Weird Medicine

Sense Of Smell May Be Capable Of Picking Up 1 Trillion Different Scents

sense of smell
Human noses, while not as powerful as the noses of dogs, might be strong in their own right: scientists believes they're capable of identifying trillions of different scents. Dennis Wong / CC BY 2.0

Humans certainly aren’t as discerning as dogs when it comes to identifying smells and following them — but that doesn’t mean that our noses aren’t capable of smelling a wide variety of different scents.

In fact, it’s likely that our noses can smell billions and even trillions of different smells. This is an overwhelming number, but it all comes down to scent, or olfactory, receptors in our nose — as the video below explains. Whenever we take a breath, air molecules enter our noses and land on the olfactory epithelium, a mucus-covered tissue lining the nasal cavity. This area is filled with millions of olfactory receptor neurons, which are smell-detecting nerves that are able to connect to and identify odor molecules.

When the odor molecules of coffee or cinnamon enter the nose, for example, they bind to specific olfactory receptors that are designed to identify that specific molecule. It’s similar to a lock and key situation; but because odor molecules have lots of different shapes that can fit in receptors, they’re capable of smelling a greater number of smells than the number of receptors that exist.

Though the exact number of our possible smells isn’t certain, scientists have recently decided that it could be as high as 1 trillion — which is enough “scratch and sniff stickers to reach from here and back to the moon, 32 times,” the speaker in the video notes. Previously, scientists had assumed our smelling range was only to 10,000, but recent research overturned that.

So while we rely primarily on our eyes and ears to get through our daily routines, don’t brush aside the importance of the human nose: On top of being a powerful trigger for memories, it can provide us with a wide palette of different smells. “Compared to our eyes and ears, our sense of smell may be the most boundless,” the speaker says.

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