Human sniff range exceeds 1 trillion odors

A new study published in the journal Science finds that the human sense of smell can detect more than 1 trillion odors, far exceeding the number previous studies have indicated.

Humans can discriminate several million different colors and nearly half a million sounds or tones, so by showing we can discriminate over 1 trillion odors, the study places the human sense of smell in a different league altogether.

The authors write that the study "demonstrates that the human olfactory system, with its hundreds of different olfactory receptors, far outperforms the other senses in the number of physically different stimuli it can discriminate."

Study leader Dr. Andreas Keller, of the Laboratory of Neurogenetics and Behavior at Rockerfeller University in New York, NY, says even 1 trillion may be an underestimate:

"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."

Head of the Lab, Prof. Leslie Vosshall, says it was generally believed that the range of the human sense of smell was around 10,000, and adds:

"Everyone in the field had the general sense that this number was ludicrously small, but Andreas was the first to put the number to a real scientific test."

The quality of an odor is a complex thing. The smells we come across in everyday life actually comprise many different molecules, of which we sense only a few. For example a rose scent has 275 molecules, but we only sense a small proportion of them.

Sense of smell is more complicated to study