And it isn’t all that bad

By Rachel Ehrenberg

Web edition: May 30, 2012
Print edition: June 30, 2012; Vol.181 #13 (p. 8)

“Old people smell” is for real — and it isn’t mothballs, Jean Naté or pipe tobacco. It’s a mild and not unpleasant odor compared with the intense, unpleasant smell emitted by 40- to 50-something guys, a new study finds.

Scientists don’t know what makes up this vintage chemical fingerprint, but the research suggests that apologies to your grandparents may be in order. The negative association with the smell of the elderly appears to be more about context than scent, says Johan Lundström of the Monell Chemical Senses Center in Philadelphia.

Lundström and his colleagues collected underarm odors from 12 to 16 people in each of three age groups: young (20 to 30 years old), middle-aged (45 to 55 years old) and old (75 to 95 years old). For five nights while they slept, the study participants wore T-shirts with breast-feeding pads sewn in the underarms. The shirts and bed linens had been washed with scent-free soap and the participants did the same to themselves before going to bed each night. They also refrained from smoking, drinking alcohol or eating foods that are known to contribute odors to bodily secretions.

Evaluators (aged 20 to 30) then sniffed the armpit pads. Evaluators rated the samples on pleasantness and intensity, guessed which of two odors came from the older donor and then labeled all of the scents by age category. The evaluators had trouble discerning young from middle-aged odors. But the odors from old donors were correctly identified more often than would be expected by chance, the research team reports online May 30 in PLoS ONE.

“These elderly odors were very distinct and easy to group together,” says Lundström. Not only that, but odors from old men were rated most pleasant, especially compared to middle-aged men. (Middle-aged woman odors were rated more pleasant than elderly woman odors.)

And descriptions of the elderly odors weren’t negative: Evaluators used phrases such as “earthy” or “mild, like stale water,” Lundström says.

“Everything changes with age, so it’s not a huge surprise,” says Dustin Penn, who heads the Konrad Lorenz Institute of Ethology in Vienna and has investigated how scents are involved in mating among people and other animals.

The possible mechanisms behind the bodily bouquets are most intriguing, he says. Perhaps the drop in testosterone that occurs in old age makes the older scents discernible. Work by Penn and others suggests that an individual’s microflora — the personal mix of bodily bacteria that can’t be scrubbed away — also contributes to Eau de You. 

The study is also interesting because it reveals that our noses know more than we know. “In many ways we are pathetic compared to dogs and other animals. But that doesn’t mean we aren’t getting any information,” Penn says. “We don’t seem to be aware of what we can do.”