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A Skunk By Any Other Name
September 16, 2010 11:31 AM   Subscribe

I have always found skunk odor and roses to share similar scent. In my opinion, it's strikingly similar, but almost nobody agrees with me. What chemical, if any, do they have in common?

I suspect more people would agree, except they are blinded by the skunk = bad smell, rose = good smell cultural norm. I do like roses, but I swear they share something. I have a good nose for this stuff, and a relatively trained palate.

Another example is that fresh pineapple and cider vinegar smell similar, to my nose. I feel certain they also share some volatile compound in common.

Am I just too imaginative, or am I on to something, here? Anyone know in specific what these smells have in common?
posted by gilrain to Science & Nature (20 answers total) 5 users marked this as a favorite
 
Rose smell is from rose oxide, geraniol, and phenethyl alcohol, while skunk smell is generally from thiols. They don't really have much in common, I think, but I am not a chemist.
posted by zsazsa at 11:39 AM on September 16, 2010


I'm not a chemist but I've been reading about this kind of thing a lot lately.

You're not imagining it! I recommend this recent book The Secret of Scent. Author Luca Turin (here he is on TED) breaks down scent chemistry for the reader in fairly simple terms. For me, one of the upshots is that there are no smell-alikes in nature. The same compounds always cause the same aromas. It's possible for things to smell close to one another, or to create scent illusions where a set of compounds combines and sort of evokes or mimics another compound, but it can never be exactly alike - because the only thing that would smell exactly like a given smell is the molecule responsible for it. And so if you smell something, a molecule in the aroma is causing it. If you notice a similarity, some similarity is really there - even if, culturally, people perceive the two things as pleasant or unpleasant.

With skunks, you smell a lot of mercaptan. That's also the category of molecules added to natural gas to give it a noticeable smell so you don't blow yourself up. Mercaptans can be associated with nice smells, like in fruit - I can't find it cited as an aroma in the scent of roses, but I've only just started looking around. This study says that men surveyed found mercaptan to be more pleasant than women did.

In any case, skunk doesn't just smell like mercaptan and rose doesn't just smell of mature rose petals. Both are combinations of compounds, so you are smelling something more complex than a single compound. And roses smell different based on their variety - some really are spicy, some are musky, some are fruity, some are floral, some are green. So there's lots of room to say that there's probably some resonance - either a shared molecule, or some similarity in the smell effects of combined molecules - between skunks and roses.

posted by Miko at 11:46 AM on September 16, 2010 [8 favorites]


Oops, The Secret of Scent. Not just about smell chemistry, it's also a fascinating glimpse into the extremely arcane fragrance industry.
posted by Miko at 11:48 AM on September 16, 2010 [3 favorites]


In the case of pineapples and cider vinegar, you are probably smelling esters. The cider vinegar probably retains some of the esters from the apples themselves.

I can sort of see the skunk vs. rose thing, and generally I agree with Miko that's probably a case of one chemical in there amongst dozens or hundreds of other chemicals that is the same or similar between the two.
posted by cabingirl at 11:52 AM on September 16, 2010


I don't actually agree with you at all, but certain types of rose oils definitely have a real acrid note to them that I can imagine your brain might equate with skunk smell. But ultimately I think it is your brain making that association, and that it has nothing whatsoever to do with the chemical makeup of these fragrances. Brains are weird, and they respond to fragrances in curiously subjective ways.

Part of the reason so many people disagree with you (besides the fact that it is mostly in your head) is that they may immediately think of the sweeter rose variations that don't share this quality, making it even harder to make this leap. If you were both there smelling and comparing samples together, you might reach an understanding.
posted by hermitosis at 12:13 PM on September 16, 2010


Brains are weird, and they respond to fragrances in curiously subjective ways.

The science-of-scent guys actually assert that this folk wisdom is not true - the sense of smell is very exact. The associations we have with scents may not agree, but the scents themselves should be detectable to everyone. As Turin says in that TED talk, that's the whole basis for the fragrance industry. For instance, if pine-scented room freshener only smelled like pine to some people, and smelled like moldy socks to others, there wouldn't be much market for it.
posted by Miko at 12:19 PM on September 16, 2010 [1 favorite]


How We Perceive a Smell
posted by Miko at 12:19 PM on September 16, 2010


I know that I should stay out of these science ask-mes (ugh), but an info for pple who may go to the literature.

There is a difference in perception at the level of the receptors/neurons, not necessarily the chemical property of the odorant for at least some of these things. As humans, there are a lot receptors that just don't function and detect odorants and variabilities between people.

Here is a great example (don't have time to find the peer reviewed article but it was published in Nature:

The same odorant from sweat smells pleasant to 1/3 of the study participants (sweet, like vanilla), putrid to the other 1/3rd, and is not detected by the other 1/3rd.
posted by Wolfster at 12:33 PM on September 16, 2010 [1 favorite]


I don't have a scientific response to your query, but know you're not alone. I've always found shit (human and animal), old leaky nasty garbage, skunk, roses, and chocolate to have vague olfactory overlap; there have been times cleaning my cats' litterboxes makes me nearly ill because it smells too sickly sweet like roses and chocolate in particular. And as anecdata, my friends who have endured durian describe it as if rotting onion, roses, and garbage all mixed together. I also think skunk smells vaguely like Chinese food if you let it linger--a cat I had growing up got skunked once and despite millions of special baths for about a month she smelled to me like Chinese food.
posted by ifjuly at 12:47 PM on September 16, 2010


I've always found shit (human and animal), old leaky nasty garbage, skunk, roses, and chocolate to have vague olfactory overlap

Indole makes stuff smell like shit (literally), but in lower concentrations it's nicely floral.
posted by soma lkzx at 1:07 PM on September 16, 2010


@ifjuly To me, skunk smells a lot like sesame oil. Granted, not in the pleasant way that sesame oil smells, and much much stronger. But there is definitely a similarity between the 2 for me. Maybe this is where the Chinese food smell comes from?

And, slightly more related to the OP's question, no one I've asked has ever shared my opinion that skunk = sesame oil. So even if your roses/skunk association is idiosyncratic, at least you know you're not the only weird one out there. ;)
posted by miss_kitty_fantastico at 1:11 PM on September 16, 2010 [1 favorite]


So strange. I think skunk smells like pistachios. No one I've pointed this out to agrees with me. I always get a little hungry when I smell a skunk.
posted by The Light Fantastic at 1:36 PM on September 16, 2010


Hm, looks like there may not be a definitive answer, and the triumphant I Am Right! party I was going to throw for my friends will have to wait.

However, a lot of interesting links have been posted, and I appreciate the other observations and experiences, too. Thanks all!
posted by gilrain at 1:38 PM on September 16, 2010


I think rather than a biological cause for this, it is more that you have an association that causes this reaction. Something from your formative years somehow linked the two and that's almost impossible to undo. Scent memory is a powerful thing!
posted by Eicats at 1:42 PM on September 16, 2010


Here is a great example (don't have time to find the peer reviewed article but it was published in Nature:

The same odorant from sweat smells pleasant to 1/3 of the study participants (sweet, like vanilla), putrid to the other 1/3rd, and is not detected by the other 1/3rd.
posted by Wolfster An hour ago [+]


But how do we know this is really at the receptor level? "Pleasant" and "putrid" are really associative, are they not? Do these people actually disagree that they are smelling the same aroma, or just disagree as to it how it strikes them? I could smell a jar of vanilla and say it smells like whiskey, and someone else could say it smells like flowers, but are we not in agreement that it's the same substance? Couldn't we identify it again out of a lineup, regardless of our interpretation?
posted by Miko at 2:01 PM on September 16, 2010


The jar of vanilla smelling like whiskey would probably be because of the alcohol. But is that really the smell, or the feeling of the alcohol in the nose?

I'm sure every smell smells the same, molecularly. But our nose receptors aren't all the same. Example: I am highly sensitive in the "rancid" smell and taste area. So it overpowers most other smells in a sample. (Usually olive oil and corn chips. And I bet that's why I think cilantro tastes like vomit.)

Another example: clearly, someone likes the taste of banana popcicles, and thinks they taste like bananas. I think the smell and taste like dumpster juice. But I love bananas. So there is some component in the artificial banana smell that I am overly sensitive to and it crosses my circuits.

As for skunk smell, I think it smells sort of like coffee.

Finally, mercaptan is not a single substance. It is a family of sulfur-based smells.
posted by gjc at 4:15 PM on September 16, 2010


The skunk's name in Bambi was Flower. I think there's a connection.

But I do know what you are talking about. I detect the similarity as well. Some people don't mind the smell of skunk. I wonder if more of these people would find a similarity to a rose smell than those who don't like the smell of skunk.
posted by SpacemanStix at 4:55 PM on September 16, 2010


Some people don't mind the smell of skunk. I wonder if more of these people would find a similarity to a rose smell than those who don't like the smell of skunk.

I don't mind it, but I don't think skunks and roses smell alike, and I've had both in my backyard. To me there is a bitter, somewhat rotten, green component that can be present in each. That doesn't mean they smell alike though, any more than the bitterness in coffee makes it taste like endive.
posted by oneirodynia at 5:46 PM on September 16, 2010


Finally, mercaptan is not a single substance. It is a family of sulfur-based smells.

That's true, and my link discusses that and lists some of the kinds. They are all pungent and share some similarities.

I'm sure some people's receptors are more sensitive than others. But the point I'm making is that they are all able to repeatedly identify the same smell as the same smell, regardless of how clearly they pick up on it or with what emotional response they interpret it. In that sense, smell isn't subjective at all. How we feel about smells might be subjective, but our ability to identify them is generally, across humans, really consistent.

Your point that one person might be smelling more X compound in a complex chemical while one smells more Y compound may be true. Still, my argument is that you can both still presumably identify the source of the smell, and identify the same source, indicating that you are able to identify the characteristics of that scent. You don't disagree that the smell is originating from banana popsicle. If someone held the scent up under your nose on a paper card, you'd presumably be able to say "smells like those nasty banana popsicles" while your friend would say "mmm, smells like cold ripe bananas in those delicious popsicles."
posted by Miko at 8:02 PM on September 16, 2010


Very interesting. I've always found the smell of skunk to resonate strongly with that of ganja, and I know I'm not alone on that one. After a little wikipedia research, I'm thinking that somehow the "rubber" part of the skunk's smell may have a compound in common with burning leaves?
posted by aarwenn at 10:16 AM on October 19, 2010


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