Imagine if every single leaf on a tree were a distinct smell-detecting cell in the nose. A dog has as many individual smell cells as every single leaf on this tree:
You, human, have only as many as each leaf on this one:
This comparison is somewhat misleading as we humans actually have about 6 million smell-detecting (olfactory receptor) cells. Bloodhounds have about 300 million olfactory receptors. With our 6 million receptors, we can identify about 1 trillion different odors. Yup. That’s the new and improved estimate for humans. With up to 50 times more receptors than humans, dogs can smell in the neighborhood of 10,000 times more odors. At least. For the average dog. Bloodhounds may have a sense of smell 100,000 times better than ours.
As fantastic as it is that we can detect 1 trillion different scents, the human sense of smell, or olfaction, pales in comparison to that of a dog. Take your pup out for a walk and nose to the ground, they are busy reading the smells. You’re enjoying the vivid sunset, your neighbor’s new landscape design, the vintage Corvette that just passed and they can’t wait to get to that pole over there. Suddenly your dog stops, circles back to sniff something near your feet, then looks up at you as if to say, “Yo, Bernadette, your standing on my sniff.” As far as your dog is concerned, you’ve just committed an incomprehensible faux pas. It’s like we live in two different worlds; we do, indeed, live in the same world in very different ways.
Humans dedicate more brain power to vision than any other sense. Dogs devote more brain to smell. Try for just a moment to think of how different your world would be if you relied on smell to navigate your way around using vision, hearing, and other senses only as supplements, like a dog. When you take your dog for a walk and they want to stop and sniff everything, they are getting the news. Who’s been by and when, what they ate, if they are ill, who’s coming their way, where the chicken bone is that someone tossed out their car window last night at sunset… all sorts of information, for all intents and purposes, invisible to us because while we CAN smell 1 trillion different odors, we all but ignore anything other than exceptionally bad or good smells when we go about our daily business. We’re too busy looking at stuff.
Now imagine a trained scent-detection dog at work. Of all the odors in their world, a veritable changing kaleidoscope of smells, they are able to focus in on a distinct set scent molecules. Bomb-sniffing dogs, money-sniffing dogs, search and rescue dogs, cancer-detecting dogs… these dogs have learned that we humans are interested in their vastly superior sense of smell for specific kinds of odors. A search and rescue dog given a scrap of clothing with one individual human’s scent on it can track that one human (out of 6 billion of us!) and follow that one human’s residual scent molecules in an environment full of the scents of everything else that has been in that area. And this complicated by the passage of time, the wind, the rain, and a whole host of other variables. What amazing focus. What extraordinary skill. Cancer-detecting dogs have learned to detect the odors produced when normal cells become cancerous. Cells! They are sniffing cells and recognizing unique cancerous changes that we haven’t yet figured out how to detect yet with our incredibly powerful DNA technologies! And for the price of treats! Bravo, you doggies! Just think: your lovable couch potato can actually do that. The catch is that they have no idea we are interested in their special talents and abilities if they even are aware that we can’t do the same ourselves.
Yes, some dogs are pretty happy reading the USA Today version of the smells while others want the Sunday edition of the New York Times or a set of encyclopedia. Either way, smells are their intellectual exercise and enrichment, the stuff of their dreams. So take your pup out for a good sniff walk and let them revel in the news of the day. They’ll love you all the more for it!
Dr. Fairy Dog Mother