<ohh/ew> that smells really <good/bad>

I was weeding next to a patch of lilies of the valley a few weeks ago and paused to appreciate the beautiful scent of the flowers. Which got me to thinking – is the characterization of scents as good or bad always learned, or are some innate?

Clearly, some are learned. I know several people who love the scent of a new car. That’s gotta be because the scent is associated with the excitement of getting a new car, right? And most would say feces smell bad, but since little kids will sometimes use them as an art medium, the yuck factor must be partially learned.

I was thinking that scents like baking bread or roasting meats are pleasant because of the association with good food, but then it occurred to me that a lot of the sensation of taste is actually smell, so I guess the reverse could be true – fresh-baked bread and hot roasted meat taste good because they smell good.

So, how much of what people categorize as smelling good or smelling bad is learned, and how much is innate? And if it’s all learned, why would those lilies of the valley smell so divine?

The reaction to most smells is innate at least initially. The vast majority of people, even very young children, react the same way to many very strong smells. In particular, almost universal negative reaction to rotting meat or sewage smells is part of a very necessary survival mechanism for example. Artificial smells that partially mimic those types of smells also cause a strong negative reactive (any strong sulfur smell or being downwind of a paper plant for example). On the positive side, many plants ranging from fragrant flowers to fruits have evolved to have an appealing smell to many different species, not just humans. The pleasant smell is an essential part of many plant’s pollination strategy even though people may breed strains that enhance it just for pleasure.

However, the reaction to some strong smells can be the result of individual differences or conditioned. Some people love the smell of certain chemicals ranging from gasoline to plastics. The odd mix of chemical smells that make up the ‘new car smell’ is an example of a smell that is partially innate but mostly conditioned - most people have found memories of getting behind the wheel of a new car and associate the smell with positive things (I love new cars but personally can’t stand the ‘new car’ smell; it gives me a headache).

The sense of smell is the one most closely linked to long-term memory very deeply in the brain. It is very easy for distinct smells to become permanently linked with very evocative memories and emotions. Those could range from a whiff of perfume an old ex used to wear to baking bread that smells like your grandmother used to make.

Smell and taste are closely linked in general but the association isn’t perfect. Some cheeses smell absolutely terrible but taste great as do some other foods like the durian fruit. It may take some effort but you can delink smells from tastes in your brain if you try enough times in cases where it is worth it. I don’t think anyone can smell raw sewage enough under any conditions and ever make it pleasant or even neutral.

Like taste, just how things smell varies among people. I read an article that stated the reason some people have an aversion to cilantro is because they can’t smell a certain chemical in it, and most of what a person tastes is really smell. Paperwhite narcissus are usually characterized as stinky or fragrant, depending on whom you ask.

This could be a fascinating study topic – do kids who make poop art have something in common with each other, the way cilantro haters are united by their sensitivity to a chemical that those of us who can eat raw cilantro as a major salad ingredient simply cannot perceive? Do these kids go on to have healthier immune systems? Increased risk-seeking behavior?

…fewer playdates?

And then you have things like the OP’s example, lily of the valley (Convallaria), which smell wonderful, but it would be a very bad idea to taste them.

Maybe not, but the sense of smell is easily deadened (temporarily) by constant exposure to any strong smell. So while a sanitation worker probably doesn’t find the smell of sewage pleasant, within a few minutes of starting work, he no longer notices that particular smell at all.

Also, the mind can get permanently inured to certain smells.

One of the unwritten requirements to graduate from my college was the ability to ignore the aroma of H[sub]2[/sub]S, as the 2nd-year students spent half of the schoolyear running what we called the “sulphuric cascade”. Do we notice it? Yeah, and it sure shouldn’t be coming from out of our fridges. But so long as it’s coming from an expectable source, we ignore it. For a different profession, I’ve met personnel in hospital labs who had serious problems with the glacial acetic but none with the feces.

I think you’d be able to find people who don’t like lily of the valley fragrance.

I run into these sorts on garden forums - they complain about scents that, even when sweet are “too strong” or “overwhelming” (night jessamine, which to me has a fantastic sweet tropical scent is one of these that turn off certain people).

There are others who declare that they can’t stand the foliage fragrance of many types of sage (they think it smells like cat urine).

The bottom line is that strong scents of any kind tend to trigger negative associations in certain people, whereas I am generally intrigued by and enjoy them (well, excluding a reek of dung and strong chemical odors). My speculation is that a lot of this revulsion is learned as a child from parental dislikes/warnings. If Mommy and Daddy are constantly telling you “Ewww! That’s nasty!”, it’ll sink in that strange/unusual odors (or tastes) are suspect.

Too bad, these people are missing out.

It would make sense for skunk smell to be universally disliked … as the animals use it as a defense mechanism. It would be useless if some predators enjoyed it.

I’ve heard the sage/cat-urine association, before – people say similar things about lantana. I don’t “get” it, myself, for either of those, and since I’m one of those who also doesn’t pick up the soapy nastiness some people dislike about cilantro, I wonder if I’m missing a particular receptor that’s common to both plant compounds.

Anyone know if the compound in sage etc. that’s responsible for the cat pee smell (to some folks) has been identified? I’d be fascinated to know it it’s molecularly similar to the cilantro-soap molecule.

I’m pretty much inured to H2S, as a result of performing sulfide staining tests at a previous job. A couple of smells that you cannot ever get used to are isovaleric acid & butyric acid. We used them in a particular type of synthetic perspiration solution (to test whether plastic parts would be stained by sweat), and the smell was just unbearable. Imagine a locker room. The smelliest, dirtiest, skankiest one you’ve ever even heard of. Now imagine that all off that funk has been concentrated into a little bottle. That’s what this stuff smelled like :eek:

At the other end of the scale, I don’t think I can smell roses. I’ve always heard people say they smell pretty, but when I try to smell one I get nothing. I can smell other flowers, but not roses.

Current commercial roses have been bred mostly for appearance rather than smell – that’s what sells them in the florist shop (even more so on the florists’ website).

Reactions to odors are certainly not universal. I find the aromas of most non-citrus fruits, peaches in particular, repulsive almost to the point of nausea. Yet I see fruit-scented soaps and shampoos and perfumes marketed everywhere, so I must concluded that I’m the unusual one.

I’m thinking that if you were 15 and having your first sexual encounter with a fantastically attractive partner while surrounded by Amorphophallus titanum, you’d probably have some serious kinks about that smell later in life.

Not to out myself as a weirdo, but I rather enjoy the scent of skunks.

Interesting. I have an aversion for cilantro (and in the process of verifying cilantro was what I thought it was : coriandre in French, I found there was a dedicated website for us Colantro haters).

Or a future in forensics.

If the only roses you have smelled are from florists, it’s understandable. Most of them have nearly no scent compared to ones people grow in their rose gardens.

Well, compared to the non-hybrid-teas people grow in their rose gardens. The hybrid tea rose is the crux of the case of the stolen scent. Old-fashioned varieties are generally aromatically strong.