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The overlooked power of scent
From disease detection to mate selection, body odour holds a wealth of biological and psychological data that humans largely ignore, research reveals.
Historical fascination with fragrance
King Louis XIV of France transformed Versailles into a palace of scent. Every room overflowed with fresh flowers, furniture and fountains were perfumed, and guests were sprayed before entering. Whether compensating for hygiene standards below modern expectations or simply indulging a passion, the monarch recognised scent's significance.
Health and diet revealed through smell
Body odour can signal illness-cholera emits a sweet aroma, while acute diabetes produces a rotten-apple scent. Mehmet Mahmut, an olfaction psychologist at Macquarie University, notes that diet also plays a role. His team found meat consumption makes body odour more pleasant, though other studies present conflicting results.
Men perceive women's body odour as most attractive during the follicular phase of the menstrual cycle, when fertility peaks, and least appealing during menstruation. This sensitivity may have helped early humans identify optimal reproductive partners.
Genetics shape our unique scent
Much of what makes an individual's smell distinct stems from genetics. In experiments, participants could match identical twins' sweaty T-shirts among strangers' garments, even confusing duplicate shirts from the same person with those of twins. Agnieszka Sorokowska, a human olfaction expert at the University of Wroclaw, explains that genes influence odour, suggesting we might subconsciously detect genetic traits through scent.
People also select cosmetics that align with their genetically determined odour preferences. Sorokowska's research shows fragrance choices can even hint at personality traits, implying Louis XIV's guests may have gleaned insights about the king from his palace's perfumed air.
Immune system clues in body odour
Studies reveal women unconsciously prefer the scent of men with dissimilar Human Leukocyte Antigen (HLA) profiles. HLA proteins help the immune system distinguish between the body's cells and potential pathogens. A partner with a dissimilar HLA profile could theoretically produce offspring with stronger pathogen resistance.
"If you have a partner who is genetically dissimilar in body odour and immune profile, your children will have better resistance to pathogens," Sorokowska says.
Agnieszka Sorokowska, University of Wroclaw
Yet, real-world evidence complicates this theory. A study of nearly 3,700 married couples found no greater likelihood of HLA-dissimilar pairings than chance. While scent preferences exist, humans don't appear to act on them when choosing partners.
Scent's role in relationships
Despite HLA's limited influence on partner selection, it may affect sexual satisfaction. Couples with high HLA dissimilarity report greater sexual fulfilment and stronger desires for children, particularly among women. Conversely, women with HLA-similar partners express more dissatisfaction and lower interest in parenthood, though findings remain inconclusive.
Evolutionary biologists argue this aligns with nature's patterns-females, who invest more in offspring, seek genetic quality cues in males. Yet, modern humans often overlook scent's signals, masking natural odours with perfumes and hygiene products.
Why humans ignore scent's signals
Mahmut suggests scent's utility has diminished over millennia as humans learned to disguise their natural odours. In complex social settings, other senses like vision can override olfactory information. For example, body odour alone accurately conveys neuroticism, but adding a photo reduces judgment accuracy-people default to easier visual cues.
In one study, married women didn't consistently rank their husbands' body odour as the most pleasant among strangers'. Another found strangers' odours stronger than married men's, possibly due to testosterone levels, which decline with age and relationship stability.
Should we trust our noses?
Sorokowska advises that if genetic compatibility is the priority, scent should matter. "But for most people, that's not the top concern," she notes. Mahmut agrees, arguing that modern life has diluted scent's evolutionary role. "We've spent tens of thousands of years hiding our natural odours," he says.
