The human nose can pick up some one trillion different scents

"People have been talked into this idea that humans are bad at detecting smells," says researcher Leslie Vosshall. "So these findings should give the whole human race a confidence boost."
By Brooks Hays   |   March 20, 2014 at 3:51 PM
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What's that smell? It could be one of a trillion -- that's how many different scents can be discerned by the human nose and brain.

Scientists had previously estimated that humans could pick up roughly 10,000 different smells. But having finally gotten around to testing that assumption, scientists found they way underestimated.

"People have been talked into this idea that humans are bad at detecting smells," Leslie Vosshall told Science Magazine. Vosshall is the Rockefeller University neurobiologist who runs the New York City lab that hosted the olfactory study. "So these findings should give the whole human race a confidence boost."

Lead researcher Andreas Keller had volunteers try to differentiate between vials of various odors. Keller and his fellow researchers mixed and matched over 128 different odor molecules to arrive at a variety of new smells -- mixtures containing up 10, 20, or 30 different components. When allowed to smell three vials, two with the same odor and one with a different random mixture of smells, the sniffers could consistently single out the odd odor.

Based on the volunteers' performances in the lab -- plus the nearly endless combination of odors researchers could potentially create by mixing 128 molecules -- scientists crunched the numbers and determined the human nose capable of detecting one trillion different smells.

“The message here is that we have more sensitivity in our sense of smell than for which we give ourselves credit. We just don’t pay attention to it and don’t use it in everyday life,” Keller said.

And while there may not even be one trillion different smells in the world, the study offers interesting insight on how the nose and brain smell -- picking up not just one molecule at a time, but recognizing different combinations.

Vosshall says the study has other implications too.

"Knowing we have these capabilities, I hope people, as they go about their business, start saying, ‘Hey, I can smell all these things.’ Maybe the companies that make scented products will start making greater use of the human capacity and develop cleaners and perfumes with new, more interesting scents," she told Science. "Maybe we’re going to start using those corners of our smell capacity that have just not been exercised lately."

[Rockefeller University] [Science Magazine]

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