Nature: Making Sense Of Smell

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Nature: Jean o’Connor sniffs around the world of olfactory research and makes sense of our sense of smell.

We all know the feeling of a memory being plucked out of the darkness through the smell of an aroma from our past, but what of the links between smell and our moods or, even more powerfully, the connection between pheromones and the survival of the species, both animal and human?

Our sense of smell, despite being a fascinating field, is one of the least studied senses. One of the odd symptoms said to be related to mild COVID-19 cases is temporary loss of smell, but more than just a passing annoyance and interference in the taste of food and drink, it’s loss could mean a lot more, as our sense of smell has been shown to be a pivotal part of a far greater array of experiences.

Memory: Why is it that certain smells bring us back to people, places or situations in such saturated clarity, more than any other channel of recall? Well, when a scent molecule arrives through the nose it is directly relayed to the amygdala, the part of the brain responsible for the processing of emotions, followed by the neighbouring hippocampus, responsible for memory formation and learning.

A smell is the only kind of information that gets telegraphed to those centres of the brain directly – all others initially getting processed through the thalamus before redistributing to other parts of the brain. This means that only smell has such a direct connection with emotions and memories.

This is why we may often initially ‘feel’ a memory via a scent, rather than see that memory in our minds. Sometimes, we may even never be able to recollect that memory related to a certain smell at all, but we will be able to feel the emotional esponse with which it was initially imprinted.

Wellness: It is because of this strong connection between our limbic, or emotional systems, and our sense of smell that odours are so strongly connected to our moods. The alerting qualities of peppermint, stimulating lemon, relaxing lavender or memory-boosting jasmine are just a few proven links between smells and our state of being.

Deeper still, we come to the world of essential oils, said to aid with everything from
childbirth to dementia and shown to reduce anxiety, lower blood pressure and
counter depression, to name but a few. Essential oils have been used all around the world for centuries.

As early as 4,500 BC, the Egyptians were using aromatic oils for many uses, including a well-known concoction called ‘Kiphi’, a mixture of 16 ingredients used both as a perfume and for its healing properties. However, it was only in 1928 that a French chemist named René-Maurice Gattefossé published the book Aromathérapie, setting out the healing properties of essential oils and becoming a popular tome for medical practices across France at the time.