owner temperament may affect the dog behavior. In this study (n = 440), we investigated the relationship between the dog owner temperament (ATQ-R), owner-perceived dog-owner relationship (MDORS) and the dog behavior in three behavioral tests: the object-choice test, the unsolvable task, and the cylinder test. Dog owner temperament influenced the dog-owner relationship. Owners with high negative affectivity showed higher emotional closeness and perceived costs of their dog, whereas owners with high effortful control showed lower emotional closeness and perceived costs. Higher dog activity during the behavioral tests was also connected with owner-perceived lower emotional closeness. Furthermore, dog breed group modulated the connection between the owner temperament and dog behavior. Owner's high negative affectivity correlated with herding dogs' lower scores in the object choice test, while the behavior of primitive type dogs was unaffected by the owner temperament. Our results confirm that human characteristics are associated with the owner-reported dog-owner relationship, and owner temperament may have a modulatory effect on the dog social and cognitive behavior depending on the dog breed group, which should be investigated further.

What Is Written on a Dog's Face? Evaluating the Impact of Facial Phenotypes on Communication between Humans and Canines

Facial phenotypes are significant in communication with conspecifics among social primates. Less is understood about the impact of such markers in heterospecific encounters. Through behavioral and physical phenotype analyses of domesticated dogs living in human households, this study aims to evaluate the potential impact of superficial facial markings on dogs' production of human-directed facial expressions. That is, this study explores how facial markings, such as eyebrows, patches, and widow's peaks, are related to expressivity toward humans. We used the Dog Facial Action Coding System (DogFACS) as an objective measure of expressivity, and we developed an original schematic for a standardized coding of facial patterns and coloration on a sample of more than 100 male and female dogs (N = 103), aged from 6 months to 12 years, representing eight breed groups. The present study found a statistically significant, though weak, correlation between expression rate and facial complexity, with dogs with plainer faces tending to be more expressive (r = -0.326, p ≤ 0.001). Interestingly, for adult dogs, human companions characterized dogs' rates of facial expressivity with more accuracy for dogs with plainer faces. Especially relevant to interspecies communication and cooperation, within-subject analyses revealed that dogs' muscle movements were distributed more evenly across their facial regions in a highly social test condition compared to conditions in which they received ambiguous cues from their owners. On the whole, this study provides an original evaluation of how facial features may impact communication in human-dog interactions.

Would You Detour with Me? Association between Functional Breed Selection and Social Learning in Dogs Sheds Light on Elements of Dog-Human Cooperation

Interspecific social learning is a main synchronizing mechanism that enables dogs to adapt to the anthropogenic niche. It is not known whether dogs in general possess the capacity of learning from humans or whether more recent selective events have affected their ability to learn from humans. We hypothesized that cooperative and independent working dog breeds may behave differently in a social learning task. Dogs (N = 78 from 16 cooperative and 18 independent breeds) had to detour a transparent, V-shaped wire mesh fence. The experiment consisted of three one-minute-long trials. The control condition did not include a demonstration. In the demonstration condition, the experimenter placed a reward in the inside corner by walking around the fence. Cooperative dogs reached the target significantly faster, while independent dogs did not detour faster in trials 2 and 3 after the human demonstration. Detour latencies were not associated with the keeping conditions and training level of the subjects. As we assembled both test groups from several genetically distantly related breeds, we can exclude the explanation that higher cooperativity emerged only in particular clades of dogs; instead, functional selection for particular working tasks could enhance capacities that affect a wide range of socio-cognitive traits in dogs.

Canine perspective-taking

An important question in the study of canine cognition is how dogs understand humans, given that they show impressive abilities for interacting and communicating with us. In this review, we describe and discuss studies that have investigated dogs' perspective-taking abilities. There is solid evidence that dogs are not only sensitive to the gaze of others, but also their attention. We specifically address the question whether dogs have the ability to take the perspective of others and thus come to understand what others can or cannot perceive. From the latter, they may then infer what others know and use this representation to anticipate what others do next. Still, dogs might simply rely on directly observable cues and on what they themselves can perceive when they assess what others can perceive. And instead of making inferences from representations of others' mental states, they may have just learned that certain behaviours of ours lead to certain outcomes. However, recent research seems to challenge this low-level explanation. Dogs have solved several perspective-taking tasks instantly and reliably across a large number of variations, including geometrical gaze-following, stealing in the dark, concealing information from others, and Guesser/Knower differentiation. In the latter studies, dogs' choices between two human informants were strongly influenced by cues related to the humans' visual access to the food, even when the two informants behaved identically. And finally, we review a recent study that found dogs reacting differently to misleading suggestions of human informants that have either a true or false belief about the location of food. We discuss this surprising result in terms of the comprehension of reality-incongruent mental states, which is considered as a hallmark of Theory of Mind acquisition in human development. Especially on the basis of the latter findings, we conclude that pet dogs might be sensitive to what others see, know, intend, and believe. Therefore, this ability seems to have evolved not just in the corvid and primate lineages, but also in dogs.

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.

Breed differences in social cognition, inhibitory control, and spatial problem-solving ability in the domestic dog (Canis familiaris)

The extraordinary genetic and behavioural diversity of dog breeds provides a unique opportunity for investigating the heritability of cognitive traits, such as problem-solving ability, social cognition, inhibitory control, and memory. Previous studies have mainly investigated cognitive differences between breed groups, and information on individual dog breeds is scarce. As a result, findings are often contradictory and inconsistent. The aim of this study was to provide more clarity on between-breed differences of cognitive traits in dogs. We examined the performance of 13 dog breeds (N = 1002 dogs) in a standardized test battery. Significant breed differences were found for understanding of human communicative gestures, following a human's misleading gesture, spatial problem-solving ability in a V-detour task, inhibitory control in a cylinder test, and persistence and human-directed behaviour during an unsolvable task. Breeds also differed significantly in their behaviour towards an unfamiliar person, activity level, and exploration of a novel environment. No significant differences were identified in tasks measuring memory or logical reasoning. Breed differences thus emerged mainly in tasks measuring social cognition, problem-solving, and inhibitory control. Our results suggest that these traits may have come under diversifying artificial selection in different breeds. These results provide a deeper understanding on breed-specific traits in dogs.

The contribution of executive functions to sex differences in animal cognition

Cognitive sex differences have been reported in several vertebrate species, mostly in spatial abilities. Here, I review evidence of sex differences in a family of general cognitive functions that control behaviour and cognition, i.e., executive functions such as cognitive flexibility and inhibitory control. Most of this evidence derives from studies in teleost fish. However, analysis of literature from other fields (e.g., biomedicine, genetic, ecology) concerning mammals and birds reveals that more than 40% of species investigated exhibit sex differences in executive functions. Among species, the direction and magnitude of these sex differences vary greatly, even within the same family, suggesting sex-specific selection due to species' reproductive systems and reproductive roles of males and females. Evidence also suggests that sex differences in executive functions might provide males and females highly differentiated cognitive phenotypes. To understand the evolution of cognitive sex differences in vertebrates, future research should consider executive functions.

Identification of genes associated with human-canine communication in canine evolution

The dog (Canis familiaris) was the first domesticated animal and hundreds of breeds exist today. During domestication, dogs experienced strong selection for temperament, behaviour, and cognitive ability. However, the genetic basis of these abilities is not well-understood. We focused on ancient dog breeds to investigate breed-related differences in social cognitive abilities. In a problem-solving task, ancient breeds showed a lower tendency to look back at humans than other European breeds. In a two-way object choice task, they showed no differences in correct response rate or ability to read human communicative gestures. We examined gene polymorphisms in oxytocin, oxytocin receptor, melanocortin 2 receptor, and a Williams-Beuren syndrome-related gene (WBSCR17), as candidate genes of dog domestication. The single-nucleotide polymorphisms on melanocortin 2 receptor were related to both tasks, while other polymorphisms were associated with the unsolvable task. This indicates that glucocorticoid functions are involved in the cognitive skills acquired during dog domestication.

Effect of Sex and Reproductive Status on Inhibitory Control and Social Cognition in the Domestic Dog (Canis familiaris)

Simple Summary

Various behavioral differences exist between male and female dogs, but very little research has focused on how sex influences cognition. Even fewer studies have taken sex hormones into account. Our aim was to investigate whether dogs’ sex and neutering status can influence two important cognitive traits: inhibitory control and social cognition. Inhibitory control was assessed using the cylinder test. In this task, the dog is required to inhibit reaching for a treat directly through a transparent barrier, and instead go around the barrier to access the treat. Social cognition was assessed using the unsolvable task, during which a food reward is visible but impossible to access. Dogs have three opportunities for action in this situation: (a) persisting with the problem independently, (b) seeking attention from a human, or (c) abandoning the task. Males were more impulsive and independent compared to females, whereas females had greater inhibitory control and were more likely to gaze at a human during a problem-solving situation. Since neutering status did not affect the results, it seems likely that these sex differences arose during early development and were not affected by levels of circulating sex hormones to a great extent.

Abstract

Sex differences in a variety of cognitive traits have long been reported in various species, including dogs. However, only a few canine studies have taken the possible effect of reproductive hormones into account. The aim of this study was to investigate the effects of sex and reproductive status of pet dogs (N = 1032) on two cognitive traits: inhibitory control and social cognition. Inhibitory control was assessed using the cylinder test, and the dogs’ tendency to initiate social contact with a human during a problem-solving situation was assessed using the unsolvable task. Female dogs had a significantly higher success rate in the cylinder test compared to males, and they spent significantly more time in human-directed behavior during the unsolvable task. In contrast, males spent significantly more time in independent behavior during the unsolvable task. Reproductive status had no significant effect on the results of the cylinder test or the unsolvable task. Our results showed that female dogs asked for more help/used a more cooperative strategy during a problem-solving situation and had greater inhibitory control compared to males. According to our results, it seems likely that these sex differences were not influenced to a large extent by reproductive hormones.

Dogs follow human misleading suggestions more often when the informant has a false belief

We investigated whether dogs (Canis familiaris) distinguish between human true (TB) and false beliefs (FB). In three experiments with a pre-registered change of location task, dogs (n = 260) could retrieve food from one of two opaque buckets after witnessing a misleading suggestion by a human informant (the 'communicator') who held either a TB or a FB about the location of food. Dogs in both the TB and FB group witnessed the initial hiding of food, its subsequent displacement by a second experimenter, and finally, the misleading suggestion to the empty bucket by the communicator. On average, dogs chose the suggested container significantly more often in the FB group than in the TB group and hence were sensitive to the experimental manipulation. Terriers were the only group of breeds that behaved like human infants and apes tested in previous studies with a similar paradigm, by following the communicator's suggestion more often in the TB than in the FB group. We discuss the results in terms of processing of goals and beliefs. Overall, we provide evidence that pet dogs distinguish between TB and FB scenarios, suggesting that the mechanisms underlying sensitivity to others' beliefs have not evolved uniquely in the primate lineage.

Domestic dogs: Born human whisperers

Domestic dogs show socio-cognitive abilities that are not found in other species, including dogs' closest living relative, the wolf. From early on dogs are good at reading human gestures and pay attention to humans' eyes and voice. Two new studies suggest that a heritable component to dogs' social cognitive skills exists and that selection during domestication must have played a role in enhancing dogs' social cognitive skills.

Personality and Cognitive Profiles of Animal-Assisted Intervention Dogs and Pet Dogs in an Unsolvable Task

Dogs are biologically predisposed to communicate with humans in cooperative contexts. They show individual differences in dog-human communication and inhibition, potentially enhanced by life experience, e.g., Animal-Assisted Interventions. This study aimed to investigate whether dogs' personality, defined by biologically meaningful neural circuits described in the Reinforcement Sensitivity Theory of Personality (RST), predicted dogs' communication, task orientation, emotional state, and approach of an unsolvable task. We also investigated the differences between dogs experienced in Animal-Assisted Interventions (AAI) and inexperienced dogs. The results indicated that a high sensitivity to the RST personality trait related to managing uncertainty (Behavioural Inhibition System, BIS) predicted fewer task orientations but increased referential and non-referential looking, which we interpreted as a way to obtain directions from the owner. Conversely, a high sensitivity to the traits reflecting tendencies to approach rewards (Behavioural Approach System, BAS) and avoid punishment (Fight-Flight-Freeze System, FFFS) predicted lower looking. High sensitivity to the FFFS also predicted more frequent task orientations, which we interpreted as frustration. Finally, the dogs in the AAI program looked more at their owner and were less oriented towards the task. These results provide empirical evidence of individual differences tied to the psychobiological personality traits in canine cognitive skills. Understanding such cognitive profiles may have an enormous impact on activities that rely upon dog-human collaborative interaction.

The New Era of Canine Science: Reshaping Our Relationships With Dogs

Canine science is rapidly maturing into an interdisciplinary and highly impactful field with great potential for both basic and translational research. The articles in this Frontiers Research Topic, Our Canine Connection: The History, Benefits and Future of Human-Dog Interactions, arise from two meetings sponsored by the Wallis Annenberg PetSpace Leadership Institute, which convened experts from diverse areas of canine science to assess the state of the field and challenges and opportunities for its future. In this final Perspective paper, we identify a set of overarching themes that will be critical for a productive and sustainable future in canine science. We explore the roles of dog welfare, science communication, and research funding, with an emphasis on developing approaches that benefit people and dogs, alike.

Cooperative Communication with Humans Evolved to Emerge Early in Domestic Dogs

Although we know that dogs evolved from wolves, it remains unclear how domestication affected dog cognition. One hypothesis suggests dog domestication altered social maturation by a process of selecting for an attraction to humans.^1-3 Under this account, dogs became more flexible in using inherited skills to cooperatively communicate with a new social partner that was previously feared and expressed these unusual social skills early in development.^4-6 Here, we comparedog (n = 44) and wolf (n = 37) puppies, 5-18 weeks old, on a battery of temperament and cognition tasks. We find that dog puppies are more attracted to humans, read human gestures more skillfully, and make more eye contact with humans than wolf puppies. The two species are similarly attracted to familiar objects and perform similarly on non-social measures of memory and inhibitory control. These results are consistent with the idea that domestication enhanced the cooperative-communicative abilities of dogs as selection for attraction to humans altered social maturation.

Early-emerging and highly heritable sensitivity to human communication in dogs

Human cognition is believed to be unique in part because of early-emerging social skills for cooperative communication.¹ Comparative studies show that at 2.5 years old, children reason about the physical world similarly to other great apes, yet already possess cognitive skills for cooperative communication far exceeding those in our closest primate relatives.^2,3 A growing body of research indicates that domestic dogs exhibit functional similarities to human children in their sensitivity to cooperative-communicative acts. From early in development, dogs flexibly respond to diverse forms of cooperative gestures.^4,5 Like human children, dogs are sensitive to ostensive signals marking gestures as communicative, as well as contextual factors needed for inferences about these communicative acts.^6-8 However, key questions about potential biological bases for these abilities remain untested. To investigate their developmental and genetic origins, we tested 375 8-week-old dog puppies on a battery of social-cognitive measures. We hypothesized that if dogs' skills for cooperating with humans are biologically prepared, then they should emerge robustly in early development, not require extensive socialization or learning, and exhibit heritable variation. Puppies were highly skillful at using diverse human gestures, and we found no evidence that their performance required learning. Critically, over 40% of the variation in dogs' point-following abilities and attention to human faces was attributable to genetic factors. Our results suggest that these social skills in dogs emerge early in development and are under strong genetic control.

Enhancing the Selection and Performance of Working Dogs

Dogs perform a variety of integral roles in our society, engaging in work ranging from assistance (e.g., service dogs, guide dogs) and therapy to detection (e.g., search-and-rescue dogs, explosive detection dogs) and protection (e.g., military and law enforcement dogs). However, success in these roles, which requires dogs to meet challenging behavioral criteria and to undergo extensive training, is far from guaranteed. Therefore, enhancing the selection process is critical for the effectiveness and efficiency of working dog programs and has the potential to optimize how resources are invested in these programs, increase the number of available working dogs, and improve working dog welfare. In this paper, we review two main approaches for achieving this goal: (1) developing selection tests and criteria that can efficiently and effectively identify ideal candidates from the overall pool of candidate dogs, and (2) developing approaches to enhance performance, both at the individual and population level, via improvements in rearing, training, and breeding. We summarize key findings from the empirical literature regarding best practices for assessing, selecting, and improving working dogs, and conclude with future steps and recommendations for working dog organizations, breeders, trainers, and researchers.

Grumpy Dogs Are Smart Learners-The Association between Dog-Owner Relationship and Dogs' Performance in a Social Learning Task

We investigated how dog-owner relationship-with a focus on possible behavioural problems-might associate with the individual variability in dogs' social learning performance. Dog owners first completed a questionnaire about their relationship with their dogs (N = 98). Then, dogs were tested in a detour test: a control group without demonstration, a group where the owner demonstrated the task and another group where the experimenter demonstrated the task. Finally, the dogs participated in two behaviour tests measuring their tractability and possessiveness. The two principal components from the questionnaire (called "overactive" and "irritable") did not show significant association with dogs' detour performance in the control group. "irritable" dogs performed better in the unfamiliar demonstrator group. These more persistent, goal-oriented dogs also looked back less at their owners during the detour. In the individual problem-solving context, the factor "overactive" had a similar effect on looking back at the owner, suggesting that the items of this component primarily are not connected to the dog-human relationship. Our results indicate that dog-human relationship has an integral role in the complex social behaviour of dogs, which warrants for the need of further empirical testing of the associations between social dynamics in dogs and their relationship with humans, including problem behaviours.

Is cognition the secret to working dog success?

Dogs' special relationship with humans not only makes them ubiquitous in our lives, but working dogs specifically perform essential functions for us such as sniffing out bombs and pulling wheelchairs for the disabled. To enhance the performance of working dogs, it is essential to understand the cognitive skills that underlie and lead to their success. This review details recent work in the field of canine cognition, including how dogs have evolved socio-cognitive skills that mimic or, in some cases, rival even our closest primate relatives. We review how these findings have laid the foundation for new studies that hope to help enhance working dog programs. This includes work that has begun to reveal the development and stability of the most important traits for service work. Discoveries like these suggest the possibility of translating what we have learned to improve breeding, selection, and training for these jobs. The latest research we review here shows promise in contributing to the production of better dogs and, consequently, more help for people.

Cognitive characteristics of 8- to 10-week-old assistance dog puppies

To characterize the early ontogeny of dog cognition, we tested 168 domestic dog, Canis familiaris, puppies (97 females, 71 males; mean age = 9.2 weeks) in a novel test battery based on previous tasks developed and employed with adolescent and adult dogs. Our sample consisted of Labrador retrievers, golden retrievers and Labrador × golden retriever crosses from 65 different litters at Canine Companions for Independence, an organization that breeds, trains and places assistance dogs for people with disabilities. Puppies participated in a 3-day cognitive battery that consisted of 14 tasks measuring different cognitive abilities and temperament traits such as executive function (e.g. inhibitory control, reversal learning, working memory), use of social cues, sensory discriminations and reactivity to and recovery from novel situations. At 8-10 weeks of age, and despite minimal experience with humans, puppies reliably used a variety of cooperative-communicative gestures from humans. Puppies accurately remembered the location of hidden food for delays of up to 20 s, and succeeded in a variety of visual, olfactory and auditory discrimination problems. They also showed some skill at executive function tasks requiring inhibitory control and reversal learning, although they scored lower on these tasks than is typical in adulthood. Taken together, our results confirm the early emergence of sensitivity to human communication in dogs and contextualize these skills within a broad array of other cognitive abilities measured at the same stage of ontogeny.

Breed Differences in Dog Cognition Associated with Brain-Expressed Genes and Neurological Functions

Given their remarkable phenotypic diversity, dogs present a unique opportunity for investigating the genetic bases of cognitive and behavioral traits. Our previous work demonstrated that genetic relatedness among breeds accounts for a substantial portion of variation in dog cognition. Here, we investigated the genetic architecture of breed differences in cognition, seeking to identify genes that contribute to variation in cognitive phenotypes. To do so, we combined cognitive data from the citizen science project Dognition.com with published breed-average genetic polymorphism data, resulting in a dataset of 1654 individuals with cognitive phenotypes representing 49 breeds. We conducted a breed-average genome-wide association study to identify specific polymorphisms associated with breed differences in inhibitory control, communication, memory, and physical reasoning. We found five single nucleotide polymorphisms (SNPs) that reached genome-wide significance after Bonferroni correction, located in EML1, OR52E2, HS3ST5, a U6 spliceosomal RNA, and a long noncoding RNA. When we combined results across multiple SNPs within the same gene, we identified 188 genes implicated in breed differences in cognition. This gene set included more genes than expected by chance that were (1) differentially expressed in brain tissue and (2) involved in nervous system functions including peripheral nervous system development, Wnt signaling, presynapse assembly, and synaptic vesicle exocytosis. These results advance our understanding of the genetic underpinnings of complex cognitive phenotypes and identify specific genetic variants for further research.