Little was known about how we (humans) smell and taste until the early 1990’s when groundbreaking research revealed that humans have less than 1000 (maybe as many as 950) discrete odor receptor sites residing in the olfactory epithelium and of those many were non-functional, essentially vestigial, with only about 300 being “active” sites. Why so many of the sites were non-functional has been explained many ways most of which have to do with our diminished need to have an acute sense of smell to alert us to danger as human society developed and we became more gatherers than hunters (and less hunted). Interestingly, the case can be made that the genesis of our sense of smell was the very earliest detection biology found in single-cell life wherein exogenous chemicals were frequently hostile if not lethal to that life and the very detection of these chemical threats and “avoidance” of them was critical to the organism’s survival.
If we “practice” smelling different odor types and learn to discriminate and “learn” them it is possible as humans for us to be able to smell and differentiate among thousands of discrete odors. Some few scent experts have trained themselves to be able to identify many tens of thousands of discrete odors. When their experience is correlated with the chemical structures of these ingredients and the olfaction-to-chemical-structure relationship is learned an ability to objectively identify and characterize new, never before available odiferous chemicals is not only possible but has been observed on multiple occasions.
The obvious questions are – HOW can we smell so many discrete smells with only 300 functioning discrete receptor sites and HOW can some (few) individuals reproducibly differentiate among 100,000 discrete smells accurately? The answers are still not know for sure but scientific study is revealing that even with lesser numbers of discrete receptor sites it is possible for some individual humans to do the seemingly impossible.
For many of us the smell and taste of a fine wine or a rich, aged brandy are examples of our entry into this olfactory description world. When you recognize that our characterization of these odors, at best, only number in the hundreds you can appreciate how much more there is to experience in our mostly unknown olfactory world.
Written by Jerry Bertrand