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Is 'old person smell' real? Yes, but it's not what you think

No matter how much you try to hide your age, you can’t nip-and-tuck your scent away. People will still be able to figure out how old you are simply by taking a sniff.

Researchers have determined that there really is an “old person smell” -- and a young person smell and a middle-aged smell -- according to a study published Wednesday in PLoS ONE.

“This study shows you can’t fake it,” says study co-author Johan Lundstrom, an assistant professor at the Monell Chemical Senses Center and at Sweden’s Karolinska Institute. “If you walk around a corner, you don’t have to look at someone to know they’re older; you can just sniff them out.”

At a time when we spray, spritz and anxiously try to scrub away and cover up our natural body odor, the new research should be reassuring to our noses. But our paranoia that we turn into pungent, musty moth balls as we age turns out to be completely wrong. Older people, in fact, have less intense -- and more pleasant -- scents than their younger counterparts, the new research indicates.

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. But they didn’t know whether body odor changed with age in an easily detectable way. 

Though this is the first study to document that an “old person smell” exists, it’s recognized in many cultures around the world. 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.

To see if people could accurately identify a person’s age through smell, Lundstrom and his colleagues asked 41 volunteers to wear a special T-shirt to bed for five nights, after bathing and washing their hair with unscented products.

Each of the unscented shirts contained underarm pads which, by the end of five days, were steeped in the volunteer’s body odor.

Pieces of the pads were then dropped into glass jars, which were grouped by age: Some jars contained scents of 20- to 30-year-olds, some the scents of 45- to 55-year-olds, and some the scents of 75- to 95-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. But they were even more accurate when they were simply asked to group together all the jars that smelled like old people. Which means that they could detect the old person smell the best.

Intriguingly, the volunteers scored old people’s odors highest for pleasantness and lowest for intensity.

Lundstrom doesn’t know why our scents change with age. But he’s got a theory that it’s got to do with reproduction.

Other studies have shown that people often choose mates that are unlike them genetically. In fact, those who marry third cousins, have the highest reproductive success, Lundstrom says. And it’s by smell that we determine how closely related we are to the person sitting next to us, even if we’re unconscious of it.

Similarly, Lundstrom suspects that some women might seek out older men because they’ve proven that they’ve got longevity genes.

“We favor the older individuals because they are survivors,” he explains. “Of course, when that developed many thousands of years ago, we didn’t get that old. So, it’s not like we’re favoring 80 year-olds.”