Ten strange facts about our sense of smell

From the time you wake up, to the moment you sleep, don’t underestimate the power of your nose. It makes your everyday eating experience pleasant and interesting and it warns us of spoiled food, and the dangers of gas or fire. It evokes strong emotional reactions and influences sexual attraction. We explore why smell is more powerful than you could have imagined.

Each individual has own distinct odour

Like fingerprints, every person has their own distinct odour. The distinct odour you have comes from the same genes that determine tissue type.

People can detect at least one trillion distinct scents

Researchers from Rockefeller University, USA, tested people’s sense of smell by using different mixtures of odour molecules.

The results, published in the journal Science, showed that the nose can smell at least one trillion distinct scents.

So how exactly does humans’ sense of smell work? When odours enter the nose, they travel to the top of the nasal cavity to the olfactory cleft where the nerves for smell are located.

There, the odourant is detected by various receptors located on the nerve cells and the combination of activated nerves travel to the brain.

The combination of activated nerves generates all the unique smells that we as humans can detect.

Women have a better sense of smell than men

The battle of the sexes rages on, but one category has a clear winner: tests have found that women have a more developed sense of smell than men, and are capable of identifying a greater number of different odours.

This is thanks to women’s orbital prefrontal region of the brain, which is more developed than their male counterpart’s.

Research shows that women have more cells in the olfactory bulb – the area of the brain that is dedicated to sense of smell – than men.

This may explain why women are reported to have a better sense of smell than men. Some believe this olfactory ability is essential for reproductive behaviours such as pair bonding and kin recognition.

It may have also evolved from an ability to discern the best possible mates, or to help women better bond with and understand newborns.

Scent cells are renewed every 30 to 60 days 

The sense of smell is the only cranial nerve — nerves that emerge from the brain and control bodily functions including eye movement, hearing, taste, and vision — that can regenerate. 

Your sense of smell shuts down when you sleep

As it turns out, the phrase wake up and smell the coffee is more true than you would imagine. 

When you are asleep, your sense of smell shuts down. You can only smell the coffee after you have woken up.

 It’s possible to smell feelings

Amazingly, our sense of smell is so developed it has been discovered that we can smell fear, disgust, happiness and even sexual arousal on other people.

A 2012 study found that smell signals exist in our sweat, helping others empathise with us when we are experiencing certain emotions.

Smell is the first sense to develop and peaks in puberty

Even before we are born, our sense of smell is fully formed and functioning.

It peaks when we are in our late teens and begins a gradual decline. People who have an impaired ability to smell, and therefore taste, tend to follow diets that are less healthy.

Smell is our most memorable sense

Have you ever wondered why a particular smell can take you back years and decades from one second to the next?

It has been discovered that we remember smells for much longer than sights, sounds, tastes and feelings.

Amazingly, people can remember smells with a 65 per cent accuracy after one year, whilst visual recall is only 50/50 after a quarter of the time.

A pleasant scent can signal powerful memories that bring us back to a great experience—while a disagreeable odour can be offensive

Loss of smell may signal future illnesses

Decreased sense of smell may be an early sign of Alzheimer’s or Parkinson’s disease.

Two studies presented at the Alzheimer’s Association International Conference 2014 found that a reduced ability to identify scents was associated with brain cell function loss and advancement to Alzheimer’s disease.

A study published in the Annals of Neurology also found that a diminished sense of smell can precede the development of Parkinson’s disease. 

Some people only receive bad smells

We thought it was bad enough suffering from anosmia, the condition in which you cannot identify any smell, but that’s nothing compared to cacosmia.

Sufferers of cacosmia will only detect disgusting scents, and even those traditional smells (freshly-baked bread et al) will smell like vomit or waste to these poor individuals. Compiled by Nailantei Norari