How old do you think you smell? A new study suggests that humans possess the ability to judge whether a person has reached their senior years just by sniffing their body odor.
People in the study correctly gauged whether the former wearer of an underarm pad was elderly or not just by sniffing it. And for the record, most didn’t think “old-people smell” was off-putting at all.
The finding “shows that there’s yet another signal hidden in the body odor that we are somehow able to extract and make use of,” said study co-author Johan Lundstrom, an assistant professor at the Monell Chemical Senses Center, in Philadelphia.
As for the notion that “old-people smell” doesn’t leave people as disgusted as you might expect, Lundstrom said the odor’s power — or lack thereof — appears to have a lot to do with whether the elderly are actually physically present. “Lacking a context, the negativity of the body odors disappear,” he said.
The study authors launched their research as part of an effort to better understand the chemical signals that people detect in body odor. Previous research had suggested that we can pick up signs of sickness in other people’s body odor and even get a sense of whether someone is related to us, Lundstrom said.
Animals appear to be able to detect age through body odor, he said, although it’s not clear why it might matter to them. One theory is that the signal could let other animals know that an animal is older and thus more likely to produce offspring because it’s managed to stay alive so long, he said.
In the new study, 56 people — 20 young (20 to 30 years old), 20 middle-aged (45 to 55), and 16 elderly (75 to 95) — wore clean T-shirts and underarm pads while sleeping. The pads soaked up a sample of each individual’s body odor.
The researchers then asked 41 young people to smell the resulting odors — from pads kept in glass jars — and try to tell them apart.
Participants were generally able to discriminate between the age groups, but they weren’t much better at it than chance, Lundstrom said. However, they were able to do a better job of grouping together body odors from older people and identifying them as coming from the elderly.
“The old-age body odor sticks out,” Lundstrom said, but it didn’t do so in a negative way. In fact, the subjects tended to think the old age body odors were more pleasant and less intense than those of other age groups.
One factor might explain that: Older men smell more like women, possibly because they’ve lost testosterone, Lundstrom said.
He also noted that the people who provided their body odor for the study were healthy. That means the older people did not suffer from problems that can occur among seniors that might affect their body odors, such as incontinence.
The “popular prejudice” against the odor of the elderly probably reflects people’s distaste for odors in geriatric wards and nursing homes, noted one expert, Tim Jacob, a professor of biosciences at Cardiff University, in England, who studies smell and is familiar with the new study’s findings.
“This is obviously an unfair association,” he said. “But if people know where the smell originates [that is, in an older person], they may be unconsciously or consciously prejudiced. In this study they did not know where the smell originated.”
So how might people be able to detect old age through smell? It’s not clear, Lundstrom said. One possibility is that we’re not detecting old age specifically, but instead a signal that “piggybacks” on chemical signs of disease in the elderly, he said.
In the big picture, “given the research showing the importance of the olfactory — smell — system among other animal species, it is likely that humans possess similar capabilities that we don’t yet fully understand, yet influence our behavior more than we realize,” said Elizabeth Krusemark, a smell researcher and postdoctoral fellow at the University of Wisconsin Madison’s Cognitive and Affective Neuroscience Lab.
Cardiff University, Elizabeth Krusemark, England, Tim Jacob
People ages 60 and older who received free bus passes undertook significantly more physically active forms of travel — such as walking or taking the bus — than those who didn’t, a British study found.
Compared with older individuals who had not received a free bus pass, those who received free passes traveled more actively, regardless of whether they were of low or high socioeconomic status, according to Sophie Coronini-Cronberg, MSc, of Imperial College London, and colleagues.
The study also showed older individuals with free bus passes walked significantly more than those without a free pass, they wrote in the Sept. 20 issue of the American Journal of Public Health.
In England, a National Bus Pass was introduced for citizens ages 60 and older with limited access in 2006, and was expanded to include all local buses anywhere in England in 2008.
“A key purpose of the concessionary scheme is to increase bus use as a means of reducing social exclusion among older people and, in particular, to ensure access to travel among those on limited incomes,” Coronini-Cronberg and colleagues wrote.
The researchers also noted that the travel access may potentially offer older people incidentally physically active travel, which “may still have a key role to play in keeping older adults physically fit.”
To study this association, the authors performed a regression analysis using data on 11,218 individuals ages 60 and older with free bus passes and 5,693 people without one, collected through the 2005-2008 National Travel Survey.
Respondents were asked about travel habits — which included phases of each journey — and were categorized as “active” or “not active.” Active travel included walking, cycling, and using public buses and trains. Not active travel included use of cars, taxis, motorcycles, and private buses.
Additionally, participants were asked about walking frequency (which ranged from three or more times weekly to less than once a year or never), age, gender, access to a car, population of geographic region, socioeconomic data, whether or not they had a bus pass, and use of bus travel.
From 2005 to 2008, the number of older participants with free bus passes rose from 56.8 percent to 74.7 percent. During this time, the median number of stages per journey decreased among pass holders, although the median proportion of journey stages incorporating physically active travel remained higher among those with the free pass versus those without.
Having the free bus pass was significantly associated with increased likelihood of active travel during the observation period, increased rate of active travel among home owners, increased use of buses, and increased odds of walking three or more times a week compared with those without bus passes.
There was a nonsignificant trend for elevated rate of active travel among participants who did not own their homes and had free bus passes versus those without free passes.
The authors added that previous research showed that “price makes a difference to transportation choice and frequency of use, particularly among those of lower socioeconomic status groups,” though they noted that increased age resulted in reduced active transportation participation.
The researchers also emphasized the net gain offered by the program, citing that physical inactivity was “estimated to cost the U.K. economy £10.7 billion ($16.8 billion) annually,” while the free bus pass program was significantly associated with increased physical activity among older patients and that the program cost £1.1 billion ($1.7 billion) annually.
The authors said the study could not be generalized due to nonresponders and that data were self-reported. They also said they could not determine whether potential health benefits were equally distributed among program participants, and noted that they did not have longitudinal data available.
England, Imperial College London, National Bus Pass