Old People Smell Different But Not as Bad as Younger People, Study Finds
We can determine a person’s age by how they smell and the elderly smell forms the base
May 31, 2012 - Old people smell different but, contrary to popular belief, the so-called 'old-person smell' is less
intense and less unpleasant than body odors of middle-aged and young individuals, according to a study published yesterday in the open access
journal PLoS ONE.report.
The new findings from the Monell Center reveal that humans can identify the age of other humans based on differences in
body odor. Much of this ability is based on the capacity to identify odors of elderly individuals.
"Similar to other animals, humans can extract signals from body odors that allow us to identify biological age, avoid
sick individuals, pick a suitable partner, and distinguish kin from non-kin," said senior author Johan Lundström, a sensory neuroscientist at
Monell.
Like non-human animals, human body odors contain a rich array of chemical components that can transmit various types of
social information. The perceptual characteristics of these odors are reported to change across the lifespan, as are concentrations of the
underlying chemicals.
Scientists theorize that age-related odors may help animals select suitable mates: older males might be desirable because
they contribute genes that enable offspring to live longer, while older females might be avoided because their reproductive systems are more
fragile.
In humans, a unique 'old person smell' is recognized across cultures. This phenomenon is so acknowledged in Japan that
there is a special word to describe this odor, kareishū.
Because studies with non-human animals at Monell and other institutions have demonstrated the ability to identify age via
body odor, Lundström's team examined whether humans are able to do the same.
In the study, body odors were collected from three age groups, with 12-16 individuals in each group: Young (20-30 years
old), Middle-age (45-55), and Old-age (75-95). Each donor slept for five nights in unscented t-shirts containing underarm pads, which were
then cut into quadrants and placed in glass jars.
Odors were assessed by 41 young (20 -30 years old) evaluators, who were given two body odor glass jars in nine
combinations and asked to identify which came from the older donors. Evaluators also rated the intensity and pleasantness of each odor.
Finally evaluators were asked to estimate the donor's age for each odor sample.
Evaluators were able to discriminate the three donor age categories based on odor cues. Statistical analyses revealed
that odors from the old-age group were driving the ability to differentiate age. Interestingly, evaluators rated body odors from the old-age
group as less intense and less unpleasant than odors from the other two age groups.
"Elderly people have a discernible underarm odor that younger people consider to be fairly neutral and not very
unpleasant," said Lundström. "This was surprising given the popular conception of old age odor as disagreeable. However, it is possible that
other sources of body odors, such as skin or breath, may have different qualities."
Future studies will both attempt to identify the underlying biomarkers that evaluators use to identify age-related odors
and also determine how the brain is able to identify and evaluate this information.
Also contributing to the research were first author Susanna Mitro of Swarthmore College, Amy Gordon of Monell and Mats
Olsson of the Karolinska Institute. Funding was provided by the National Institute on Deafness and Other Communication Disorders of the
National Institutes of Health.
The Monell Chemical Senses Center is an independent nonprofit basic research institute based in Philadelphia,
Pennsylvania. Monell advances scientific understanding of the mechanisms and functions of taste and smell to benefit human health and
well-being. Using an interdisciplinary approach, scientists collaborate in program areas of sensation and perception; neuroscience and
molecular biology; environmental and occupational health; nutrition and appetite; health and well-being; development, aging and regeneration;
and chemical ecology and communication. For more information about Monell, visit
www.monell.org.
May 31, 2012 - Old people smell different but, contrary to popular belief, the so-called 'old-person smell' is less
intense and less unpleasant than body odors of middle-aged and young individuals, according to a study published yesterday in the open access
journal PLoS ONE.report.