An incredibly sophisticated molecule detector senses the air.
It begins to collect samples, processing them in its olfactory factory, where individual molecules search for its precise corresponding docking station, like the right key going into a precise lock.
The information about what molecules are present, and whether they’re safe for humans, is processed by an incredibly powerful local supercomputer. The humans with the supercomputer and molecule detector can then go about their lives safely, without thinking too much about how this process works.
You probably know what I’m talking about. No? Do I hear two no’s?
There are everyday things in the world—things we experience every day—that have a way of invoking a sense of wonder in me. The way we smell things is one of those things we tend to take for granted, but there’s an incredible story going on.
Molecular Matchmaking
While we’re over here inhaling and exhaling, giving little or no thought to what our nose is up to, our molecule managers are working 24/7, starting with the way air gets in: your nostrils. They condition the air by adding humidity and warmth, if needed. They filter out unwelcome particles.
But the real magic happens deeper within, in a specialized tissue called the olfactory epithelium. About six million tiny receptor cells (in humans) act as docking stations, waiting for the right molecules. Each of these receptors is like a bouncer at a club: only a certain type can get in.
As soon as this connection is made, an electrical signal goes to the brain. The connecting molecules complete a circuit of sorts, and ions flow from the olfactory cell to the temporal lobe, the part of your brain that sits behind and under your ears.
If the signal matches a stored memory, you will recognize the odor.
When I brew my morning coffee, I often think about this connection being formed. This is a truly wonderful process: nature has created a powerful program (hardware and software inclusive) that processes individual molecules, designed to keep us safe and help us find delicious things to drink.
Our real-time chemical analysis lab is a masterpiece of evolution, a gateway to another world of experience. However, our sense of smell pales in comparison to our best friends.
I know I just got done telling you about how amazing our own noses are, but stop for a moment to think about our canine friends. Instead of 6 million olfactory receptor cells, dogs have something like 200 million, depending on the breed.
One time around 1998, when I was at a dog park, an older man turned to me with an observation, as we watched the dogs walk around sniffing the ground where other dogs had once peed. This stuck with me, and I think it’s accurate:
This is their version of reading the newspaper every morning.
Maybe it’s more like Instagram or Notes, though, but pardon the somewhat dated analogy.
The information dogs take in through their noses is immense. They can detect certain odors at concentrations as low as one part per trillion.
Ever walk near a kitchen and smell something vaguely sweet and savory smelling? You might be able to pick out that they used one ingredient in the recipe. Now imagine discerning every individual ingredient used in a recipe, and every component those ingredients are made up of.
A dog’s olfactory prowess is so advanced that they can even smell time.
That’s right! Molecules gradually leave an environment, but not all at once. Dogs can use these clues to understand when something happened. It’s no wonder that dogs are sought after for search and rescue missions, the occasional criminal investigation, and even the occasional medical diagnosis.
Our canine friends understand the world in a way we can only dream of.
The Wonder of Odor
The next time you go into a public bathroom, don’t linger too long, but do think about the process of tiny molecules bombarding the inside of your nose. Think about those millions of little cells reaching out for these molecules, and imagine those molecules being rejected by those bouncers until they find a home.
Find something better to smell—say a freshly baked loaf of bread, or maybe some freshly cut grass. Really take a minute to envision the extraordinary machinery at work.
If you have a dog in your life, watch them as they sniff. Let a mundane walk around the block become an adventure for both of you! Try and imagine what they’re “seeing” as they’re sniffing.
Finally, let me know: what are some of your favorite things to smell?
The best image of this is the idea that when you smell a fart you are literally sampling airborne fecal matter.
Great, Andrew! I really appreciate the way you “translated” the science of smell.
Reverence for the sense of smell is more important than ever as our environments warm and viruses spread more quickly.
When I lived in Rhode Island, my dog (nose to the ground- Dachshund) got epilepsy from the run off of my neighbor’s weed killer. I researched some great science writing (e.g. Candice Pert). We moved to the mountains of Western North Carolina.
Baron Valdi lived a long life without medication.🐾