Sniffing Like We See

In last weekend's NYT magazine, Cathleen Schine reviewed Alexandra Horowitz’s Inside of a Dog: What Dogs See, Smell, and Know, a book about the world from a dog's point of view. A taste:

Dogs, as anyone who has ever met one knows, sniff a lot. They are, says Horo­witz, “creatures  of the nose.” To help us grasp the magnitude of the difference between the human and the  canine olfactory umwelts, she details not only the physical makeup of a dog nose (a beagle nose has 300 million receptor sites, for example, compared with a human being’s six million), but also the mechanics of the canine snout. People have to exhale before we can inhale new air. Dogs do not. They breath in, then their nostrils quiver and pull the air deeper into the nose as well as out through side slits. Specialized photography reveals that the breeze generated by dog exhalation helps to pull more new scent in. In this way, dogs not only hold more scent in at once than we can, but also continuously refresh what they smell, without interruption, the way humans can keep “shifting their gaze to get another look.”