Smells like teen friendship: How scent influences social choices

College women smelled each other's T-shirts in new study to evaluate "friendship potential."

Apr 18, 2025 - 18:26

Smells like teen friendship: How scent influences social choices

There are so many factors that can influence how we perceive others, which in turn can determine the people we choose as platonic friends or romantic mates. We certainly make snap judgments based on physical appearance, but scent can have a powerful influence, too. According to a new paper published in the journal Scientific Reports, two heterosexual women meeting for the first time rely partly on scent to judge whether they want to be friends with each other, deciding within minutes—practically at first whiff—whether there is friendship potential.

Social olfactory research largely stems from evolutionary psychology, specifically the work of Swiss biologist Claus Wedekind in 1995. Subtle chemical signals from pheromones are known to play a role in attraction in many species. Scientists had already found evidence in fish and mice that the major histocompatibility complex (MHC) genes, which are critical for immune system function (and useful in determining tissue compatibility for transplants, for instance)—showed a marked preference for sexual partners with different MHC genes, perhaps as a way of keeping the gene pool well-mixed and protecting against inbreeding.

Wedekind introduced the so-called "sweaty T-shirt" method to study the possible role of MHC in mate preferences in humans. Male participants wore the same T-shirt for two days, which were then placed in identical boxes. Women participants then smelled each shirt and indicated which ones they found most sexually attractive. Wedekind found that the women overwhelmingly preferred the T-shirt smells of men who had the most dissimilar MHCs to their own. The only caveat: The preference was reversed in women who were taking oral birth control.

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