A Nose Is a Nose

A Nose Is a Nose

The world as perceived by a dog is quite different from the one with which humans are familiar. The dog's eyes can't distinguish hues, only tones, so they see a world of black, white, and various shades of gray. The human eye has two kinds of light receptors: rods and cones. The cones are color sensitive, so humans can recognize 120 to 150 different hues. The rods take over in the dark and do not distinguish color or details. This is the world the dog sees.

Seeing means far less in a dog's life than it does in a human's, because other senses take over. A dog's hearing is about 140 times more acute than the auditory sense in humans, and scent discrimination is thousands of times more keen. It can be said that animals with scent discrimination smell their world; humans see theirs. Humans can no more imagine the vivid range of sensations revealed to a dog by its highly developed olfactory sense than a polar bear might imagine the landscape of an Amazon jungle.

During the early 1960s a series of famous experiments was conducted at a leading university to determine the sense of smell possessed by dogs. The scientists used iodoform (a compound of iodine analogous to chloroform), selected because of its distinctive odor. They found that, although the sense of smell varied among certain breeds, all dogs showed an extraordinary ability to detect odors. The average dog could detect iodoform in a solution of one part to four million, even when it had been disguised with four or five other powerful scents.

Packed with many times more olfactory nerves than are allotted to the human nose, the dog can pick up the distinguishable odor of every living thing, animal or vegetable. Since each human being smells different to the dog, it will not mistake stealthy bungling burglars for its faithful human companions. The dog can also detect variations in odor resulting from emotional or physical conditions such as illness, joy, or fear. When it smells fear, the dog may be expected to take advantage of the adversary. Freshly fallen snow and dampness hold scent very well, so dogs are efficient at sniffing out victims of avalanches, floods, or tornadoes.

Dogs and humans share one feature, although they display it differently. Each human may be identified by his or her fingerprints, since no two people, even identical twins, have the same pattern. Each dog also has an identifying characteristic, but again the nose reigns supreme, for each noseprint is unique. And if we recall how the dog recognizes each person it meets, we may realize that the odor of a human may be as identifiable as a fingerprint.

From the book: 
Petrified Lightning