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What would you do if you had no sense of smell?

The views expressed are those of the author and are not necessarily those of Scientific American.


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A smelly meeting. | Photo by Tom Freidel. CC. Click on image for license and information.

No, really. What would you do? What scents would you miss the most? Freshly laundered sheets? A certain perfume or cologne worn by someone you care about? Mom/dad/Aunt Jane’s meatloaf? The roses in your garden? While I might miss my favorite perfume, I’ll tell you what I wouldn’t miss: subway body odors. But what about if you never had a sense of smell—how would you even know what to miss? And how would your life be different?

The latter questions were the subject of a paper published in the open access journal PLoS One. The ability to smell can undoubtedly be useful. It can warn you of a gas leak or that the milk or meat you’re about to consume is bad. It could tell you that the iron is on or that you’ve stepped in something unpleasant. It entices us to eat—can you resist the savory smells of your favorite meal? Data from the NIH reports that 1%-2% of people in North America have a smell disorder that may range from the reduced ability to detect odors (hyposmia), which can be a temporary result of having a cold, to the inability to detect odors completely (anosmia). (That percentage rises to 15%-20% when global populations are counted.) Isolated congenital anosmia (ICA) occurs when otherwise healthy people are born without a sense of smell. And it’s rare: researchers estimate that 1 in 5,000-10,000 are afflicted (globally). But for those few individuals, how are their lives changed? This was the question that Ilona Croy and colleagues set out to answer:

If the sense of smell is important for ingestive behaviour, environmental hazards and social communication, like described above, how are these domains affected in patients with ICA? Do ICA patients have trouble maintaining their weight or do they obtain no joy in eating, for example? Do they accidentally eat spoiled food? Do they also worry about their body odor? And do they feel different in social situations? Or are people without a sense of smell not affected at all by this deficit and is olfaction just overestimated?

It turns out that these individuals don’t experience significant differences in quality of life. In fact, they often don’t realize that they’re missing anything—and that makes sense: how can you know something is missing if you’ve never had the item to begin with? Often, anosmia is diagnosed when someone close to the person notices a discrepancy in responses to offensive odors, which researchers believe may indicate that smell may not be as crucial to the ways we experience the world.

A survey of individuals with ICA also reveals that there may be other sensitivities to consider (1). For example, individuals with ICA reported a higher incidence of household accidents and a greater degree of social insecurity. The former relates to things like leaving the iron on or drinking spoiled milk. In this case, individuals reported developing coping strategies—”Hey, does this smell okay to you?”—to reduce difficulties. The latter reflects concerns about social relationships. The researchers propose that olfactory cues can provide important—subtle—information about other people that could help guide appropriate social interactions. In the absence of these cues, having ICA may result in hesitation in social settings. However, the authors are careful to note that additional research is needed to confirm both points.

It makes sense to a certain degree: Anything that might impact your ability to function within a social setting might heighten social insecurity, but it might have less to do with olfactory cues from others, and more to do with concerns about self—along the lines of “Does my breath smell?” or “Is my deodorant still working?”. Can you actually smell anxiety? I’m not sure, though you might be able to sense it and read it from body language and in other cues. And if you were in a situation where you could smell the fear on someone else, well, my guess is that you’d already know he was frightened. While pheromones may play a role in mate selection and in influencing behavior, their function in human relations remains somewhat mysterious.

One of the findings from the study is that individuals with ICA report being breast fed as often as controls. The reseachers note that this is somewhat surprising given the importance of smell for infants in locating the nipple. I think perhaps this is less surprising than one might suppose: human mothers can presumably guide their infants to the nipple if needed. Croy and colleagues also note that there does not seem to be noticeable effects on eating behaviors, which they find odd given the link between smell and taste. And while a decrease in appetite is often reported in individuals with hyposmia, the lack of a noticeable effect in eating behaviors in individuals with ICA may be the result of being socialized without a sense of smell. If the individuals and those closest to them are unaware of being different initially, then they’re likely not being treated differently at meal times—and we can’t forget that we just don’t know what the relationship between ICA and taste is.

Ultimately, smell may be less important to daily life activities for humans than for other members of the animal kingdom for whom a sense of smell is tied to daily survival—in part because we belong to social systems that can provide support and help us cope in the face of what might otherwise present a challenge. But this doesn’t mean smell is a dispensable sense.

Notes:
(1). The sample for the survey was small (n=32), but given the rarity of anosmia, this may be suitable for preliminary suggestions.

Reference:
Croy I, Negoias S, Novakova L, Landis BN, & Hummel T (2012). Learning about the Functions of the Olfactory System from People without a Sense of Smell PLoS ONE, 7 (3)

Krystal D'Costa About the Author: Krystal D'Costa is an anthropologist working in digital media in New York City. You can follow AiP on Facebook. Follow on Twitter @krystaldcosta.

The views expressed are those of the author and are not necessarily those of Scientific American.



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  1. 1. sdv 7:18 pm 03/21/2012

    It’s curious that 1-2% of North American population have smell disorders, but 15-20% of global population does. That’s a huge difference. Why is that?

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  2. 2. Krystal D'Costa in reply to Krystal D'Costa 9:54 am 03/22/2012

    It’s a good question, and honestly, not one that I know the answer to. I’ve been thinking about possible social and cultural issues that might prevent smell disorders from being reported—maybe it has to do with the state of healthcare. I don’t have a breakdown by country, but it could be that there are more reported cases in places where healthcare is more accessible to more people than in the US and elsewhere.

    Also, I think there is a wide range of what might constitute a smell disorder. The parameters for this metric aren’t really defined, but if temporary decreased smelling ability is included, it could inflate the percentage.

    Would love to hear other thoughts on this.

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  3. 3. markevalentine 10:28 am 03/22/2012

    Being someone who has never been able to smell, this article caught my eye. Although I never drank spoiled milk, it has ended up in my mouth a few times. The conjecture on social occasions I don’t think is well founded. While very young, not having a sense of smell was not a consideration; I did not even know I could not smell. When older, compensating behaviors were well established and I still don’t consider it. It should also be considered that other senses are more relied upon. I still have taste and I am very sensitive to the texture of food.

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  4. 4. Krystal D'Costa in reply to Krystal D'Costa 10:45 am 03/22/2012

    Mark, thanks for confirming my suspicions about socialization and compensating behaviors. I’m curious: How did you realize you can’t smell? Was it along the lines of the ways described above?

    This study was definitely exploratory and there seems a lot to delve into. The texture of foods isn’t something that they really explored here, but it’s interesting avenue—and could possibly reveal some things about picky eaters.

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  5. 5. wendyxc 11:11 am 03/22/2012

    A friend of mine who has no sense of smell was embarrassed and confused when people literally recoiled from her as she entered a store. It turned out that her dogs had gotten skunked in the backyard the day before and then slept with her. She tells this as a funny story, but it made me realize just how profound her loss is–to sleep with two skunked dogs and not notice is amazing/horrifying.

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  6. 6. Krystal D'Costa in reply to Krystal D'Costa 1:06 pm 03/22/2012

    Wendy, the value of a fence shouldn’t be underestimated!

    That’s a great example a challenge related to not being able to smell. Did someone finally tell her?

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  7. 7. markevalentine 4:12 pm 03/22/2012

    Boy! I can relate to the skunk story! Growing up, I lived in the country. When I was in junior high, I came home, let our dog in the house and played with him; he had a run-in with a skunk during the day. We took tomato juice baths together that night.

    I don’t think there was a specific event that made me realize that I could not do something everyone else could. It was more of a process. When I was very young, I remember people shoving things in my face and asking, “doesn’t it smell wonderful?” I would agree, but not really understand what they were talking about. They would be confused when I had no reaction to bad smelling things, or not react to something they were smelling. By junior high, I understood that I could not smell. However, I would still pretend that I could, just to avoid explanations. Actually, I still do.

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  8. 8. Krystal D'Costa in reply to Krystal D'Costa 9:15 am 03/23/2012

    Mark, thanks again for coming back to the discussion. Your responses have been important in showing how easily we create can create adaptive strategies. I think in some ways it might be easier to cope if you were born without a sense of smell as opposed to losing it due to an accident or an illness. You just sort of went along with what folks were telling you without a sense for what you might be missing—knowing that you’re no longer able to do the things that you once could do creates a larger psychological block to adapting than just sort of rolling with something to avoid explanations.

    I totally get why you’d just agree that you could smell things—and why you’d still do it. It might become a bigger issue for others than it really seems to be for you.

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  9. 9. Soupmaker39 9:25 am 03/25/2012

    I’m 65 and have never had a sense of smell. I, too, pretend I can smell. If you tell people you can’t, they look at you as if you have two heads.

    My mother had the world’s best sense of smell! She was a human bloodhound. She could never understand how she had a kid like me. Back then, we had a gas stove and stove-top drip coffee pots. In my teens and early twenties, I burned up a number of pots. I remember my mother running in…”You burned the coffee pot! How could you do that?” I said, “Oh, I was in the back of the house and didn’t hear it.” She screamed, “HEAR IT? HEAR IT? I could smell it from four doors up the street. Are you serious?”

    I get along by enlisting help sometimes. A smoke alarm went off for no reason during the day, and I asked my neighbor to come and smell my house, in case something was smoldering somewhere. I rely on my husband for things like perfume. In the second-hand clothing store, I ask someone if a garment smells, since apparently some of them do.

    I wish I could smell the pleasurable things like flowers. I ask my husband to describe how some things smell, and if he says something like “smells like curry,” I imagine it smells like curry tastes.

    I guess the gas thing is the most serious. Everybody here has gas heat. I always imagined that’s how I’d die–not notice a leak when I’m alone and either asphyxiate or blow myself up. Now my husband’s retired, so I usually have a good nose on site.

    I’m happy to hear that this condition has a name. I’ve only met one other person who can’t smell, and I was glad to meet him. It’s so rare, apparently–one feels like the only one who has it.

    Kitty

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  10. 10. ssmro 1:15 pm 03/25/2012

    I am 57 and have never had a sense of smell. I have never discussed this to a doctor, so it may not be reported often. This is probably because like mentioned before, it was a very gradual realization, I didn’t miss something I never had. The first clue I had was in Junior High when a teacher was doing an experiment to see if we could guess what we were eating with our eyes covered. I could not tell the difference between an apple and a pear. I didn’t think much about it at the time, so it was many years later when I realized I had no sense of smell. It was just hearing people talk about what they smelled and realizing that I didn’t, not even a skunk. It has not affected my eating, except that now I do look at milk carefully. I don’t think it affected anything I did, because I didn’t know I was missing something. I used to think people were just exaggerating about what they smelled sometimes.

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  11. 11. FordExec 4:40 pm 03/25/2012

    I began to gradually lose my sense of smell in my thirties, and eventually lost it completely. I am now 57, and rely on others, mostly my wife, to identify smells for me. I’ll ask her to check milk for me, or if she smells something hot, or burning, she follows me around while I check. My sense of taste is greatly affected, and I can taste sweets and very hot/spicy foods best. I sometimes think I smell something that no one else does, and I think it is the memory of a smell I knew years ago that my brain is reminding me of. I’d like to be contacted for any future tests or studies.

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  12. 12. Lauren5171 8:16 pm 03/25/2012

    I can never remember having a sense of smell (and I’m 54) so this article caught my eye. Thank you for shedding some light on something that is rather strange and always made me feel a bit different from others. It’s not something I can ever remember reading or hearing about and yet I’ve always been extremely curious about why I can’t, what it’s like to smell, how it has affected me,etc. My experiences are very similar to the other comments here. There was really just a gradual realization that I was not experiencing what others were, which was perplexing when I was a child. You learn pretty quickly that perfume is off limits – didn’t want people passing out around me! I’ve got stories about skunks too, and always find it rather amazing that I don’t even realize what most people find gag-inducing!

    I too have learned to pretend I can smell in some situations because it is simply easier than trying to explain; however, I will often ask family and friends to describe smells to me. I imagine different smells to be similar to their taste or what they look like (e.g., a floral scent means “pretty” or “feminine” to me). It’s funny but one of the first things people ask if I tell them I can’t smell is, “can you taste??” Apparently smell and taste are closely linked – but I believe I taste just fine. It does make me wonder if food actually tastes much better with a sense of smell.

    It’s so interesting to hear about others’ experiences – I’ve never met anyone else who couldn’t smell. Would love to learn more and hear from others. The whole issue about it affecting social interactions and possibly contributing to social insecurity is also fascinating. That certainly describes me!

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  13. 13. ipaintportraits 10:22 pm 03/25/2012

    At first I thought “Wow-it’s about time!” but as I read on, it was disappointing to read way too much guesswork and not enough real facts about this condition and how it affects those of us born with a sense of smell.

    In fact I am not sure how someone who can smell can even begin to write about the world of those of us who cannot smell, with any degree of accuracy!

    For the most part the comment about “you don’t miss what you never had” is very true :-) . You would be surprised how we don’t even think about it.

    But there’s more to it than the writers even know. My fraternal twin had an amazing sense of smell but my eldest daughter also has no sense of smell leading me to believe that somewhere in our background was another relative who could not smell. So the factors of heredity were not even mentioned.

    Can we taste? Well yes -sweet, sour, bitter, but apparently not with the advanced sophistication of a “smeller.” But heck we don’t know what we’re missing remember?

    Not understanding our world is common among “sniffers.” Doctors easily understand all about people losing a sense of smell but I have never met a doctor who “really” believed or understood that I had no actual sense of smell from the beginning :-) (of course, even my family did not believe for years.)

    But as to the “theory” that a lack of smell could lead to social issues? What possible series of facts led to that ridiculous hypothesis? It’s even more surprising in a science magazine where guesswork should not even be considered until proven. If anything the fact that we can’t smell bad breath, alcohol breath, poor hygiene or personal gas means we get along in any and all personal and group situations with far more aplomb than any of our sensitive “nosy” friends :-) .

    My hope would be that in the future, the researchers spend more energy on facts and less on vague generalities before they come to random conclusions.
    We would hate to be dismissed so randomly!

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  14. 14. Krystal D'Costa in reply to Krystal D'Costa 10:43 am 03/26/2012

    Thanks so much to everyone who has chimed in to share their stories. Given the number of people who have stepped forward to talk about their experience, I suspect that ssmro is correct: the discrepancy in North America is likely related to the rate of reporting on the condition. I can understand concerns about being out of sync with the general population and being treated like a test subject.

    Lauren, yes, food and taste are related, but we don’t know to what degree. People who lose their sense of smell report a decreased ability to taste—though it seems some sense of the extremes of spicy and sweet are retained, as per the example by FordExec. However, some people with ICA report never being able to taste to begin with. It will be interesting to see what research reveals in coming years.

    Portrait, I’m sorry you were disappointed. This article reports on interesting research, which is admittedly and plainly exploratory. And the nature of this blog is to consider such research in light of human relationships, which is where the conjecture enters the discussion. There’s much here still to learn—but I hope the community response has been helpful to you.

    Edit: This post was sent along to me via Twitter, and may be of interest for further reading:
    Anosmia Matters: Whether You Can Smell Or Not

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  15. 15. bpadj 12:46 pm 11/30/2012

    Krystal, please comment . I was born with Kallmann syndrome. No olfactors. I didn’t really realize I couldn’t smell until high school. It was just normal for me. It wasn’t until science class my freshman year our teacher passed around a beaker of ammonia for us all to smell. I could of sucked it all in. Didn’t smell a thing. I reacted by watching everyone else to react and I did the same thing. After that I always wonder what would happen if I passed out and they tried to use smelling salts on me and I didn’t react.LOL The stories I could tell I could go on and on. I can taste sweet and sour and salt but really cannot taste mixed flavor. No herbs can I taste. Just bland but I still eat with no problem. I do have problems with texture. Fat is like slimy snot in my mouth but others love the flavor. I do have a big concern for gas in my house. I have about killed myself mixing chemicals at times. If I walked in and there was a gas leak I would never know. I tend to throw a lot of food out too soon because I can’t trust It could be spoiled. I had a terrible experience the other day. I bought a couple of fresh turkeys to stick in the freezer after thanksgiving and at the check out some juice spilled out. The clerk about gagged. Now here is my problem, I would of taken those home stuck them in the freezer and pulled one out and cooked for my family. We would of all been sick. Do you know of any detector out there people like myself can use to protect ourselves. padjenb@yahoo.com

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  16. 16. mlaitine 11:36 am 02/4/2013

    I had a sense of smell up until August of 2008. That is when I had my brain hemorrhage. I was very lucky to only lose my sense of taste and smell. To this day the doctors have no idea what truly caused it. How did I realize my new found lack of smell and taste? My wife and I were eating strawberry shortcake for dessert the night we got back home from the hospital. When I finished eating, I sat thinking about what I just ate and at that very moment it very shockingly occurred to me, “I didn’t taste it!” Since then I ask my wife to smell stuff for me that I have questions about. I feel though that sometimes my smell wants to come back because sometimes I think I can smell certain things, but it may just be a “smelling memory” that is tricking me. I miss the smell of a campfire most. However, if I am not allowed to smell that anymore but still have my life, than I will take that without hesitation.
    I do wonder though, what type of job occupations do not require a sense of smell? Besides, perhaps the office types of occupations that is.

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  17. 17. Mollykins8H 6:16 pm 06/24/2013

    I am only 13 years old. I’ve known I had ICA for as long as I can remember. Both my parents can smell perfectly, but my uncle can’t, so we think that’s why I can’t either. I actually enjoy telling people that I’ve never been able to smell, because its fun to see all their reactions! I also find that my taste is a bit messed up. I’m very picky, and I can’t stand spicy foods. Its very fun to search the web for sites like these, though, where people try to figure out what anosmia is like. I enjoy being different from everyone else. :D

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