Human Sense of Smell Underestimated 278
Benjamin Long writes to note a study, by a team of neuroscientists and engineers, that demonstrated that humans can follow a scent trail — an ability that most had assumed only animals possessed. Furthermore, the study demonstrated for the first time that humans make use of differential information from the two nostrils. The researchers blindfolded college students who crawled through grass to sniff out a chocolate-scented trail. Here is the abstract of the paper in Nature Neuroscience. From the article: "The humans, however, still sniffed much more slowly than dogs, which may partially account for canines' greater efficiency at scent tracking. [A commentator] says that despite their relatively sluggish speed, the fact that subjects improved with training is noteworthy. 'I think that shows the effect of our distinctively different behavior in actually using this sense,' he says. 'The dog [has] been doing this its whole life, and humans [were] just asked to plunge in the first time they've ever done it.'"
Re:Student Dignity (Score:5, Interesting)
before i settled on computer science i took a couple of pysch classes. We were required to participate in a couple of experiments each semester so that's probably why they did it.
sense of smell first to develope (Score:3, Interesting)
I, for one, can't even smell my own breath.
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We Smell in Stereo (Score:5, Interesting)
Richard Feynman did a number of smell experiments with his first wife, Arlene. He would leave the room and she would handle bottles and books then he'd return and see if he could determine which ones she'd touched. He was able to find them. It's detailed in Surely Your Joking, Mr. Feynman [gorgorat.com].
There! And I didn't make any smelling cracks about misunderestimating or Uranus or "once you get past the smell it tastes all right".
Following scent trail? My mom did it! (Score:5, Interesting)
When I was young I used to hate that stuff, especially because my mom would throw blocks of it in the curries without powdering them. One bite of that chunk, and you will curse everyone in sight. So enraged I was, that I once stole her entire stash of asafoitida. I wanted to throw it away in garbage, but I was young and scared and did not dare throw it all away. So I hid it in a trunk in the loft. And, yes as I said in the subject line, my mom sniffed it out and found the stash. So yes, humans can sniff out very aromatic substances. But faint traces like a dogs do [note the significant absence of the apostrophe after the s in dogs] ? I am not so sure.
Not all humans can (Score:5, Interesting)
My first job after graduating from college was working as a computer programmer at a US Air Force base. I worked in the main building for our section of the base and our colonel one day was having a VIP come by to visit him. He walked out to the main area and smelled something burning. Convinced that his canine sense of smell had saved the day and wanting to show off for his visitor, he promptly called the base fire department and demanded that they send a truck out to investigate "the burning wires smoldering within one of the walls". The base fire department dispatched a truck and the firemen investigated and told the colonel that what he smelled was burnt popcorn from the break room and there was nothing smoldering within the walls. The colonel then did the only thing that a military man who has just embarassed himself could do. He promptly banned microwave popcorn.
Re:Duh? (Score:1, Interesting)
Unless you were blindfolded, you could have used your eyes to look for the burning plastic. And since you knew that the light bulbs were on (and hot), you could have used your powers of deduction to guess that the chandelier was a likely place to look.
Of course, since you never informed the researchers about your "amazing feat", it's not terribly surprising that they didn't know about it.
smell (Score:5, Interesting)
My sense's of taste and smell are so actute now - it's amazing! I can smell people smoking a few cars in front of me - peoples aftershave and perfumes are most times extreme and putrid (I believe it must be animal urine in them)
The weirdest experience was the re-living of memories evoked through smell, that I had long forgotton. Apparently, smell is the sense most connected to memory, I literally feel younger than ever (36yrs old in reality) Now I can smell the deeper complexities within freshly cut grass that I had completely forgotton. Quit that damn cigarette - you really do get your life back (lots more money too)
Dosn't prove smell in stereo (Score:2, Interesting)
Much of common life destroys basic senses. (Score:5, Interesting)
One thing I noticed, during bootcamp was that my sense of smell became incredibly accute. While, I'll award the reader with the fact that I was a prior smoker to bootcamp, I will say that non-smokers DEFINATELY noticed the difference as well.
While it's not likely we as a society will retort back to nature in a sense, I will say, the body naturally cleans itself and the only reason a "bum" stinks as bad as he does is in relation to all the non-natural environment surrounding him. Not only that, but we are so used to the man made scents, that natural scents tend to stand out even more.
For example... while some city women will think a man from the country is being a sexist pig who treats women like objects... the fact is, men CAN smell women and from a considerable distance away.
OK. Let me stress this, becuase this is when it hit me like a brick during boot camp. It was almost a "holy shit do I have a Marvel Comic superhero nose?", no I don't and you don't either. But, when at a club, a female can be practically touching you and you might smell her perfume. In the work place, a female sitting in the next cubicle might not make her presence known until she makes sufficient noise to catch your attention....
After five weeks into boot camp, a female division walked past the barracks we were at, and walked up stairs. I would accurately judge the distance to about 50 feet away, and every single guy in the barracks literally smelled the girls. We didn't have to hear them. We didn't have to see them. We could smell them and knew they were there. The scents were distinguishable too, not just a generic feminine hormone release into the air. If two girls were in the next room, the guys three rooms down could smell two different scents.
When I was a kid, females weren't allowed to go hunting, irregardless of what time of month or whatever they washed their bodies with. Until boot camp, I always thought it was a wives tale that women gave off that much odor... but I swear to you. Yes, if I am able to smell a female just as well as see her from 50 feet away... then a deer or buck with much better noses can certainly smell a human female from 100 yards away. A man could probably smell the presence of a female much further than 50 feet away, it's just that's the distance I know for a fact and even at 50 feet, the scent was unbelievably strong. How far away before it becomes a hint? The girl might as well have showered in perfume and stood two inches behind me.
Nowadays, away from the lack of everyday luxuries and eminties, inhalation of cigarette smoke, car exhaust, overwhelming stench of plastics and asphalt... no, I couldn't tell you if a girl with no perfume is sitting five feet over in the next cubicle. It's somewhat sad. But, you are capable of doing it. Most people who go on long hunting trips in the wilderness know what I'm talking about. Without all this crap we deal with, this man made crap, nature gave us some pretty interesting abilities that have been long taken for granted or the use is nolonger really needed.
The scent of the girls is what blew me away the most. So vivid, so strong so unexpected. But, I also realized that a lot of other things that might have been overlooked or not processed certainly was while in boot camp. Such as the bed of flowers outside the barracks... yeah, you can smell those things. In modern day life, much of those scents are still hitting our nose, but if they remain being processed it's either at a subconscious level or outright ignored altogether. Anyway, it doesn't surprise me that a group of college students was able to smell a trail of chocolate in the lawn. Doesn't surprise me one bit.
Re:Duh? (Score:5, Interesting)
Most people underestimate their sense of hearing as well. Have you ever seen any of those blind people who can use echolocation to scan an area? Pretty impressive. When I first saw a video of it, I decided to experiment around. I spun around in my (then apartment) to disorient myself, with the intent of "clicking" to orient myself. However, I found something odd: I couldn't disorient myself. There was a faint electrical hum in one corner of a room on the opposite side, and that was enough that my mind automatically reoriented me, even though that sound was undoubtedly bounding off of all sorts of surfaces to get to me. Our sense of hearing provides an excellent direction-finding ability, so the only extra components for echolocation is the ability to A) get a good echo, and B) to be able to handle more complex echo returns.
So, I went online to see what experiments were out there. Apparently, they've done experiments in which humans are blindfolded and told to walk as close to an object as possible without running into it. They vary its distance with each run. At first, people either run into it or are way off. However, with successive runs, they become quite good at avoiding collision, ending up right next to the object. However, if you muffle their footsteps and plug their ears, they lose their ability to do this. The echoes from their footsteps are enough for them to find the object.
Re:Student Dignity (Score:2, Interesting)
Re:Not all humans can (Score:3, Interesting)
Re:We Smell in Stereo (Score:3, Interesting)
Dogs have to learn to use their scenting ability too, and the more native ability they have, the faster they learn to use it. Most toy dogs never learn to really use their noses, nor do many cats, even when they have need (frex, outdoor cats that have to hunt their dinner). It's rather like how someone who is naturally good at math learns higher math much more readily than someone who starts off with no inherent grok of math.
Smoking, or living in a smoking household, will kill your scenting ability in a hurry. I've noticed that Cajun-spiced food does the same thing, so delicious as it is, I don't eat it.
I never thought of scenting as "stereo" but should have, since scents are typically "directional"... you can tell what angle they're at and about how far away, rather like you would with sight or hearing.
I was reading a book called (Score:5, Interesting)
Crystal Fire [amazon.com] and they had an interesting anecdote about the beginnings of semi-conductor research. In the late 1930's early 1940s the scientists at Bell labs were experimenting with silicon to see if they could build rectifiers and other electronic components out of it. At the time there really wasn't any theory about how these things might have worked. Some silicon rods showed semi-conductive behavior, some didn't. Finally they found one rod that showed strong semi-conductive behavior. They couldn't figure out what it was that made this rod special until the scientists and machinist who worked on it said that when it was cut or ground it gave off the same smell as one of the old carbide lamps that were used on many automobiles until the late 1920s. One of the chemists realized that what they were smelling was trace amounts of phospine gas, which meant that the rod has phosphorous in it. This was a surprise as the levels of phosphorous in the sample were so small that they didn't show up in a spectrographic analysis, it was the noses of the scientists and machinist that gave them the clue that the proper trace impurities in silicon would enhance the semi-conductive behavior.
Agree no surprises. Richard Feynman documented it (Score:5, Interesting)
Many people who suspect their spouses of affairs also observe this ability too (knowing in which rooms a guest's been in).
This shouldn't be a surprise to anyone; and it's pretty sad that the obvious gets passed as new, novel research.
Re:Duh? (Score:3, Interesting)
you could have used your eyes to look for the burning plastic.
I could have, but didn't. And that's a bit impractical looking at every square inch of the room to identify something small and burning (if you can even see what's burning).
And since you knew that the light bulbs were on (and hot), you could have used your powers of deduction to guess that the chandelier was a likely place to look.
Actually, I was predisposed to look for electrical shorts to find the burning source. It was only by following my nose that I figured out that wasn't it.
Re:Stereo smell. (Score:3, Interesting)
I'm curious if the researchers produced CFD models of different types of nose to compare the mechanics of different nose structures against the ability of those same nose structures to give stereo information, etc. I somehow doubt it - I'm begininning to be rather skeptical over the ability of researchers to actually study something as opposed to merely report on it - but this is the sort of information that would allow the results to be understood and interpreted in context. It would also be good if modern brain activity imaging could be used to see what the brain actually does TO interpret scent in stereo. How is the information correlated, and what with? Obviously, imaging is too expensive to do on a first-round study that sounds like it was more a recreational piece of research than something anyone expected to get real results from.
As it stands, we know that a result occurs without knowing actually knowing a whole lot about what happens, why, how or even when. (There's a huge time lag between when the data is collected and when the person acts on it.) A result is good, but when that's all you have, it's no more science than alchemy or spell-casting, and without quantifiable data, is not really any more repeatable. We've moved on past the stone circles and ritual magic - at least, I hope so. It would seriously make a mess of the server room if they started ripping out guts there in Druid rituals.
Re:Stereo smell. (Score:5, Interesting)
For our eyes, that's not really true. Our eyes are placed slightly apart, looking forward so that their respective fields of vision overlap each other. Then our brain calculates how far away objects are from us by noticing how much inward each eye has to rotate to hold the object in focus.
Prey animals, like deer and cows for example, have eyes mounted on totally opposite sides of their heads, like our ears. Each of their eyes sees an almost complete separate image. Their total field of vision is almost 300 degrees. Owls are predators par excellance, and have stereoscopic ears set just below their eyes. Their entire face is bowl-shaped like a radar dish.
So, if we evolved solely as prey animals, we probably would have eyes on the sides of our heads, near our ears. If we evolved solely as hunters, we would probably have forward facing ears that we could rotate, like cats or wild dogs. There is some debate, but some anthropologists argue that our forward-facing eyes and stereoscopic vision comes from having to navigate in trees. This is also backed up by the fact that we have 3-color vision, which you need to see ripe fruit, where as hunters like cats and dogs see in black and white. There are vegetarian, tree-dwelling monkeys that have forward-facing eyes, stereoscopic vision, and have 3-color vision*.
It is interesting that smell, if it is truly a stereo sense, would have both nostrils so close together. Maybe that's because light and sound waves don't get mixed up as much as scents on the wind, so each input would be very different. Also, smell seems to be a short-range sense, whereas sight and sound are long-distance senses. I don't mean that prey animals don't smell things far away, but it's not as usefully accurate as long-distance hearing or vision. If you're relying on smell to tell you when things are sneaking up on you, it will probably be too late by the time you really get a good whiff. A sound or a sight really tells you where they are, and which direction you need to run in. My guess would be that the stereoscopy of smell would be useful when you are examining something up close, such as a plant or carcass.
*By 3-color vision, I mean that we have specific receptors cell in our eyes for 3 discrete wavelengths of light -- red, green, and blue. Some birds, for instance, have four.
Re:Stereo smell. (Score:3, Interesting)
Re:sense of smell first to develope (Score:3, Interesting)
Through a process called sensory adaptation [wikipedia.org], your brain automatically starts to ignore persistent stimuli. Ever notic how if a room has a particular smell, you only notice right after you walk in? The perception fades after a period of exposure; something similar happens with the smell of your breath.
If you told us that you couldn't smell other people's breath, then I'd wonder about your sense of smell.
Re:Duh? (Score:1, Interesting)
Re:Duh? (Score:3, Interesting)
When was the last time you saw an animal create art? Or music? Or contemplate quantum physics? Or do something out of moral duty? Or exhibit any signs of any sort of religion at all? If your dog, or any other animal on the planet did any of these things that humans do on a regular basis, it would make world-wide news.
Yes, there are certainly some similarities between the biology of humans and animals. But to ignore the differences is just as willfully blind as those who ignore the similarities.
Re:Stereo smell. (Score:2, Interesting)
Try and taste anything if you've got you're nostrils blocked!
Individuals' scents, subconsciously different (Score:4, Interesting)
I remember reading (somewhere) a scent-related experiment which was suggested for kids. The purpose was to demonstrate that people can differentiate the odors of other individuals even though they don't consciously smell anything at all.
The procedure went something like this:
Distribute a freshly-cleaned T-shirt in a zip-lock bag to all participants. Groups trying this experiment should be small, less than 10 people. Each person should bathe in the evening and wear the T-shirt overnight, placing it back into the zip-lock bag in the morning (no distinctive folding or rolling, just shoved in). When everyone is back together again, the bags are gathered while a non-participant draws numbers from a hat, writing the number on the bag and recording who brought it. The number correspondence is kept secret. Bags are then passed around and participants try to guess who wore each shirt.
The article I was reading said that you should expect "uncanny" accuracy, the difference in scent seeming like a "hunch" or a "feeling" rather than a conscious recognition.
Now the even weirder part. A similar experiment was done where the shirt-wearers were unknown to the sniffers. The people smelling the shirts were given a set of photographs, and asked which one the shirt seemed to belong to. Apparently, they scored correctly by a significant margin.
Now, since I'm busy I'll just leave it up to the reader (and Google, perhaps) to find the sources.
Re:sense of smell first to develope (Score:3, Interesting)
You can absorb gasses via the digestive tract, if you have farts building up in there some of them will be aborbed, and will circulate.
Eventually reaching the smell cells. Via the Sensory adaptation mechanisim mentioned above, you end up not being able to smell parts of your own fart, so it doesn't smell as bad to you when it's in the room.
PS. I have nothing to back this up, I made it up myself. Is it true? Where are those Ig Nobel researchers?
Re:Duh? (Score:2, Interesting)
Chickens, when fed at random intervals, will start to develop weird behavior based on their guesses at what the cause of being fed was. That sounds a lot like most religions I'm aware of.
Most people in the world see things as they already believe them to be.
Re:Duh? (Score:5, Interesting)
At first I thought "OK, what the hell kind of bogus ninja crap is this?" And at first there were many cheeks getting tapped. But before too long, most of us found that we could in fact block the punches. Not fast ones (I moved away shortly after this so I don't know what the others achieved in the end), but it was still pretty weird. Even in a room full of rustling gis, you would still be able to get enough audio cues (and at first, tactile ones from the touching knees) to tell more or less where the hit was coming from.
It was pretty cool. I'd love to know how far that could be taken.
Torben
I Think I'll Hang On to my Beagle... (Score:3, Interesting)
Dog to Human: Wanna go get some meat?
Human to Dog: Yeah. You run on ahead, don't forget to let me know where you are, and I'll follow along with this stick. I just figured out how to put some sharp flint on the end of it. Should do a good job of killing that gazelle or whatever it is.
Dog to Human: AROOO!
Later that same evening...
Human to Dog: Get away from that! Let me hack it up with this sharp piece of flint.
Dog to Human: Good job! If you don't mind, I'll just gorge myself on the leftovers so I can go home and regurgitate some for the wife and pups.
Human to Dog: Yeah, I'm taking the good parts. My wife has been gathering some kind of green stuff, and she'll put it on the meat and apply fire to it. Good eating!
No wonder humans are generally so fond of dogs. We're hunting buddies from way back.
Re:Duh? (Score:2, Interesting)
I'm not saying that Jean Claude's movies Kickboxer and Bloodsport are documentaries, but I would wager that the blind fighting parts portrayed in those movies are significantly more fact than fiction. IOW, I think it can be taken pretty far.
Here's something to ponder - the capabilities of human vision and the interpretation of what we see, all the amazing things we take for granted like driving a car in bad weather, doing 3D cad, flying fighter jets, whatever. The brain's processing power that interprets visual information so impressively is also available for the ears as well - and the nose, and touch, what about taste? It involves training, don't you think? Blind people do braille pretty well, and identify people by their footsteps, and so on. The amazing feats are available through practice, but no-one does it because we don't have to. hmmm....
Re:sense of smell first to develop (Score:2, Interesting)