The Science of Smell

Our senses help us understand the world around us. We are able to accomplish many tasks with the help of our hearing, sight, and feeling abilities. The sense of smell, however, can be easily overlooked. We know that animals use their overly sensitive sense of smell to figure out almost everything about their environment and other animals. When it comes to the human use of smell, it is often treated as more of a luxury sense, something that we use to enjoy the atmosphere at a restaurant or perfume store. It may be surprising to learn that humans can use their sense of smell to predict danger, recognize individuals, and discern which foods to eat.


Olfaction is the scientific name for smell. It is explained as a chemoreception that organized your sense of smell. Olfaction plays a bigger role in your life than you may think. Your sense of smell works together with our sense of taste to help you recognize different flavors. Your nasal cavity houses many olfactory receptors. Odorants connect to certain places on these receptors to alert you of a smell. Glomeruli aggregate signals take the odorants to the olfactory bulb. AT this point, the information triggers the brain with different identifying factors. These may not only be identity of familiar things, but may also be related to memory or emotion.


Scent is a big part of the attraction that occurs between two people. Pheromones are given off by the body and picked up on by the opposite sex. Pheromones may be more prominent during different times of a woman’s menstrual cycle. During ovulation, the scent may change to be more becoming to potential mates. In this case, the sense of smell helps to secure the survival of the species.

There are also studies that show smell helps to indicate whether or not two people are related. Nature has us set up to not be interested in those we are related to. When our sense of smell repels siblings as potential mates, it helps to minimize the chances of accidental incest. Our sense of smell also helps to determine the best mate for reproductive purposes. MHC (HLA) genes are necessary genes for the immune system. Children with parents that have different MHC genes often have better immune systems. When two people with the same MHC genes reproduce the offspring may not be as healthy. Olfactory senses ensure that we are normally attracted to someone with different MHC genes.


Babies are also drawn to the scent of their mother. This helps with bonding and establishes the mother as the provider of nourishment and comfort. Sometimes parents leave a piece of clothing of theirs with their babies when they go out. This familiar scent can help comfort a child. Our senses can help us positively identify those that are related to us by blood. This means that at wife cannot identify her husband or stepchildren by scent. A mother can only identify her biological offspring. Siblings are also able to recognize each other by scent. Half-siblings, however, are not able to tell that they are related using smell. The parts of the brain responsible for family identification through smell are the dorsomedial prefrontal cortex, the frontal-temporal junction, and the insula.


Animals have an advantage, as they can sense minute changes in those around them, through scent. They know when a human or animal is about to become violent or is fearful. While humans may have been more in-tune to the smells of their environment at some point, this has changed quite a bit. We often do not differentiate similar smells. This means that we may not accurately determine the onset of danger. This confusion may even enhance the possibility of anxiety disorders, such as OCD. Those with OCD and other anxiety disorders often perceive danger where there is none.

We do have some remnants of this ability left, however. We know when to throw out old food, as the smell is offensive. Recognition of this helps us avoid eating spoiled food, and becoming ill. Pregnant women have an increased sense of smell all-together. Many pregnant women report much stronger smells in their environment. This is thought to be the body’s way of protecting the baby. Some women avoid a variety of foods because the smell makes them sick. Spoiled foods are also much easier to recognize with this increased sense of smell.

Memory and Emotion

Scent is one of the strongest forms of memory. Like music, a certain smell can immediately take you back to a moment in your earlier life. This is called the “Proustian memory effect.” You may remember your grandpa’s aftershave or your grandma’s perfume perfectly well when you smell it on someone else. These memories stay with you even from early childhood. Emotion is often tied up in these memories. You may be overcome with sadness or joy upon smelling certain items. Scent is linked to associative learning. Studies have been done that issued an electric shock to individuals as they were exposed to different smells. They soon associated the smell of a certain type of grass with danger or pain. The subjects were unable to tell the different grass smells apart prior to the study, as well. The shock taught them to recognize a certain grass and to associate it with pain.

State of Mind 

Certain smells are associated with a calm state of mind. This helps people to relax with essential oils and special lotions. Plants like lavender and chamomile are considered to be relaxing scents in some parts of the world. Citrus smells, for example are associated with energy in North America. Culture and how a person is raised may play a part in what a society, as a whole, considers calming or energetic in a scent. Your memories may also easily play into your state of mind. If you have fond memories of growing up on a farm your comfort scents may be very different from a city dweller.

Our sense of smell may surprise us sometimes. We are exposed to an extreme amount of smells on a daily basis. Sometimes we do not take the time to think about each one, however. Smells that trigger memory can also bring heightened emotions. Humans learn to associate smells with certain types of stimuli and responses. Family relations and the human race are protected by the ability to discern, and non-relatives, when looking for a mate. This is nature’s way of lessening the possibility of incest. Your sense of smell can help you determine safety factors. Our olfactory abilities go far beyond what we give them credit for.

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