Although humans now rely less on the sense of smell for their survival, it is an integral part of the evolution of our species.

Evolution of the sense of smell

In our earliest years on earth, the sense of smell was vital for both humans and animals, enabling them to locate food and water, identify danger and even choose a mate. This evolutionary importance has been underlined by studies that have found that we are better at smelling odours that are more relevant to our survival. For example, it has been found that humans are better at identifying the aromas produced by plants while animals such as dogs are better at identifying the smells of prey. This indicates that smell as a trait was passed down to us by our omnivorous, plant-gathering ancestors and, for example, to dogs by their carnivorous ancestors in order to aid survival.

The senses work together

Not only is the sense of smell an important sense in its own right, but it has a great effect on our other senses and the functions of our body and mind. For example, 80 per cent of what we taste comes from what we smell, which is why food can become bland when you are sick or have a stuffy nose. The sense of taste itself is relatively basic: there are only five predominant tastes: sweet, salty, sour, bitter and umami. Our sense of smell helps to formulate a more accurate and complex flavour profile. Because the sense of smell is so closely connected to taste, when this is impaired food can become tasteless and cause people to change what they eat.

Loss of sense of smell

From our ancestors we have also inherited innate associations with certain smells and dangers. When smelling a gas leak, smoke or rotten food, these unpleasant odours cause our bodies to send pain signals to the brain to warn of possible danger. Not only do some odours trigger self-preservation in the event of imminent danger, but the loss of the sense of smell can be an early indicator of a more distant danger. In some cases, loss of smell can be an early warning sign of serious diseases such as Parkinson's, Alzheimer's and multiple sclerosis. Loss of taste and smell has been a more commonly reported symptom of COVID-19. For some, loss of smell can be life-changing. In extreme cases, depression of smell can even lead to depression and dampening of emotions, as smell is processed in the same part of the brain as emotions. Because life always finds a way, human beings have an incredible capacity for adaptation. If anything, we can recognise the importance of smell in our lives and appreciate all that it does for us.