It's Flashcards Friday at Math Science History. I'm Gabrielle Birchak, your host, and by the
time you're done listening to this, you will tell yourself, ah, this makes sense. Why? Well,
today we are exploring the olfactory system, our sense of smell. I love puns. Our olfactory
system is one of the oldest sensory systems in evolutionary history, and though it often
gets overlooked compared to sight or hearing, it shapes the way we move through the world
more than most of us realize. So, let's start at the biological level. Every breath you take
pulls air through your nasal cavity, where millions of tiny neurons line a small patch of
tissue called the olfactory epithelium. Sitting high inside your nose, this patch, about the size
of a postage stamp, is home to specialized receptors that detect airborne molecules.
Each of those receptors is tuned to recognize a specific molecular shape. When a molecule,
say the one that makes coffee smell like coffee, yum, lands on the right receptor,
it triggers an electrical signal. Speaking of coffee, don't forget to visit Math Science History
and click on that coffee button and donate to the podcast because every donation you make
keeps this podcast up and running. So, back to electrical signals. That signal travels along the
olfactory nerve to the olfactory bulb, a brain structure just behind your forehead. From there,
the message fans out into the limbic system, the emotional center of your brain. And this is what
makes smell so powerful. Unlike sight and sound, which route through the brain's thalamus before
reaching conscious thought, olfactory signals take a shortcut straight to the amygdala and the
hippocampus, the regions responsible for emotion and memory. That's why a whiff of an old perfume
or the smell of rain on pavement can instantly bring back forgotten memories or emotions
without a single word or image. Now, let's talk about this sense that is older than we are.
Smell predates sight and hearing in evolutionary history. Some of the earliest life forms,
even simple bacteria, could detect chemical gradients in their environment. They moved
toward nutrients and away from toxins. That primitive version of smell has evolved for over
500 million years. That's amazing. In humans, olfaction becomes more specialized but remains
deeply tied to survival. Anthropologists believe that our early ancestors used smell not just to
find ripe fruit or detect spoiled meat, but also to recognize one another, family, tribe,
and even potential mates. We still do this subconsciously today. Studies show that people
can identify their siblings, partners, and even their own t-shirts by scent alone. And here's a
twist. Humans have about 400 types of olfactory receptors, but those receptors can combine in
patterns to detect over a trillion different odors. That's right, a trillion. It's like having
400 piano keys but being able to play endless symphonies. When you smell freshly cut grass,
chocolate, or ozone after lightning, your brain is decoding a complex chemical cord.
Now, what are the benefits of smell? Well, our olfactory system does more than remind us of
grandma's cookies. And if grandma didn't bake, maybe, I don't know, her beer breath. My grandma
was not an alcoholic for the record. You know, she was a lot of fun, but no, she did love her
beer. So anyhow, our olfactory system keeps us healthy, alert, and emotionally balanced.
So let's look at the three major benefits. One, it keeps us safe. Smell is a built-in warning
system. It detects gas leaks, smoke, spoiled food, and even illness. Before modern technology,
it was one of our best defenses against danger. In fact, certain diseases subtly change a person's
scent profile. Research has shown that dogs, even trained humans, can detect illnesses like
Parkinson's, COVID-19, or cancer based on scent cues. Our ancestors relied on the sense to avoid
rotten meat or to notice when something was off in the environment. Losing your sense of smell,
a condition called anosmia, can make daily life riskier because those cues disappear.
Two, it enhances our emotions and our relationships. Because smell connects directly
to the limbic system, it's tightly linked with emotion. Smelling something pleasant like lavender,
vanilla, or citrus can immediately lift mood and lower stress levels. Smell also influences
attraction. We tend to be drawn to people whose natural scent is different from our own immune
profile, increasing genetic diversity in offspring, an evolutionary bonus wrapped in romance.
Three, it improves memory and learning. Smell can strengthen memory recall. That's why some
educators and neuroscientists recommend pairing a certain scent, like rosemary or peppermint,
with study sessions, then reintroducing the same scent during exams. The olfactory cue helps the
brain retrieve stored information more efficiently. It's not magic, it's neurobiology in action.
Of course, losing your sense of smell can be distressing. People with anosmia, whether from
a viral infection like COVID, a head trauma, or even aging, often describe it as losing part of
themselves. Food becomes bland, memories fade, even emotions flatten. After the COVID pandemic,
many people experienced temporary anosmia, which sparked new research into olfactory recovery.
Now, this is cool. Scientists have discovered that olfactory neurons can regenerate,
something that doesn't happen with most senses. Through consistent olfactory training,
smelling specific scents twice a day, many people regain partial or full smell over time.
The brain, it turns out, can relearn to smell. And smelling is not just biological,
it's historical and scientific. So, what can you do with your olfactory system? Now that you know
how remarkable your sense of smell is, here are three things you can do to put your olfactory
system to work. One, use smell to boost focus and memory. Try scent association. When you're
studying, writing, or working on a creative project, use one specific scent, perhaps rosemary,
peppermint, or lemon essential oil. Those are nice. Over time, your brain links to that aroma
to concentrate. The next time you need focus, smell that same scent again. Studies from North
Umbria University and Wheeling Jesuit University have found that rosemary can improve memory recall,
while peppermint can sharpen your attention. That is so cool. It's like creating your own
cognitive shortcut. Two, just as you can train your muscles, you can train your sense of smell.
Perfume makers, chefs, and wine experts do this all the time. It's called olfactory training.
Start small. Each day, pick three to five distinct scents, coffee, citrus, rose, cloves,
and spend a few seconds identifying each one. Try describing them beyond the obvious. Is it warm,
sharp, earthy, or metallic? Over time, your brain becomes better at distinguishing subtle
differences, and that exercise can even help repair smell loss from illness or aging. Three,
our third flashcard, reconnect emotionally with smell. We live in a visually dominated world,
but smell can ground us in the present. Try a smell walk. Step outside and focus entirely on
scent, grass, rain, exhaust, flowers, even the changing air before a storm. Notice how each smell
tells a story about place, season, or memory. This kind of sensory mindfulness has been shown
to reduce anxiety and increase emotional well-being. You are literally breathing your
way into awareness. For me, though I can't drink it, I love the smell of beer. I wonder why.
Thank you for listening to Flashcards Fridays at Math, Science, History.
I hope this podcast made sense to you. Sorry, puns. Until next time, carpe diem.