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Odor Discrimination

March 26, 2014

The human nose may be capable of distinguishing one trillion unique odors.



The discerning nose. I’m Bob Hirshon and this is Science Update.

(Susanne Bard)

(Susanne Bard)

Our sense of smell isn’t nearly as sensitive as that of dogs. But according to Rockefeller University researcher Andreas Keller, we don’t give our noses enough credit. He wanted to find out how many different odors the human nose can tell apart. So he gave volunteers a series of “sniff tests”, in which they were asked to distinguish between two different odors.

ANDREAS KELLER (Rockefeller University):

And we found that if you have two mixtures and more than 50% of their components are different, people usually can discriminate them. And then we did math to calculate how many mixtures are there that all differ from one another by 50% or more, and that number is one trillion.


That might sound astronomically high, but Keller says we only encounter a small fraction of these in daily life. He adds that being able to tell whether food has spoiled by discriminating odors played a key role in human evolution. I’m Bob Hirshon, for AAAS, the science society.