The Sense of Smell Is More Important Than You Realize

If sight is a human's most important sense, why do we have only four types of light receptors but more than 1,000 types of smell receptors? It could be because smell is the most rudimentary sense: even single-celled bacteria have the ability to "smell," or otherwise interpret chemical signals in their environment. This primitive origin has made smell unique among our five senses. Watch the videos below to learn more.

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Smell Basics

Here's how your sense of smell works, and why it's so important.

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Key Facts In This Video

  1. Smelling is an essential part of your genes. 00:42

  2. People rate memories triggered by smell as more emotional than by sight or sound. 02:17

  3. Smells can occur in the womb before we're born. 02:41

How Smell and Taste Are Intricately Linked

When you lose your sense of smell, you lose a lot of other sensory information, too.

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Key Facts In This Video

  1. All of our senses involve sensory cells that translate stimuli into action potentials, a process called transduction. 00:56

  2. Scientists estimate that humans can identify about 10,000 different smells. 04:39

  3. All tastes register on all parts of the tongue—there are no specialized areas for specific flavors. 07:06

Why Memories Triggered By Smells Are More Vivid

It has to do with how your brain is wired.

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Key Facts In This Video

  1. Memories linked to smells are often stronger and more vivid than those linked to sights or sounds. 00:43

  2. Other senses are routed through the thalamus, which sends them to the necessary processing centers. Smells go directly to an area linked to the memory centers of your brain. 01:19

  3. A 2013 study found that smells are more strongly connected to emotional processing centers than verbal cues are. 01:54

Why You Stop Smelling Scents You're Used To

Some think it may have been a protective adaptation.

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Key Facts In This Video

  1. You don't notice the smell of your own home because of a process called sensory adaptation. 00:26

  2. One theory states that adapting to the smells of our environment allows us to quickly notice new smells. 01:15

  3. Physical activity can slow down the olfactory adaptation process. 01:53

Doctors Can Identify Some Diseases By Smell

Different diseases let off different scents, and those can be useful for a doctor's diagnosis.

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Key Facts In This Video

  1. Different diseases give off different odors. Sometimes doctors can diagnose you based off of how you smell. 00:07

  2. If you have a burn wound infected with the bacteria Pseudomonas, it might smell like grape juice. 00:44

  3. Scientists have created electronic noses that can detect faint traces of compounds that are associated with different diseases. 01:24

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