Twelve millennia of selective breeding have created hundreds of distinct dog breeds, yet they're still all one species - even a chihuahua and Great Dane could successfully interbreed. But all those physical changes have deeply altered how dogs' brains work.
Dogs with shorter snouts - in other words, the ones that are the most physically different from their wolf-life ancestors - have experienced some extreme changes in their brains. Some breeds have seen their brains rotate forward a whopping 15 degrees, and the region of the brain that controls smell has permanently altered its location. Considering how fundamental the sense of smell is to a dog's perception of the world, that is a very big deal. As the University of Sydney's Paul McGreevy, one of the main authors of this new study, puts it:
"We think of dogs living in a world of smell — but this finding strongly suggests that one dog's world of smell may be very different from another's."
His colleague Michael Valanzuela expanded on what they found:
"We found strong and independent correlations between the size and shape of a dog's skull, and brain rotation and the positioning of the olfactory lobe. As a dog's head or skull shape becomes flatter — more pug-like — the brain rotates forward and the smell centre of the brain drifts further down to the lowest position in the skull."
As Dr. Valanzuela explains, the most astounding thing is that dogs' brains can actually handle such huge differences in the shapes of the skulls that house them. Dogs have already shown unprecedented levels of variety in their different physical breeds, but the variation in brain organization is an even more fundamental and thus more incredible form of diversity across the species. The next step for their research will be to trace these changes to potential differences in the brain function of various dog breeds.