An organism’s behaviour and cognitive traits are shaped through selection pressures as well as through ontogenetic influences1,2. Animals are faced with social and physical challenges in their environment, ranging from finding food to cooperation among group members3. From both, evolutionary and ontogenetic perspectives, a more complex environment can advance social as well as physical cognitive abilities4. Domestication is a special case, as here, non-human animals adapt to the human environment. This adds new challenges and selection pressures that were not posed on the wild ancestors and may relax some of the requirements on traits that are critical for survival in the wild5. For instance, domesticated species may have acquired social skills to interact with their human partners (social cognition), and may have lost skills relating to independent problem-solving and understanding their physical environment (physical cognition).

Regarding social cognition, research in the last two decades shows that pet dogs are particularly sensitive to human communicative cues6. As such, they outperform other animals in following human gestures to objects7,8,9,10, and often use human-provided information only if they have been addressed through ostensive cues (calling their name, eye-contact, etc.) beforehand11,12,13. Dogs seem to develop these skills earlier than their closest wild-living relatives, wolves, even when the latter are extensively human-raised14. This indicates that selection pressures during domestication have influenced dogs’ ability to communicate with humans which, if enabled by human socialization, can be further improved by life-long experiences7,15.

Compared to dogs, wolves seem to benefit more from observing conspecific and human actions that are not directed at them. Wolves follow non-communicative human gaze more often than dogs, and seem to pay more attention when observing others’ behaviours, which they, in turn, use to skilfully solve tasks16,17,18,19,20. No research has specifically addressed, however, whether wolves can go beyond attending to others’ behaviour and infer the intention underlying this behaviour. Studies show that dogs do not differentiate between humans’ intentional and accidental actions21,22,23, but may interpret gaze as a cue of someone’s intention to approach a certain object8,24. Due to the limited data comparing wolves’ and dogs’ understanding of behavioural cues, it is currently unknown whether and how domestication has affected this domain of social cognition. However, given wolves’ higher attentiveness to conspecific and human behaviours in previous studies, there is reason to believe that wolves would outperform dogs in comprehending behavioural cues. Dogs on the other hand tend to ignore behavioural cues when the cue is not specifically addressed to them through eye contact13. In addition, it has been theorized that the developmental effects of living among humans could improve animals’ use of intentional behaviours, a phenomenon referred to as ‘enculturation’25.

Dogs perform rather poorly in tasks that require understanding causal connections or physical characteristics of objects26. Not even intensive training on object manipulation and solving physical problems improves their performance27. Further, pets living in close contact to humans learn to rely on human help instead of solving problems independently, more than pets living outside of the house28. This suggests that dogs that live more independently, could potentially be better problem-solvers. One evolutionary theory that explains dogs’ poor performance in the causal domain is the information processing hypothesis. This hypothesis suggests that selection pressures that advance causal understanding and thus problem-solving in wild animals, have relaxed on their domesticated counterparts due to a buffering effect of human care29,30. Moreover, dogs’ different feeding ecology as compared to wolves may have altered their performance in the causal domain31. As dogs scavenge for food in waste stably distributed around human settlements while wolves search for and hunt prey actively, the feeding ecology hypothesis proposes that dogs might have evolved reduced causal insight, persistence and exploration. Indeed, wolves were found to be more persistent and explorative than dogs when confronted with novel objects or environments31,32. Thus, a manipulative problem-solving task may not be the most useful method to compare physical cognition in dogs and wolves, as the better success of wolves may reflect their greater persistence in exploration, rather than a more advanced causal understanding.

Here we aimed to investigate how selection pressures during domestication and/or ontogenetic effects might have influenced dogs’ and wolves’ social and physical cognition. Within the social domain, we differentiated between the use of communicative and behavioural cues given by a human. Regardless of cognitive domain, animals needed to choose between two containers (one baited with food while the other was empty) cued differently in an object-choice task but did not need to manipulate an object to solve a problem. After the cue was performed, the animals could indicate their choice by touching one of the two targets fixed on the ends of a table, on which the containers were presented. This table was placed against a fence on the other side of which the animals were free to move.

To test for differences in social cognition, we differentiated between the use of communicative and behavioural cues given by a human who sat visibly behind the table. For the communicative cues, the experimenter repeatedly called the animal’s attention in order to cue it the correct choice (i.e. looking or pointing at the correct container), while for the behavioural ones, the experimenter showed behaviours that could indicate her intention to access one of the containers or its contents (i.e. reaching out to or trying to open the correct object). In contrast, to test the animal’s physical cognition, causal cues were provided while the experimenter was hiding under the table (i.e. a container producing noise while shaken versus a container that made no sound, an inclined shape versus a flat shape). In addition, all animals were tested in a control condition to check whether they could find the baited container based on smell. All animals were tested in 2 sessions consisting of 14 trials. To investigate based on which cues the animals could infer where the food was hidden, we recorded the number of correct choices in each of the four conditions (communicative, behavioural, causal and control). Furthermore, to measure how attentive the animals were we coded the proportion of time the animals spent in front of the testing table (position) and spent gazing in its direction (orientation).

To test for the effects of domestication on the three cognitive domains, we compared dogs (n = 14) and wolves (n = 12) raised and kept under identical conditions. Finally, to address the effects of living in human homes, we compared dogs socialized with humans but living in captive packs to enculturated pet dogs living in human families (n = 12). We expected that, (i) pet dogs would outperform pack dogs and pack dogs would outperform wolves in following more difficult human communicative cues whereas (ii) wolves would benefit more from observing behavioural cues and (iii) would be more successful in using causal cues than pack dogs, who would be more successful than pet dogs.