Elderly people do emit a characteristic odor, but it turns out they might actually smell better than younger people, according to a new study published online in PLoS ONE.
Researchers at Monell Chemical Senses Center in Philadelphia found that people could distinguish among the body odors of different age groups.
They asked 41 people to evaluate odors collected from the armpits of study participants from three different age groups - people between the ages of 20 and 30; between 45 and 55; and between 75 and 95.
The evaluators rated the odors from the younger groups as more unpleasant than the odors from the elderly participants, and they also found that the older people's odors were less intense. The evaluators could also determine that odors came from old people, but could not correctly attribute the odors from the other groups.
These findings, said co-author Johan Lundstrom, confirm the popular belief of an "old people smell."
"We do have an old people odor, but when taken out of the popular context, it doesn't smell as bad," said Lundstrom.
The study also found that younger men smelled worse than younger women, but among the participants older than 75, men and women smelled pretty much the same.
It's not clear exactly what's behind the ability to discriminate between the age groups and the sexes, the authors wrote.
"An older study found that there is one chemical that varies with age, but we don't know if that's the chemical people are picking out," Lundstrom said.
It's also possible that the loss of testosterone, changes in the skin, changes in the sweat glands or a combination of these factorsplay a role in why the sexes don't smell much different at older ages.
There may be an advantage to being able to discern the smell of old age among animals.
For example, the authors wrote, "older male insects have a higher reproductive success than their younger competitors," and "reproductive success is a highly sought-after trait."
The authors also believe it's likely that had the evaluators been aware that the odors came from elderly people, they may have rated them as more unpleasant.
Future research, they continued, will focus on identifying the mechanism behind age-related body odor discrimination.