As we go about our daily lives, the olfactory receptors in our noses are constantly picking up air borne molecules of various shapes and sizes that are then interpreted as different smells. Most of the time we are relatively unaware of this whole process until a smell becomes strong enough for us to take notice and pay attention.

We are able to detect literally thousands of different smells, which can either be perceived as neutral, pleasant or unpleasant. Interestingly, not all of us are able to detect the same smells. As each receptor in our nose is encoded by a different gene, if that gene missing in our DNA we would be unable to detect certain smells. For example, many people cannot detect the smell of camphor.

Quite often when describing smells that are pleasant we will use words like scented or having an aroma, a fragrance or a perfume but when it is unpleasant we may describe it as having a stench, or something that smells or stinks. Although we all process smells in the same way physiologically, how we actually perceive a particular smell is very much linked to psychology and our emotional responses as well as our cultural backgrounds.

So, just as we have different tastes, we can also have different perceptions of smell. What would be considered a pleasant smell to one person, may not appeal much to someone else. We only have to think about the wide variety of scents and colognes available on the market to understand that. If we all liked the same smells then there would only be variations of the same perfumes or indeed aftershaves on sale.

Why our sense of smell is very useful

There are some smells which are almost universally unpleasant. These smells can be described as sickening, repugnant and wholly undesirable to even to the most hard-nosed individuals. In these cases could our senses be warning us that something is wrong or detrimental to our health and wellbeing? It would certainly appear so. Who wouldn't prefer the aroma of freshly baked bread or the smells lingering in the countryside after a shower of rain over the putrid smell of a blocked drain or the nauseating stench of rotting meat, both of which can be hazardous to our health?

Consequently, our sense of smell can be very useful. The smell of smoke or leaking gas for example can help to warn us of impending danger, and when food begins to decay the resulting smell deters us from wanting to eat it. At the same time our sense of smell can significantly increase our enjoyment of food as it is closely linked in with the sense of taste. Pleasant smells can also help us enjoy our surroundings more. There is evidence that smells can even influence our mood, our stress levels and our physical and mental health too which is why aromatherapy has become so popular.

Finally, when we sniff the flowers in our garden or in the countryside, what we actually smell are the organic molecules or esters emanating from the flowers and it is possible to recreate these esters today to produce an amazing array of delicate fragrances and perfumes.