How Someone Smells May Dictate Whether You’ll Be Friends

ITHACA, N.Y. — That inexplicable “click” you feel with some people might be your nose making decisions your brain hasn’t caught up to yet. New international research reveals our sense of smell silently guides who we befriend, with someone’s natural scent mixed with their perfume or deodorant predicting friendship chemistry better than their appearance – and our noses actually update these preferences after we’ve chatted.

The research, published in Scientific Reports, explains that friendship decisions stem from personal preferences about others, including various sensory cues.

“People take a lot in when they’re meeting face to face. But scent — which people are registering at some level, though probably not consciously — forecasts whether you end up liking this person,” says study author Vivian Zayas from Cornell University, in a statement.

For the study, forty female participants between 18-30 years old (average age 21) took part in an ingenious “speed-friending” experiment. Each participant had their photograph taken and received a plain cotton t-shirt to wear for about 12 hours during normal daily activities. They were instructed not to modify their typical hygiene routines – continuing to use their regular deodorant, perfume or other products – essentially capturing their natural “diplomatic odor.”

Before meeting in person, participants viewed 100-millisecond flashes of other participants’ photographs and rated their “friendship potential” on several criteria. On the day of the speed-friending event, participants first smelled and rated the t-shirts worn by people they would later meet. Then came the main event: a series of four-minute face-to-face conversations with approximately ten different partners, followed by friendship ratings after each interaction.

Next, participants smelled and rated the same t-shirts again. Their evaluations changed significantly based on how much they enjoyed talking with each person during the brief interaction.

This challenges conventional wisdom about first impressions, which typically emphasizes visual cues like facial features and expressions. While we consciously focus on what we see, our noses appear to be quietly influencing who we befriend.

Breaking down the statistics, researchers found that both visual cues (from photographs) and olfactory cues (from t-shirts) independently predicted how much participants would like each other after meeting in person. However, the olfactory cues appeared to have an even stronger influence than the visual ones.

People’s reactions were all over the map. Almost half of what made someone seem like a good friend came down to personal taste, not how generally nice they looked or smelled. In other words, a scent one person loves might turn someone else off, showing just how personal and unique friendship chemistry really is

The researchers found that everyday smells play an active role in how we decide who we like. Our brains actually start linking certain scents to how we feel about someone, even in the early stages of a friendship.

Throughout human history, odors have served as “heuristics,” allowing quick assessments of whether someone might be friend or foe. While much research has focused on how body odor influences mate selection, this study breaks new ground by examining its role in everyday, platonic relationship formation.

Unlike some previous research that removed all fragrances to study natural body odor alone, this study intentionally included participants’ daily personal care products, making it more relevant to real-world social settings where we rarely encounter someone’s unmasked natural scent.

As relationships develop, this odor-association process likely continues, potentially reinforcing emotional connections. Anyone who has found comfort in smelling a loved one’s clothing during separation is experiencing this phenomenon firsthand.

While we focus on what we see and hear, our noses appear to be silently steering us toward certain friendships through a biological evaluation system millions of years in the making. Perhaps trusting our gut feelings about new acquaintances really means trusting our noses.