The nose perceives a trillion odors

The sense of smell of humans is much more sensitive than expected

03/21/2014

The human nose can distinguish over a trillion (1,000,000,000,000) odors. This is the result of an American study by Rockefeller University in New York. The nose far surpasses the eyes and ears in perception. So far, estimates suggest that the human olfactory organ can only differentiate between about 10,000 different odors.

Nose has phenomenal abilities
The human nose can perceive significantly more odors than previously thought. This is the conclusion reached by Leslie Vosshall, an expert in olfaction at Rockefeller University, and colleagues in their study .„The message is that our sense of smell is much more sensitive than we think“, so Vosshall. „We just do not pay attention to this and put it little in everyday life.“ More than a trillion odors could perceive our nose, write the researchers in the magazine „Science“.

In the 1920s, a study came to the conclusion that the human sense of smell can distinguish around 10,000 smells. „Everyone in this industry had the suspicion that this number is ridiculously small“, explains Vosshall. But only his colleague Andreas Keller have checked the number in scientific tests.

Odors are "composed of many molecules and are very complex". According to scientists, "the scent of the rose alone consists of 275 different components, of which only a small percentage is consciously perceived". This complexity means that research into the sense of smell is much more difficult than examining sight or hearing. Compared to the nose, eyes and ears are much less true. For example, estimates suggest that the eye can see between 2.3 million to 7.5 million colors and that the hearing can register around 340,000 audible sounds.

The sense of smell today plays a subordinate role in everyday life
For their study, the researchers gave each of the test persons three ampoules containing fragrance mixtures. Two were identical, one differed in a few fragrance components. „Our trick was to use a mixture of odor molecules, and we use the share of overlapping two concoctions to measure the degree of sensitivity of the sense of smell“, reports Andreas Keller. The study participants were asked to find the sample in the tests, the smell of which differed slightly from the others. The test was repeated 264 times with each subject to obtain representative results. An extrapolation finally revealed that "the human nose can distinguish around 1,000,000,000,000 smells".

The researchers suggest that the relatively minor importance of the sense of smell today could be related to the upright gait. Because the primitive man was much closer to the ground, the source of most odors, because of his stooping hold with his nose. Add to that the habits and conveniences of the modern world, which no longer cause many odors, because they are already prevented in advance, for example, by refrigerators and daily showers. „This may explain our attitude that smelling is insignificant compared to hearing and seeing, "Keller explained, adding that the results of the study are a step towards exploring the difficult-to-grasp quantity of perception of the sense of smell, paving the way for would allow more in-depth investigations, the scientist said.