There have been plenty of studies on the human vision and hearing senses, but there is rarely one on our smelling sense. But this time, a group of researchers at Rockefeller University in NYC decided to break the rule and have arrived to a fascinating conclusion.
Normally, a smell is a mixture of hundreds of different odorant molecules, and particular combinations of these give rise to a variety of smells, such as chocolate and flowers.
Based on this idea, these scientists produced three types of mixtures out of 128 odours, having 10, 20 or 30 of them in each mixture with different combinations. These were then given to a group of inexperienced volunteers, in the form of three samples: two of the same mixture and a different one.
Results were collected, and using mathematics such as the probability theory, they reached the verdict that there were more than a trillion combinations of those odours, which is also quite an underestimate since there are many more existing odours.
These results differ drastically from previous experiments, like the last one, made in the 1927, which said that humans were able to tell only 10,000 smells apart.
Not only that, but it also makes the olfactory sense defeat the visual sense since it can distinguish far more stimuli. In fact, the human eye can differentiate 10 million colours (which is still pretty good), but means that our sense of smell is 100,000 times more varied than the sense of vision.
The obvious conclusion was that the more common odorants two substances shared, the harder it was to distinguish them. However, volunteers proved to be quite good at distinguishing smells, but not as good at naming them. A possible reason is that although we have more than 400 receptors in our nose, the olfactory nerves are not connected to the area in the brain where language is used.
It is still very remarkable that humans have the capability of setting apart such a great number of smells, and scientists are already working on expanding their knowledge on the smelling sense using this investigation and its consequences.