Sense of smell is linked to sexual orientation, study reveals

The human nose can not only sniff out suitable sexual partners, but it works especially well for gay men, according to the first study of how body odours are linked to sexual orientation.

The human nose can not only sniff out suitable sexual partners, but it works especially well for gay men, according to the first study of how body odours are linked to sexual orientation.

Gay men showed a strong preference for the body odour of other gay men in the scientific test of how the natural scent of someone's body can contribute to the choice of a partner.

Although previous studies have shown that body odour plays a role in making heterosexual men or women attractive to members of the opposite sex, this is the first study that has investigated its role in sexual orientation. Charles Wysocki of the Monell Chemical Senses Centre in Philadelphia, a non-profit research institute, said the findings underline the importance of natural odours in determining a sexual partner whatever the sexual orientation of the person involved.

"Our findings support the contention that gender preference has a biological component that is reflected in both the production of different body odours and in the perception of and response to body odours," Dr Wysocki said.

The study involved 24 heterosexual and homosexual men and women who for around nine days were subjected to a "wash-out" period when they used scent-free soap and shampoo and did not eat food with garlic, cumin or curry.

After this, they wore sterile cotton pads under their armpits for a day. These were collected and stored to use as a bottled source of their body odour. A panel of 82 heterosexual and homosexual men and women, not including the donors of the armpit pads, were asked to sniff each bottled body odour and evaluate its pleasantness according to a set of criteria. In a study in the journal Psychological Science, the scientists found: "Heterosexual males and females preferred odours from heterosexual males relative to gay males; gay males preferred odours from other gay males.

"Heterosexual males and females and lesbians over the age of 25 preferred odours from lesbians, relative to the odours from gay males; gay males preferred the odours of other gay males relative to lesbians," they say.

Dr Wysocki said the strongest finding was that gay men prefer the smell of other gay men and that lesbians responded differently to body odour compared to heterosexual women. "The overall conclusions are that the body odour you most prefer or least prefer does not depend on where it comes from but it also depends on who you are, in other words, your sexual orientation," Dr Wysocki said.

Gay men preferred the odours from gay men and heterosexual women, but odours from gay man were the least preferred by heterosexual men and women and by lesbians, he said. Other studies showed that body odour is linked with a set of genes involved in controlling the immune system - called the major histocompatability complex - and heterosexual men and women preferred the odour of those with a different set of these genes to their own. One theory is that this could be an evolutionary mechanism to avoid inbreeding. The latest study suggests the genes involved in body odour may also play a role in sexual orientation.

"The bigger picture is that body odour is determined in part by gender orientation which is not something we can have predicted. And it's possible that the genes involved in body odour are also involved in later life in gender orientation," he said.