Why old people smell

Contrary to harmful stereotypes of older people, age-related changes in body odor likely have nothing to do with personal hygiene. The major odor compound at play is called 2-nonenal. When certain chemicals break down in the body with age, 2-nonenal is one of the byproducts.

The breakdown of omega-7 unsaturated fatty acids may be the biggest source of 2-nonenal. Experts have only detected 2-nonenal in people over the age of Levels appear to only increase with age. While environmental and lifestyle factors can also influence body odor, 2-noneal appears to be responsible for the distinct, slightly musty odor associated with older people. Keep in mind that experts are still trying to fully understand how body odor changes with age.

Instead, it may just be the result of interactions between skin gland secretions and bacteria living on your skin. The type of bacteria that live on your skin are different in various life stages.

Likewise, the chemicals and compounds in your body can change with time, too. But experts believe evolution is part of the picture. Infants, teenagers, young adults, and middle-aged adults each tend to have slightly different body odors. Experts believe these specific scents help keep the human species alive and well. For example, that fresh baby smell may be more appealing to mothers, which helps with bonding. Since the discovery of 2-noneal, several companies have started developing personal care products designed to mask the scent of older people, particularly in Japan.

In fact, that study found that participants rated the odors of older individuals as less unpleasant and less intense than the odors of some younger groups. The researchers speculate that it might be because of age-related changes to metabolism or changes in the amount of some other chemical in skin secretions.

Another big question still hanging in the air is what purpose, if any, an age-related change in smell serves. Humans and some non-human animals can tell the difference between older and younger individuals by smell, and some animals are known to be more attracted to the odor of older individuals and have more success mating as they age.

One possible explanation for this is that older individuals may have some genetic advantage that allowed them to survive longer and makes them more attractive mates, and that distinct age-related odor is an advertisement for their genetic quality. BY Matt Soniak. Scientists have long known that our bodies give off scents that contain a variety of chemicals and that those chemicals can convey a lot of information. The Japanese, in fact, have a special word to describe how old people smell: Kareishu.

Earlier studies in animals showed that body odor changes with age, Lundstrom says. He wondered whether that might be true for people, too. Pieces of the pads were then dropped into glass jars, which were grouped by age: Some jars contained scents of to year-olds, some the scents of to year-olds, and some the scents of to year-olds.

The researchers then rounded up another 41 volunteers and had them sniff the jars. The volunteers were then asked to guess the age group associated with the scent in each jar and to rate the intensity of each scent and its pleasantness. The volunteers were pretty good at figuring out the ages -- better than would be predicted by chance.