A team of European researchers analyzed 850 dogs and concluded modern breeds have larger brains than ancient breeds, a pattern they link to more complex social environments and closer interactions with people. Notably, modern domesticated dogs have smaller brains relative to body size compared to their wild ancestor, the gray wolf, a trend also observed in other domesticated species, which can have brains up to 20–24% smaller than their wild counterparts.

The study, published in the journal Evolution, drew on data collected and interpreted by researchers from the ELTE Institute of Biology, the Ecological Research Centre in Hungary and Stockholm University. Lead investigators said the change in brain size corresponds with how breeds live and the tasks they perform alongside humans.

“The results show that the breeding of modern dog breeds has been accompanied by an increase in brain size compared to ancient breeds,” said Enikó Kubinyi, senior research fellow at the Department of Ethology at ELTE Institute of Biology.

Researchers noted a relationship between genetic distance from the wolf and brain size: “Dog brains are getting larger the further genetically that they have evolved away from a wolf,” the team reported as a broad pattern in their analysis. This shift may reflect not just evolutionary pressures but also the challenges and complexities inherent in cooperative social interactions.

Niclas Kolm, a researcher at Stockholm University, framed the change in functional terms. “Different dog breeds live in varying levels of social complexity and perform complex tasks, which likely require a larger brain capacity,” he said, pointing to variation in the social and working roles of breeds across modern environments. This relationship between social interactions and cognitive development suggests that dogs, much like other animals, are driven to select for larger brains and sophisticated cognitive abilities.

Evolutionary biologist László Zsolt Garamszegi of the Ecological Research Centre emphasized energetic trade-offs in brain evolution. “There is no need to sustain the energetically costly large brain, and the freed-up energy can be directed toward other purposes, such as producing more offspring,” he said, describing one possible consequence when large brains are not maintained.

The team drew on samples and comparative measures across breeds to reach their conclusions. Their interpretation suggests that increasing social and environmental complexity in modern human-dog contexts may be associated with larger brains in some modern breeds, although the study found no direct effect of functional selection category on relative brain size. Dog owners can also enhance their pets’ cognitive development through regular social contact with people and friendly dogs, further stimulating their brains and improving their overall well-being.

The findings and their interpretation are summarized in a feature at Popular Mechanics, which outlines the study’s main arguments and quotes from the researchers involved.

The study team listed the ELTE Institute of Biology, the Ecological Research Centre and Stockholm University as the institutions conducting the work. Their paper appears in the scientific journal Evolution and adds to an ongoing conversation among biologists about how domestication, breeding, and human environments shape canine cognition.

Where this line of research goes next will depend on further comparative work and on linking brain-size measures to behavior and life history across breeds. For now, the study presents a clear numeric foundation: 850 dogs were examined in the analysis that produced these conclusions.

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Original reporting: view the original article.