How is it possible to recognize different smells

So the result in question could be tens of orders of magnitude — a factor of one with dozens of zeros after it — larger or smaller than first reported. The Science paper that made such a splash sought to answer a simple question: How many different smells can the average human smell? We have clearly defined boundaries for human vision nanometer wavelengths on the electromagnetic spectrum and hearing , hertz , and we also have a pretty good understanding of the resolution of these senses—that is, how far apart two colors or frequencies have to be in order for our senses distinguish them.

Most of the scents we encounter in nature are actually mixtures of tens to hundreds of different, odorous molecules. The question of how well we can smell, then, might be reframed as this: How different do two scents have to be, in terms of their chemical makeup, for the human nose to tell them apart? They concocted mixtures of 10, 20, or 30 different fragrant compounds, drawn from a collection of scents including things like orange, spearmint, and anise.

Over and over again, it's reported that we can only distinguish between about 10, 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, to 10, 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, different scents" figure, concocted in the s, 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 s 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.

A big part of the reason it took so long to accurately gauge our scent sensitivity is that it's much more difficult to do so than, say, test the range of wavelengths of light the human eye can perceive, or the range of soundwaves the human ear can hear.

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Sense for scents traced down to genes Aug The whiff of white could hide strong odours Nov Olfactory search at high Reynolds number Sep Rockefeller University Smell Study. Noam Sobel. Reprints and Permissions. Morrison, J. Previous articles:. Several factors, including genes, skin type, and diet are related to how smells smell. Even the weather can alter an odor. Smell disorders most often stem from injuries to the head and upper respiratory infections.

Other causes include hormonal disturbances, dental problems, and exposure to chemicals such as insecticides and solvents can also cause smell disorders. Radiation for treating head or neck cancer can create smelling problems as well. A nose that's in less than tip-top condition can affect taste buds too.