Smell is the ugly stepchild of the sense family. Sight gives us sunsets and Georgia O’Keefe. Sound gives us Brahms and Aretha Franklin. Touch gives us silk and hugs. Taste gives us butter and ripe tomatoes.

But what about smell? It doesn’t exist only to make us gag over subway scents or tempt us into a warm-breaded stupor. Flowers emit it to make them more attractive to pollinators. Rotting food might reek of it so we don’t eat it. And although scientists haven’t yet pinned down a human sex pheromone, many studies suggest smell influences who we want to climb in bed with.

Olivia Jezler studies the science and psychology that underpins our olfactory system. For the past decade, she has worked with master perfumers, developed fragrances for luxury brands, researched olfactory experience at the SCHI lab at University of Sussex, and now is the CEO of Future of Smell, which works with brands and new technologies to design smellable concepts that bridge science and art.

In this interview, Jezler reveals the secret life of smell. Some topics covered include:

how marketers use our noses to sell to us

why “new car smell” is so pervasive

how indoor air is often more polluted than outdoor air

the reason why luxury perfume is so expensive

why babies smell so damn good

how Plato and Aristotle poo-pooed our sense of smell

This interview has been condensed and edited for clarity.

Quartz: On a scientific level, why is smell such an evocative sense?

Olivia Jezler: Our sense of smell is rooted in the most primal part of our brain for survival. It’s not linked through the thalamus, which is where all other sensory information is integrated: It’s directly and immediately relayed to another area, the amygdala. None of our other senses have this direct and intimate connection to the areas of the brain that process emotion, associative learning, and memory.

Why? Because the structure of this part of the brain—the limbic system—grew out of tissue that was first dedicated to processing the sense of smell. Our chemical senses were the first that emerged when we were single-cell organisms, because they would help us understand our surroundings, find food, and reproduce. Still today, emotionally driven responses through our senses of taste and smell make an organism react appropriately to its environment, maximizing its chances for basic survival and reproduction.

Beauty products like lotions and perfumes obviously have their own smells. But what unexpected businesses use scent in their branding?

It’s common for airlines to have scents developed for them. Air travel is interesting because, as it’s high stress, you want to make people feel connected to your brand in a positive way. For example, British Airways has diffusers in the bathrooms and a smell for their towels. That way you walk in and you can smell the “British Airways smell.”

It’s also very common in food. You can design food so that the smell evaporates in different ways. Nespresso capsules, for instance, are designed to create a lot of odor when you’re using one so that you feel like you’re in a coffee shop. I’m sure a lot of those make-at-home frozen pizza brands are designed to let out certain smells while they’re in the oven to feel more authentic, too.

That’s an example of the “enhancement of authenticity.” Another example might be when fake leather is made to smell like real leather instead of plastic.

So we got used to the smell of natural things, but then as production became industrialized, we now have to fabricate the illusion of naturalness back into the chemical and unnatural things?

People will feel more comfortable and they’ll pay more for products that smell the way we imagine them to smell.

Yes, that’s it. People will feel more comfortable and they’ll pay more for products that smell the way we imagine them to smell. For example: “new car smell.” When Rolls Royce became more technologically advanced, they started using plastic instead of wood for some parts of the car—and for some reason, sales started going down. They asked people what was wrong, and they said it was because the car didn’t smell the same. It repelled people from the brand. So then they had to design that smell back into the car.

New car smell is therefore a thing, but not in the way we think. It is a mix of smells that emanate from the plastics and interiors of a car. The cheaper the car, the stronger and more artificial it smells. German automakers have entire olfactory teams that sniff every single component that goes into the interior of the car with their nose and with machines. The problem then is if one of these suppliers changes any element of their product composition without telling the automaker, it throws off the entire indoor odor of the car, which was carefully designed for safety, quality, and branding—just another added complexity to the myriad of challenges facing automotive supply chains!

Are these artificial smells bad for us?

Designed smells are not when they fulfill all regulatory requirements. This question touches on a key concern of mine: indoor air. Everybody talks about pollution. Like in San Francisco, a company called Aclima works with Google to map pollution levels block by block at different times of the day—but what about our workplaces? Our homes? People are much less aware of this.

We are all buying inexpensive furniture and carpets and things that are filled with chemicals, and we’re putting them in a closed environment with often no air filtration. Then there are the old paints and varnishes that cover all the surfaces! Combine that with filters in old buildings that are rarely or never changed, and it gets awful. When people use cleaning products in their home, it’s also putting a lot more chemicals into the house than before. (You should open your windows after you clean.)

In cities like New York, the indoor air is three times worse than outdoors.

We’re therefore inhaling all these fumes in our closed spaces. In cities like New York, we spend 90% of our time indoors and the air is three times worse than outdoors. The World Health Organization says it’s one of the world’s greatest environmental health risks. There are a few start-ups working on consumer home appliances that help you monitor your indoor air, but I am still waiting to see the one that can integrate air monitoring with filtering and scenting.

Manufacturing smell seems to fall into two camps. The first is fabricating a smell when you’ve taken the authenticity out of the product. But then other brands simply enhance an existing smell. That’s not fake, but it still doesn’t seem honest.

Well, to me they seem like the same thing: Because they are both designed to enhance authenticity.

There’s an interesting Starbucks case related to smell experiences and profits. In 2008 they introduced their breakfast menu, which included sandwiches that needed to be reheated. The smell of the sandwiches interfered with the coffee aroma so much that it completely altered the customer experience in store: It smelled of food rather than of coffee. During that time, repeat customer visits declined as core coffee customers went elsewhere, and therefore sales at their stores also declined, and this impacted their stock. The sandwiches have since been redesigned to smell less when being reheated.

This is starting to feel a bit like propaganda or false advertising. Are there laws around this?

No, there aren’t laws for enhancing authenticity through smell. Maybe once people become more aware of these things, there will be. I think it’s hard at this point to quantify what is considered false advertising.

There aren’t even laws for copyrighting perfumes! This is a reason why everything on the market usually kind of smells the same: Basically you can just take a perfume that’s on the market and analyze it in a machine that can tell you its composition. It’s easily recreated, and there’s no law to protect the original creation. Music has copyright laws, fragrance does not.

That’s crazy. That’s intellectual property.

It is. As soon as there’s a blockbuster, every brand just goes, “We want one like that!” Let’s make a fragrance that smells exactly like that, then lets put it in the shampoo. Put it in the deodorant. Put it in this. Put it in that.

Well if the perfume smells the same and is made with the same ingredients, why do we pay so much more for designer perfumes?

High fashion isn’t going to make [luxury brands] money—it’s the perfumes and accessories.

What differs is the full complexity of the fragrance and how long it lasts. As for pricing, It’s very much the brand. Perfume is sold at premium for what it is—but what isn’t? Your Starbucks coffee, Nike shoes, designer handbags… There can be a difference in the quality of the ingredients, yeah, but if it’s owned by a luxury brand and you’re paying $350, then you’re paying for the brand. The margins are also really high: That’s why all fashion brands have a perfume as a way of making money. High fashion isn’t going to make them money—it’s the perfumes and accessories. They play a huge, huge role in the bottom line.

How do smell associations differ from culture to culture?

Because of what was culturally available—local ingredients, trade routes et cetera—countries had access to very specific ingredients that they then decided to use for specific purposes. Because life was lived very locally, these smells and their associations remained generation after generation. Now if we wanted to change them, it would not happen overnight; people are not being inundated with different smell associations the way they are with fashion and music. Once a scent is developed for a product in a certain market, the cultural associations of the scent of “beauty,” “well-being,” or “clean” stick around. The fact that smells can’t yet transmit through the internet means that scent associations also keep pretty local.

For example, multinational companies want to develop specific fragrances and storylines for the Brazilian market. Brazilian people shower 3.5 times a day. If somebody showers that much, then scent becomes really important. When they get out of the shower, especially in the northeast of Brazil, they splash on a scented water—it’s often lavender water, which is also part of a holy ritual to clean a famous church, so it has positive cultural connotations. Companies want to understand what role each ingredient already plays in that person’s life so that they can use it with a “caring” or “refreshing” claim, like the lavender water.

Lavender is an interesting one. In the US, lavender is more of a floral composition versus true lavender. People like the “relaxing lavender” claim, but Americans don’t actually like the smell of real lavender. On the other hand, in Europe and Brazil, when it says “lavender” on the packaging, it will smell like the true lavender from the fields; in Brazil, lavender isn’t relaxing—it’s invigorating!

In the UK, florals are mostly used in perfumes, especially rose, which is tied to tradition. Yet in the US, a rose perfume is considered quite old-fashioned—you rarely smell it on the subway, whereas the London Tube smells like a rose garden. In Brazil, however, florals are used for floor and toilet cleaners; the smell of white flowers like jasmine, gardenia, and tuberose are considered extremely old-fashioned and unrelatable. However, in Europe and North America, these very expensive ingredients are a sign of femininity and luxury.

Traditional Chinese medicine influences the market in China: Their smells are a bit more herbal or medicinal because those ingredients are associated with health and well-being. You see that in India with Ayurvedic medicine as well. By comparison, in the US, the smell of health and cleanliness is the smell of Tide detergent.

Are there smells we can all agree on biologically, no matter where we’re from, that smell either good or bad?

Yes: Body fluids, disease, and rotten foods are biological no-nos. Also, natural gas, which you can smell in your kitchen if you leave the gas on by mistake, is in reality odorless: A harmless chemical is added to give gas a distinctive malodor that is often describes as rotten eggs—and therefore act as a warning!

The smell of babies, on the other hand? Everybody loves the smell of babies: It’s the next generation.

Do you wear perfume yourself?

I wear tons of perfume. However, if I’m working in a fragrance house or a place where I smell fragrances all the time, I don’t wear perfume, because it then becomes difficult to smell what is being created around me. There is also a necessity for “clean skin” to test fragrances on—one without any scented lotions or fragrances.

Why does perfume smell different on different people? Is it because it reacts differently with our skin, or is it because of the lotions and fabric softeners or whatever other smells we douse ourselves in?

Cancers and diabetes can be identified through body odor.

Generally, it’s our DNA. But there are different layers to how we smell. Of course, the first layer is based on the smells we put on: soaps and deodorants and whatever we use. Then there’s our diet, hydration level, and general health. An exciting development in the medical world is in diagnostics: Depending upon if we’re sick or not, we smell different. Cancers and diabetes can be identified through body odor, for instance. Then on the most basic level, our body odor is linked to the “major histocompatability complex” (MHC), which is a part of the genome linked to our immune system. It is extremely unique and a better identifier than a retinal scan because it is virtually impossible to replicate.

Why don’t we care more about smell?

The position that our sense of smell holds is rooted in the foundation of Western thought, which stems from the ancient Greeks. Plato assigned the sense of sight as the foundation for philosophy, and Aristotle provided a clear hierarchy where he considered sight and hearing nobler in comparison to touch, taste, and smell.

Both philosophers placed the sense of smell at the bottom of their hierarchy; logic and reason could be seen and heard, but not smelt. The Enlightenment philosophers and the Industrial Revolution did not help, either, as the stenches that emerged at that time due to terrible living conditions without sewage systems reminded us of where we came from, not where we were headed. Smell was not considered something of beauty nor a discipline worth studying.

It’s also a bit too real and too closely tied to our evolutionary past. We are disconnected from this part of ourselves, so of course we don’t feel like it is something worth talking about. As society becomes more emotionally aware, I do think smell will gain a new role in our daily lives.

This article is part of Quartz Ideas, our home for bold arguments and big thinkers.