“Nothing revives the past so completely as a smell that was once associated with it”  – Vladimir Nabokov

MOST people like some smells, such as the fragrance of roses. As Shakespeare noted: “That which we call a rose by any other name would smell as sweet.” 

Some we universally don’t like, such as dirty nappies, vomit or roadkill.

At a more cerebral level, Margaret Thatcher observed icily: “I smell the stench of appeasement in the air.”

You may have wondered how smell gets from its source to us? Or perhaps not. Scientist Julius Sumner Miller would have said: “Why is it so?”

Smell travels through the air, from its source to our noses, through a process called “olfaction”. Olfaction occurs when tiny molecules from an odour-emitting source are carried through the air and reach our noses. A smell is spread more efficiently by air movement, which is why carnivore predators stalk their herbivore prey from downwind.

These odour molecules bind to specialised sensory receptors in the nasal cavity, triggering electrical signals that are sent to the brain, where they are interpreted as a particular smell.

The process of olfaction starts with the release of odour molecules into the air from a source, such as food, flowers or perfumes. These odour molecules are usually small and volatile, meaning they evaporate easily and move freely through the air. 

When an odour molecule reaches our nose, it contacts the mucus that covers the olfactory epithelium, a specialised patch of tissue located in the upper part of the nasal cavity. 

The odour molecule then binds to a specific type of receptor in the olfactory epithelium, triggering a chain of events that result in the generation of an electrical signal.

The final step in the process of olfaction is the interpretation of the electrical signals in the brain as a particular smell. This interpretation is based on patterns of activity in the olfactory bulb and other parts of the brain, as well as past experiences and memories associated with different smells. 

For example, the smell of freshly baked bread might trigger memories of childhood and evoke feelings of comfort, while the smell of bushfire smoke might trigger feelings of alarm.

In conclusion, the sense of smell is a complex process that involves the release of odour molecules into the air, the binding of these odour molecules to receptors in the nasal cavity, the transmission of electrical signals from the receptors to the brain, and the interpretation of these electrical signals as a particular smell. This process allows us to detect and experience a wide variety of different smells, and to associate these smells with memories, emotions, and other experiences.

Two interesting quotes about smells:

“A wedding is a funeral where you smell your own flowers” – Eddie Cantor

“I judge people on how they smell, not how they look” – Jennifer Lopez

On a smell-related lighter note:

A Catholic priest is driving to New York and gets stopped for speeding. The state trooper smells alcohol on the priest’s breath and sees an empty bottle on the floor of the car. He says: “Father, have you been drinking?” “Just water,” says the priest. The trooper says, “Then why do I smell wine?” The priest looks at the bottle and says, “Good Lord! He’s done it again!”

Two children order their mother to stay in bed on Mother’s Day. As she lies there looking forward to breakfast in bed, the smell of bacon floats up from the kitchen. After a good long wait she finally goes downstairs to investigate. She finds them both sitting at the table eating bacon and eggs. “As a surprise for Mother’s Day,” one explains, “we decided to cook our own breakfast.”

Julie Andrews will no longer be endorsing Revlon Vibrant Shades lipstick. She claims it breaks down too easily and makes her breath smell. In a statement she said: “The super colour fragile lipstick gives me halitosis.”

An Australian aid worker flies to Africa to do some charity work. It’s an eye-opening, shocking experience for someone who has never travelled internationally before. The poverty, the starvation, the noise, the fighting… the smell. “Yes,” she concludes, “I’m never flying economy again.”

Clive Williams is a Canberra columnist.