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Humans altered dogs' brains: study

Independent.co.uk
Dogs are a weird bunch. They range in size from bearish behemoths to pipsqueaks like Milly, a Chihuahua holds the Guinness record for World's Shortest Dog at less than four inches.
Some breeds are fast runners. Others are jumpers, swimmers or diggers. Bloodhounds specialise in sniffing, while greyhounds hunt primarily by sight. Border collies excel at herding, Jack Russell terriers at flushing foxes from dens.
Over at least 15,000 years, and especially since a Victorian-era dog-creation craze, selective breeding by humans has resulted in a single species with more physical variation than almost any other in the animal kingdom.
And now, scientists have provided the first evidence that all of this selective tweaking has
not just changed dogs' sizes, shapes, colours and behaviours.
It has also altered the way their brains are built.
The research, published in the journal JNeurosci, began with MRI scans from 62 dogs who had visited the University of Georgia Veterinary Teaching Hospital for neurological evaluations.
All the dogs, representing 33 breeds, were discharged with clean bills of brain health. But their scans provided the scientists with a treasure trove of data.
"The first question we wanted to ask was: are the brains of different breeds of dogs different?" said Dr Erin Hecht, a neuroscientist studying dog cognition at Harvard University and lead author of the study.
Indeed, from Dachshunds to Dobermans, the scientists found well-defined differences between dog brains, even after accounting for things such as the pooches' overall size and shape.
By looking at the areas of the dogs'
brains that varied most across the breeds, the scientists were able to create maps of six neural networks linked to certain functions, such as the sense of smell or movement.
The team found the shape of these networks "correlated significantly" with common traits associated with each breed, as described by the American Kennel Club.
"Brain anatomy varies across dog breeds," Dr Hecht said, "and it appears that at least some of this variation is due to selective breeding for particular behaviours like hunting, herding and guarding."
In other words, not only do the shapes and sizes of canine brains vary by breed, the structures within those brains also are different.
This discovery helps explain what makes a Maltese act like a Maltese, or a boxer like a boxer.
Jeffrey Stevens, director of the Canine Cognition and Human Interaction Lab at the University of Nebraska at Lincoln, called the stud/s use of existing MRI data "clever" and its premise “exciting".