Do old people really smell different?

No, you weren't imagining it: Grandma's house really does smell different. New research confirms that elderly people emit a distinctly different "aroma" than other adults, and that may even be a good thing. Here, a concise guide to the smelly study:

How was the experiment designed?

Researchers at Monell Chemical Sense Center divided 41 volunteers into three age groups: Young people ages 20 to 30, middle-aged people ages 45 to 55, and an older group 75 and up. Participants were all given the same odor-free soap, shampoo, and laundry detergent, and were asked to avoid spicy foods, which can affect the smell of sweat-gland secretions, while taking part in the research. For five nights in a row, participants slept in T-shirts with odor-capturing pads sewn into the armpits. Researchers then cut the pads out, put them into jars, and had a separate group of volunteers attempt to guess the age range of a person by sniffing the pads.

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What did they find?

When participants took a whiff of the pads, they were twice as likely to identify the smell of someone in the oldest age group correctly than other adults. The results support "the cross-culturally popular concept of an 'old person odor,'" write researchers in the journal PLoS One. Researchers also had participants rate the pads on a "pleasantness" scale.

So which group smelled the best?

When both genders were accounted for, the oldest group prevailed with the most pleasing smell overall. When the groups were broken down further into genders, middle-aged men reeked the worst, and young men didn't fare much better. The scent of middle-aged females was judged to be most pleasant. (See this helpful chart for the gender breakdowns.)

Why does our smell change when we age?

Body odors result from an interaction between skin gland secretions and surface bacteria on the skin. As we get older, our glands change, which may explain why the groups had distinct odors. But why do older adults smell better? One theory suggests that the pleasant aroma is a signifier for "good genes" that allowed participants to live to an older age (and made them more attractive to potential mates). Or it could have something to do with hormones. "As you grow older, you smell more and more like a woman," study author Johan Lundstrom tells the Los Angeles Times. "It's almost as if you're going back to what happened before puberty."

Sources: Los Angeles Times, LiveScience, NBC Universal, Washington Post