The Human Nose Can Distinguish Between One Trillion Smells

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The Human Nose Can Distinguish Between One Trillion Different Smells

New research says our olfactory system is far more sensitive than we thought
By Joseph Stromberg

smithsonianmag.com

March 20, 2014

You may have heard this one before: Humans, especially compared to animals such as dogs, have a remarkably weak sense of smell. Over and over again, it's reported that we can only distinguish between about 10,000 different scents—a large number, but one that's easily dwarfed by that of dogs, estimated to have a sense of smell that's 1,000 to 10,000 times more sensitive than ours.

It may be indisputable that dogs do have a superior sense of smell, but new research suggests that our own isn't too shabby either. And it turns out that the "10,000 different scents" figure, concocted in the 1920s, was a theoretical estimate, not based on any hard data.

When a group of researchers from the Rockefeller University sought to rigorously figure out for the first time how many scents we can distinguish, they showed the 1920s figure to be a dramatic underestimate. In a study published today in Science, they show that—at least among the 26 participants in their study—the human nose is actually capable of distinguishing between something on the order of a trillion different scents.

"The message here is that we have more sensitivity in our sense of smell than for which we give ourselves credit," Andreas Keller, an olfactory researcher at Rockefeller and lead author of the study, said in a press statement. "We just don't pay attention to it and don't use it in everyday life."
null Vials of odors used by the researchers to test participants' sense of smell. (Photo by Zach Veilleux / The Rockefeller University)
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