Convergent evolution of the social brain? A comparative dog-human fMRI approach (EVOSOCBRAIN)

Humans are often described as social beings, and much of the success and dominance of our species on planet Earth is due to our very sophisticated abilities to co-operate and work together. In order to cooperate, we must be able to understand the intentions, thoughts and emotions of those around us, as well as coordinate with them through aspects such as social learning and behavioural coordination. An intensely debated question in the behavioural and neurosciences is the extent to which human social abilities and skills are unique, or whether other animal species also have them, or at least precursors of them. This question is still largely investigated by comparative research on other primates (such as chimpanzees and macaques) or rodents (rats and mice). However, such an approach neglects the fact that abilities or, more generally, the characteristics of a species can arise not only in the course of divergent evolution, but also through so-called convergent evolution.

While divergent evolution describes the extent to which traits could have developed from those of our more closely related ancestors, convergent evolution refers to the phenomenon that similar traits can be explained not only by evolutionary relationship, but also by adaptations to similar environmental conditions that have occurred in the course of evolution. This is where our research project came in. We have developed methods and research approaches to investigate the brain structure and function of specially trained domestic dogs using brain scans (functional magnetic resonance imaging). The focus was on abilities such as social and emotional perception, perspective taking in relation to thoughts and beliefs of other conspecifics and humans, as well as (precursors of) empathy. Our research demonstrates that the brains of dogs process social information in a partially similar ("analogue") way to humans, but that there are also specialisations that indicate different brain mechanisms and processing methods. Figure 1 summarises one such result. In addition to showing the examination setting of one of our dogs in the MRI scanner (Fig. 1a), it shows how dogs and humans perceive images of faces and bodies of other dogs and humans and which brain activities this is associated with. While humans in this study process bodies and faces in specific subregions of the brain, this is only the case for bodies in dogs (Fig. 1b). The latter moreover react to images of other dogs with activation in their olfactory brain (Fig. 1c), which can be explained by the special significance of odours for dogs. In addition to these substantive results, a central additional goal of the project was the development of improved MRI measurement approaches. For example, we co-developed and validated an MRI coil in the project (see Fig. 1a) and refined analysis models that can be used to examine dogs' brains with greater accuracy.

Overall, the project and the interdisciplinary collaboration implemented in it have enabled the establishment of an inter-university research unit (Faculty of Psychology and Messerli Research Institute, https://ccnu.univie.ac.at). This will sustainably establish Vienna as a world-leading centre for comparative neuroimaging research on dogs and humans.