HUB's LIST of medical fun facts

“Memories, imagination, old sentiments, and associations are more readily reached through the sense of smell than through any other channel.”
~ Oliver Wendell Holmes Sr.

Your memory of smells are the memories that last the longest. If it is an aroma (grandma’s cookies baking) or an odor (a teenager’s sneaker in July), recognizing a familiar smell can cause a flood of memories of a long-gone past inside your brain  . . . and in your heart. Why is that? One reason may be that the olfactory nerves in your nose have a short and a direct path to the brain centers associated with memory and emotions. What you see with your eyes has to travel way back to the visual cortex in the very back of your brain to be recognized, bypassing the centers for memory and emotions.

Our sense of smell can’t hold a candle to the sense of smell in dogs. And, it turns out, that sense of smell is wondrous in all dogs, not such Bloodhounds and German Shepards (which are known to stink  too) Dogs have millions more smell receptors in their noses then we do. Dashunds have about the same number of smell receptors as the Bloodhounds and the Shepards, but those two breeds are easier to train apparently. Also, Bloodhounds were plentiful in the South and their loud baying helped the pursuers know where they were, while also intimidating the pursuee. Pigs have actually better smell senses than dogs, but they weren’t used extensively since people did not enjoy them cruising through their houses, sniffing everything and doing other less socially accepted bodily functions.  AND it was difficult to train them not to dig up soil outside with their snouts as if they were hunting for truffles.

Several types of dogs have been trained for a variety of skills; finding dead bodies (four feet deep in dirt, underwater, and even through a stone patio built to hide a murder victim!), spotting narcotics in suitcases at the airport (again, pigs would even be better, but who would accept them rooting around the baggage claim area), detecting land mines, ruling out bedbugs (you can hire a service that gives you an embossed certificate that your abode is free of bed bugs after a German Shepard inspection). Obviously the dog’s sense of smell is better than its vision, particularly at the skill of facial recognition. My friend’s rescue dog, whom I have known for years, barks at me (and other familiar people) every time I arrive until he sniffs my hand.

The German Shepard is the favorite breed to use because they are more easily trained than other breeds, though the training is not easy. It requires a single trainer bonding with the dog, not all Shepards are trainable to change their behavior when detecting a certain smell (usually obvious within a month or two of training), and evidence shows that the trained dogs get better at detection the more they do it.

But the sense of smell remains an actual mystery. Perfume manufacturers and wine connoisseurs have no real idea how they do it. We know it is just about various chemicals wafting through the air and into our nose, but efforts of developing an artificial nose   (1999) to replace a trained dog are just in the infancy stage. (2018) As Cat Warren (no pun intended) says in her book What The Dog Knows (2013), “Artificial noses won’t shed and won’t bite. They won’t get tired and overheated. They will detect parts per trillion of anything. They will put sniffer dogs out of business. Any day now.” 

To close on a politically correct note, and, to avoid too many irate “feedback comments”, cats have a good sense of smell too . . . we think. We have all read the stories of the aloof nursing home cat that jumps on and sleeps on the person’s bed the night before the person dies, or the cat who cruises the waiting room in a hospital and cozies up to the person who has cancer.  Of course, cats are harder to study then dogs . . .  and they are famously untrainable.

This entry was posted on Friday, August 1st, 2025 at 11:17 AM and is filed under evidence-based medicine, medical trivia, Neuroscience. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.