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

HealthSmell
23/06/2022

Olfactory receptors are not unique to the nose | Nature

A coloured transmission electron micrograph of an olfactory neuron (orange).Credit: Steve Gschmeissner/SPL People are estimated to be able to discriminate between anywhere from 10,000 to more than one trillion different…
HealthSmellTechnology
23/06/2022

Restoring smell with an electronic nose | Nature

Image: Sam Falconer One of the many aspects of the COVID-19 pandemic that has taken the world by surprise is the vast swathes of people who lost their sense of…
FlavourSmellTasteVisual
23/06/2022

Salt & Straw’s latest ice cream topping is actually a perfume | Fast Company

What does ice cream smell like? That’s a trick question, because ice cream doesn’t actually smell like anything. Even if your favorite flavor contains fragrant ingredients, when held at such low temperatures,…
PheromonesSmell
22/06/2022

Baby’s Superpowered Scent Can Manipulate Parents’ Moods, Researchers Find | VOA News

https://www.youtube.com/watch?v=m1NSQL_4AVQ Why would the smell of a baby's head calm men but rile women? It may be another example of how we're more animal than we like to think. Source:…
ArtMultisensorySmellTasteVisual
22/06/2022

Smoke & Mirrors unveils new art-inspired cocktails | The Spirits Business

Singapore-based rooftop bar Smoke & Mirrors has released the second instalment of its signature cocktail menu: The Real Art of Drinking Volume II. Smoke & Mirrors is located on top…
HealthSmell
21/06/2022

Many Still Suffer From Covid-19-Related Smell Loss. Here Are Some New Insights Into Why | Forbes

Woman smelling flowers. GETTY Remember back in the earliest days of Covid-19, when one of the first telltale signs of infection was loss of sense of smell? Ever wonder why…
HealthSmell
21/06/2022

Scents of mystery: Author Paola Totaro explores the sense of smell after she lost her own | Sunday Post

A model in Vogue, 1964, with, at her ear, a teardrop- shaped bottle of Diorissimo perfume by Dior. Paolo Totaro’s mother wore Dior perfume when she was going out and…
Smell
20/06/2022

How the travel industry uses your sense of smell to enhance your holiday | The Conversation

Shutterstock/Pheelings media Freshly baked bread. Newly cut grass. A salty sea breeze. Most people have a favourite smell that evokes fond memories or feelings of comfort. This sensory appeal has…
ArtAugmented + virtual realitySmell
20/06/2022

So, you can now SMELL the metaverse? | Creative Bloq

(Image credit: Byredo) The metaverse is a strange place, and it's getting even stranger with its first perfume launch. Yes, you read that correctly; a perfume for a digital virtual…
InterestingScientificSmellTaste
17/06/2022

Do our genes determine what we eat? Study could pave the way to personalized nutrition guidance based on our taste perception | Science Daily

Preliminary findings from a new study involving more than 6,000 adults found that taste-related genes may play a role in determining food choices and could, in turn, influence cardiometabolic health.…
MultisensorySmellVisual
17/06/2022

Why sounds and smells are as vital to cities as the sights | Technology Review

AMRITA MARINO When David Howes thinks of his home city of Montreal, he thinks of the harmonious tones of carillon bells and the smell of bagels being cooked over wood…
Smell
16/06/2022

Experimental architecture history exhibits spaces with smell | Archinect

© California College of the Arts. In conjunction with the symposium, "Test Sites: Experiments in the History of Space", the California College of the Arts (CCA) Architecture Division will stage…
Augmented + virtual realitySmell
10/06/2022

OVR Technology releases its ‘INHALE 3’ Virtual Reality scent platform for mental health and wellbeing | Auganix.org

OVR Technology, a provider of olfactory virtual and augmented reality (VR/AR) technologies, has recently announced the release of its INHALE 3 Wellness Platform, the third iteration of its immersive VR…
MultisensorySmellVisual
09/06/2022

Living la dolce Velveeta: New nail polish leaves your fingers smelling like melted cheese | USA Today

Velveeta has teamed up with Nails Inc. to produce cheese-scented nail polish. The collection includes a two-pack of red and yellow nail polish ($15) – so you can make it look like…
SmellTechnology
08/06/2022

Machine that uses a live insect antennae to sniff out disasters…it’s ‘Smellicopter’ | OPB

Meet the Pacific Northwest-built machine that uses live insect antennae to sniff out disasters Melanie Anderson pulls aside a small curtain in a dark closet. A dim red bulb is…
MultisensorySmellTouch/Feel/TextureVisual
06/06/2022

Upscale Home Fragrances Are Getting More Creative | InStyle

CREDIT: GETTY IMAGES Before essential oil diffusers, we had candles. Before then, we had reed diffusers and incense, not to mention our favorite bouquets. The act of making our homes…
HealthSmell
06/06/2022

Why coffee can smell like garbage for people with parosmia | Zyri

For many people, the 2-furanmetanotiol can smell like a exquisite coffee, but for others it can be disgusting. The compound is one of 15 that chemists have identified as triggering the parosmiaa condition that makes…
NeuroscienceSmell
03/06/2022

How do our brains process smell? | Forbes Advocate

THE NOSE KNOWS: Researchers believe the way we perceive smell is linked to our ability to respond to danger, with a bad smell more likely to herald bad news than…
Smell
01/06/2022

Smell of Vegemite factory given special heritage recognition by Melbourne council | The Guardian

The distinctive smell of Vegemite should be acknowledged in any future development at the factory, the Melbourne deputy mayor says. Photograph: The Age/Fairfax Media/Getty Images Scent familiar to ‘generations of…
SmellTechnology
26/05/2022

How do you make an electronic nose smart? | Advanced Science News

A smart electronic nose that mimics the human nose with its millions of receptor cells and ability to differentiate smells. An electronic nose or e-nose is just as it sounds:…
BrandingMemoryMultisensorySmellTasteVisual
24/05/2022

The Scotch Malt Whisky Society Create Literal Memory Boxes | The Luxury Editor

The Scotch Malt Whisky Society (SMWS) has created memory boxes as part of their Flavour Hunters festival celebrating whisky month in May. Partnering with professional psychologist Dr Ansgar Endress, Scottish…
InterestingSmell
24/05/2022

Animal behaviour: Female mice release banana-scented urine when pregnant to deter males | New Scientist

A pregnant harvest mouse (Micromys minutus) and a pup: females will fight to protect their young, and use their urine to remind males of the fact. Klein and Hubert/NaturePL Pregnant…
Smell
24/05/2022

Scientists Recreate Cleopatra’s Favorite Perfume | Smithsonian Magazine

Researchers want to recreate the smells of civilizations like ancient Egypt.  Photo by AMIR MAKAR/AFP via Getty Images Bit by bit, modern researchers are helping reveal what living in ancient…
HealthScientificSmell
20/05/2022

Loss of smell linked to Alzheimer’s cognitive impairment and biomarkers | NIA.NIH.GOV

Decline in sense of smell is connected to faster buildup of Alzheimer’s disease-related pathology seen in brain scans, according to new research focused on older adults who live outside of…
Augmented + virtual realityMultisensorySmell
19/05/2022

Inside the smell-o-verse: Meet the companies trying to bring scent to the metaverse | Fast Company

Inside San Francisco’s Museum of Craft and Design, a long hallway painted eggshell blue is lined with the most extraordinary devices. A glass globe that uses trained bees to detect…
MultisensorySmellVisual
18/05/2022

Magnum ice cream and Nails.INC teamed up to launch ‘chocolate-scented’ nail polish — and the colors are also really pretty | Yahoo

Credit: Magnum ice cream x Nails.INC Our team is dedicated to finding and telling you more about the products and deals we love. If you love them too and decide to purchase…
HealthSmell
18/05/2022

Trained scent dogs detect airline travelers with COVID-19 | CIDRAP

Dragos Cojocari / iStock "Sniffer dogs" may be able to use their highly developed sense of smell to single out people infected with COVID-19, regardless of whether they have symptoms,…
EducationMultisensorySmellVisual
17/05/2022

A whiff, sound and taste of Christchurch: New exhibition uses senses to reimagine the city | Stuff.co.nz

SUPPLIED Eau Tautahi is an art perfume created by Jo Burzynska. It will be released as part of her new multisensory opening at Christchurch’s Arts Centre on Tuesday. Surveying her…
HealthSmellTaste
16/05/2022

Smell, Taste Loss Less Likely With Newer COVID Variants | MedicineNet Health News

Since the early days of the pandemic, loss of smell and taste have been tied to COVID-19 infection. But a new study shows those telltale traits are much less likely with the Omicron variant than the…
Augmented + virtual realityBrandingMultisensorySmellSoundTasteTechnologyVisual
12/05/2022

Council Post: Are Multisensory Experiences The Next Frontier Of Building Brands In The Metaverse? | Forbes

GETTY We’ve all heard the phrase “perception is reality.” Each of us as consumers perceives our world differently. The individual reality we each see is just that—individual—and it changes from…
Smell
10/05/2022

The Smelly Truth about Malodors: A Deep Dive | Aryballe

You’ve likely seen us use the term “malodor” in some of our conversations around scent monitoring. And while the name in itself is simple enough to understand (mal – meaning bad),…
MultisensorySmellTasteVisual
09/05/2022

The Benefits of Wine Include Activating Multiple Brain Regions | Now

When wine connoisseurs discuss the complex flavors of a particular wine, they are sharing a multisensory experience that involves more brain regions than almost any other human activity. Whether you…
EntertainmentMultisensorySmellVisual
06/05/2022

Irish Spring Built a ‘Nice-Smelling’ Shower for Stinky Gamers | Muse by Clio

Sometimes, hardcore gamers get funky. And you KNOW what we're talking about ... B.O.! They play for hours on end, days sometimes, barely stirring from their chairs, sweating like maniacs,…
Smell
05/05/2022

The Case for Smelling Like a Sexy Vegetable |  | High Snobiety

HIGHSNOBIETY / GETTY IMAGES / DIPTYQUE / D.S. & DURGA / COMMES DES GARÇONS PERFUMES / LE POTAGER When Thierry Mugler launched Angel in 1992, the perfume set the standard for…
BrandingEntertainmentSmell
05/05/2022

There is no damn way Baby Yoda smells like this | Polygon

Photo: Homesick/Lucasfilm An air freshener that smells like gardenia and rosemary? This is not the way If you buy something from a Polygon link, Vox Media may earn a commission.…
Artificial IntelligenceSmellTasteTechnology
05/05/2022

Robot Chef with Ability to Taste Food Unveiled | Fine Dining Lovers

Photo: ©University of Cambridge The rise of robots in restaurant kitchens has been well documented, with many claiming that the automation of cooking and preparation could act as a solution to the…