Skip to main content
Humans manage to pick up hundreds of thousands of different scents with only a few hundred types of receptor. Pixabay

The nose is, at its most basic level, a tool for filtering through the chemicals of the outside world, sorting, weighing, and categorizing the trillions of molecules of all shapes and sizes that waft over us. In a study out this week, scientists opened a window into a basic step in the sensation. Reporting Wednesday in Nature, researchers documented the first images of an odor receptor at work—providing clues on how animals have evolved to sort through that endless variety.

“The example that I often think about is the smell of coffee, which you identify as being a distinctive aroma,” says Vanessa Ruta, a neuroscientist at the Rockefeller University. “It’s made of about 200 different molecules, and none of them individually evoke a strong perception of the smell of coffee. If you compare it to other sensory worlds that we live in, the chemical world is much larger and variable.”

It’s so complex that picking it apart requires an enormous array of sensors. In fact, about five percent of the mouse genome is used to build olfactory receptors. But even that diversity doesn’t explain our ability to smell: Humans manage to pick up hundreds of thousands of different scents with only a few hundred types of receptor.

That’s because smell recognition works a bit like piano music. Think of each receptor as a key. Two different odors may hit a few of the same notes, but each will activate a unique chord of receptors. The brain then understands these chords as smells. Some chemicals might span dozens of receptors, while others—especially life-and-death compounds like pheromones and toxins—might hit just a single note.

What’s remarkable is that multiple chemicals can activate the same receptor to begin with. Oftentimes, the physical structure of a chemical fits tightly into a receptor, like a key in a lock. But “olfactory receptors are like a lock with many keys,” says Ruta, the study’s senior author.

“The mystery of olfaction—the magical thing about it—is just the vast nature of the chemicals that any individual receptor in our nose have to detect,” Ruta says. “So here we have some insight into how that kind of flexible detection occurs.”

Using an electron microscope, the paper’s lead author, Josefina del Marmol, also a neuroscientist at the Rockefeller University, was able to capture the first images of the interaction between an olfactory receptor and a bound scent molecule.

The team conducted the research in jumping bristletails, a wingless, whisker-bottomed insect that’s closely related to the silverfish. It’s also thought to resemble some of the earliest insects, meaning that it might be a window into evolutionary deep time. “Most animals have tens, dozens, hundreds of receptors,” says del Marmol. “The bristletail has only five. And they’re biochemically simpler than most modern insects.”

To capture the images of binding, the team bathed receptors in DEET, the insect repellant, and eugenol, a key smell in cloves. Eugenol is known to bind tightly to insect odor receptors, while DEET is a very differently shaped

Both bound to one receptor—as did almost 70 percent of the odors they tested. “They’re quite different in their structure and chemical features, and yet they can both be recognized by this one receptor,” says Ruta.

The images showed that chemicals fit into the receptors relatively loosely, more like balls in sockets than keys in locks. “Different odorants find different ‘binding modes,’” says Ruta. “They orient within the pocket slightly differently.”

When an odorant does settle onto a receptor, it pulls open a pore, allowing a stream of ions to send a signal to the animal’s nerves. “A lock and key mechanism can be very strong, because there’s this great specificity,” says Ruta. “But here they’re not very strong interactions. It’s a very small change. The pore only has to open a little bit.”

Humans, like all vertebrates, developed our sense of smell independently from insects, and so the findings won’t apply directly to our own noses. Our last shared ancestors with the insects were underwater, and used different senses for detecting chemicals.

But in the millions of years since, vertebrates and invertebrates have developed remarkably similar strategies for smelling. The receptors themselves are similar, and it hooks up to the nervous system in a similar, unique pathway.

“Whether you’re a honeybee or a human, you still have to be able to detect a wide variety of odorants in the environment,” says Ruta. And they’re essentially the same smells. “It’s an example of convergent evolution: [Vertebrate receptors] are a completely distinct family of proteins, but they do basically the same thing to detect chemicals. I suspect that a lot of the principles for broadly-tuned receptors are going to be the same in both families.”

The researchers also tweaked the receptor slightly to understand how small mutations might affect its ability to detect chemicals. “Just one amino acid had a huge impact across the entire receptor,” says del Marmol. “It sort of scrambled the way the receptor responded. So that has very interesting implications for how insects can evolve a new complement of receptors in a very small amount of time.”

“Each animal has its own little musical piece—its own orchestra,” she continues. “The same keys, the same compounds, will have a very different meaning for different animals.”

In other words, when there’s an unfathomably large set of possible chemicals to smell, it pays to be able to detect new things with only tiny tweaks, much like the human immune system constantly mutates to hunt for new pathogens. At the same time, Ruta says, they’ve found that other olfactory receptors can have a nearly identical architecture despite being composed of entirely different proteins.

And that means that the work might also provide some insights into how smell has evolved over time.

“Unlike senses that are more stable in time and space, if you’re a fly that moves to a different tree, you have a completely different sensory experience,” says del Marmol. “At the same time, when the angiosperms developed flowers, the world changed, and there were smells that didn’t exist before.” It might be the flexibility of odor receptors that allowed animals to adapt to that new world.

Source: We have now seen our sense of smell in action | Popular Science

Recent smell-related articles

ArtSmellVisual
16/09/2021

Travel across five cities around the globe for Diptyque’s 60th anniversary | Emirates Woman

As Diptyque has transformed the olfactory world for 60 years, the Maison has curated a special programme entitled ‘The Grand Tour’. From limited-edition creations by renowned artists to international pop-ups…
BrandingInterestingMarketingSmell
15/09/2021

How ‘new car smell’ is created at Nissan | Automotive Testing Technology International

Part of the rigorous design, development and testing process for Nissan’s new Qashqai involved formulating a ‘new car smell’. The unique role of creating this scent, which is said to…
InterestingSmellTaste
10/09/2021

The First World Taste and Smell Day Invites You to Smell the Roses and Savor the Flavor on September 14, 2021, A Day to Celebrate Our Senses | Newswire

Toiling away in the background, our senses of taste and smell are underappreciated. On September 14, the organizers of first-ever World Taste and Smell Day invite you to celebrate the…
BrandingExperientialMarketingMultisensorySmellTasteTouch/Feel/TextureVisual
09/09/2021

First look: Diageo opens incredible Johnnie Walker Experience in Edinburgh | Daily Record

Guests will be able to explore hundreds of flavours (Image: Diageo) Scotland's newest whisky attraction, the Johnnie Walker Princes Street Experience, has opened in the heart of Edinburgh. The eagerly awaited eight-floor visitor experience, which…
Smell
09/09/2021

Man admits he loves the smell of the London Underground | MyLondon

We're not sure we can get on board with this... (Image: Victoria Jones/PA Wire) If you’ve ever stepped on the Tube and taken in a deep breath to enjoy the…
HealthSmell
09/09/2021

For older adults, losing your sense of smell may be an early health warning | MSU Today

Q&A with epidemiologist Honglei Chen Michigan State University is one of the top 100 research universities in the world and a member of the prestigious Association of American Universities, widely…
ArtInterestingMultisensorySmellTouch/Feel/TextureVisual
08/09/2021

This artist is mapping Bengaluru though its unique aromas | Hindustan Times

Indu Antony began work on Bengaluru Smellscapes in February. Eventually, her project will be represented as a book with a foldout map and perfume pads, so you can take a…
ArtEntertainmentMultisensorySmellSound
08/09/2021

Musician creates unique concert experiences that involve sight and smell | Evanston RoundTable

Yang, left, and Matt Agnew, play a concert at the Stan Mansion. (Photo by Gay Riseborough) A new not-for-profit is setting out to engage all five senses with its symbiosis…
HealthSmellTechnology
08/09/2021

Identifying the scent of a failing lung transplant with innovative eNose | Health Europa

© iStock/Davizro Researchers based in the Netherlands have developed a revolutionary electronic “nose” that is proficient in smelling out when a lung transplant is starting to fail. The electronic nose…
MemorySmell
02/09/2021

Why Smells Can Trigger Powerful and Emotional Memories | Prevention

GETTY IMAGES Walking by a park, the smell of fresh-cut grass instantly transports me back to the relaxed, carefree Saturdays of my childhood. I’m overcome by nostalgia as I recall…
MemorySmell
01/09/2021

Sent Studio wants to make candle scents linked to your memories | Timeout Melbourne

Photograph: Supplied The sense of smell is closely linked to memory, and trying to hunt down the perfect candle  scent that can bring that wave of nostalgia into your life…
Augmented + virtual realityMultisensorySmellSoundTechnologyVisual
31/08/2021

Ketamine One, OVR Technology Partner to Provide Scent-Enabled Virtual Reality for Patients | Hit Consultant

What You Should Know: – Ketamine One is now collaborating with OVR Technology to provide a first-of-its-kind VR scent experience as part of its patient treatment programs to provide its INHALE Wellness Platform over…
InterestingMultisensorySmellTouch/Feel/TextureVisual
25/08/2021

Construction company in Poland creates flower-scented asphalt | NY Post

A construction site near a newly-opened portion of a ring road is seen in Warsaw city September 20, 2013. Reuters/Kacper Pempel Polish construction firm Budimex and refiner Lotos have created…
BrandingInterestingMarketingSmellTechnology
24/08/2021

How digital olfaction could make inroads with grocers and consumers | Grocery Dive

Courtesy of Aryballe From aiding with product creation to sniffing out spoiled food, technology that mimics the way humans smell has the potential for wide applicability. Someday, consumers may rely…
SmellTechnology
23/08/2021

Replicating Our Sense of Smell Is One of the Hardest Problems in Tech | Bloomberg

 Koniku’s Konikore device. PHOTOGRAPHER: RYAN MOLNAR FOR BLOOMBERG BUSINESSWEEK A new generation of companies is homing in on one of the hardest problems in tech: replicating our sense of smell.…
ArtInterestingMultisensorySmellSoundTouch/Feel/Texture
17/08/2021

Dutch museum fills ‘Blind Spot’ with exhibit for visually impaired | Channel News Asia

A visually impaired visitor, Farid el Manssouri, touches during the exhibition "The Blind Spot" by artist Jasper Udink ten Cate and experience designer Jeroen Prins, aimed for blind and visually…
HealthSmell
17/08/2021

Since COVID, increased concern over smell loss is prompting new research | California News Times

Credit: Unsplash / CC0 public domain One day in kindergarten, Alex Pieracuccini sat down, watched his companions pass around the spices, and sniffed them out as a sensory exercise. Currently…
HealthSmell
13/08/2021

Vancouver Coastal Health’s canine scent detection team now detecting COVID-19 | My Powell River Now

There is another weapon in the fight against Covid 19 in BC… a pack of virus-sniffing dogs. Vancouver Coastal Health’s (VCH) canine scent detection team “Canines for Care” has been…
EntertainmentInterestingMultisensorySmellSoundTasteTrendyVisual
12/08/2021

Epson projection enhances 11-course tasting menu | AV Interactive

Six Epson laser projectors fixed with a UST ‘periscope’ lens, are providing a 360° experience designed by Sysco Productions at a new DC-Comics themed restaurant and bar venue in London.…
MarketingSmell
12/08/2021

Resident Evil perfumes are now on sale | GamesRadar+

(Image credit: Capcom) Capcom has released a line of new fragrances inspired by its tentpole Resident Evil franchise. The three perfumes – each one inspired by a different Resident Evil…
MemorySmell
12/08/2021

One of my favorite memories smells like garbage | Public Opinion Online

I hate covid.  Not only can it make you sick or worse, but it is keeping me away from my beloved Kasba Lake Lodge.  This time of year for more…
InterestingMultisensorySmellSound
11/08/2021

You can now buy a record store scented candle | DJ Mag

It smells like “pressed vinyl and warm woods, accented by notes of sweet blossoms, hints of amber, and soft fruit” A candle apparently scented to resemble a record store is…
Augmented + virtual realityHealthInterestingSmell
11/08/2021

Switzerland’s ‘Silicon Valley of smell’ prospers in age of big data | Financial Times

The pandemic has changed how people want themselves, their clothes and their homes to smell A vegetarian steak is tested at the headquarters of Swiss group Firmenich, one of the…
MarketingMultisensorySmell
11/08/2021

IKEA offers scented candles that smell like their famous meatballs to its loyal customers | Republic World

Credit: UNSPLASH Ikea, famous for the Swedish meatballs served at its stores' cafeterias, will now offer scented candles that smell like them to its loyal customers. The Swedish company, IKEA,…
SmellTechnology
11/08/2021

Electronic nose can distinguish various mint scents | Electronics360

The combination of sensors and materials simulates the sense of smell. Source: Amadeus Bramsiepe, KIT An electronic nose (E-nose) with an artificial sense of smell can recognize different mint species…
CommunicationInterestingMultisensoryPheromonesSmell
10/08/2021

Your dog has a rich interior life it’s not telling you about | Salon.com

Gossiping Malamutes (Getty Images) From conveying personal data via scents to using body language to "speak," dogs are secretly great communicators Dogs and humans have co-evolved to the point that…
ScientificSmell
10/08/2021

We have now seen our sense of smell in action | Popular Science

Humans manage to pick up hundreds of thousands of different scents with only a few hundred types of receptor. Pixabay The nose is, at its most basic level, a tool for…
HealthInterestingSmell
27/07/2021

Dogs can smell everything and more. Even diseases like cancer | The Print

Representational image of a dog. | Photo: Mannat Chawla | ThePrint Dogs are able to detect cancer while it still hasn’t yet spread to other parts of the body. This…
HealthNeuroscienceSmellTaste
22/07/2021

Study indicates COVID-19 causes brain damage, even in mild cases | CTV News

Brain scans of people who recovered from COVID-19 had more brain atrophy in parts of the brain that control taste, smell, and memory. A year and a half into the…
EmotionsInterestingMemorySmell
21/07/2021

Ford Mach-Eau novelty fragrance offers gasoline scent for EV owners | Slashgear

In what is apparently a very real thing, Ford teamed up with fragrance company Olfiction to develop Mach-Eau, a bottled scent that gives those who sniff it nostalgic undertones of…
EmotionsInterestingMemorySmell
21/07/2021

A new Ford survey lays bare the nostalgia wall we’re hitting in a switch to cleaner transportation | InsideHook

According to a Ford survey, 20% of people would miss the smell of gas the most if they switched to an EV Frank Rothe/Getty Images We as a species need…
MemorySmell
21/07/2021

How Memories of Smell Are Planted in the Brain | Psychology Today Canada

Specific smells that are encountered during early postnatal development can become hardwired in the mammalian brain if their neural connections to the olfactory bulb aren't pruned, a new study in…
HealthSmell
21/07/2021

How Do Dogs Sniff Out Diseases? | Discover Magazine

(Credit: Fernando Coelho/Shutterstock) Researchers don't always know how the dogs get the job done — but they know how to train With names like Bella, Duke and Darwin, detection dogs make headlines on a…
FlavourSmellTaste
20/07/2021

Scientists on the scent of flavor enhancement: Researchers study sense of smell to optimize food for consumption | Science Daily

With hopes to capitalize on the smell factor in flavor development, researchers are exploring how the route an aroma takes to get to the olfactory system, through the nose or…
InterestingSmell
15/07/2021

The Scent of Danger Makes These Fish Hulk Out | Hakai Magazine

Gilthead seabream are the first marine fish known to physically transform when exposed to a predator. Photo by Franco Banfi/NPL/Minden Pictures Some fish go through pronounced, yet reversible, physical changes…
ArtMultisensorySmellVisual
15/07/2021

Construction scaffolding reimagined as fantastical lemon grove in Midtown Manhattan | Livebl

Photo: @citrovianyc/Facebook A construction site springing up in your neighborhood is not always a welcome sight. Beyond the noise and traffic congestion, scaffolding often makes for cramped sidewalks and an unsightly…
Close Menu

Random sensory quotes

“We are excited by the amount of interest we have had in our programs and the possibility of opening a local Learning Center in the Austin community. This overview is an excellent opportunity for parents and educators to learn how a person’s sensory system is connected to learning, and how focusing on processing, rather than methods, can make a significant difference in an individual’s learning in a relatively short time period.”

— Nanci Bell