TORONTO – New research shows that despite social stigma, the so-called “old person smell” is less unpleasant than the scents of young or middle-aged people.
In fact, old men had the least intense neutral smell with old women also fairly neutral, but slightly more intense.
A team from the Monell Center conducted a study revealing that humans can tell the age of others based on differences in body odour. The team was inspired by previous studies involving non-human animals and their ability to discriminate age via odour.
Turns out, smells can allow people to “identify biological age, avoid sick individuals, pick a suitable partner, and distinguish kin from non-kin,” said senior author and sensory neuroscientist John Lundström.
“Elderly people have a discernible underarm odour that younger people consider to be fairly neutral and not very unpleasant,” said Lundström in a statement. “This was surprising given the popular conception of old age odour as disagreeable.”
The researchers note that a unique “old person smell” is recognized across cultures, well-known in the Japanese language with the special word “kareishu.”
Figure 1.B. from Mitro S, Gordon AR, Olsson MJ, Lundström JN (2012) The Smell of Age: Perception and Discrimination of Body Odors of Different Ages. PLoS ONE 7(5): e38110. doi:10.1371/journal.pone.0038110
The study, published in the journal PLoS ONE, tested participants’ ability to differentiate the body odours of people from three categories: young (20-30 years), middle-age (45-55 years) and old age (75-95 years).
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Body odours were collected from the three age categories with 12-16 people in each group. Participants slept in unscented t-shirts with underarm pads for five nights. These pads were then cut into pieces and placed in glass jars, then assessed by 41 young evaluators.
The evaluators knew they were smelling used underarm pads (which were made in Ontario), but were not told any other information. They were asked to:
• Identify which pads came from the older donors
• Rate the intensity of odours
• Rate the pleasantness of odours
• Estimate the donor’s age for each sample
Not only were the old-age odours driving the ability to differentiate age, but the results showed that the smell associated with old age was rated as less intense and less unpleasant than the scent of both of the younger groups.
While the negativity sometimes linked with the “old person smell” may be due to social associations with the elderly and bad hygiene or sickness, this new research paints a different picture.
“We demonstrate that otherwise healthy, hygienic elderly individuals have a characteristic “old people odor” that is, taken out of its context, not a negative odor,” says Lundström. “It was rated as neutral.”
Lundström pointed to McGill University research showing how important context is when it comes to perceived pleasantness of smell. He explains that “changing the label of an odor can make the rating of its pleasantness change entirely.”
The Monell Center noted that future research will aim to find underlying biomarkers that people use to discriminate age through odour, as well as how the brain is able to identify and evaluate this information. Lundström also notes the possibility that “other sources of body odors, such as skin or breath, may have different qualities.”
The Monell Chemical Senses Center is an international non-profit scientific institute that investigates taste and smell based in Philadelphia, Pennsylvania. Funding for this study was provided by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health.
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