Your house 'smells like home.' What's behind that signature scent?
Our homes smell.
Think of your grandparents' house or your best friend's apartment and a particular scent may come to mind. In your own place, you almost certainly don't notice it every day, but return from vacation and it hits you: that particular, hard-to-describe aroma that signals comfort and familiarity.
There is a strong connection between the things we smell and how they make us feel - which explains why we so readily associate meaningful locations with their odors. But when we say a place "smells like home," we are actually describing a combination of many scents, coming from a multitude of sources.
The most obvious culprits, says scent designer and olfactive expert Dawn Goldworm, are the objects that we buy specifically because of their smells, such as air fresheners and candles. Laundry detergent, soaps and cleaning products also contribute to the overall aroma. So does the food we cook and bring into the home.
Then, Goldworm says, there's the smell of you.
"We are walking perfumes, from our hair gel to our body lotion to our shampoo, our body wash, our toothpaste," she says. "Individual people have their own unique smell, too - their own unique DNA sequence that makes up the way that their body smells."
Our personal smells are tied to the major histocompatibility complex (MHC) that governs our immune system, says Pamela Dalton, a cognitive psychologist at Monell Chemical Senses Center. It's this genetically determined body odor that allows hounds to track a specific person, and the same "olfactory fingerprints," as Dalton calls them, contribute to the overall smell of our homes.
More obvious traits are also at play. Households with only adults, for instance, will smell differently from houses with kids who, Goldworm says, tend to bring in scents associated with childhood - such as plastic toys, waxy crayons and Play-Doh. As for pet owners, homes with litter boxes don't smell the same as homes with birdcages or dogs that have rolled in the grass.
Aside from how we live, the scents of our homes hint at where we live. Older buildings made from wood and brick smell differently than newer construction with lots of adhesives and plastics (such as vinyl flooring), which can emit odors. Paint and carpets similarly release volatile organic compounds that contribute to smells and combine with other scents in our homes.
Outdoor air quality is another factor: "If you're in Beijing for instance, they have a higher level of air pollution than, say, if you live in Ibiza," Goldworm says. "So that's going to affect not only the smell that can enter your windows and the cracks in the home, but also how that gets infused over time within the materials that the home or the building is constructed from."
While factors such as air quality are mostly out of our hands, for hundreds of years, humans have attempted to curate other scents at their homes as a part of communicating their identities, says William Tullett, an associate professor in sensory history at Anglia Ruskin University in England. In the 16th and 17th centuries, Europeans burned frankincense as an early insecticide and rosemary in an attempt to ward off diseases, but they also used smells for pleasure. Potpourri was in fashion, and Tullett says the discovery of an 18th-century vase with fake flowers indicated that scented pastes were used when real flowers weren't available.
Today, says Tullett, "some people go on about having the smell of books in their homes and they have cases full of them, so their identity is about being a kind of a bibliophile. Or you're someone who wants to appear as if they're engaged with the natural world ... so you fill your house with the smells of plants and flowers."
But even if you've carefully plotted your home's aroma, you probably don't regularly notice it yourself. Olfactory adaptation - or "nose blindness" - prevents us from smelling odors after just a few breaths. The receptors in our nasal cavities stop responding when the airborne molecules that are part of scents bombard them, says Dalton.
"It's like a jackhammer outside your office," she says. "On day one, you can't think. On day two, it's a little better. By the end of the week you're not even hearing it anymore unless I draw your attention to it." Scent, she explains, adapted as an evolutionary advantage - it's a sense meant to warn us against present dangers, such as rotten eggs or poisonous fruit. Once we deem an environment safe, the smell of it tends to pass quickly from our consciousness. "It makes sense that we should pay attention to not something that is constantly in the background, but something that changes."
Even so, the scent of our homes matters because it becomes entangled with our recognition of comfort and security. The tie between human emotions and sense of smell is also stronger than with other senses. Dalton explains that the olfactory part of the brain is connected to the limbic system, which is where our emotions take place.
"When we smell something that we like or that is familiar, it can give us a very good nurturing sense of, 'Oh, I belong here,'" says Dalton. "We think that's been a protective mechanism for millennia in terms of understanding what could be happy, healthy or harmful."
The smell of our homes and those of the people we care about tend to fuse themselves to our memories, too, in part because emotion and recollection are strongly linked. This is why we often associate smells with particular moments in time, especially from childhood.
Says Goldworm: "Those are the emotional indicators that we use to create our entire world as adults and to get back to those feelings of safety and comfort and love and joy."
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