Smell ties directly to emotion and memory, making scent a powerful trigger of past relationships.

Body odor can carry immune cues, subtly shaping attraction through biological compatibility.

Chemosignals may heighten attention, but they don’t override judgment or relationship dynamics.

Emma was sitting on a packed train when a man squeezed in beside her. Like most riders, summer was plastered across his face. Beads of sweat rolled down his temples and his shirt clung to his skin.

She first noticed him reaching for the bar next to her. But she truly took him in when the mix of his sweat and cologne filled the train car. She recognized the fragrance immediately. It was Curve—the cheap cologne her ex used to wear.

A year ago, she would have felt flooded and nauseous. The late-night arguments, the romantic getaways to Florida, and the hollow ache of heartbreak; the smell would have ruined her day.

But 20 years had passed. She was now in love with Daniel. The scent no longer made her brace for impact. Instead, she found herself smiling—grateful to have loved so deeply, and grateful to love again now.

Emma thought of the T-shirt Daniel had left behind, the one she sometimes sniffed between dates while closing her eyes and remembering his kiss goodbye. Then she brought herself back to the present and took the smell in more carefully.

Beneath the cologne, beneath the sweat, the man didn’t smell sour or bitter. Just freshly sweaty. Salty. Sweet. Human.

He wasn’t strikingly handsome. But he smelled great.

While Emma took it all in, the woman next to her raised her hands toward the scowl on her face, trying to shield herself from the smell.

Same man.Same scent.Two different nervous systems.

One reason lies in how closely smell is tied to memory.

Unlike sight or sound, smell has a direct pathway to the amygdala and hippocampus—the regions involved in emotion and autobiographical memory. Because of this connection, memories triggered by scent are often more vivid and emotionally intense than those triggered by sight (Herz & Schooler, 2002).

When Emma once felt sick at the scent of her ex’s cologne, that reaction wasn’t about pheromones. It was an associative memory. Over time, the smell had become linked to heartbreak, and her body reacted before her mind could fully explain why.

Now, years later and secure in a different relationship, the same scent triggered nostalgia instead of pain. The smell hadn’t changed—but the meaning attached to it had.

But memory isn’t the only system involved when we smell someone.

The “Sweaty T-Shirt” Study

Smell can also carry biological information.

In a well-known experiment, researchers asked men to wear plain cotton T-shirts for two nights without deodorant or scented products (Wedekind et al., 1995). The shirts were then placed in boxes with small sniffing holes, and women leaned over the boxes to rate the scent for pleasantness.

The researchers had also analyzed everyone’s immune system genes, known as the major histocompatibility complex (MHC).

Women who were not using hormonal contraception tended to prefer the scent of men whose MHC genes were different from their own. One explanation is that immune-system differences could lead to offspring with broader disease resistance.

But the findings are modest and nuanced. Later studies found that hormonal contraception can shift scent preferences (Roberts et al., 2008), suggesting attraction is biologically influenced but also hormonally sensitive.

In other words, smell may only slightly bias attraction.

What About Pheromones?

Popular culture often attributes attraction to “pheromones,” but the science is more subtle.

Humans do not appear to have a single proven sex pheromone. Instead, researchers study chemosignals—chemical compounds in sweat that can influence mood or attention.

For example, a compound derived from testosterone and found in male sweat, called androstadienone, has been shown to slightly increase physiological arousal and activate brain regions involved in hormonal regulation when women are exposed to it (Wyart et al., 2007).

In plain terms, this doesn’t create instant attraction. It may simply make someone a bit more alert or attentive.

Other neuroimaging studies show that male- and female-typical scent compounds are processed differently in the brain depending on sex and sexual orientation (Savic et al., 2001). The brain recognizes these signals as socially relevant—but recognition is not the same as desire.

These signals may nudge perception. They do not override judgment.

Smell, Safety, and Bonding

Emma’s memory of the T-shirt she sniffs between dates reveals another layer: attachment.

Research shows that smelling a romantic partner’s worn clothing can reduce stress responses (Hofer et al., 2018). Over time, a partner’s scent can become encoded as a signal of safety.

But this encoding can change. If a partner becomes critical, distant, or unreliable, their scent may begin to cue tension rather than comfort—just as Emma eventually came to associate her ex’s cologne with painful interactions.

Meanwhile, the woman with the sanitizer was engaging a different system altogether: disgust sensitivity, sometimes described as part of the brain’s “behavioral immune system.” For her, body odor triggered a protective response.

Emma, by contrast, may have distinguished between the clean, salty smell of sweat and the sour odor that signals poor hygiene.

Context, expectation, and experience matter.

The same scent can signal attraction, safety, or aversion depending on history, meaning, and awareness.

So, Does Smell Determine Attraction?

Smell may attract us to someone. It may quicken our pulse. In some cases, chemistry feels immediate and visceral—shaped by immune cues, hormones, and subtle chemosignals.

But biology is only one layer of the system.

As one of my mentors often says, we are social animals (Aronson & Aronson, 2018).

That is to say, we bond—or detach—based on how we are treated when we express our needs. Over time, our experiences reshape perception. The same scent that once signaled safety can come to cue dread if it becomes associated with criticism or neglect. And a partner’s smell can calm us when it has become linked to reliability and care.

Smell does not operate in isolation. It is filtered through memory, attachment, and meaning. Our experiences with a partner determine whether their presence feels comforting or unsettling—whether their scent draws us closer or makes us brace.

This doesn’t mean we’re too complex to understand. It means attraction is dynamic. And much of what ultimately sustains a relationship—trust, responsiveness, and mutual respect—lies within our control.

Biology may open the door.

But how we treat each other determines whether the body relaxes—or recoils—when that person walks into the room.

And how we treat each other is shaped by how we ourselves were treated—by the relationships that molded our attachment patterns long before we ever stepped onto a crowded train.

More on that in my next post: How to Change Your Attachment Style for the Better—and Keep Others from Changing It for the Worse.

Aronson, E., & Aronson, J. (2018). The social animal (12th ed.). Worth Publishers.

Granqvist, P., Vestbrant, K., Döllinger, L., Liuzza, M. T., Olsson, M. J., Blomkvist, A., & Lundström, J. N. (2019). The scent of security: Odor of romantic partner alters subjective discomfort and autonomic stress responses in an adult attachment-dependent manner. Physiology & behavior, 198, 144-150.

Herz, R. S., & Schooler, J. W. (2002). A naturalistic study of autobiographical memories evoked by olfactory and visual cues: Testing the Proustian hypothesis. American Journal of Psychology, 115(1), 21-32.

Roberts, S. C., Gosling, L. M., Carter, V., & Petrie, M. (2008). MHC-correlated odour preferences in humans and the use of oral contraceptives. Proceedings of the Royal Society B: Biological Sciences, 275(1652), 2715-2722.

Wedekind, C., Seebeck, T., Bettens, F., & Paepke, A. J. (1995). MHC-dependent mate preferences in humans. Proceedings of the Royal Society B: Biological Sciences, 260(1359), 245–249.

Wyart, C., Webster, W. W., Chen, J. H., Wilson, S. R., McClary, A., Khan, R. M., & Sobel, N. (2007). Smelling a single component of male sweat alters levels of cortisol in women. Journal of Neuroscience, 27(6), 1261-1265.

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