Does your nose help you choose friends?

People support the polite fiction that we don’t sniff each other all the time. Despite our best efforts, we all have our own scents, pleasant and less pleasant. if we are like other land mammalsour special perfume can mean something to our fellows.

Some of them, such as the smell of a person who has not washed for a whole month, or the characteristic smell of a baby who pretends not to have just filled his diaper, speak for themselves. But scientists who study the human sense of smell, or your sense of smell, are wondering if molecules emanating from our skin can register on some subconscious level in the noses and brains of those around us. Do they carry messages that we use in decisions without realizing it? Maybe they even shape who we like and dislike to spend time with?

Indeed, in a small study published Wednesday in the journal Science Advances., researchers examining pairs of friends whose friendship “clicked” from the start found intriguing evidence that each person’s body odor was closer to that of their friend than expected by chance. And when the researchers invited pairs of strangers to play together, their body odor predicted whether they felt they had a good connection.

There are many factors that influence who people make friends with, including how, when, and where we meet a new person. But perhaps one thing we’re paying attention to, the researchers suggest, is how they smell.

Friendship scientists have found that friends have more in common than strangers—not just things like age and hobbies, but also genetics, patterns of brain activity and appearance. Inbal Ravrebi, a graduate student in the lab of Noam Sobel, an olfaction researcher at the Weizmann Institute of Science in Israel, wondered if a particularly quick friendship that seems to spring up in an instant has an olfactory component – whether people can find similarities in their smells.

She recruited 20 pairs of so-called clique friends who described their friendship in this way. She then put them through a regimen common in body odor studies: for a few days, stop eating foods like onions and garlic that affect body odor. Avoid aftershave and deodorant. Bathe with unscented, laboratory-provided soap. Then put on a fresh, clean T-shirt provided by the lab and sleep in it so it smells good before handing it over to scientists for testing.

RS. Ravrebi and her colleagues used electronic nose to assess the volatiles emitted from each T-shirt, and 25 other volunteers also assessed the similarity of odors. They were interested to know that the smells of friends are indeed more similar to each other than the smells of strangers. This could mean that the smell was one of the things they picked up on when their relationship started.

“It is very likely that at least some of them used perfume when they met. Ravrebu suggested. “But that didn’t hide what they had in common.”

However, there are many reasons why friends might smell the same — eating at the same restaurants, having similar lifestyles, etc. — making it hard to tell which came first, the smell or the foundation of the relationship. To try it out, the researchers had 132 strangers, all of whom smelled like T-shirts at first, come into the lab to play a game of mirroring. Pairs of subjects stood close to each other and had to imitate each other’s movements while moving. After that, they filled out questionnaires about whether they felt connected to their partners.

The similarity of their scents, strikingly, predicted whether they felt a positive connection 71% of the time. This discovery means that inhaling a smell similar to our own causes pleasant feelings. It might be one thing we pick up on when we meet new people, along with things like where they grew up and whether they like sci-fi or sports. But dr. Sobel warns that if this is the case, it is just one of many factors.

The Covid pandemic has curtailed further research using this Ms. design so far. Ravrebi and colleagues; experiments in which strangers get close enough to smell each other have been difficult to arrange.

But now the team is looking into the possibility of changing people’s body odor to see if subjects who are made to smell come together in the same way. If smell correlates with their behavior, this is further evidence that, like other land mammals, we can rely on our sense of smell to make decisions.

They and other researchers will explore the mysteries of how our personal fragrances, in all their complexity, interact with our personal lives. Every breath can say more than you think.

“If you think of a bouquet that is body odor, it’s at least 6,000 molecules,” the doctor says. Sobel said. “We already know about 6,000 – that’s probably a lot more.”