Heavenly scent

New Scientist, 03 July 1999

THE smell from an old lady's armpits can raise your spirits, a scientist in Pennsylvania claims. Her work also suggests that in contrast, the scent of a young child does nothing to improve your mood.

Studies using animals have shown that smell is vital for conveying information. Rodents can detect and transmit fear through smell, for instance, and animals often identify a high-ranking member of a group by its smell. A recent study has shown that people can distinguish the body odour of both happy and fearful people (This Week, 1 May, p 25). But the impact of body odour on people's moods has hardly been explored at all.

Denise Chen of the Monell Chemical Senses Center in Philadelphia hoped to find out more. So she recruited 30 volunteers in six different categories: girls and boys aged between three and eight, young adult women and men in their early twenties and elderly women and men in their seventies. The volunteers all gave samples of their body odour by strapping a gauze pad under each armpit and keeping it there for 10 hours.

The participants were not allowed to use any perfumes or deodorants, or eat strong-smelling foods, in the four days before the samples were collected. They could shower, but only with unscented soap and shampoo. Odours were also collected from the homes of all the donors and combined into a neutral control smell.

Chen then asked 308 university students to complete a 36-part questionnaire that assessed how positive their mood was. Then they smelled the gauze pads from one of the six categories of people -- without being told what the smells were. After this, the students answered the questionnaire a second time, this time with the questions shuffled around.

People who had inhaled the samples taken from old women's armpits responded significantly more positively, Chen found. "Old women had an uplifting effect," she says. The smell of young men, on the other hand, produced a depressive effect. In general, the smell of older people improved mood, as did smells from females, Chen will report in a future issue of the journal Physiology and Behaviour.

Jeannette Haviland, of Rutgers University in New Jersey, who also worked on the project, says it's possible that hormones make the body odour of young people signal aggression. But hormonal changes may make the odour of older people, especially women, signal that they are approachable. Alternatively, it could be that women in their golden years are generally happy, and that their odour can transmit this mood. "The airborne chemicals that we collected from them -- "l'eau de grandmère" -- may indicate that state," says Haviland.