Have you ever noticed a distinct scent emanating from elderly individuals or nursing homes? Well, it turns out that “old person smell” is more than just a figment of the imagination—it’s a real phenomenon, and science is beginning to unravel its secrets.
In a peculiar study conducted in 2022, researchers made a fascinating discovery: humans can discern the age of others based solely on their scent. The experiment involved collecting body odors from individuals of various age groups. Participants were instructed to wear T-shirts with underarm pads for five consecutive nights to absorb their sweat. These pads were then cut into pieces and placed in jars, which were subsequently sniffed by fortunate volunteers aged between 20 and 30 years. These volunteers were tasked with rating the pleasantness of the aromas and estimating the age of the odor donors.
The results were intriguing. The study team noted that humans, like other animals, possess the ability to distinguish age through body odor alone. Furthermore, they found that the effect was primarily driven by body odors emitted by older individuals. However, the exact mechanism behind this olfactory phenomenon remains unknown, even in non-human species.
Interestingly, the distinct “old person smell” appears to transcend cultural boundaries. In Japan, it is referred to as “kareishu.” The study highlighted that elderly individuals emit a discernible underarm odor, which younger individuals consider fairly neutral and not overly unpleasant. This finding contradicts the popular notion of old age odor as universally disagreeable. However, the researchers suggest that other sources of body odor, such as the skin or breath, may exhibit different qualities.
Another study discovered that specific compounds, including 2-Nonenal—an unsaturated aldehyde with an unpleasant greasy and grassy odor—and certain lipids on the skin, increase in concentration as individuals age. These compounds are believed to contribute to the distinct smell associated with aging.
Regarding the purpose and significance of producing and detecting these smells, Johan Lundström, a sensory neuroscientist and senior author of the study, suggests a potential link to mate selection. Similar to other animals, humans may extract signals from body odors to identify biological age, avoid individuals with compromised health, choose suitable partners, and distinguish kin from non-kin. Lundström further notes that older male insects tend to be preferred over younger ones due to their higher reproductive success, indicating that longevity signifies adaptive qualities in the animal kingdom.
While there is still much to learn about the exact causes and potential advantages of the “old person smell” in humans, further research is needed. Scientists remain curious about the evolutionary significance and underlying mechanisms of this intriguing olfactory phenomenon.
The main findings discussed in this article were published in the journal PLOS One, marking a significant step toward unraveling the complexities of “old person smell” and shedding light on the mysteries hidden within our sense of smell.
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