Hacker News new | past | comments | ask | show | jobs | submit login
Do older people have a different smell? (nytimes.com)
50 points by bookofjoe 7 days ago | hide | past | web | favorite | 67 comments

Babies smell.

My friend, undergoing radiation therapy for cancer, had a distinct smell. As have those treated with specific chemotherapies.

Athletes smell. Indoor and outdoor athletes differently. Pool swimmers of chlorine, open-water swimmers of the sea.

Parkinsons and Alzheimers appear to have distinctive smells.

Diabetes is characterised for its distinct smell (and taste).

We are chemically-regulated, processing, producing, and (to an extent) signalling systems. The notion that there are associated perceptible scents is exceedingly probable.

Another aspect of older people (and again: Parkinsons and Alzheimers in particular) is a loss of the sense of smell. Which may mean that odors otherwise noticeable and addressed aren't.

> Another aspect of older people (and again: Parkinsons and Alzheimers in particular) is a loss of the sense of smell. Which may mean that odors otherwise noticeable and addressed aren't.

I highly suspect you hit the nail on the head here from personal experience: My grandma no longer has any sense of smell (or taste, actually) at all. I recall at one point discovering a particularly pungent smell was caused actually by a cleaning solution, I think it was like an old can of Lysol that had no substance designed to improve it's scent, that of course, she wasn't aware smelled worse than death.

My biggest fear was things such as her potentially not noticing a natural gas leak, because the default indicator depends on a sense of smell. (I found out you can buy "explosive gas detectors", which are different than carbon monoxide detectors, if you want an audible alert for this.)

I've directly encountered the gas-hob-on-but-unlit scenario myself with someone whose sense of smell is virtually completely gone, and it terrifies me.

(How far gone? They are unable to distinguish, or detect, the sents of various Dr. Bronners soaps, directly before them.)

And mercaptan[1] (the oderising component in municipal natural gas) is among the most detectable scents in existence. The reasons why it was introduced[2] and its alternate uses[3] are worthwhile reads. As I've noted elsewhere, virtually all safety regulations are written in blood, this one the 295+ souls claimed at New London.



1. https://en.wikipedia.org/wiki/Methanethiol

2. https://en.wikipedia.org/wiki/New_London_School_explosion

3. http://zacon.ca/stench-gas/

It seems methanethiol is not the odorising component in natural gas. Methanethiol, CH_4S, is a putrid gas found in smelly cheese, poo, bad breath etc. "Most gas odorants utilized currently contain mixtures of mercaptans and sulfides, with t-butyl mercaptan as the main odor constituent in natural gas"[0]

T-butyl mercaptan (tert-butylthiol) is (CH_3)_3CSH.

[0] https://en.wikipedia.org/wiki/Tert-Butylthiol

I was indicating mercaptan, specifically. I thought the Methanethiol page was the relevant one at Wikipeida for it, though "mercaptan" itself redirects to "Thiol" (https://en.wikipedia.org/wiki/Thiol).

I'm a shitty chemist.

The broader point was about smells, sensitivity, oderising alarms, and a bit of safety history.

> and it terrifies me

You can get natural gas alarms cheaply e.g. on Amazon. Since natural gas is lighter than air, they should be mounted above the hob area.

You know how horrible 2-part epoxy smells? She can't smell it an inch from her nose. I mean zero sense of smell.

I can relate. And yes, it's terrifying.

The more so because the condition is quite often coincident with a tremendous state of denial. Anosognosia:


https://opinionator.blogs.nytimes.com/2010/06/20/the-anosogn... (part 1 of a 5-part series)

You seem to have a comma in your link. Fixed: https://en.wikipedia.org/wiki/Anosognosia

Backpacking can cause an ammonia type smell from burning fat and muscle breakdown. It's a smell similar to the smell from homeless people that I always just assumed was because both backpackers and homeless bathe less often than others, but that is just a coincidence of both group's bodies breaking down muscle from not enough of protein/carbs/nutrients.

I believe what you're referring to is called "keto breath" in the keto-diet community. It's due to acetone, which is one of the ketones produced while in a state of ketosis / fasting.

The author of "Where's the Next Shelter?" (Appalachian Trail through-hike memoir) talks about this condition. He had to get protein into his supplies ASAP to prevent further muscle loss.

Great book, and he narrates the audio version himself which made it really feel like he was sharing his story with me personally. He’s a Marine Corps vet and software engineer. I’d love to buy him a beer some day.

Same here. He made my commutes awesome for a few weeks.

Swimming seems a special case because that's a clearly foreign substance attached to the body.

More interesting are cases where the lifestyle causes smellable long-term changes to body chemistry that can't be cleaned off.

Immersing yourself in chlorine for large stretches of time probably messes with your skin's biome, though I agree probably not to the extent that the change alone would produce a discernible smell.

>though I agree probably not to the extent that the change alone would produce a discernible smell.

If you do it often (e.g. swim professionally), why not?

That's a plausible component. The chlorine also dries out the dermis, which may change its scent.

Remove modern chemicals (detergents, perfumes) from the equation, and lots/most of what we call “body smell” would be VOCs, the composition of which depends on nutrition and microbiome among other things. So I find the concept of age/culture/lifestyle related smell very plausible.

But these things are not easy to research as reliable VOC detection requires lab setup (GC-MS)

True, though the odor persists for days.

Technically, althlete odors generally are foreign substances / interactions, at least in part.

Also Hepatitus-C. My great uncle during WWII would identify which soldiers were infected based on smell. He was right in every case.

I have diabetes, what do I smell like?

Roughly: rotten apples.

(Not sure if you spoil the barrel or not though.)

It’s a bit harsh to say rotten apples. In my view the smell is subtly saccharine and reminiscent of fermentation,... with maybe a hint of applesauce.

I wonder if part of the answer is different habits with respect to perfumes, soaps, and also in how homes are furnished, decorated, maintained and what products are used (cleaning, detergent). And smoking, too.

I could tell a friend had just left their home from the odor when they lived at a particular place¹, and sometimes, I can tell if some item of clothing has been left at some place (not that I'm special at that).

The odor the author of the article could smell at her place after renting it for a month could have been a (mix of) perfume(s) their guests used.

Obviously, people have their own odor on top of (or under, more accurately?) that.

¹ in a forest ­-- no, I'm joking.

As someone that sees smells (synesthesia), the answer is yes. The reason I presume is simple, hormone levels change as you age and thus you smell different.

It really isn't simple. Humans are host to multiple microbial biomes. Why is not understood, but younger people are more biologically active. Hormones are certainly involved, but with smells the bacteria and yeasts living on the skin and in the lungs contribute the most to odor.

How did you notice you were seeing smells (and not everybody is)?

Synesthesia is very hard to explain. It's like explaining color to the blind.

I have mild synesthesia myself - I hear flavors. I can say "I hear flavors", but that doesn't help to tell you what different flavors sound like, because sounds themselves are very hard to describe in words.

The best way to experience something like synesthesia is under the influence of LSD or similar drugs. Not that I recommend it, but it does work. "When colors taste like music" is my favorite description ever.

Do noises prevent you from fully tasting food? (sorry if these questions are boring to you)

I asked this question in my previous comment because I've read about people having synesthesia discovering quite late that no, to most people, smells or figures don't have any specific color or character (depending on the involved senses), during a conversation in which they take for granted that their interlocutor experiences it too.

My father himself kind of realized that contrary to many people, he sees months of the year as a ring, when I spoke about synesthesia, and said that some people having synesthesia may see numbers or years in a specific shape, that does not change across their whole life (and, indeed, he confirmed this point about him).

My wife has fairly classic synesthesia, with letters and numbers having colours and "character" etc. I don't have that, but I do have exactly what you described with numbers, months of the year, and years having an unchanging position in a mental 3-d model. The model for each of these is a bit different, but each could be described as a kind of winding road.

So I wouldn't say I'm synesthetic, but at the same time I can't really point to a clear difference between how my mind associates numbers with locations in a spatial structure, and how my wife's mind associates them with colours.

I also can't really say how those associations are different from the kinds of associations that the mind seems to make to anchor new experiences and information into memory. I'm not explaining that very well, but overall I half think synesthesia seems more like just an atypical manifestation of a probably universal human trait, and less like a rare oddity.

I also have some representation for numbers and for the days of the week, but it would not be 3D, more like 2D, and kind of dynamic, too: the view is relative to the “focused” number / day. Same thing as you, the representations are different for numbers, days of the week and months. The days are horizontal, and months too. Numbers, not so much. Kind of horizontal up to ten, and then vertical up to twenty, and then I would not know how to describe it. There is a kind of break for each tens up to one hundred, with numbers being mostly horizontal but not quiet, and each teen somewhat higher than the previous one. Negatives have the exact same place as there opposite. Days of the months are the same as numbers. Anyway, describing this is kind of pointless. This representation does not feel very precise.

These representations are the same since as far as I can remember. I know that some people I discussed with don't think they have such a representation for numbers or dates. It seems to correspond to the description given in [1].

I think it may have an impact on my memory, at least for dates (but nothing extraordinary). It's usually easy to remember meetings and events in the year, because they somewhat appear in the representation, I don't really need a calendar if there are not too much things scheduled (but I note in a log, just in case, and it's not completely reliable too).

You might have calendar synesthesia [2,3], and maybe me too, but maybe weaker than yours or my father's.

And yeah, it's not something we really see, its a representation that automatically comes into the mind without us trying to at all. Right?

Maybe many people actually have some form of synesthesia.

[1] https://en.wikipedia.org/wiki/Synesthesia#Number_form

[2] https://www.thecut.com/2016/11/the-form-of-synesthesia-where...

[3] https://fr.wikipedia.org/wiki/Synesth%C3%A9sie#Synesth%C3%A9...

Translation of [3]:

> Like “numerical synesthesia”, spatio-temporal synesthesia is a mental map of the days of the week and/or months of the year. People having this kind of synesthesia state that they can “see the time” as a ribbon, a ring or a circle for instance. According to some studies, these people would have particular synaptic connections in their brain, allowing them to live time like a spatial construction.

> Like all the forms of synesthesia, “spatio-temporal” also shows a permanent feature: tested months later, someone having synesthesia will report the same experiences they had previously reported.

Calendar synesthesia sounds like a good match with mine, although for me it's very much a "mind's eye" thing, not like an image projected into my visual field. In article 2, the researchers are said to have asked their subject to recite every third month going backwards, apparently to test that it's not just a mind's eye visualization. I get similar speeds as their test subject, and do go through the months in my mental image to help with the task. However, since for me it is a mind's eye visualization, I'm not sure the test as described is very useful.

The Wikipedia article points out that in theory, all logical synesthetic combinations are possible. I suspect that if you tested broadly for any kind of synesthetic experiences, you'd find a significant portion of the population had them, maybe even the majority.

> for me it's very much a "mind's eye" thing, not like an image projected into my visual field

Same for me.

> In article 2, the researchers are said to have asked their subject to recite every third month going backwards, apparently to test that it's not just a mind's eye visualization

I would be terrible at this task. I don't see the whole year (week) at once. This representation would not be of any help for that. It's here when I am scheduling / planning, or when someone is saying / I'm reading a date.

No, sounds don't prevent me from tasting food. But certain types of sounds are severe migraine triggers for me, and my migraines are definitely related to synesthesia and sensory issues. Over the past 20 years or so, my migraines evolved to mostly go after my sense of smell. It's bizarre, trying to explain that a smell can hurt as much as a burn - worse, it happens with smells I normally like.

Sounds that trigger migraines are mostly certain kinds of echoes - the kind from sharp sounds in large, hard rooms like gymnasiums. I can't really be in a gym with people applauding.

For a friend of mine, different music has different colors. Some music has frightening colors. She can't listen to that music.

Which other similar drugs? I haven't ever had that happen under LSD.

Fascinating. Could you describe what some different smells look like to you?

Smells for me are sphere like with usually one color, but occasionally a gradient between two or three. But the big difference is the texture or peaks and valleys on the shape.

Is it overlaid on your visual field, or more of a parallel mental construct?

Also, are there any particularly noteworthy smells in terms of representation?

I have to admit, the idea of a visual artifact for smells is amazing!

It isn't overlaid in my visual field, more like how you imaging or remember things in your head, very hard to describe. I usually don't pay attention but it is just there.

noteworthy? If I concentrate I can follow the trail of someone with a strong sent that had walked by in the last say 10 minutes like a blood hound. I _know_ when fish is labeled incorrectly when I do my weekly grocery shopping. I know when that person from work says they are quitting smoking, but have had a smoke and are lying. Just walking around outside, the amount of death from animals would surprise you.

Very specifically on the visually side I come across a food item that looks slightly different. No one else notices this change in smell but it is a fun game realizing that maybe the recipe changed ever so slightly or something.

Mostly I learned long ago to not talk about it in person because then people get very curious and then get extremely self conscious.

I don't have this in general, but when you were talking about someone who is quitting smoking I just realised that I have a distinct visual impression of the smell when a smoker really needs to have a smoke. It's kind of yellowish and it falls off them and gathers at their feet like a kind of fog.

I'm a super taster for a few things and I suspect that whatever odor that is, I can detect it better than most. Anyway, thanks for your description!

>>It isn't overlaid in my visual field, more like how you imaging or remember things in your head

So to be more exact you can "see" smells with your mind's eye but you do not actually see anything with your physical eyes when smelling something.

haha yeah it isn't like I "see" a purple haze floating over the grass and moving in the wind or anything.

More when I smell the grass I "see" in my mind what that smell looks like (purplish).

I have synesthesia and I 'see' sounds, but see is a misnomer. There is a visual component to audio but it's not a hallucination in my visual field. It's definitely in my mind's eye, but it is consistent which leads me to believe it's more than just imagination. Some sounds are definitely 'purple'.

If scent is of interest to you, I suggest you read Perfume by Patrick Suskind. I couldn't help but notice the distinct smell of everything and everyone after reading this book.

One of those books[1] that are really hard to translate to another medium. The movie tried, but somehow the book can give you a better approximation about the sense of smell.

[1] Another one is the upcoming adaptation of The Colour Out of Space

We read this for my book club. I would never have read it by myself. The historical setting is also interesting.

The Netflix series (six episodes) is quite good.

Penn & Teller: Bullshit Season 8 Episode 8 did an experiment to try to verify this. They couldn't find that people could predict who is old and who isn't via a sniff test.

Unfortunately, that experiment could just as well have been testing people's ability to smell the difference.

Penn & Teller would not have an interesting show if their experiment didn't support the claim they were making.

One thing I remember very distinctly from when I was much, much younger is how my grandfather smelled. A very distinct smell that I always attributed to his heavy tobacco smoking and sweaty manual labor as a master cabinet maker. He died when he was in his sixties, from a heart attack. I was in sixth or seventh grade.

A few years ago, I was astonished when I realized that I could smell that exact same smell again. Only this time, to my horror, I discovered that I was now the source of that exact same precise smell. Only I don’t smoke, and my labor is mostly mental.

It’s not a knock-you-over-with-body-odor smell. You can cover it with deodorant or other perfumery type of application. But it is the baseline smell, minus all additional covering odors.

I finally decided that it must be a combination of genes and aging, since I am now close to the age when I recall that my grandfather smelled like this.

My dog was chased around as a puppy by an old lady with oven mitts.

Now he gets anxious when he smells old people. So from my anecdotal evidence, I think they probably have a distinct smell.

My theory is that the smell is distinct because of pharmaceuticals. A lot of older people are on all sorts of medications. I think a lot of medicines cause the body to give off differing odors. From personal experience, I've noticed my body odor change when on different medicines. And have actually noticed that other elderly people I've been around have a faint chemical odor to them.

I don't know if I'm old, but my wife and I are in our mid-40s and we agree that we smell differently than we used to smell, for instance when we were in our early 20s.

I used to be the 1st person mosquitoes went after, fair-skinned as I am. I had a surgery recently and for several months a few of my blood metrics have lower than normal levels (hemocrit, red cell count, platelet count, etc). Now I watch others slapping at mosquitoes which seem no longer attracted to me. My theory is I don't "smell" as good to the little bloodsuckers.

A lot of older people don't shower or bathe as often as young people because they're worried about slips and falls. I'm surprised that the article didn't consider that.

Two of the three studies defined "old" as people 40 or 41 and older, so frailty might not be a large factor.

(Those two studies had different conclusions. The third study defined "old" as 75 and older, but found the most intense and unpleasant orders in middle-ages males, 45-55, so again, frailty doesn't seem likely to be a significant factor in terms of a strong or bad old smell.)

Edit: also, I kinda doubt your assertion about the bathing habits of older people. I wonder what you base that on?

Never smell anything differently on my grandparents, parents, elderly around me. Maybe it's not a widespread myth?

I started taking probiotics about three months ago and I definitely have a different stink than I used to.

What do old people smell like?


I'm not sure people understood your innocuous joke...I did.

My gran has no nose.

How does she smell?


Well, they certainly smell awful to me. Especially old women. That's a very distinctive smell. I could recognize an old woman without the use of any of my other senses.

Sucks to be you

TBH it does. It seems like I generally have a more sensitive sense of smell than most people. It's annoying, because the result is: a lot more things have a bad smell for me.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact