Qualities you might seek in a friend: loyalty, honesty, and ... a similar body odor to your own? A new study suggests the latter is a factor, even if we're not aware of it, reports the New York Times. When we meet new people, we sometimes feel an “immediate strong click that makes us feel as if we have already been good friends for years," says researcher Inbal Ravreby of the Weizmann Institute of Science in Israel, per New Scientist. Her team wondered if body odor might be part of the reason and tested the theory by recruiting 20 pairs of friends—these were non-romantic, same-sex pairs who say their friendship "clicked" from the start.
The researchers used an "electronic nose" to sniff shirts worn to bed (making sure that perfumes or deodorants didn't sway things) and discovered that people who were friends were far more likely to naturally smell like each other than strangers. In a separate part of the experiment, they had two strangers engage in a non-verbal game, then conducted a sniff test on their shirts afterward. Sure enough, the similarity of their odors "predicted whether both felt there had been a positive connection 71 percent of the time," per the Times.
"We conclude that there is indeed chemistry in social chemistry," says the study published last week in Science Advances. Other mammals, of course, are known to sniff each other to determine friend or foe, but humans might not be conscious of it. Previous research has shown that heterosexual couples are sometimes drawn to each other because they smell differently, notes New Scientist, perhaps because people are subconsciously seeking a healthier genetic mix. (More discoveries stories.)