05 June 2015

Smelling Sense

Welcome back. A recent Berkeley Wellness Alert reminded me that I left you hanging in my blog post Vulture Dining. You may recall the scene:

A formerly live squirrel being examined by a visiting vulture on the street in front of our house in our former neighborhood. I had expected or hoped the bird would remove the dearly departed, but Big Bird surrendered to the passing vehicles and flew off leaving everything in place.

So What Happened, Warren? 


Although it was trash collection day, the truck had already passed. That left it up to me.

I carefully shoveled the remains into a plastic bag, twisted and tied the bag closed, then slipped that bag into another plastic bag, which I also sealed securely. I placed the package into an open trash container in our garage, thinking my job was done. Mistake.

The next day, the pungent odor hinted that I should have covered the container, which I belatedly did. Four days later, the trash was collected; however, weeks later I was still airing and spraying the container to eliminate the reminder.

Olfaction


Smelling a flower. (Photo
from multiple websites)
Before we move on, you might want to clear the air. Think of aromas like your grandmother’s baking, the turkey in the oven, coffee brewing, flowers, baby powder, crayons, chocolate. OK? Ready?

As you likely surmised, the Berkeley Alert reviewed olfaction, the sense of smell. I was surprised the discussion never used the word “dog.” And though it touched on nostrils, noting that one of our two is normally dominant, how could it not mention the ability of rats and moles to smell in stereo, a topic covered in my post Stereo Seeing and Smelling?

Instead, the review was about you and me and our not so unusual sense of smell, which they wrote can detect at least 10,000 different odors. I regret having to point out that a 2014 study from The Rockefeller University and Howard Hughes Medical Institute calculated that number to be more like one trillion!

Olfactory Facts of Interest

Nevertheless, the review emphasized the importance of olfaction, gave a brief summary of the 2004 Nobel Prize winning finding of how we recall and distinguish odors, and offered several other items of interest. For example:

-Women tend to have a keener sense of smell than men.
-The ability to perceive a specific odor declines with continuous exposure to the odor.
-Odors can affect the release of certain neurotransmitters, encouraging mood change, relaxation or even reduced pain; but the effect varies with culture, genetics and associations.
-While many things can temporarily or permanently reduce the sense of smell and might require medical diagnosis, there is a general decline after about age 40. (Hyposmia is a reduced ability to smell; anosmia is a total inability, dysosmia is misperception of smells and phantosmia is olfactory hallucination.)

Searching a bit, I found some additional items I thought were interesting (see P.S.):

-African-Americans and Hispanics begin to experience age-related loss of smelling earlier than Caucasians.
-The sense of smell is the only cranial nerve that can regenerate, and scent cells are renewed every 30 to 60 days.
-We can smell fear and disgust through sweat.
-Every individual has a unique body odor, which, like a fingerprint, might be recognized, for example, by victims of violent crime.

Wrap Up

Beyond all the fond memories of my late mother, I always think of her if I smell mothballs. She would salt the white marbles on stored sweaters and blankets or just about anything that didn’t move. Recently, my brother had a mothball alert, when the departing tenant of a neighboring apartment left mothballs that threatened my brother’s cockatiel. It’s a hair-raising story, but…well, it’s my brother’s story. Thanks for stopping by.

P.S.

University of California, Berkeley Wellness Alert:
www.berkeleywellness.com/self-care/preventive-care/article/making-sense-smell
Nobel Prize statement on the 2004 award to Richard Axel and Linda Buck for their discoveries of odorant receptors and the organization of the olfactory system:
www.nobelprize.org/nobel_prizes/medicine/laureates/2004/illpres/index.html
Science Magazine paper on humans’ ability to discriminate over 1 trillion smells: www.sciencemag.org/content/343/6177/1370
Sense of smell facts on Everyday Health and Mirror websites:
www.everydayhealth.com/news/incredible-facts-about-your-sense-smell/
www.mirror.co.uk/lifestyle/health/20-fascinating-facts-sense-smell-1977351
Psychological Science journal paper on chemosignals communicating human emotions: pss.sagepub.com/content/23/11/1417
The Journals of Gerontology Series A paper on racial disparities in olfactory loss: biomedgerontology.oxfordjournals.org/content/early/2013/05/19/gerona.glt063.full
PLOS ONE journal paper on “nosewitness” identification:
journals.plos.org/plosone/article?id=10.1371/journal.pone.0116706

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