How Many Smells Can You Smell?

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We walk through life led by our noses. Literally. Because they're on the front of our faces. The sense of smell might be one of the oldest, but how does the science of smell work? How sensitive are our noses? Why are smell-related memories so vivid? How many different smells could we possibly smell? Find out in this week's It's Okay To Be Smart!
Check out this amazing essay on smell from Lewis Thomas (1980), it's a beautiful piece of science writing: cplab.net/heap/on-smell/
Evolution of human olfactory receptor genes: www.ncbi.nlm.nih.gov/pmc/artic...
Pseudogenes in olfactory system: www.ncbi.nlm.nih.gov/pubmed/12...
The nose as an emotional time machine: www.nytimes.com/2008/08/05/sci...
Smell memories are often the most vivid: aeon.co/magazine/psychology/wh...
Sperm olfactory receptors: www.ncbi.nlm.nih.gov/pubmed/16...
How many smells can we smell?
neuroecology.wordpress.com/20...
www.sciencemag.org/content/343...
You and Your Senses, starring Jiminy Cricket: • You and your Senses of...
Have an idea for an episode or an amazing science question you want answered? Leave a comment below!
-----------------
It's Okay To Be Smart is written and hosted by Joe Hanson, Ph.D
Email me: itsokaytobesmart AT gmail DOT com
Facebook: / itsokaytobesmart
For more awesome science, check out: www.itsokaytobesmart.com
Produced for PBS Digital Studios
Joe Hanson - Creator/Host/Writer
Joe Nicolosi - Director
Amanda Fox - Producer, Spotzen Inc
Kate Eads - Associate Producer
Andrew Matthews - Editing/Motion Graphics
Katie Graham - Director of Photography
John Knudsen - Gaffer
Dalton Allen - Post-Production Intern
Theme music:
"Ouroboros" by Kevin MacLeod
Other music via APM
Stock images from Shutterstock

[@Alinilz]

When I was 13, I moved into a new house that needed a lot of housework, namely, painting. At the time I was a big fan of Linkin Park and Coldplay, and I would listen to their songs while painting the walls. To this day, whenever I listen to either a Linkin Park or a Coldplay song, I can smell the paint.

[@Yasmeentea]

The smell of the earth after it rains... Amazing.😃😊😄

[@besmart]

You're in luck, I have a video about that! kzbin.info/www/bejne/onjGdmiubdhjeJo

[@iceage287]

For me that smell is very relaxing

[@Claego]

Jasmine Tea I think the word for that is petrichor

[@Claego]

the smell of petrichor is actually the result of oils collected in soil and rocks, rain causes a range of compounds in them to be released into the air to mingle with geosmin. This gives us the smell after rain :)

[@mikethegoo]

Maseofbass on average: the best smell on the world is just cut grass... the worst sound on earth is a baby crying and the best image in the world depends on who you are and what you like

[@mrsoizescreative8287]

When I smell burning logs, I become very nostalgic of the long summer nights around the campfire telling stories with my cousins.

[@techi9818]

I still recognize my mom's smell. I used to steal her pillows when I was little.

[@virtualalias]

The smell of plastic (like new electronics or packing materials) reminds me of those plastic pools where the water holds up the sides and how much fun I had in them as a kid.

[@billmcnichols7316]

I was 4 years old - I tied my shoes for the first time after my nap. My mom cut me a fragrant orange to eat. It's an indelible memory

[@besmart]

I love all these comments sharing special scent memories, but this one especially. The power of smell is strong!

[@titansoftime]

I had to look up "indelible". Thanks for the new word =]

[@ASLUHLUHCE]

I first read 'inedible'

[@acle_oficial]

THAT SMELLY SMELL THAT SMELLS... SMELLY

[@Xiros-cs4wg]

lel

[@atomicsquidofdoom3685]

*ANCHOVIES*

[@RobloxDeadzoneHacks]

Smelling fish

[@ColbyB23]

Whenever the season is changing. I always smell the previous years previous season I never understood why. Thanks for for the insight.

[@johnwomea9449]

repeatation in your memory but not of the chemical around you. it occur only in your brain

[@niggogado]

i cant smell because i am voldemort.

[@wizardemail]

민박선 HE HAS A NOSE, IT'S JUST REALLY, REALLY FLAT.

[@108wee]

+Mary Norris it's suppose to be inspired from a snake but snakes smell from their tongue sooooooo yeah

[@KenjiStarwolf]

Whats also interesting is that the nose of every animal is close to the mouth! Cause you got to smell what ya eatin!

[@jismeraiverhoeven]

well smell and taste ARE connected. without smell, your food also has less taste (so if you dont like certain food, plug your nose and it will be less bad then usual). generally i find stuff smells the same way as they taste wich is funny because it can smell wonderfull but taste horrible (roses for example). this also means that you can know how something will taste just by smelling it (so if you wanted to know what blood tastes like, just smell it)

[@katiebouch]

This video was very interesting and a little bit depressing. I have no sense of smell, I never have. I am super curious about what smell is and how it works since I just have to try to imagine scents. Yes, I do have a sense of taste, and I enjoy the taste of food. Thanks for the great video. Would you consider doing one on people who can't smell at all and some of the things that might have gone wrong to prevent this sense from developing in a person?

[@samuelradziwon2407]

Katie B it is like tasting but long distance and some times very off putting with bad smell or food that tastes good some times smells bad and vise versa.Sorry! if this makes you sad

[@sheriffathyabdelkarim]

Katie B I am anosmic since birth too =( we are so rare

[@mikethegoo]

Katie B just imagine the taste of food, but through your nose, that's practicly what the smell of the food is.

[@qiyucai]

Yeah... i cant smell either... it kinda sucks to be totally honest

[@mikethegoo]

Qiyu Cai I can imagine seeïng thag I use smell a lot more tgen the avarage humam, I even fuckin use it to get aroused so I would be sad to lose it... sorry for you

[@Guillaurent]

The smell of rain before it falls. Gets me the urge to run indoors :)

[@DescendingAngels]

The smell of mooshed plants on my hands I got from playing in the forest as a child is my most memorable smell. :) I feel happy every time I smell it.

[@VR_Wizard]

I like the smell of my pillow it makes me soooooo sleepy.

[@mikethegoo]

neil barro mine smells like (for me) the perfect mix between cum, a little saliva, love pheromone ( I am very passionate) laziness, sleep and body odor (mostly made up of foot sweat that is but a little diffrent because it is not all foot sweat)

[@carlosmp2043]

Mike the Goo Thank you Kanye, very cool!

[@xavierxrc]

You never disappoint on your videos. Your Grandma was very funny. The resemblance is uncanny, lol.

[@ShubhThakkar]

Around the age of 12, I used to go trekking with my dad on a hill and I still remember the smell of the deep breath that I used to take after reaching the 2nd top (the hill is divided into 4 tops, the 4th being the topmost one), to this day I think thats the smell of oxygen.

[@mikethegoo]

Shubh Thakkar but I think that we have evolved to make oxygen be melllless to us. I however do not prive you wrong because I am not sure about that. (that word tho, so many l's... only 4 but a lot at once for a word)

[@codexolotl]

I'd like to say I have a special memory with something awesome smelling but sadly I have Allergies and can't smell at all! Except for very strong smells and my favourite time is Christmas because I can smell most of the things like peppermint and even sometimes Christmas trees and gingerbread and other cookies cooking in the oven. My favourite Christmas was when I got to help make some flat cookies that look a bit like waffles and are called tie plates and helping make some homemade gravy for the turkey dinner :3

[@mashobane9982]

There is a specific flower that I call the smell of my childhood because when ever I smell it it takes me back to a specific memory! I instantly have a mood uplift

[@louisachibert5812]

Thanks. Loved your explanation and animation.

[@UberMegustador]

Q:How Many Smells Can Chuck Norris Smell? A: All Of Them! :D

[@HeyJD123]

Chuck Norris's feet never smells, his nose does. Chuck Norris's nose never runs, his feet does.

[@phonomancer_thepossum6279]

I have a set of zoology books from 2006 and ever time I open them I have the coolest nostalgia from the smell of the pages.

[@harold_Shitmum]

What a kick ass video!! That was really interesting. Well done to the maker/s of this film.

[@shiraztyebji7059]

For me, the smell is the most strongest memory, bringing flashes of visuals from the past; one i can mention is the smell of a 'new book', reminds me of end of summer holidays and beginning of a new semester year. Thanks for the awesome videos. Stay curious!

[@joshgadget]

The bunks at my summer sleep away camp in Wisconsin a very particular smell that I can recall very clearly. When I brought my wife and kids to the camp a few years back the smell was still there and the nostalgia was crazy.

[@kittyeyes19]

I actually created my own smell memory on purpose. When I traveled to Mexico, I wore a certain perfume for the first time and wore it the entire time I was there. When I put the same perfume on now, it makes me "homesick" for Mexico and brings back vivid memories of my time there. I was the first time I was able to "program" my brain in a purposeful way, even if that purpose was just to trigger strong emotions.

[@juliasadler7771]

There's this flower perfume, I think it's called "Chloé Narcisse", wich my mom used to wear all the time until I was about 5. Recently, I opened a cupboard and was greeted by an open bottle of the stuff that almost knocked me over. The only word that comes to mind is "childhood". I think since I smelled it all the time I can't really connect it to a specific memory.

[@freecurls3958]

Very interesting, as always! It is true smells bring back the most intense memories! Thanks for sharing with us!

[@jonathaneby1440]

I used to go to the Knoxville Zoo when I was a little kid. And around mid afternoon we always went by the area of the Zoo that held elephants, zebras, giraffes, gazelle, merest and more. The section of the African Savanna always had a distinct smell of the crap of large herbivorous mammals, and I grew to love the smell for the adventures, animals, and sometimes snacks that the African Savanna and eventually the zoo as a whole would bring. Now when ever I smell the smell of large animal doing, wether it be at a farm, another zoo, or even a place where human feces are prevalent, my mind goes back to the Zoo, and how much I loved it there.

[@jackiezimmerman5319]

For me, my sound memories are more memorable. Like my trip to Colorado, I would listen to the same sound over and over, and now when ever I listen to it, I think of Colorado.

[@Spiderboydk]

I love the smell of newly harvested grain. It instantly reminds me of the warm summer holidays of my childhood where my brother and I played The Floor is Lava on the straw bales on the field.

[@theobserverproject952]

outstanding Joe, Very well done...

[@oweniness]

smelling a random dish soap at Walmart made me think of my great grandma who died when i was 6ish

[@rottis5042]

Sad

[@kinrythium]

A freshly cleaned building reminds me of the first day of school. Like freshly waxed floors, swept carpets, cleaned windows, it all just reminds me of the first day of school. It's very nostalgic.

[@AugustThor438]

My first cologne was Davidoff cool water and now 20 years later I bought it again and it takes me back in time to 1995

[@Hortonscakes]

I wish this video was longer but it's all good! 💯💯💯

[@platinumruby]

Perry Ellis 360 that smell reminds me of a good friend of my mom and the memory it brings to it is her working at a restaurant with a Caribbean shirt on with flowers in an outside environment

[@BrandonNevermind]

The scent of Dial hand soap instantly triggers a happy feeling in me, because it was the same kind that the summer camp I went to as a kid used. It triggers no specific memory, and I had to dig in my memory to remember *that* as being where it came from, but it does trigger a nostalgia-like feeling and can change my mood.

[@manumalus]

The smell of night-jasmine brings me back to my grandmother's old house and to my grandmother herself. She had those on her porch. It's one of the best smells for me.

[@sebastianchandler4934]

you should explain the science behind people liking weird scents such as skunk. people always ask me why I like it, but I want to give them a simple answer rather than a drawn out long answer.

[@Claego]

the smell of termites chewing on wood reminds me of when I was 7 or 8 and we had an infestation

[@tricorn7982]

Love your videos

[@coregurlz]

Most of the smell I smell did trigger a lot of memorable memory of childhood. I really miss them.

[@olredkin]

It's funny that exactly yesterday ended our theater project with a theme "Smells carry memories"

[@Rika_Is_Tired]

5 years later this is Randomly recommended to me

[@Hollykindredjins]

The smells of Channel No.5 and CK Obsession always remind me of my mom after all they are her favorite perfumes.

[@MaoRuiqi]

cooking popcorn, comfort plus good times forthcoming; baking bread, familial love and peace.

[@DestructorEFX]

I was born with a problem on the nose and I cant smell nothing except alcohol :'(

[@VR_Wizard]

+Destructor EFX Do you know why only alcohol triggers your smell receptors? What is about other kinds of alkohol like Pentanol or Propanol?

[@DestructorEFX]

Christoph Geske Well, I think that I can smell alcohol because it's a very strong smell.

[@BagelBoyyy]

+Destructor EFX Try smelling cocaine.

[@phillipdisilvestri3572]

+BagelBoyyy bahahaha

[@nicolaiveliki1409]

What else do you need?

[@supermewis]

I went on a trip to Malaysia when I was in high school, and my mom bought me a bottle of antibacterial gel. I found what remained of the gel and used it by chance a few years later and I was transported right back to all my memories and feelings form the trip. Time travel!

[@juliefoenspetersen]

For my first birthday my grandparents got me a toy bunny, which I grew up with and took very good care of it. It had a special smell that made me feel safe. And I remember when I lost it at school my parents got me one that looked just like it, but the smell wasn't there, and I didn't feel anywhere near the affection I had felt for the other.

[@Nipponing]

That pixelated picture of the painting is way more advanced than what you could do on Atari. XD

[@melmelodies8730]

Cats and Vannilla are my memory smells, and I love it! Vannilla because it's soothing, and Cats because they are SO FLIPPING ADORABLE!!!!

[@shantiwolff4768]

The smell of the salty air at the ocean brings back lots of good memories

[@SuperioRobot]

For me, the smell of certain kinds of heated or even molten plastic, conjures EXTREMELY specific memories of when I was a child at my local zoo. They had machines all around the park, that if you picked an animal, it would (on full display) make a plastic mold of the animal right then and there. That smell, lingers in my mind very powerfully.

[@lesporches]

That fresh rain smell

[@delvesdg]

I have a special part of my nose reserved for the Marine Corps Rifle Range. The mixture of the smell of South Carolina air, wet grass, hot brass, spent gun power, and pure determination.

[@kannusingh7003]

how do we remember and recall that smell of something particular, example smell of fruits or anything because I believe that those odour molecules just touch our neurons and go away?

[@manrajdhanda]

The smell of a certain liquid hand soap always reminds me of the video game 'command and conquor' which I used to play on my computer when I was about 8 years old

[@ericvilas]

There's this old couch we have, and if I open up the cushions and smell inside them, I can still smell the scent of a house we used to live in. THAT is some good scent keeping.

[@BrittonDeJong]

when i go for walks i smell this weird house smell coming from the neighbors and it always brings me back to my childhood, not sure what the smell is

[@Funkyleyray123]

My grandparents house brings me memory to me really

[@magiv4205]

The smell of my grandma's old house is simultaneously comforting and painful. Comforting because it reminds me of my childhood which I spent mostly in that house, and painful because now it's just a lifeless shell of its former self and all the beautiful trees and flowers have been cut down and all the old toys and books thrown away.

[@gaillewis5472]

I remember the scent of medicated gauze from after a childhood ear operation. When I picked up the same fragrance on my cat's right paw after surgery, I told the veterinarian Soiree had "all-better smell." He understood and smiled.

[@heavymetaljess_]

The smell of Magic the Gathering cards was always such a specific smell that brought me happiness from my childhood. When I got back into the game in about 8 years ago, I realized something was different almost immediately. I took another break from the game and when I started playing again last year, the smell has shifted yet again. It's a very subtle difference, but each of the smells reminds me of a different time period and all three recall good times.

[@kristinemedina2839]

When i smell dried-up paint inside homes or public cubicles..i remember the ocean and the boats i used to ride where you smell the same odor inside their docks or bathrrooms

[@tushnaben]

I am extremely addicted to this channel!

[@XPimKossibleX]

Chlorine and wet paint give me my most nostalgic memories. Chlorine from the pools in of childhood in Israel (they had way too much), and wet paint also from my childhood in Israel because my mum was an interior designer.

[@Dr_Bille]

The smell of cinnamon takes me right back to those childhood christmases, when there was still magic in the world

[@bluesoul3963]

there's a smell that makes me freeze and I lose all intentions on moving but I can't find out what it is. and it's not a bad smell ether.

[@Aeturnalis]

When I was 20, I was tripping on acid and ended up at a greenhouse in Southeast Michigan (someone asked if I wanted to come, and being high makes it hard to say no lol)... they were growing mulberries in the front of the greenhouse. About 6 or 7 years later, a scent of mulberry candle gave me a flashback, it was wild. It only lasted for about 10 seconds, but it was a powerful feeling.

[@truephase3581]

Looks for a very important smell... oh yeah summers at the pool with the chlorine smell 😁

[@ely_emile_]

please do a video on the sense of taste

[@anaraug]

There's a part in Anathem where the characters discuss the fact that our sense of smell works on the quantum level--in the book this means that we can smell food created in universes with different nucleosynthesis processes than our own but we can't taste or digest it. I'm not sure how accurately this reflects reality, but it certainly agrees with the notion of there being more detectable smells than colors or sounds.

[@brenaecsax]

The smell of a pack of unwrapped mini starbursts. I cant remember whats its from, its i remember it.

[@wadeo.778]

When I smell salt water I always think of Ocean City, NJ because I go there every year (except the few years I go to Disney world) for vacation

[@ayeshar2541]

for some reason, the certain smell of hand sanitizer reminds me of kindergarten, since we would have snack time right after nap time, and we would put on hand sanitizer

[@abdmajidkhalfet5139]

Good ! voir ok ,merci

[@rickseiden1]

When I was a kid, my great uncles owned J&J Stationary in Westwood, NJ (Now Five Corners Convenience Store). The place had a very distinctive smell. I can't describe it, or remember it, I just remember that it existed. Many years later, as an adult, I was on a project near Westwood, so I took a trip to the old store. I walked inside, and was hit by the smell. It wasn't unpleasant, or really strong, but it was part of my childhood. Part of me. It brought back memories of being in the store with my uncles. Minding the register when I was too young to really do it. Getting free candy and free toys. That day really truly convinced me that smells are strongly linked to memories.

[@yumisang505]

I remember the smell of my mothers old garden as a child and sometimes the salads i make remind me of the garden because the taste is the same as the garden smell

[@yumisang505]

Might've sounded old but its true

[@fartzinwind]

OOH OOH That Smell Can't you Smell that Smell... Damn you It's Okay to Be Smart, now I have to look up that video after this.

[@besmart]

Whiskey bottles, and brand new cars…

[@luciferbroke7875]

I guess you're smelling the fatzinwind

[@redplays7678]

Reading that make me think if smell spelling is even right

[@5TailFox]

I wonder, if I were to point the little remote thing at the bird & press the shutoff button, would it make that sound, too?

[@sportier]

Every time i smell a cheap vanilla room spray, i automatically remember carmageddon, pc game. Its amazing that it feels like i get slapped with all these memories of the game, is like watching a movie of myself play the game within that second!

[@obern7039]

I spent a large portion of my early childhood (the first 2 years) in hospital due to a rare genetic disease I had as an infant. I can not remember any of this but the odor of disinfectants is, to this day, triggering some odd memory flashback... (don't worry, I fully recovered)

[@naolucillerandom5280]

Play doh. Me making play doh flowers, thinking the smell was bad.

[@JillH1995]

Every time I smell orange Kool Aide, it reminds me of the time my mom made playdoh and colored it with Kool Aide. I'm 90% sure she also made other colors/scents that same day, but it's the orange I remember the most.

[@beefcakeandgravy]

I have a pretty good sense of smell, I can smell things from a long way off, like the bakery or someone smoking in a car 5 or 6 places ahead of me in traffic. Also I often get "phantom smells", that aren't actually there. An example is a burning wood smell (fresh burning, not left over ash smell) even when my stove hasn't been lit for a few days. Burning plastic is another common smell I get, when there's nothing to cause it, (nothing electrical running etc). I can sometimes smell diesel or fuel when I'm nowhere near those substances. I can sometimes smell things no one else in my family can, like when there's a storm on it's way (that hasn't actually started yet) My missus thinks I'm crazy but when it happens, but I KNOW it's there. Oh, and It's Okay To Be Smart How come you can't smell your own breath? (even when other people say it's bad)

[@salvatoredel-re580]

I love the smell that you feel when you are close to getting to the beach...

[@clawziin1824]

This is a lie. I can smell a chicken nugget from the other side of the world if im hungry.

[@AB-Prince]

Howlandheaddresses ArtandCS kawaii desu

[@startheforgetful5422]

2:30 the 4th old lady is the one from that one meme, and in it she's pointing a gun 😂😂😂😂

[@sarahwiley2783]

My grandpa would smoke cigars and chew tobacco a lot. It annoyed me while he was alive and I always begged him to stop because the smell was so nasty, but a few months after his passing I walked by a man smoking a cigar and instantly I broke down in tears. Now I find comfort in the smell. And recently I even went to a store and talked to a man who started chewing the same brand my grandpa chewed, and as I smelled it on his breathe all I could think of was hanging out with my grandpa. No other senses trigger such strong memories of him than those two smells.

[@pantpissakornpant7749]

It is very informative

[@wyatt4840]

The smell of my father's aramis cologne that sticks with me and reminds me of when he used to pick me up when I was little from daycare.

[@hfangle13]

The smell of Scotch tape reminds me of Christmas

[@ericvilas]

There's an acne lotion that I used to use a few years ago. One of its ingredients was sulfur, meaning it had a very, VERY distinctive smell. Although I don't use it anymore, I do have what's left over from that time, and every so often I smell it. For some reason, it brings up an incredibly pleasant memory from that time period, but I can never place it. I can't ever figure out what exactly that memory is. But I know it reminds me of _something_, it's just barely out of my reach.

[@ontyam]

How do you use italics on comments?

[@bendadestroyer]

i remember it being 10,000. so where did the number 1,000,000,000 come from and does that mean dogs have 4,000,000,000 or is the exponential?

[@besmart]

bendadestroyer Check the references in the description to learn more about the 1 trillion estimate, which just came out in 2014. It seems that the 10,000 smells estimate was literally pulled from thin air and has no basis in any science.

[@Schoko4craft]

1,000,000,000 Billion 1,000,000,000,000 Trillion

[@fudgeconspiracy690]

i never threw away my first drawing tablet 'cause i LOVE how it smells

CERN's library, despite the Internet-induced digital revolution, subtly smells as it did 25 years ago. That's a vivid olfactory memory that takes me back to the good old times.

[@rebeccarakuza2845]

I feel like that's one word away from being a Dr suess title for some reason

[@Lord_Otter]

I love the smell of happyness and rainbows.

[@ChocolateMilkMonster]

Im a 'anosmia' means i have a limited and somedays no smell at all. whats up with my nose?

[@RainAngel111]

When I was young, My grandma made these amazing cinnamon apples, by basically taking out the core whole, and not cutting open the apple. no hole in the bottom, just the top. sort of like a pumpkin. then she filled it with some kind of cinnamon/clove mixture and let it soak through and she baked them. we had them for dessert one thanksgiving. I still remember the taste and smell, but I couldn't tell you anything about who else might've been at the dinner or what we talked about. I also remember going to this open-air market in the mariana islands, and eating some REALLY good kebabs. I have had many good kebabs later in life, but none quite so good as those, with the fat still sizzling, the unique mixture of dressing and herbs they used, with a slight smell of smoke and char from the grill. mmmm.