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Can we Measure and Quantifying smell? (Dog Experiment)

  1. Oct 1, 2012 #1
    So right now I am shadowing a 8th grade science teacher at Drew Charter school and I was helping a student work on his idea come up with a science fair project.

    The student wants to study what kind of smells do dog's prefer over other's but using household (safe items), food, and dirty clothing. The student need to come up with a way to quantify his measurements. I was perplexed by how people measure smell (units?), so I suggested to him that he could do simple bean counting of dog's preferences from a large sample size (like 100 dogs) with 10 choices done in a random order.
    This got me wondering later about if their was prehaps a more concrete way to measure smell intensity and preference.

    In biology, is their a scientific way to quantify and measure smell? If so what are the units? Can it be measured by scientific equipment? Are common smells classified on a standardized scientific scale or taxonomic way to classify smell?
    If not then how do we know dog's can smell better? How do we say a smell is weak or strong?

    Any suggestion or comment would be appreciated.
  2. jcsd
  3. Oct 1, 2012 #2


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    You have many questions that I don't have an answer to, but the fact that dogs can be trained to detect smells that are undetectable to the human nose is a clear indication that their nose is more sensitive.
  4. Oct 1, 2012 #3
    True, I feel like culturally we have enough evidence to suggestion what we know about dog's smelling better to the point that a friend of mind mentioned that maybe they have done MRI scans on dog's brains. I fell like because of common sense their should have some work in actually measuring smells or measuring how dog's smell and quantifying sensitivity.

    However, I feel like I do not know enough about the biology of smell to know what to look for.
  5. Oct 1, 2012 #4


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    I googled How Much Better Is A Dog's Sense Of Smell, and got some good hits. (lots of wiki stuff which I didn't follow, but some more reputable sources as well)

    You might try the same Google search to continue your reading.

    This PDF was near the top of the list, and two of the references at the end seem to refer to dog physiology...


    (it's a bit slow to serve up, so be patient)...
  6. Oct 2, 2012 #5
    I don't remember what they're called but there are devices that can count parts per million of chemicals in the air. This would be as close to a "smelling machine" as there probably is, and the relative intensity of a smell must surely be linked to how many ppm's of the operative chemical there are in the vicinity.
  7. Oct 7, 2012 #6
    Well, I guess we can actually count the number of nasal receptor cells in a dog's nose and a human's nose and get some kind of ratio from that. I understand a dog's sensitivity is thousands of times greater than a human's.
  8. Oct 7, 2012 #7
    Dogs are always looking up but smelling down. Of course they can sniff out poop and death skillfully at great distances, but there skill is myopic. They can only smell the tree , and never the forrest.
    Human's sniff out mathematical theorems which, "reflect a robust platonic world that is not of our making". I will stick with my nose for the time being.
  9. Oct 8, 2012 #8


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    Sorry but I have no idea what you're trying to say here. How is our sense of smell qualitatively different to a dogs?
  10. Apr 12, 2013 #9
    Maybe use threshold detection levels - something a dog really wants, and use it first at high dilutions in air. Increase the concentration slowly until the dog responds. Can compare with threshold levels in humans but unlikely that the receptors are identical in every regard - there are almost certainly qualitative (smell type) as well as quantitative (sensitivity) differences.

    Preferences between smells are much more complex, depending on hunger, mood, competing smells, and complementary smells. For example, a dog may like dirty laundry if his master is away, but not be interested in it when he is present. This experiment could be very frustrating.
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