"Odors have a power of persuasion stronger than that of words, appearances, emotions, or will," Peter Süskind writes in his psychological thriller, Perfume (1985). "The persuasive power of an odor cannot be fended off, it enters into us like breath into our lungs, it fills us up, imbues us totally. There is no remedy for it."
Recent analysis of the psychological powers of smell indicates that Süskind's ode to the olfactory, if a touch dramatic, was not as hyperbolic as it might sound. Rachel Herz, a professor of psychiatry and human behavior at Brown University and the author of The Scent of Desire (2007), has continued her work deciphering the most mysterious of the senses in her newest book, out next week, That's Disgusting: Unraveling the Mysteries of Repulsion.
Herz chalks up much of the connection between smell and emotion to the geography of the brain; the olfactory bulb is an element of the brain's limbic system, the part associated with memory and feeling. The area of the brain that deals with smell has direct access to the amygdala, which deals with emotion and the hippocampus, responsible for associative learning.
But her most intriguing insights, perhaps, come in separating our primitive response — a baby wrinkles her face after encountering something bitter — from the learned emotion of disgust, which is much more sophisticated.
Scent and disgust are very much about context, after all. Consider the spit in your mouth — then consider drinking a glob of it in a glass. Or the pungent smell of cheese at an artisanal shop and the smell of mold in a dank alley.
We are the only creatures that feel the emotion of disgust, Herz says; animals will spit out something bitter, but they don't care about frolicking in filth, or carrying carcasses around in their mouths.
At work, here: a higher order understanding of death.
"It's not fear, which is an automatic thing that gets you running away as fast as possible," she says. "It's the potential for slow and uncertain death."
Humans are the only animals with big enough brains to figure out that something could potentially lead to death — that in six weeks, you could be six feet under. "This is complex learning," she says, "and disgust is learned from the codes of the society in which we live."
And it is those same social cues that allow smell to evoke a range of emotions as potent, as complex, as disgust: love, desire, grief. The stuff of literature. Perhaps Nabokov put it most simply, and wonderfully: "Smells are surer than sights or sounds to make your heartstrings crack."