Facts about smell (2014)

Interesting blog in general. For example, these "facts I learned this week" were cool[1], and there is this little gem in Weaknotes 14:

> Someone suggested we should be building ‘frictionless’ experiences the other day. I asked them to elaborate and they had a great point about sign up flows that I didn’t disagree with. But I loathe the word ‘frictionless’ in this context. Friction is what is keeping me on my chair right now. It stops us all from sliding all over the place like eels writhing across a canteen floor. Friction in services helps us make decisions. Amazon’s sign-up to Amazon Prime at the checkout is so frictionless I keep frigging doing it by accident and not realising. Friction is useful and important.

I like the style and brevity of the posts.

[1] http://alicebartlett.co.uk/blog/weaknotes-15

I'd always thought of butter as being mostly odourless, until at some point aged 30+ I accidentally bought some that actually smelled of something - and, who knew! It was a huge surprise.

I have ever since always sought this out - unpasteurised salted French PDO stuff seems to be the thing to go for - but while I now know that it is possible to get butter that smells of something, and I now know I like it, I'm still not sure I'd class butter in general as something that smells of anything in particular.

This line of thought did remind me of this article I read a few years ago, though: https://slate.com/human-interest/2011/05/eating-cheese-in-ch...

"Another said that the selection “smells like Russians”. “The difference,” he added, “is that the stinky things Chinese people eat give them smelly breath, while stinky dairy things affect the sweat that comes out of your skin.”"

(It's possible this is some genetic thing. I worked with a guy recently who would refuse to eat cucumber, on account of its strong taste and aroma, that would taint anything with which it came into contact! - meanwhile, I always thought cucumber rather watery and tasteless. Maybe very slightly gently peppery, if you got a good one that was particularly strong-tasting... by cucumber standards, at any rate.)

Loved this post! Wished there were more posts like this written by by domain experts: short, succinct (no jokes, unnecessary examples), leads to many interesting thoughts on the subject and has clear references.

The fact that smell works so differently than our color perception is very interesting to me. Color perception is mathematically so neat to analyze: there are 3 or more (in some animals) basis functions corresponding to receptors and you build on that. I wonder why smell didn't evolve like that but developed so many different types of sensors. Probably the fact that it evolved much earlier is a factor (the more elegant solution was not hit upon by Nature) or maybe there is some other reason (important smells also evolved but all colors were available for training from day 1).

The phrase "the latest research seems to suggest that humans can smell up to 1 trillion different scents" is interesting since it treats smells as discrete entities, while you can't do the same with colors since they gradually change from one to another with no boundaries.

> Anyways, grapefruit is number 1 there on the list of smelly smells, but how smelly is grapefruit?

I wouldn't say there is no evolutionary advantage there. Grapefruits are extremely high in compounds that lower the body's metabolism and alter drug absorption. In the wild an otherwise benign ingestion of toxins, concentrated alcohol, or even toxoplasmosis from food poisoning could prove fatal when mixed with these compounds. As a result those chemicals have a distinctly bitter taste and strong aroma.

People developed that detection mechanism because it can prevent death.

https://en.wikipedia.org/wiki/Grapefruit%E2%80%93drug_intera...

Somewhat related to smell, here's a fun chemical that you might not have heard about: thioacetone. Thioacetone (and some other organosulfur compounds) are extremely malodorous. During distillation of this chemical in the German city of Freiburg, it resulted in vomiting, nausea and unconsciousness within a radius of 0.75km of the laboratory. It's also reported to smell worse when diluted and the odor is referred to as "fearful".[0]

[0] http://blogs.sciencemag.org/pipeline/archives/2009/06/11/thi...

Check out other works in Derek Lowe's Things I Won't Work With series for other similarly dangerous chemicals. I first learned of thioacetone from him and have seen other articles of his floating around HN as well.

As someone who developed parnosmia later in life (I can only smell certain things), I found this article very interesting. Living without the ability to smell is somewhat more isolating than one would think. That, and I have to really trust someone if I want an opinion of whether the milk's gone bad

For those interested in the olfactory world, there is this beautiful novel „Perfume: The Story of a Murderer” by Patrick Süskind. I read it as a teenager and it changed my world. Unfortunately, the title already suggests that the English translation may not be as good as the original in German.

Oh my. Cucumber! There really is nothing quite like it to my nose. I've only known two other people who are quite as sensitive... and one of those is my eldest child.

I've come to physical blows with asshats who think it is funny to test me, because it tastes of nothing to them.

In reference to fact 2, ‘Simon Tatham Has No Sense Of Smell’ FAQ¹ always struck me as interesting. Even just for the obvious things like being wary of gas appliances, somehow such a thing had never occurred to me.

[There are plenty of other cool things on his site beyond just the puzzle collection and putty.]

1. https://www.chiark.greenend.org.uk/~sgtatham/smell.html

I have an extremely strong sense of smell, inherited from my mother. Both of us are able to detect smells at lower concentrations and identify them more accurately than almost anyone else I know. My partner has told me that there are many things she didn’t even realise had a smell until I pointed it out—she is not anosmic, because she could recognise the smell after I drew her attention to it, as long as it has a high enough concentration. I have identified people I know by smell (who left their sweater behind at the party?), detected someone slicing cucumbers or celery a few rooms away, can identify what the neighbours are cooking, have pinpointed the location of certain types of ant nest, and more. If anyone is studying smell and wants to use me as a guinea pig, feel free to get in touch! I also have synaesthesia, which may play a role in how I process smells, but it seems to be mainly a physical thing.

So I am one of the rare people who were born without a sense of smell aka congenintal anosmia. Most people you run into with anosmia lost it due to an accident or medical procedure but as far as I can tell, I've never had it. Several other people on my dad's side of the family also have it which reinforces my belief that it's genetic.

I usually bring this up with co-workers along the lines of "If I smell bad or you smell smoke, PLEASE TELL ME!" which usually starts a whole series of questions mostly b/c people want to know what it's like.

I usually explain it like this: "Think of aluminum foil. Now think of fresh out of the oven baked bread. When I say 'baked bread' to you I imagine that a smell pops into your head and all kinds of memories are attached to it. When you say 'baked bread' to me it's like when I say 'foil' to you. There is no memory or sense attached to it all."

Even more interesting is that I didn't even realize I had no sense of smell till I was 19. Growing up I always thought that feeling in your nose in, say, a fried chicken place was smell and my sense was just weak (my sister has an AMAZING sense of smell). It was a room mate "breaking wind" in college that finally triggered the "ah ha" moment.

Not only was this a good read - the site is well done the way a site should be: Painstakingly hand-crafted, very much reflecting the style of the writing - short, sweet, fluff-free, unpretentious, to the point, and highly competent. And that footer is pure genius.

I bought a air filter with a smell detector. The smell detector can detect a fart and then ramps up the fans, but it can also detect some feelings/emotions like anxiety. This makes me believe our subconscious can pick up these feelings as "smells".

Here is a fascinating (and entertaining) talk by smell scientist and perfume writer Luca Turin, describing his quest to explain how smell works: https://www.youtube.com/watch?v=yzOcvINn8Iw

Tomte, thanks, not particularly for the original reference to the article about smell, but for directing us to the person in question and all the great stuff she has written. I got lost for an hour an 45 minutes.

Thank you!

Can't we treat the receptors as black boxes, and ask people to describe different smells while we also perform various measurements on the gasses, and then perform various data analysis techniques?

I was recently wondering why we don't have a neat way of organizing smell, sort of like a periodic table... surely there's got to be a way to think about smells in a more structured way

> The ability to smell these things presents no evolutionary advantage and does not seem to be related obviously to how the nose works.

It's better to not make evolutionary claims!

Do other people notice the distinctive smell of stainless steel?

Concise and informative, thank you for sharing.

Apparently dogs can be trained to smell cancer with 99% accuracy:

https://www.ncbi.nlm.nih.gov/pubmed/16484712

And maybe some exceptional humans too:

https://www.psychologytoday.com/us/blog/heal-the-mind-heal-t...