Does Your Nose Help Pick Your Friends?

By: Joelle Luo

Although we like to think we are not constantly smelling one another, humans are actually

smelling each other all the time to figure out who they are compatible with. Everyone has their

own odors, and if we are like other land mammals, our particular “scent” might mean something to other people.

Some smells, like the reek of someone who hasn’t showered all month, or a toddler pretending they didn’t need a diaper change, are self-explanatory. But scientists who study human olfaction, or the sense of smell, wondered if the molecules wafting off our skin may be registering at some subconscious level in the noses and brains of people around us. If this is true, it might even be affecting who we do and don’t like spending time around.

In a small study published Wednesday in Science Advances, researchers investigating pairs of

friends whose friendship “clicked” from the beginning found intriguing evidence that each

person’s body odor was closer to their friends than expected by chance. When the researchers got pairs of strangers to play a game together, their body odors predicted whether they felt they had a good connection.

There are many other factors that contribute to whom people become friends with, but one of

them is how they smell.

Scientists who study friendship have confirmed that friends have more in common than

strangers. Not only are they similar in age, or have similar hobbies, but their

genetics, patterns of brain activity, and appearance are similar as well. A graduate student in the lab of Noam Sobel and olfaction researcher at the Weizmann Institute of Science in Israel, Inbal Ravreby, was curious whether particularly swift friendships, which seem to form in an instant, had an olfactory component. In other words, whether people might be picking up on the similarities in their smell.

To try and confirm this theory, Ravreby recruited 20 pairs of “click friends”, who both

characterized their friendship as an instant click. She put them through a regimen that is

common in many human body research activities: stop eating foods like garlic and onions for a few days because they affect body odor. No after-shave and deodorant. Bathe with an unscented soap that is provided by the lab. Put on a clean lab-provided t-shirt and sleep in it so it has your odor, before giving it to scientists for review.

Ravreby and her colleagues used an electronic nose to assess the odors on each T-shirt, and 25 other volunteers assessed the similarities of the smells. They were shocked to find that the

friend’s odors were more similar to each other than those of strangers, which means that odor

was one of the things they hung on to as their relationship began. “Although it is very possible

that at least one of them was using perfume when they met,”, Ravreby said, “it did not mask

whatever they had in common.”

The similarities of their odors predicted that there had been a positive connection in their

friendship 71% of the time. That finding implies that sniffing a similar odor to our own generates better feelings about that person.

As of now, the team is looking into modifying people’s body odor to see whether subjects

who’ve been made to smell similarly still band together. If scent correlates with their behavior,

that’s more evidence that humans, like other terrestrial mammals, have been drawing on our

sense of smell to find people we are compatible with.