Researchers determined that the human nose can detect one trillion odor mixtures; past estimates have suggested we can smell only 10,000.
"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," Leslie Vosshall, Robert Chemers Neustein Professor and head of the laboratory, said in a Rockefeller University news release.
The scents we encounter on an everyday basis are a "complex mix of molecules" the news release reported. The scent of a rose is made up of 275 components, but only a few are dominant.
In order to test the true sensitivity of the human sense of smell researchers asked participants to see if they could pick out scent mixtures that differed slightly from the others.
"Our trick is we use mixtures of odor molecules, and we use the percentage of overlap between two mixtures to measure the sensitivity of a person's sense of smell," Andreas Keller, of Rockefeller's Laboratory of Neurogenetics and Behavior, said in the news release
The mixtures were made up of 128 odor molecules that are found in scents such as "orange, anise and spearmint," the news release reported. The participants were given three vials, two were identical and one was slightly varied. The study subjects were asked to pick out which scent was different.
While the participants' ability to determine the odd scent out varied, they tended to be able to pick out the difference in mixtures containing 51 percent of the same components.
"It turns out that the resolution of the olfactory system is not extraordinary - you need to change a fair fraction of the components before the change can be reliably detected by more than 50 percent of the subjects," collaborator Marcelo O. Magnasco, head of the Laboratory of Mathematical Physics at Rockefeller, said in the news release. "However, because the number of combinations is quite literally astronomical, even after accounting for this limitation the total number of distinguishable odor combinations is quite large."
The researchers believe even the one trillion estimate is too low.
