14 DAY TRIAL // In a first-of-a kind study, scientists have shown that selective breeding of domestic dogs is changing their physical appearance and also the disposition of their brains. The study's authors from the University of New South Wales and University of Sydney, have published their research in this month's Public Library of Sciences journal PloS One.
Experiments have shown that the brains of many tiny dogs have rotated as mush as 15 degrees, and the region of their brain that controls smell has completely changed its location. These changes, occurring in general in dogs, are the result of over 12,000 years of selective breeding, following functional and aesthetic characteristics. All these changes inside dogs' brains raise questions about the dogs' behavior.
Scientists say that no other species has captured humans' affection and companionship like dogs. The fact that such deliberate and complex changes in their biology have been made through breeding, shows that in the canine genome there is a unique capacity of adaptation.
“Canines seem to be incredibly responsive to human intervention through breeding. It's amazing that a dog's brain can accommodate such large differences in skull shape through these kinds of changes – it's something that's hasn't been documented in other species,” Dr Michael Valenzuela, from UNSW's School of Psychiatry said.
Scientists from the University of New South Wales' Brain and Ageing Research Program and Sydney University's Faculty of Veterinary Science analyzed dogs' brains across a range of breeds, by using magnetic resonance imaging (MRI).
“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,” said study co-author, Dr Valenzuela. “As a dog's head or skull shape becomes flatter – more pug-like – the brain rotates forward and the smell center of the brain drifts further down to the lowest position in the skull,” he added.
Co-author Associate Professor Paul McGreevy from the University of Sydney said: “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 to another's.”
Some breeding cause health problems and specific disorders, like pug encephalitis and hip issues in the case of the German shepherd. Still until now, nobody knows exactly what are the effects of human intervention on dogs' brains.
Dr Valenzuela said that “The next obvious step is to try to find out if these changes in brain organization are also linked to systematic differences in dogs' brain function.”