“He could smell the readiness of onion in every one of its stages of cooking and knew exactly what stage worked best for each dish. He could identify the exact rapidity with which milk had to boil before adding the lemon to make the cheese curd separate into paneer. He could sense exactly when to add the tomatoes to tie together the onion, garlic, and ginger so that the curry came together perfectly with the oil separating from it in syrupy rivulets.” ~ Pride, Prejudice, and Other Flavors
I get that I am intrigued by a plethora of topics that bore others to sleep. Still. Haven’t you ever wondered why cats, for example, seem unbothered by odors that make you want to upchuck? Along that line, we know there are people–usually women–whose overuse of fragrance takes your breath away as they pass you in the grocery store. How is that? First, we’ll take a reductive look at how olfaction works.
It's Magic!
It might as well be magic. We can’t see it happen, and we can’t figure out any way to make it stop or start, generally speaking. It just is. In brief, the back of human noses have millions of sensory neurons, and these react to odor molecules that float into the nasal cavity. The tips of these neurons contain proteins. They bind the molecules and function as receptors to odor stimuli. The reception generates an electrical signal to the brain’s olfactory bulb. In turn, it transmits this data to other parts of the brain:
- The piriform cortex identifies the odor.
- The thalamus, which is the brain’s Grand Central Station, relays all sensory information.
- Some of this information goes to the orbitofrontal cortex, which integrates that data with taste information.
- Some goes to the hippocampus and amygdala, both of which are regions that relate to memory and learning.
This description, as hard as it may be to follow, is an oversimplification. Still, you can see why some odors (or fragrances) bring to mind long ago experiences, and also why you might not be able to enjoy your food if you have a stuffy nose. Smell and taste are physiologically connected.
Note that I received–nay, earned–my first D in high school biology. Science has never been where I shine the brightest. You would be well-served to go to the source if you have any curiosity about the process: Brain Facts.
A Few Animals with Amazing Sniffers
- The African elephant, but it’s only fair that a 7′ trunk full of receptors should rank high on the list.
- The bloodhound tops the list for dog breeds – no surprise.
- Bears’ noses help them locate food sources, sometimes from more than a mile away.
- Male silk moths don’t have noses, but they have receptors on their antenna that help them detect pheromones released by potential mates.
- Cows’ sense of smell assists in not only finding food, but also the most nutritious grasses, as well as detecting predators.
For the complete listing, check out becausetees.com.
Why Don't We All Sense Smells the Same Way?
The short answer is that our ability to process smells is a function of our DNA, just like our eye color and whether we’re right- or left-handed. From Duke University, we learn that humans have about 400 gene receptors and more than 900,000 variations on those. This means that whether we think something smells delicious or disgusting is subject to the way our individual brains are processing the information. As an example, and according to the Cleveland Clinic, a small percentage of the population has the OR6A2 gene, which makes them eschew cilantro. Poor darlings.
Another factor that also complicates the outcome is that when we sense any odor, we aren’t smelling just one thing. Our brains consider the combination of odors, and they can be substantial. A May 20, 2020, National Institutes of Health article* states that sometimes hundreds or thousands of different odors combine to form a person’s perception of one smell. Consider that “Your morning cup of coffee can contain more than 800 different types of odor molecules.” (How the Nose Detects Complex Odors)
One more thing. According to the Cognitive Neuroscience Society in a November 2014 article, women are generally more sensitive to odors than men. Additionally, evidence suggests that the brain’s olfactory regions differ anatomically between women and men.
The Why Behind Animals Detectecting Smells Better Than Humans
Some would attribute the bloodhound’s ability to find rabbits to the length of its nose and the number of receptors. But what if it’s more than that? What if humans simply don’t focus as well? What if we don’t give a second thought to the smell of bacon in the morning (freakish thought, that), or the fragrance of a Mister Lincoln rose petal with the dew still balancing on its petals? Agreeable “smells”, both of them, but in the moment, do we appreciate the ability?
I have written about the Gift of Fear by Gavin de Becker, and described his solid advice to listen to your body when it tells you to fight or flee. Shouldn’t we have the same perception of every one of our senses? Shouldn’t we recognize the amazing gift we have to detect all manner of things we can’t see? Consider the downside of not being able to detect smoke, mold, or natural gas. We are all “fearfully and wonderfully” made. We just need to work on awareness.
I like the idea of testing our sniffing ability. Some things like cinnamon or garlic have heavy scent. It is a gift to be able to identify fragrances and i am happy to still have that hift. Interesting.