Some dog breeds are incredibly fast runners and some, like the Bloodhound, are known for their smelling ability. Some are small, but what they lack in size they make up for in their activity levels.

Other dogs were bred specifically to be good companions. And then there are those strong and smart working dogs – such as the Great Dane and Boxer.

Brains tweaked as well

Whether it was for hunting, herding or guarding, dogs have been purposely bred by humans to perform specific tasks for hundreds of years.

Today, thanks to this selective breeding, there are more than 400 dog breeds in the world. In fact, dogs have more physical variation than almost any other animal on earth.

And now, for the first time, a new study has discovered that this practice has not simply tweaked dogs’ sizes, colours and behaviours, but also their brains.  

The study’s lead author, Dr Erin Hecht, a neuroscientist studying dog cognition at Harvard University and his colleagues mention that although dog breeds are known to vary in cognition, temperament, and behaviour, the neural origins of the variations were previously unknown.

The research, published in JNeurosci, investigated the effects of selective breeding on the brain structure of 62 dogs from 33 dog breeds through magnetic resonance imaging scans. The dogs had the neurological evaluations done at the University of Georgia Veterinary Teaching Hospital. The scientists found that there was wide variation in brain structure that was not simply related to body size or head shape. 

Greatest variance across breeds

The team also went on to examine the areas of the brain that vary the most across breeds. This led to maps of six brain networks that were each linked to at least one behavioural characteristic. All six brain networks had proposed functions varying from social bonding to movement. The maps showed that the variations in behaviours across different dog breeds were correlated with anatomical variations.

Purpose of the study

The researchers of the study claim that studying this neuroanatomical variation in dogs offers a unique opportunity to study the evolutionary relationship between brain structure and behaviour. All 62 dogs in the study were pets and not working dogs.

Dr Hecht explained that her team is also trying to better understand why and to what extent variations between “high-skill performers and low-skill performers” in the same breed occur. “For example, [the difference between] border collies who are winning herding competitions out in the real world and siblings of those dogs who, for whatever reason, would rather just sit on the couch,” she said.

If the researchers have managed to find a reason for these differences, Jeffrey Stevens, director of the Canine Cognition and Human Interaction Lab at the University of Nebraska at Lincoln commented: “Imagine what might be discovered in the brains of working dogs.”

Daniel Horschler, a PhD student at the University of Arizona’s Canine Cognition Centre, said the variation found across the breeds could also prove to be an important model for understanding how brains work in general.

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