Alexandra Horowitz teaches at Barnard College and runs the 'Dog Cognition Lab' there. Horowitz has penned many books about dogs, and - in this informative volume - writes about the sense of smell in dogs and humans.
Alexandra Horowitz
Alexandra Horowitz with her dogs, Finnegan and Upton
Horowitz begins with a brief introduction to her own canine snufflers, Finnegan and Upton, and goes on to describe the dog olfactory system in some detail. In short, odor molecules are sniffed into the dog's nostrils and follow a hurley burley journey back to the nasal tissue, which sends signals to the brain. There the message is interpreted: poop? biscuit? the annoying cat next door? The human olfaction system is somewhat similar to that of a dog, but less complex and less sensitive.
Dog olfaction system
There are innumerable kinds of smells, but most people - except for sommeliers and perfumers - don't have the vocabulary to describe them. We know we like bakery smells and don't like sewage smells. We may even be able to say one is buttery and caramelly and the other is urinous and fecal, but that's about the extent of our descriptors. Be that as it may, smell - a form of 'chemosensation' - is an important evolved strategy. It tells organisms to avoid things that are toxic and to move toward things that are beneficial.
Animal 'smell organs' come in many varieties: molluscs smell with their tentacles; male silk moths with their feathery antennae; nematode worms with an opening near their front tips; elephants with their trunks; and so on.
Humans, of course, have noses, but we use them very little compared to other animals. In fact, smell is the sense most people say they would be willing to lose. This would be a huge mistake, however, because taste is 80% smell. The flavor of delicious food APPEARS to come from the mouth, but REALLY comes from the nose. You can test this by holding your nose while eating.
In additon, smells can be incredibly informative. Helen Keller, who was blind and deaf, was "exquisitely sensitive to smell." From a sniff, Keller could tell the work a person was engaged in, because the odors of wood, iron, paint, and drugs cling to the clothes of those that work with them. Thus Helen could distinguish a carpenter from an iron worker, and an artist from a mason or a chemist. Even when a person passed by quickly, Helen knew whether she/he had been in the kitchen, garden, sickroom, etc.
Presumably, anyone could do this with practice, because approximately 1% of our genome codes for olfactory receptors (this is a lot, considering how complex we are). Experiments have shown that mothers can pick out the smell of their newborn's shirt from a mass of baby shirts; kids can pick out the smell of their siblings, even after not seeing them for two years; dog owners can tell which of two blankets THEIR pooch has used; people can detect which of their friends/family has handled a book by its aroma; etc.
To test and improve her sense of smell, Horowitz participated in an olfaction study at Rockefeller University, consisting of 10 two-hour sessions. During each session, Horowitz sat in front of a computer with a bin of 100 or so small bottles by her side. The procedure was to open a bottle, take a sniff, and key in a response.
The odor was evaluated for strength; pleasantness; and familiarity as well as specific characteristics: fruity; fishy; grassy; urinous; edible....etc. (there are 17 options). Horowitz acknowledges that she found almost all the aromas unnamable, though she recognized coconut, bubble gum, pencil shavings, almond extract, wheat grass, and Smarties candy. Some of the smells were horrible....but she had to smell them all.
Horowitz made additional efforts to improve her sensory acuity, including:
- An organized 'walking and smelling tour' of a New York City neighborhood, to sniff and identify odors she'd been missing or ignoring.
- A tracking exercise near the Quabbin Reservoir in Massachusetts, where she saw signs of bears; flying squirrels; cottontail rabbits; deer; etc. Horowitz was instructed to look for claw marks; shed hairs; paths foraged through undergrowth; depressions in grass; fur where an animal lay/nested; and excretions - droppings; secretions; pellets; and so on. The scientist was told to "get down on your knees and stick your nose right in."
- A wine tasting class in Napa Valley, California.
- A consultation with a perfumer.
- Sniffing practice with a 'smell testing kit' gifted by her husband.
Smell testing kit
Of course a dog's nose is exponentially better than a human nose. If you walk into a house and smell a tray of cinnamon buns baking, it will smell like a trillion cinnamon buns to your dog. Thus dogs make excellent detectors and trackers.
Horowitz visited the University of Pennsylvania's 'Working Dog Center', located in an abandoned Dupont Chemical Plant.....where sniffer dogs are trained. Canines can be taught to detect anything that has a smell, such as: a lost person; a specific drug; an explosive; an invasive plant; a cancerous cell; a destructive insect; animal scat; and so on.
At the Working Dog Center, a successful 'detection' is rewarded with a vigorous game of tug.....and this is how the dogs are trained. In an old building, a trainer and a dog play tug with a towel that has a particular scent (like cocaine, for example). The trainer then throws the towel, and the dog retrieves it. The trainer then hides the towel, and the dog finds it. Little by little, the towel is replaced with the scent alone, and the dog learns to 'alert' on that aroma. This type of training goes on for the pooch's entire working life, to keep her/him up to snuff.
Sniffer dogs at work
After watching the indoor training session at the Working Dog Center, Horowitz observed dogs in the field, searching for a person hiding in a barrel. Dog 1 took 42 seconds; Dog 2 - who stopped to poop - took 92 seconds; Dog 3 took 34 seconds....and so on. The author noted that each dog had its own style, and each was a model of efficiency.
Lastly, Horowitz returned inside to watch dogs participate in an exercise for 'Human Remains Detection' (HRD). To the scientist, the training substance smelled sweet and vominous, like a carnation rotting in water. However, dogs are attracted to this type of 'death odor' - which is produced by cells breaking down. Canines who do well in HRD become cadaver dogs.
Cadaver dogs at work
Other dogs may be trained to do medical diagnoses. For example:
- A 44-year-old woman's collie-doberman mix became focused on her left thigh, constantly sniffing at a mole there, and even nipping at it - as if to bite it off.
- A 66-year-old man's labrador began to obsessively sniff his thigh, which seemed to have a patch of itchy eczema.
- A 44-year-old woman's dachshund puppy started showing undue interest in her left armpit.
In each case, the dog had discovered a malignant tumor! 😞 It's not yet known what smell attracted the dogs' interest, but it might be aberrant protein synthesis by cancer cells. Could sniffer dogs be trained to be 'diagnosticians?' This is currently being studied at Penn's Working Dog Center.
One area with a "perfect convergence of dogs' desires and our own" is truffle detection. Truffles - which are underground mushrooms - smell wonderful to dogs and are very valuable to people. A golf ball size Perigord truffle from France sells for over 100 dollars, and enormous 2 ½ pound truffles have sold for hundreds of thousands of dollars. Thus, some sniffer dogs have been trained to locate truffles.
Dog being shown a truffle
Truffle dogs at work
Pile of truffles
Unlike sniffer dogs, our pet pooches - who get fed at home and discouraged from dallying on walks - have let their noses go dormant. The good news is, their snufflers can be reactivated. Horowitz's dog Finnegan was taken to a Long Island Obedience school, where the 'smelling classes' were "his favorite place on Earth." (Maybe he'll learn to find a million dollar truffle. 😍)
The book is interesting and informative, but a bit dry and repetitive. Still, well worth reading for people interested in the subject.
Rating: 4 stars
Definitely going to check this book out. I have dogs in every book I write.
ReplyDeleteI think most books are better with dogs Jacqui. 🙂🐶
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