How Smell Works

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another_jim
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#1: Post by another_jim »

A breakthrough article published in Nature begins to decode how the sense of smell works. We can distinguish thousands of different aromatic compunds, but only have a few hundred different types of smell receptor. Apparently, unlike working on a lock and key system, like most chemical receptors, smell receptors are each triggered by a wide variety of chemicals. It's the particular combination of triggered receptors, which the brain puts together like like numerals in a number, or letters in a word, that identify the aroma.

That's been a pet theory of mine since after the time I realized good coffee tasters will say "that's a nice Kenya" rather than "I'm smelling blackcurrants and cloves." So it's nice to see that despite the deluge of the flowery descriptions, not just for coffee and wine, but for just about anything that smells, real expertise is the ability to put all the elements together, and know what you are smelling.
Jim Schulman

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happycat

#2: Post by happycat »

Interesting, thanks.

I gotta think the chain to coffee descriptions is a little longer and works like this:

olfactory sensors signal
neurons fire in patterns that light up memories
limbic system activated by memories, triggers emotions
frontal lobe evaluates patterns through sociocultural influences (personal experiences, language, values, labels, training)
words are chosen and spoken based on emotions, memories, culture and intellectual effort

My wife is from Japan and I am from Canada. She has a better smeller than I do and our flavour/aroma dialogues are always interesting. She is highly experienced as a former pro cook in fusion cuisine. However, I have ideas about aroma, flavour and texture I cannot always express without producing samples and saying, "That's what I was talking about."
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jbviau
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#3: Post by jbviau »

Yes, thanks!

NB: the full-text article (figures and all) is available here--just click "Download PDF."

I've got Harold McGee's "Nose Dive" and Barwich's "Smellosophy" on my nightstand waiting for me to dive in, and I'll add this to the pile.
"It's not anecdotal evidence, it's artisanal data." -Matt Yglesias

Marcelnl
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#4: Post by Marcelnl »

Interesting article, I'll read it in full!

From what I gather on the quick it may work the same for other senses....in the Audio scene plenty flowery language is being used to describe how a piece of equipment sounds but ultimately it comes down to finding the right words to describe a few key elements of sound (and perception of it). IME perception of taste and sound (and likely vision too) is something one either has or needs to develop, some can never develop acuity but most people get better at it with more 'training' (aka lots of experience and critical listening/tasting etc)

The Inuit have many words to describe snow, where we struggle to describe more than a few (always including the usual joke to go with that example, yellow snow).
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another_jim (original poster)
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#5: Post by another_jim (original poster) »

That's a different and equally interesting story -- not how we sense, but how we think and talk about what we sense. We know what stuff looks like; so if we see a tree, or a car or John from across the street, we can identify them. We know less about how stuff sounds like, and even les about how stuff smells like, so simply identifying them by sound or smell doesn't work very well.

At least for us. Presumably dogs can do with smell and bats with sound what we can do with sight. The interesting part is that while dogs out smell us and bats out hear us; it isn't as huge a disparity as the gap in our being able to ID things. We have also stopped using smells and sounds (except speech, of course)) to build our worlds, so the translation from smelling or hearing to thinking has been interrupted.

My beef with the way coffee (and wine or beer) tasters are trained is that it's the equivalent of saying "I see green pointy places and brown gnarly places" instead of "I see a tree." If you can't use your senses to identify stuff; you aren't using them well. The aesthetic appreciation should come after the ID.
Jim Schulman

mdmvrockford
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#6: Post by mdmvrockford »

Jim, great find! Thanks for sharing the article.
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GC7
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#7: Post by GC7 »

thanks for the article Jim. I will get to it asap. Presently reading Walter Isaacson's new book on Doudna's discovery of gene editing. It's in my research wheelhouse and like most of his books very good. I have Tom C's recommended book on smells in the pile as well (https://www.amazon.com/dp/1594203954/?c ... _lig_dp_it)

I find neurobiology and the complex nature of the brain along with immunology daunting though I've published some pretty seminal papers in neurobiology with great collaborators. If you have more interest in smell, look up articles or reviews by Richard Axel at Colombia University. He used his molecular biology skills to pioneer decoding olfaction. It got him a Nobel.

I've often wondered what it would be like to smell as my kitties do if just for a day. The variation and variability among humans and especially animals is astounding. Color is another fascinating sense that varies greatly and fir good use by different animals. I highly recommend Life in Color with David Attenborough on netflix. It will open your eyes (pun intended) to some amazing uses of color. Smell I think is similar.