Nehaveigur

Not Man the less, but Nature more

2026-05-21

Questions about Smells: The most specific of our senses

Humans may be able to distinguish between one trillion different smells, even though our noses are degenerate compared to most mammals.

Dogs seem not to mind most smells that humans dislike. How do smells that appear bad to humans and dogs differ?
Why is there so little demand for unscented shampoo, moisturizer and deodorant? They’re hard to find, indicating that most people prefer scented products.
When I went to China last summer, I came across a new and pervasive smell. I think it may have been from a disinfectant, but I’m not sure. For days afterwards, and even after returning from China, I kept imagining the smell. More recently, I used a portable toilet that had an extra-strong artificial scent that I kept smelling for hours afterwards. I know others have described the phenomenon of smell sensations that persist after the actual scent is gone. What’s going on? My best guess is that our olfactory receptors bind some scents so tightly that they remain constituitively activated for days or hours.
Relatedly, I am occasionally experiencing phantom smells, i.e. smells that only I and no-one around me is able to detect. This is happening more often since I temporarily lost my sense of smell after COVID. I haven’t heard anyone else describe this phenomenon, but I’d like to know what’s going on.
What’s the relation between illness and our ability to smell? Why is anosmia seem to be a warning sign for dementia?
Good writers can paint a picture with words so that it appears almost as vivid in the reader’s inner eye as if they were seeing it. I have not yet encountered a writer who has been able to describe a smell I have not encountered before so that I can imagine it. Why is that?
What is it about smell and childhood memory, as famously described by Marcel Proust? Is it simply that us being able to detect a trillion different smells means that we associated extremely specific memories with each scent, or is there something else going on?
How difficult would it be to build a device that detects and labels smells at a comparable sensitivity and specificity than our noses? This would enable us to unambiguously label smells and may lead to some interesting smell-related conversations.