Humans Have Bred Dogs so Much We've Fundamentally Changed the Shape of Their Brains

Humans have changed the shape of dogs' brains by breeding them for specific traits over time, according to scientists.

As dog owners know, different breeds have different skills and temperaments. While golden retrievers make the perfect guide dogs, German shepherds are better equipped to assist police, for example. The authors of a paper published in JNeurosci explored whether different skills—such as hunting using sight or scent, guarding or companionship—correlate with differences in brain structure.

The researchers used an MRI scanner to examine and map the brain networks of 62 male and female purebred dogs across 33 breeds, ranging from basset hounds and beagles to golden retrievers and greyhounds.

The scans revealed that dogs of different breeds have significantly different brain anatomy, in ways that are not just the result of the size of the dog's body or brain, or the shape of its skull. Instead, the changes appear to be partly down to humans.

Study co-author Erin E. Hecht, Assistant Professor in the Department of Human Evolutionary Biology at Harvard University, told Newsweek: "These differences are at least partially due to selective breeding for particular behaviors."

The study indicates "that there has been strong, recent selection pressure on brain organization in individual breeds of dogs, suggesting that humans' effects on dog brains can occur very quickly in evolutionary time," she said.

"I think it's pretty profound that our species has shaped the brains of another species on the planet," Hecht argued.

dog, pet, owner, animal, stock, getty,
Scientists have investigated how humans have influenced dogs' brains. A woman looks at a dog in this stock image. Getty

Asked what the research could be used for, Hecht explained: "This research suggests that we could to use neuroscience to better understand behavior in dogs, and to more effectively breed and train dogs for specialized skills. On the other hand, it opens up a new window to examine fundamental, basic science questions about how brains produce behavior and how brains evolve over time."

Hecht acknowledged the findings were limited because the dogs were picked opportunistically at a vet clinic. That means, as far as the researchers know, the animals were family pets, and weren't using breed-specialized skills like herding or hunting.

"It means that despite these dogs not actively performing these skills, we can still see specializations in their brain for them, which I think is pretty amazing! I imagine that if we studied dogs who are actively performing these behaviors, we might see even clearer effects." The team plans to do that next.

Hecht invited the owners of working dogs living near the University of Georgia to get in touch and potentially take part in a study.

"We'd love to hear from them!" she said.