The Memory of Smell

As we all know, humans can see, hear, touch, taste, and smell. Whatever we have seen or heard, we can remember. Sometimes, we can even recall someone's touch.

Similarly, we can remember the smell of something tasty, sweet, or refreshing—like flowers, mountains, the sea, or a fountain. Basically, we store these sensory memories in our brain. But in this article, I want to emphasize more on the "Memory of Smell."

Have you ever smelled something that suddenly reminded you of something else—something nostalgic? For example, I recently smelled a perfume that immediately reminded me of a familiar person who used to wear the same fragrance.

From ancient times, the sense of smell has played an important role in survival and decision-making—whether it was choosing a mate, identifying food, or sensing whether someone was friendly or threatening. Smell has its own science.

The Science of Human Smell (Olfaction)

In very simple terms, when we sniff, air carries odor molecules into the nasal cavity. These molecules bind with olfactory receptors—around 400 different types—and through various combinations, we can detect thousands of different odors.

The signals then travel through nerves to the brain, reaching the amygdala (the emotional center) and the hippocampus (the memory center). This direct connection is what makes smell so powerful in triggering emotions and memories.

Interestingly, about 80% of what we perceive as taste is actually smell. That's why, without even taking a bite, we can often "taste" food just by smelling it.

Another fascinating fact is olfactory adaptation. When we are constantly exposed to a particular smell, our brain begins to "tune it out," making it invisible to us. That's why every home has a unique smell that the residents don't notice—but visitors can.

Over time, even we stop recognizing the smell of our own space. Yet, if we return after a long absence, we can detect it again.

The Uniqueness of Smell

Each of us has a unique "odor fingerprint" shaped by genetics, diet, and health. For example, from my experience, a person who consumes a lot of dairy products often carries a distinct scent that makes it easy to guess their diet.

Smell even plays a role in social and emotional bonds. Research suggests that close friends and family members often share similar scent profiles due to shared environments and habits.

Smell and Nostalgia (The Proust Effect)

Smell is unique in how it connects to memory. Other senses like sight and sound first pass through the thalamus, which acts like a filter before reaching memory and emotional centers.

Smell, however, bypasses this filter and goes directly to the amygdala and hippocampus. This means smell-related memories are often stored in their raw, vivid form, remaining intact for many years.

That is why a single whiff can suddenly bring back long-forgotten moments, often with powerful emotions. The French writer Marcel Proust described this beautifully when he wrote about how dipping a madeleine cake into tea released an overwhelming flood of childhood memories. This phenomenon is now known as the Proust Effect.