Oh, How He Smells Us

My living room fills with the scent of the bright orange fall candle glowing in the corner. The label calls it an “invigorating blend of aromatic eucalyptus, juniper berry, and fresh sage … as crisp as fall air.” But my nose detects another note—something waxy and warm and familiar.

It smells a little like crayons.

Suddenly, I see the torn cardboard box, the rainbow lines of nubby and worn supplies, and the textured newsprint of my Jem and the Holograms coloring book. These flashbacks prove for me what scientists have long told us, that scent is tied to memory.

Mothballs can remind us of Grandma’s wood-paneled den, cinnamon of our favorite cookies, and Vicks VapoRub of being curled up in a childhood comforter.

The portion of the brain that detects smell, the olfactory bulb, has special connections to processing memory and emotions. Unlike when we discern images of sounds, we basically detect smell by forming a memory of that smell.

We have about 400 odor sensors in our brains, called olfactory receptor proteins. Each whiff of something new—pumpkin pie, peppermint, burning leaves—activates a custom pattern of these sensors depending on the type and intensity of the smell. Since many of them will go off with each scent, scientists have struggled to identify which receptor responds to each chemical compound in a particular smell. Even with just 400 functioning sensors in the human brain (compared to over a thousand in animals like mice and dogs), the possible combinations top 1 trillion.

We have no set pathways or patterns to process a smell until we smell it for the first time, and the sensors go on and off accordingly. Every time after that, when we breathe in a scent, we return to the ...

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