Although humans rely less on smell now for our survival, it has been an integral part of our species’ evolution.
In our earliest years on the earth, smell was vital for both humans and animals, as it allowed them to locate and track food and water, identify danger, and even choose a mate. This evolutionary importance was stressed when studies found that we are better at smelling scents that are more relevant to the survival of ourselves and our species. For example, humans have been found to be more apt at identifying aromas produced by plants while animals such as dogs are better at identifying scents higher in compounds associated with meaty prey. This signals that scent as a trait has been passed down by our omnivorous, plant gathering ancestors, and carnivorous, hunting ancestors in the case of dogs, in order to aid in our survival.
Not only is scent an important sense in its own right, but it has a great deal of effect on the other senses and functions of our body and mind. For instance, 80% of what we taste comes from what we smell, which is why foods can become flavorless when you’re sick or if you plug your 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 formulate a more accurate and complex flavor profile. Since smell is so closely connected to taste, when it is impaired food can become tasteless and cause people to change what they eat.
Also inherited from our ancestors are innate associations with certain scents and danger. When one smells a gas leak, smoke, or food gone bad, these unpleasant smells trigger our body to send pain signals to our brain in warning of possible danger. Not only do certain smells trigger self-preservation in cases of imminent danger, but the loss of smell can be an early indicator of a more far removed danger. In some cases, the loss of smell can be an early warning sign for the later onslaught of serious diseases like Parkinson’s, Alzheimer’s and multiple sclerosis. The loss of taste and smell has been a more commonly reported symptom of COVID-19, of which the lasting effects are not yet known. For some who experience the loss of scent, their lives can completely change. In extreme cases, smell depression can even lead to depression and blunting of emotions, as scent is processed in the same part of your brain as emotions. As life always finds a way, humans have an incredible ability to adapt. If anything, we can recognize the importance of scent in our lives and appreciate all that it does for us.