
Facts about smell (2014) - Tomte
http://alicebartlett.co.uk/blog/five-facts-about-smell
======
lucb1e
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](http://alicebartlett.co.uk/blog/weaknotes-15)

~~~
simonebrunozzi
What does this mean exactly?

> “James’” is the US English way to do singular possessive proper nouns.
> “James’s” is British.

~~~
lucb1e
Singular possessive "proper" nouns. I don't know what a non-proper noun is,
but I don't see how it's relevant for the example so I'll ignore that.

Possessive is that it is of someone. "John has a cat. It is John's cat."

Singular is, well, one: we are talking about one John (with a cat), we are not
talking about multiple people called John.

But there's a special case if the noun ends in an "s", like "James": how can
you pronounce the possessive part if it already ends in an s? Apparently, the
US does it different from the British: they use "It is James' cat" instead of
"It is James's cat."

For similar questions, you might find this site useful:
[https://ell.stackexchange.com](https://ell.stackexchange.com) (or, for more
advanced questions:
[https://english.stackexchange.com](https://english.stackexchange.com) ).

------
tom_
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...](https://slate.com/human-interest/2011/05/eating-cheese-in-china.html)

"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.)

~~~
n4r9
I found that part surprising. I think I know what butter smells like, but for
it (and the rest of that list) to come above blue cheese and sulfur??
Incredible.

~~~
taejo
The list is the most smellable things _by detection threshold_ , which is
quite different from perceived _intensity_ (many compounds have quite a low
threshold above which they don't smell any stronger). It wasn't clear to me
whether the author was aware of this distinction.

------
Jun8
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.

~~~
avip
What we call "smell" in aggregate is a collection of responses to different
molecules. There is no obvious way to add, filter or model these compounds.
While all "light" (and sound) could be described in terms of frequency and
amplitude, the simplest of organic compounds is an order of magnitude more
complex.

------
austincheney
> 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...](https://en.wikipedia.org/wiki/Grapefruit%E2%80%93drug_interactions)

------
vichu
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...](http://blogs.sciencemag.org/pipeline/archives/2009/06/11/things_i_wont_work_with_thioacetone)

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.

~~~
blattimwind
> to smell worse when diluted

It's possible that non-diluted concentrations smell so intensely that it
appears like it smells less. Similar to various chemicals where after a while
the smell fades, even when the concentration in the air remains the same.

~~~
vram22
Or it's possible that the chemical reacts with water when diluted with it, and
the reaction forms another chemical which smells worse than the first. Some
things do react with water, it's not totally inert, IIRC from school
chemistry.

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seymour333
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

~~~
zorga
If you have to even ask, throw it out.

~~~
Wh1zz
I'd rather not make another trip to the shop

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n1000
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.

~~~
diminish
Am I missing anything deeper in Suskinds work except an olfactory genius's
murderous quest for the perfect scent?

I think, a non-dark version of this novel could be interesting too.

~~~
samatman
May I suggest the excellent “Jitterbug Perfume” by the incomparable Tom
Robbins? It’s an all-time favorite.

------
ehecatl
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.

------
JNRowe
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](https://www.chiark.greenend.org.uk/~sgtatham/smell.html)

------
evincarofautumn
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.

------
alexpotato
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.

------
interfixus
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.

------
z3t4
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".

~~~
airstrike
Link? That sounds incredibly interesting

~~~
iknowstuff
Found this:
[https://www.dailymail.co.uk/sciencetech/article-1196856/You-...](https://www.dailymail.co.uk/sciencetech/article-1196856/You-
smell-terrified-We-detect-scared-scent-new-study-shows.html)

------
kieckerjan
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](https://www.youtube.com/watch?v=yzOcvINn8Iw)

------
cognivore
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!

------
amelius
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?

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airstrike
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

~~~
mobilejdral
When I smell things I see them (synaesthesia?). The idea that others can't
easily categorize smells is funny to me. The color, shape and texture of a
smell are the biggest ways I would describe what I see when I describe a smell
so it is more multidimensional than something as simple as a two dimensional
grid.

~~~
taejo
If you ask two people the colour of a certain object (under the standardised
lighting conditions) you _usually_ get the same answer (or variations on the
same answer: "turquoise" vs. "blue", for example, but there's a fairly well
understood vector space in which these fall). Ask two synaesthetes what colour
a _smell_ is, though, and I suspect the answers you'd get are much less
correlated (that's certainly the case for the colour of numbers) though there
are cultural aspects (apparently the colour synaesthetes see in letters are
very often the exact colours those letters had in the poster or book they
learnt the alphabet from).

------
vlmlee
> 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!

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karmakaze
Do other people notice the distinctive smell of stainless steel?

------
drakonka
Concise and informative, thank you for sharing.

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

[https://www.ncbi.nlm.nih.gov/pubmed/16484712](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...](https://www.psychologytoday.com/us/blog/heal-the-mind-heal-the-
body/201809/can-humans-smell-cancer)

