words by willow defebaugh
As humans, our sense of smell informs our memories, histories, and futures, playing a crucial role in how we perceive the world.
“An hour is not merely an hour, it is a vase full of scents and sounds and projects and climates.”
I’m walking through my neighborhood in Brooklyn when a soft spring wind carries with it a scent that is sweet, but not sickly so. The floral fragrance is at once foreign and familiar, transporting me to a time that I can’t quite place. We all have them: those aromas that transmute memories, their notes navigating us to the past. I’m thinking about whiffs of lilac that lure me back to the tree my mother tended in our backyard growing up, the earthy sandalwood that will always remind me of my time in India, the sultry scent of jasmine that was my first perfume.
For humans, scent plays an often overlooked role in how we perceive the world. When we breathe in our environments, odor molecules stimulate and bind to specific sensor proteins within our noses called olfactory receptors, which can vary greatly from human to human. Any given molecule can activate a combination of different receptors, resulting in diverse imprints and perceptions that vary from person to person. Take the molecule androstenone as an example, which many smell as urine, some identify as sandalwood, and others cannot detect it at all.
A study published in the journal Neuropsychologia found that olfactory stimuli result in even more brain activity than visual stimuli. And the neuroscience behind the scent-memory connection is clear: smell is overseen by the brain’s olfactory bulb, a structure that interprets and sends the information from odors to other parts of the brain for processing. These smells take a direct route to the amygdala and hippocampus which house our emotions and memories, coaxing our past associations to the surface.
Much of what we attribute to taste is actually more owed to our olfactory senses. Humans are only really able to taste five rudimentary flavors: sweet, salty, bitter, sour, and savory. The many complex food profiles we relish—the rich delicacy of chocolate, the floral spice of vanilla—are actually scents from the molecules that make their way to your nasal epithelium while eating. It’s our sense of smell that takes the simple and mundane and turns it into delectable complexity. And in shaping our preferences, smell is understood to play a pivotal role in our inner ego.
Our sense of smell permeates our relationships, too. A study published in the Journal of Personality and Social Psychology found that the scent of a loved one can reduce cortisol levels (the hormone associated with stress). Meanwhile, a study from Science Advances found that people with similar body odors are more likely to form friendships. And scientists who worked on a third study, this one from the University of California San Diego, confirmed that people’s scents play a significant factor in social behavior, preference, attraction, and even falling in love.
Beyond our interhuman relationships, scent intertwines us with the more-than-human world as well. According to a study in Curr Genomics, olfactory receptors are hundreds of millions of years old, and are thought to exist in all vertebrates. In fact, the development of the olfactory bulb may have even been a prominent factor in the dramatic growth of the mammal brain. Our ability to smell is ancient, tying us to the many scents that have sprawled from the tree of life.
In so many ways, our sense of smell tethers us to the past: our memories and our shared history. And yet, as I stroll the streets and attempt to place this smell, this fragrance I could swear I know so well, I wonder if it might belong to the future—a memory not yet made. I close my eyes and try to hold it: this specific space and time, this precious hour that I might someday associate with such a fragrant smell, the feeling of life blooming in and around me in new dimensions.