Dogs and humans have been living and working together for more than 30.000 years and it has been proposed that dogs have evolved evolutionarily novel characteristics supporting the development of a close relationship with their human partners. This might be a premature suggestion though, because we know very little about the social relationships dogs develop with their conspecifics. Therefore, currently it is not possible to tease apart whether dogs use their intraspecific behavioral repertoire to interact with humans or if they indeed evolved specific adaptations to socialize with them. The proposed dissertation has three aims: analyze and compare the relationships that dogs form with humans and with conspecifics; examine dog owners’ ways of interacting with their dogs and their effects on dog behavior; investigate a potential biological mechanism mediating these effects (DNA methylation of the oxytocin receptor gene, OXTR).
The methods comprised detailed behavioral analyses (of both dogs and owners), physiological measures (i.e. salivary cortisol levels), and epigenetic analyses.
In particular, by taking a bottom-up approach, different components of dogs’ relationships with conspecifics and heterospecifics (i.e. humans) have been examined, described, and compared based on their function in stressful situations. The results, taken together, showed that dogs’ intra- and interspecific relationships are complex and diverse. A comparison between them revealed that, in some cases, other dog companions can better function as stress buffers than owners.
A similar approach has been used to analyze the components characterizing dog owners’ interaction styles. Similar to the human parenting components, warmth, social support in stressful situations and behavioral control were identified as owners’ interaction styles components. It emerged that owners can greatly vary in their way of interacting with their dogs, and that the dogs’ way of dealing with social stress is associated to their owners’ behaviors. Although no direct connection between owners’ interaction styles and OXTR methylation was found, associations between this epigenetic modification and dogs’ social behavior have emerged, confirming the regulatory role of the oxytocinergic system in dogs.
Overall, the present thesis emphasizes the complexity of dogs’ social behavior and social relationships and it proposes dogs as a model of social flexibility. In addition, it shows that conspecifics play an important role in a dog’s social life, and that the relationship that dogs build with humans might not be that unique after all. Once again, it shows that the oxytocinergic system has a key role in modulating dogs’ social behavior, and it provides a new system to examine in future studies: epigenetic variation of the OXTR. Furthermore, it highlights the importance of characterizing the owner’s behavior for a better understanding of dogs’ reactivity to stress and of the dog-human relationship. The parallelism with human parenting behavior suggests that humans’ caregiving behavior can be characterized by the same components, whoever the caree is (a human child or an individual belonging to a different species).
The interdisciplinarity of the thesis brings together theories and methods from different fields (human social psychology, ethology, anthrozoology, behavioral endocrinology, and genetics) and creates a bridge between them, for a more comprehensive understanding of the characterization and development of social relationships.