Dogs' Brains Reorganized by Breeding
For thousands of years humans have changed dogs' looks through selective breeding. Now it seems we've actually reordered many breeds' brains in the process.
(See dog-evolution pictures.)
A new brain-imaging study examined 11 carcasses from 11 different dog breeds, both long-snouted, such as the greyhound and Jack Russell terrier, and short-snouted, such as the mastiff and pug.
The team found that the brains of many short-snouted breeds have rotated forward by as much as 15 degrees.
Furthermore, in these breeds the brain region for smell, called the olfactory bulb, has drifted downward toward the base of the skull, perhaps significantly altering the dogs' all-important source of smell, researchers say.
Since the first wolf was domesticated an estimated 12,000 years ago, "selective breeding has produced a lot of [anatomical] variation, but probably the most dramatic is in terms of skull shape," said study co-author Michael Valenzuela, a
