Have you ever noticed a distinct scent associated with older individuals? Often described as “old person smell,” this phenomenon is more than just an anecdotal observation. Many cultures recognize it, and science has begun to delve into the biological reasons behind this age-related odor. But is it truly unpleasant, and what does it tell us about aging?
The Anecdotal Evidence and Cultural Recognition of Elderly Odor (Kareishuu)
The idea of a unique scent linked to aging isn’t new. People across various cultures have long acknowledged a particular odor associated with the elderly. In Japan, there’s even a specific term for it: kareishuu. This widespread recognition suggests that there’s a real phenomenon at play, something detectable enough to be noticed and named across different societies. You might have encountered this scent in places frequented by older people – perhaps a slightly musty, stale, or even mothball-like odor in elevators, nursing homes, or even on clothing.
The Science Steps In: Research Confirms “Old Person Smell”
While the concept of “old person smell” might seem like folklore, scientific research is starting to validate it. A study published in PLoS ONE explored this very topic using blind smell tests. Volunteers were asked to sniff pads soaked with the sweat of young, middle-aged, and elderly individuals. Interestingly, participants could reliably identify the scent of the elderly. However, they found it more challenging to differentiate between the scents of young and middle-aged people.
Lundström’s Study: Blind Smell Tests and Surprising Results
The study, led by Johan Lundström at the Monell Chemical Senses Center, involved collecting sweat samples from different age groups. Volunteers wore t-shirts with absorbent pads in their armpits for five nights. Then, a separate group of participants, blindfolded, were asked to smell these pads and rate the odors.
The results were quite surprising. Contrary to the common negative perception of “old person smell,” volunteers actually rated the odor of elderly individuals as less intense and less unpleasant compared to the odors from middle-aged and young people. In fact, middle-aged men’s sweat was rated as the most intense and unpleasant. Furthermore, while participants struggled to pinpoint the age from young and middle-aged samples, they were significantly better at identifying the elderly scent. This suggests that “old person smell” is not necessarily about being offensive, but rather about having a unique and recognizable characteristic.
What Causes “Old Person Smell”? Biological Factors
So, what’s behind this distinctive odor? The answer lies in the changes our bodies undergo as we age, specifically concerning our skin glands and the compounds they produce.
Skin Glands and Bacterial Interaction
Our body odor is largely influenced by the secretions from three types of skin glands: sebaceous, apocrine, and eccrine. Sebaceous glands produce sebum, a waxy substance that lubricates the skin. Apocrine glands, mainly in armpits and groin, release sweat that becomes odorous after bacteria interaction. Eccrine glands, all over the body, produce odorless sweat.
As we age, the activity of these glands changes. Hormonal shifts and metabolic changes affect the composition of sweat and sebum. Bacteria on our skin break down these secretions, producing volatile organic compounds that create body odor. The specific mix of these compounds can change with age, leading to a different scent profile in older individuals.
The Role of 2-Nonenal
One key compound identified as potentially contributing to “old person smell” is 2-nonenal. Research has found that levels of 2-nonenal are higher in people over 40 compared to younger individuals. This organic compound has been described as having a “grassy and greasy odor.” It’s a product of the breakdown of omega-6 fatty acids on the skin as we age, and its increased presence could be a significant factor in the perceived change in body odor. Interestingly, 2-nonenal is also found in cucumbers and aged beer, suggesting that while distinct, it might not inherently be unpleasant.
Debunking Myths and Understanding Perception
The research challenges the negative connotations often associated with “old person smell.” The study showed that people don’t necessarily find it more offensive, just more recognizable. This suggests that the perception of “old person smell” as disagreeable might be more of a social stigma than a genuine sensory aversion. Perhaps it’s the association with aging and mortality that colors our perception, rather than the odor itself being inherently repulsive. Comparisons to the smell of old books, often considered comforting or benign, further support this idea that the scent might be more about familiarity and recognition than unpleasantness.
Evolutionary Roots and Potential Purpose of Age-Related Odor
Why would humans evolve to have a distinct age-related odor? Scientists speculate that it could be linked to our evolutionary past and serve a biological purpose, possibly related to health and mate selection.
Johan Lundström suggests that the ability to detect age through scent might be a way to “distinguish the sick from the healthy – not overt sickness, but underlying cell decay.” As we age, our bodies naturally undergo cellular changes and a degree of “decay.” This subtle olfactory cue could have been advantageous for our ancestors in identifying healthier individuals or recognizing vulnerability within a social group. In the animal kingdom, scent plays a crucial role in communication, including age recognition, and it’s plausible that humans retain a vestige of this ability.
Conclusion
The phenomenon of “old person smell” is scientifically real, linked to changes in body chemistry as we age, particularly the increased presence of compounds like 2-nonenal. However, research indicates that this odor is not inherently unpleasant, and is in fact often perceived as less intense and offensive than the body odor of younger individuals. The negative perception might be more rooted in social biases than objective sensory experience. Understanding the science behind age-related body odor helps to demystify it and suggests that it might even hold evolutionary significance, potentially linked to age and health detection. Instead of a negative attribute, “old person smell” might be a unique olfactory signature of aging, a natural part of the human life cycle, and a testament to our complex biological processes.
