Smell: The Olfactory Sense

Written by: Anna Pafenberg

Did you know that smell is more important than you think? The human sense of smell is called ‘Olfaction’. Our sense of smell is vital to our health in determining danger and food sources. Compared to dogs and cats, our sense of smell cannot compare. However, our detection is precise enough that it helps us greatly. 

Evolutionarily, our sense of smell is the oldest and most primal sense that humans have. It helped us in early evolution by determining safe and healthy food sources. Our nose also can sort through thousands of olfactory chemicals to determine what they are and how they affect us. Airborne cells enter the body through the nose and mouth and stick to the mucus at the back of our throats. These cells are neurons, which are cells that connect directly to the brain. The brain then processes these smells. Some of the information processed from the neurons is stored in memory, and other information triggers a response from the brain to the body to perform an action. Basically, the sense of smell among many others is controlled by your brain, not your nose! When you smell something bad, it’s your brain smelling it, not your nose. There are over 10,000 different odors, and only 400 cell types. Unfortunately, scientists don’t know why there are so few cells compared to the odors.

The part of the brain that processes smell is called the Olfactory Bulb. Coincidentally, that is connected to the Limbic system that controls human emotions. This explains why smell is the most memory invoking sense. When you smell something familiar, it triggers an emotion which in turn helps with memories. People become transported back to the moment they smelled something the second they smell it again.

The human sense of taste, called the gustatory system, relies heavily on the olfactory sense. For example, if you plug your nose when eating you might not be able to tell the difference between an apple and potato! People who have long time illnesses and a reduced sense of smell have a hard time using their gustatory sense. In ancient China, Egypt, and Greece, they developed many perfumes and products that utilized the olfactory sense. This shows that humans have always been interested in the role it plays in our lives. Considering we don’t have to use it to survive, humans have taken this prehistoric sense and turned it into a pleasurable way to communicate through senses.