In their new study, Lundström and his colleagues sewed absorbent nursing pads into the armpits of T-shirts and asked volunteers of different ages to sleep in the shirts for five consecutive nights. Knowing about earlier research on animal body odors and age, Lundström decided to test whether smell also informs how people evaluate age. Perhaps the smell really did emanate from the residents. Every now and then, he gives scientific talks at an elderly care center in the greater Philadelphia area that-he realized one day-smells almost exactly like the nursing home his mother managed in Sweden when he was young. Johan Lundström of the Monell Chemical Senses Center studies human and animal body odors and how the brain responds to smells. The more sweat on the skin, the more chemicals for the bacteria to break down, and the stronger the body odor. All these fluids begin to stink when bacteria break down the various chemicals they contain-especially steroids and lipids-into smaller, odorous molecules that easily waft into the air. Eccrine sweat glands, found all over the human body, exude a clear, odorless, salty liquid throughout life. Likewise, apocrine sweat glands-which are only located in a few places, such as the armpits and genital region-rev up during puberty. The sebaceous glands, which secrete a waxy substance called sebum to lubricate and waterproof the skin, are particularly active during puberty and throughout most of adulthood. Human body odor also changes with age, depending largely on the activity of various skin glands and how the substances they release interact with bacteria. In other studies, investigators discovered that people, too, can tell the difference between old and young otters and rabbits by using scent cues. Researchers have shown that the body odors of some animals-including mice, black-tailed deer, otters, owls and rabbits- change with age and that animals can distinguish their young and old peers by smell. Combined with earlier research, the new findings suggest that people retain a latent ability to gauge someone's age based on their odor, a talent inherited from evolutionary ancestors that might be linked to the ways animals recognize the sick and dying. Contrary to the popular notion that old person smell is disagreeable, volunteers in the new study rated the odors of the elderly as much less unpleasant and intense than those of the middle-aged and young. In a new study, blindfolded volunteers reliably recognized the aroma of the elderly by sniffing sweat-soaked armpit pads, although they had a much harder time correctly matching pads to the young and middle-aged, and they were not able to make fine distinctions about age based on scent alone. Many different cultures have recognized the phenomenon-the Japanese even have a word for it, kareishuu-but the biological truth of old person smell remains uncertain. You know this aroma: it's "old person smell."Īnecdotally, the unique scent of the elderly lingers wherever they live and in any confined spaces they have recently occupied, such as taxis and elevators. It's awfully warm, and a peculiar odor seems to hover in the air nearby-a stale, musty odor tinged with something as acrid as mothballs. There's something unusual about the subway seat you just claimed.
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