Study Shows Breeding Has Altered Dogs’ Brains

For thousands of years humans have been breeding dogs to perform specific jobs  — German Shepherds are used as police dogs, Labrador Retrievers are used as guide dogs for the blind. Now, a new study shows that these roles dogs were bred for are reflected in their brain structure.

The research team — including Stony Brook Anthropology Professor Jeroen Smaers — showed that humans have significantly altered the brains of different lineages of domestic dogs in different ways through selective breeding. The findings are published in the Journal of Neuroscience.

“Studying the brains of domestic dogs provided us with the exceptional opportunity to investigate how quickly brains change when animals are faced with strong behavioral selection pressures,” Smaers said. “Our results demonstrate that in only a few hundred years, the brains of domestic dogs have caught up with those selection pressures by altering specific networks of brain regions.”

The team, led by Erin Hecht from Harvard University, examined MRI scans of 62 male and female purebred dogs of 33 breeds. Dog breeds are known to vary in cognition, temperament, and behavior, but the neural origins of this variation are unknown. The dogs’ heads were different shapes and sizes, but could not explain the variation in the layout of their brains.

The researchers looked at six networks of brain regions that were bigger or smaller from dog to dog. The pattern they discovered led them to believe that these regions were probably working together in different behaviors. The research team then compared how the six networks differed between dogs based on the traits they were bred for and found that each of the six brain networks covaried with behavioral traits like sight hunting, scent hunting, guarding, and companionship. They concluded that neuroanatomical variation is not simply driven by brain size, body size, or skull shape, and is focused in specific networks of regions.