How Being Man’s Best Friend Has Shaped Dogs’ Brains

The relationship between man and dog has come a long way since ancient humans domesticated the first wolves. Humans have dramatically changed dogs’ temperament and appearance, both through extensive breeding programs and through training individual dogs. It’s little surprise then that researchers studying dogs using an imaging technique found that breeding and training have also changed their brains.¹

The research, published in the Journal of Neuroscience, suggests that modern dog breeds, such as the Border Collie and Labrador Retriever, show differences in the brain networks that control communication compared with ancient breeds like the New Guinea Singing Dog and the Samoyed. Scientists also compared the brains of trained service dogs with those of dogs released from training at a young age. This analysis suggested that dog training created smaller, more targeted differences in brain networks controlling the senses.

Modern and Ancient Breeds Compared

Mélina Cordeau, a study coauthor and neuroscientist at Harvard University, and her team recruited 108 pet dogs that were part of the Canine Brains Project database, which helps scientists study the evolution of dog brains. The researchers scanned the brains of each pooch using magnetic resonance imaging (MRI), which reveals the structure and connectivity between brain regions. The dogs were split into two groups depending on whether they came from modern or ancient breeds. The researchers had predicted that the modern dogs’ brains would have become more specialized due to the influence of breeding practices.

There are plenty of ways in which scientists measure specialization in the brain. One is the extent to which the brain’s two hemispheres look different from each other. Greater differences, called hemispheric asymmetry, are thought to reflect greater specialization in brain areas. The team found that modern breeds showed greater asymmetry than ancient breeds. These changes reflected how the dogs’ brains had become more specialized to process cues and cooperation-linked thinking.

The researchers had also recruited 28 dogs that were current or released service dogs. All these animals had the same genetic background and had been bred and socialized in the same way. The released dogs had been taken off their training program early due to non-behavioral issues such as allergies. By comparing these two groups, the researchers hoped to see the effects of a long-term intensive training regimen on the brain, independent of genetic or breeding effects. These two groups had differences in their brains, but at a more granular level. The trained service dogs showed changes in specific pathways linked to processing and responding to others' communication.

What Makes a Trainable Dog Brain?

The scientists then looked at whether specific brain features predicted how trainable their dogs were across all 108 pooches. They found that dogs with higher levels of brain connectivity were reported by their owners to be easier to train.

The researchers hope that the findings will add to the understanding of how to communicate with dogs. “More broadly, I think this type of research can help us better understand not only dogs, but also the human–dog relationship. By identifying how dogs process human communication, and how breeding and training shape these abilities, we may eventually be able to improve the way we interact with dogs, refine training approaches, and make assistance-dog training more effective and better adapted to each individual dog,” said Cordeau in a statement.