Why are we so sensitive to bodily odors?

[moe darklight]

This is something I've always asked myself: why do we find our own natural scent as a species so repulsive? I mean, think of all the completely unnatural hygienic routines we have to undergo each and every day just to not offend other people with our various odors.

It seems like there is a logic to why things usually smell "bad":
- a rotten apple smells bad to us, because it would cause us to be ill, so finding that apple's smell repulsive is a helpful trait we've evolved
- poo smells bad, because it also poses various health risks, and it's helpful to feel the need to stay as far away from it as possible (flies have evolved to find that same smell attractive)

So, I can understand why the smell of extreme filth on a human would be unattractive: rotten teeth, extreme body odor, etc. would all indicate poor health (possible infection, disease, or unwanted traits for offspring); but it seems to me we have evolved to be irrationally sensitive to bodily odors—

For example, if I were to meet a girl that just went a week without showering and brushing her teeth, even though there is nothing technically wrong with her and logically I should find her just as appealing (ie: neglecting one's hygiene for a few days is not likely to pose a health threat... hell, even doing so for a month wouldn't; we've survived as a species for thousands of years of not showering and brushing our teeth every day*), I would still find her completely unattractive, even repulsive; even if she was incredibly attractive physically, my repulsion to the odor of someone who has neglected their hygiene for just a week (ie: the natural odor of a member of my own species) would overpower any other attractive qualities she may have.

I'm not even sure if this qualifies as a question. Maybe it's just a general observation.

* did people in the middle ages open-mouth kiss? because they never brushed their teeth then. gross.

 

[Math Is Hard]

For example, if I were to meet a girl that just went a week without showering and brushing her teeth, even though there is nothing technically wrong with her and logically I should find her just as appealing (ie: neglecting one's hygiene for a few days is not likely to pose a health threat... hell, even doing so for a month wouldn't; we've survived as a species for thousands of years of not showering and brushing our teeth every day*), I would still find her completely unattractive, even repulsive; even if she was incredibly attractive physically, my repulsion to the odor of someone who has neglected their hygiene for just a week (ie: the natural odor of a member of my own species) would overpower any other attractive qualities she may have. [/SIZE]

I think this depends on the situation. If you were dropped into the middle of a Survivor episode, and met her as a cast member, there would be explanatory reasons for the dirtiness, and you might be forgiving. On the other hand, if you met her in a normal social situation, the dirtiness might give you some general information about her undesirable habits or even her mental stability (since this is a big violation of social norms), and cause you to shy away.

 

[moe darklight]

Yea in the survivor case I would understand it rationally, but it still wouldn't help much in masking the smell, and therefore I would still find her unattractive at that moment. I mean, it seems like our brains are pretty much hard-wired to find such smells repulsive.

 

[Ouabache]

...it seems like our brains are pretty much hard-wired to find such smells repulsive.

Perhaps this falls better under sociology or neurosciences. I am thinking it is how we interpret this information. In older civilizations (European civilizations pre- and during middle ages, or aboriginal cultures; do we know how they perceived attractiveness/repulsion based on smell?

We ought to consider the notion of pheramones as a component of body chemistry. In my experience, I've found body chemistry to override any pungent unwashed smell or sweat of a mate. My lady tells me, clothes that have my smell on it, are comforting when I have to be away for extended periods of time. You might also google a string like "smell, odour, attraction, repulsion", there are other forums where folks have shared their experiences. Here is a related study regarding armpit odour: (reference)

 

[RetardedBastard]

At least for me, it depends on who the person that smeels bad is as to weather or not I'll find find the smell attractive. I mean, if the person who reeks of sweat is a woman I'm attracted to, then I don't care if she just finished running the marathon, I'd be quite turned on by all her sweat. (sorry, just being honest). Anyone else on ther other hand, I'd be quite repulsed under most social circumstances.

 

[Moonbear]

Yea in the survivor case I would understand it rationally, but it still wouldn't help much in masking the smell, and therefore I would still find her unattractive at that moment. I mean, it seems like our brains are pretty much hard-wired to find such smells repulsive.

Actually, I don't think we're hard-wired to find those odors repulsive. An interesting thing about the sense of smell is that our perceptions of odors varies with context. The exact same chemical odorant can smell like vomit in one context and fresh buttered popcorn in another context. We've been raised to find body odor repulsive when we smell it as a sign of uncleanliness (lack of fitness...someone who is perhaps lazy or prone to spreading germs). But, if nobody around us ever showered, we'd likely simply become accustomed to the odor and not even notice it, or might only notice the more subtle variations that are cues to attractiveness or unattractiveness.

As an example that might be more accessible, when most people walk onto a farm for the first time, they wrinkle up their nose at the smell of the animals and their waste. But, if you work on the farm all the time, you really stop noticing that at all. Or, I've even driven past a farm and gotten a whiff of the air and thought, "Mmm, fresh silage," while everyone else was noticing, "Eww, stinky cow manure." I'm quite accustomed to being on farms around cow manure, so unless they've just spread copious amounts out on a field as fertilizer, where nobody can help but notice it, I don't really notice that, but notice the other odors instead...I notice silage because I don't smell it as often...the cattle next to me graze on grass pasture and hay.

I've also noticed that if a man is very attractive to me, and has just come in from working hard and is all sweaty, his odor doesn't bother me. I don't find it actually pleasant, but more of a neutral, as in it isn't repulsive, it's just like coming in smelling like engine grease if he's working on a car, or grass clippings if he was mowing the yard, just odors you can identify, but aren't really attractive or repulsive.

 

[Dale]

This is an interesting question. I think some of this is a social or cultural question. I have definitely noticed that some cultures have different standards of body odor acceptability than mine. But I think all cultures have some standard. It might be useful to figure out the common threads underlying the various cultural standards. Then you could study the "biological" and "cultural" components somewhat separately.

I could see all sorts of evolutionary reasons that violating such a norm, either the cultural or biological side, should make a prospective mate less desirable.

 

[moe darklight]

Maybe it would make an interesting study: how do the brains of people from different cultures/environments react to the same smells, and how a person's brain reacts to conditioning to an odor he finds offensive.

Maybe the thread does belong in brain sciences. I was thinking about this more from an evolution standpoint, assuming we've evolved to find such smells offensive, but didn't consider the possibility that we're not hard wired that way.

 

[bioquest]

Some people lose their sense of smell (So they don't smell their clothes, themselves, etc) due to allergies and I guess things like poisioning, etc. and I've heard losing the sense of smell can be the first sign of a brain tumor or some people can have a really diminished sense of smell. Also in an attempt to smell good people can use scents that are overpowering and as a result smell bad. And you may just have a really sensitive nose so scents that don't smell overpowering to other people can smell overpowering to you. which is bad because overpowering scents=bad smell. I don't have much of a sense of smell so I just try to shower lots and get my boyfriend/mom etc to smell my clothes and stuff like that. I'm both happy and unhappy I've pretty much completely lost my sense of smell. I'm getting checked for a brain tumor just because my sense of smell is so completely gone and that's probably one of the first signs of a brain tumor? but maybe its just gone because of years of allergies and stuffed up noses it's probably possible to re-train your sense of smell though? which is kind of what I want to do.

I don't think we would dislike the smell of each other if we all showered and wore clean clothes and non-overpowering scents

 

[binzing]

Ive never, even at the end of a PE class, noticed BO on a girl.

 

[bioquest]

I use a ton of unscented deoderant/anti-persperant and stuff like that maybe girls pay more attention to that stuff than guys do. I think they do

 

[binzing]

Yeah of course they do, but I'm saying before even going back to locker rooms.

 

[JonMoulton]

Unpleasant body odors usually are bacterial products. We sweat, the bugs feed, their metabolic products don't smell good. Fresh sweat doesn't smell so bad; it's the bacterial metabolites that reek.

 

[mgb_phys]

It's a cultural thing.
Consider Napoleon's plea to Josephine, "Home In Three Days. Don't Wash,". Compared to modern America's obsession with selling you anti-perspirants and deoderants. The ads even show you someone doing a strenous workout in a gym but first covering himself in anti-perspirant!

 

[DaveC426913]

Body odour did not used to be repellant, but in recent centuries the split between well-off and destitute has widened. Body odour is now associated with lack of success.

What I find ironic is that, in modern times, a well-tanned body is now desirable, whereas in recent centuries, a well-tanned body was associated with manual, outdoor labour. It was the pasty-milky complexion that was desirable because those who were well-off did not have to work outdoors to make a living. (Aristocrats used to actually bathe in vinegar to heighten the palour of their complexion.)

 

[mgb_phys]

And fat used to be glamorous, skinny meant poor and destitute.

 

[moe darklight]

I guess it is more cultural than I thought.

Call me a snob then, but I like my girls showered .

 

[Danger]

It's a cultural thing.
Consider Napoleon's plea to Josephine, "Home In Three Days. Don't Wash,".

Yup. And medieval women would rub a handkerchief, or frequently an apple, in their pits and present it to a knight heading off to war. Whatever the rest of the odour, there are pheromones present.

And was it Ogden Nash, or Bertrand Russell, or (who the hell was it?). Anyhow, one of those famous literary types was at a social gathering and some society ***** told him, 'You smell.' He calmly responded, 'No, Madam, you smell; I stink.'

 

[Ouabache]

I have a sense of Déjà Vu about this thread.. Actually, we covered similar ground in a couple of earlier threads. this one titled No shower month, began on May 2005. Several comments on the current thread were expressed on 3 yrs ago on 'No shower' thread.. Then there was a thread about Armpit Odor beginning Sept 2004.

 

[moe darklight]

two weeks?? the longest I've gone is a day. both times we had plumbing problems at home and the water wasn't working, and both times I called in sick to school and work. There's NO way I'd leave the house without a shower.

Yup. And medieval women would rub a handkerchief, or frequently an apple, in their pits and present it to a knight heading off to war. Whatever the rest of the odour, there are pheromones present.

ewwwwww, please don't tell me they ate that apple! why an apple?? who wants a sweaty apple that smells like an armpit?

I'm so glad I live in the 21st century.

 

[lrwells]

Even if a woman finds a man's strong body odor after a hard workout or a hard day at work to be offensive it's proven that, biologically, many women will actually begin ovulation in response to that same odor. In the middle ages, a man who was entering a dangerous competition, like jousting, would put a linen or silk hankerchief under his armpit and then offer this "personalized" love token to the lady he wished to impress. (sound familiar?) This was considered as romantic to a woman then as a sweet smelling bouquet of roses is today. Likewise, even if a woman has a strong vaginal odor due to lack of bathing (not infection,) it's been proven that men will often still react to that odor with an erection. I think, in recent culture, the propoganda and subsequent popularity for stringent hygene to prevent disease has just changed our social view of body odor, not our biological reaction to it.

 

[Pythagorean]

I'm convinced I have pheromones.

 

[Evo]

In the middle ages, a man who was entering a dangerous competition, like jousting, would put a linen or silk hankerchief under his armpit and then offer this "personalized" love token to the lady he wished to impress.

No, actually the woman would give him her scarf to wear.

 

[pgardn]

On another note it appears in humans that the neurons associated with olfactory sensations regenerate quicker than any other in the brain.

But alas this does not explain the strange chicken soup odor my brother used to give off after a nervous sweat... Bizarre... And his feet, good God, toe cheese maximus. Serious fermentation going on in those tennis shoes.

 

[Math Is Hard]

My cat loves stinky feet.

 

[Ouabache]

My cat loves stinky feet.

Does your kitty open its mouth slightly, after a http://www.youtube.com/watch?v=Q32E883EQyc"?

 

[lisab]

Does your kitty open its mouth slightly, after a http://www.youtube.com/watch?v=Q32E883EQyc"?

I've seen my cat do that after grooming her, um, hindquarters . Fortunately I knew what it meant, otherwise I'd be perplexed. Seeing a cat do that is a mixture of bizarre and hilarious.

 

[DaveC426913]

They do this to bring the odor receptors in the roofs of their mouths to bear.

Humans have them too. Certain odors (such as perfumes) can surprisingly, be smelled in the roof of your mouth.

 

[Ouabache]

Fortunately I knew what it meant, otherwise I'd be perplexed. Seeing a cat do that is a mixture of bizarre and hilarious.

I have had cats do this and I had the same reaction you did.

They do this to bring the odor receptors in the roofs of their mouths to bear.

Are we hinting at the http://en.wikipedia.org/wiki/Flehmen_response" response.
I am not surprised we have a similar response. Here's another http://www.youtube.com/watch?v=n1Z6Nz8FuPc" with the Flehmen response.

 

[Math Is Hard]

I actually haven't seen her do a Flehmen response in a number of years. She's a very old cat (17) and I wonder if her vomeronasal sensing has gone downhill in her old age.

 

[chemisttree]

Perhaps it's because old cats don't have much to smile about.

 

[DaveC426913]

Perhaps it's because old cats don't have much to smell about.

Corrected.

 

[lilythmagebor]

Unpleasant body odors usually are bacterial products. We sweat, the bugs feed, their metabolic products don't smell good. Fresh sweat doesn't smell so bad; it's the bacterial metabolites that reek.

Correct. This is the response that better answers the question. Your body doesn't by itself stink. It's the bacteria that flock to the moisture on your body that stinks. And because many bacteria are not kind to us, we have an adverse response to this. The fact that people used to go months without bathing and it did not stop them from social and sexual activity may mean that we only now have so many [smelly] bacteria. Sweat that has just come off of you and has not yet had contact with the smelly bacteria has no noticeable smell.
As far as feces and flatulence smelling, this is primarily due to what we eat. I imagine things you eat which cause an excessive amount of methane byproduct will give you smellier farts, because methane by itself stinks.

 

[Ouabache]

methane by itself stinks.

Actually http://scifun.chem.wisc.edu/chemweek/methane/methane.html" is an odourless gas. Perhaps you are thinking of natural
gas of which methane is a large component. In that case a sulphurous
component (e.g. http://en.wikipedia.org/wiki/Methanethiol" ) is added, which gives its characteristic scent.

 

[chemisttree]

Don't forget 3-methylindole, AKA skatole. That's the pure stuff.