Harold McGee – The Science of How Smell Works on Modern Wisdom with Chris Williamson

Check out Episode Page and Show notes

Key Takeaways

  • Human smell receptors actually bind to smell molecules so, for a second, what you’re smelling is actually a part of you
  • Your sense of smell is dependent upon:
    • How close you are to whatever it is you’re smelling
    • How deeply you breathe in
    • How often you breathe in
  • Losing your sense of smell reduces the pleasure component of eating
  • The brain has 400 different receptors of smell– more than for taste
  • Studies of human physiology show that lavender has a relaxing effect and citrus has a stimulating effect
  • Human toddlers don’t seem to have adult revulsions to certain smells and researchers don’t know why
  • The more offensive your poop smells, the more it indicates you’re eating stuff that isn’t good for you
  • Smell is more episodic than vision – it’s easier to have experience attached to it

Intro

Harold James McGee (t:@Harold_McGee) is an author who writes about the chemistry and history of food science and cooking. 

Books

Nose Dive by Harold McGee – a field guide to the world’s smells

On Food and Cooking by Harold McGee

Smell 101

  • Smell is a perception generated in the human brain by inhaled molecules
  • The molecules react with receptors in the nose and the brain turns those reactions into perception based on prior experiences,
  • Human smell receptors bind to smell molecules, so for a second what you’re smelling actually becomes a part of you

Taste and Smell

  • The dominant aspect of flavor is smell which is enhanced by exhaled air as it passes from the mouth through the nose
  • Much of what is thought of as flavor in your mouth, is actually smell
  • Smell depends upon:
    • How close you are to what you’re smelling
    • How deeply you breathe in
    • How often you breathe in = sniffing

Losing Your Sense of Smell

  • A temporary side-effect of Covid is a loss of sense of smell
  • Losing your ability to smell reduces the pleasure component of eating – you can feel food in your mouth (texture) but can’t taste it
  • There are 400 different receptors of smell in the brain– more than taste receptors

Tech and Smell

  • Smell-a-vision was tried in the 1970s with scratch and sniff cards used at movie theaters
  • At Disney’s Wings-of-Flight ride in Disneyland, the aromas of grass and sea spray are piped into the room to enhance the sensual experience
  • Newer technology tried using digital coding to release molecules at certain viewing points, but so far hasn’t been effective – it’s difficult to get rid of smells once you’re done with them

Human Physiology and Smells

  • Human physiology can be affected through smells
  • “Studies have shown that particular smells can have a physiological effect on humans and is culture-dependent.” – Harold McGee
  • Generally, lavender has a relaxing effect and citrus has a stimulating effect
  • Why? These smells are less individual molecules and more a “bouquet of different smells”

Smell and Evolution

  • One of the earliest senses developed by evolving man was smell
  • The sense of smell was important for the survival of animals and early man to both find food and to avoid danger
  • However, human toddlers are neutral – they don’t seem to have adult revulsions to certain smells and researchers don’t know why
  • Pre-historic history suggests the planet had a strong Sulphur smell (volcanoes and hot springs) until photosynthesis began and introduced oxygen

Emotional Attachments to Smell

  • The sense of smell goes much deeper into the parts of the brain that make impressions on us than other senses
  • Your vision is on all the time, with a smell you can’t ignore it or tune it out
  • Smell is more episodic than vision – it’s easier to have experience attached to it

Unique smells

  • Certain incense woods are intoxicating with rich and layered aromas
    • e.g., Agarwood also known as oud
  • The agar scent is produced by a Southeast Asian tree infected by fungus – the resin produced by the tree to defend itself produces the scent
  • Ambergris comes from the lower digestive tract from sperm whalse and is popular with perfumeries for its flowery scent
  • The smell of fresh soil is from a molecule generated in the soil called geosmin
  • The scent of rain on stones is  the liberation from the surface of all things living there

Why Excrement Smells

  • Excrement Smells because of your microbiome – the closer your poop smells like newborn poop the healthier your microbiome is
  • The more offensive or sulphury your poop smells, the more it indicates you’re eating stuff that isn’t good for you
  • Some animals, like gorillas, eat their own excrement but not before smelling it first

The Smell of Plants

  • Flower and plant smells are synthesized by the plant itself – they aromatically pleasing because it’s not the smell of decay
  • Animal scents are essentially the smell of the breakdown of tissues and microbes
  • Plants’ smells are meant to ward off predators and repel animals

A Dog’s Nose vs. the Human Nose

  • Dogs have almost the same basic set of receptors as humans do
  • Dog advantage – their noses are closer to the ground
  • Human advantage – humans have much more processing power to make sense of what they’re smelling
  • Dogs smell with short repeated intakes (sniffs) of molecules
  • When humans sniff it piques the brain’s attention
Modern Wisdom : , , , , , ,
Notes By EWerbitsky

More Notes on these topics

Top Insights and Tactics From

31 Best Podcasts of All Time

FREE when you join over 12,000 subscribers to the
Podcast Notes newsletter

No Thanks