The Sense of Smell Ensures Your Survival
The sense of taste and smell is one of our most influential senses. Emotions and experiences that we associate with taste and smell often determine whether we like the food or think something smells bad. While menthol scent makes some think of sweets, others think of medicine and sore throat.
The sense of taste is vital for our well-being and our survival
Tongue taste buds
It is the last checkpoint before we eat or drink potentially harmful things. The taste must both assess the nutritional value of the food and protect us from eating something poisonous.
The papillae are on the upper side of the tongue. The taste buds sit on the papillae and differentiate between the different flavors.
- Salt food maintains the body's salt balance. Available in capers, salted nuts, and soy.
- Toxic or spoiled foods often taste sour. Also available in lemons and other harmless foods.
- Sweet foods contain carbohydrates that provide energy. Available in fruits, berries, honey, and syrups.
- Many poisonous plants taste bitter. Also available in coffee and dark chocolate, for example.
- Amino acids, which are building blocks for enzymes and proteins in the body, give the umami taste. The taste is found in, among other things, broth, parmesan cheese, fish, seafood, mushrooms, and seaweed.
The sense of smell is one of the oldest senses in mammals, and although humans have a bad sense of smell compared to dogs, for example, scents play a vital role in our lives.
Taste impressions not only arise with the taste of the tongue but are a combination of taste and smell. When we are cold, the food loses much of its flavor.
Odor impressions are created when scent molecules stimulate scent cells in the mucous membrane of the nose. The nerve strands of the cells run through small holes in the bottom of the skull to the olfactory nerve and from there to various centers in the brain.
Taste impressions arise when stimulation of the tongue’s taste buds by molecules dissolved in the saliva of the mouth. In total, we can register five different flavors: sweet, sour, salty, bitter, and umami.
All taste impressions are different combinations of these five
In addition to giving the food a taste, the sense of smell and taste prevents us from eating or breathing in harmful substances that smell or taste bad, such as ammonia steam or sour milk.
Body smells play an essential role for parents to recognize their children and for newborns’ ability to distinguish their mother from all other mothers. Smells also affect our sexual behavior.
For example, women are more attracted to men who smell of the male sex hormone testosterone when they ovulate than at other times in the menstrual cycle.
Previous studies have shown that we prefer the scent of a person who has an immune system that differs as much as possible from our own. This is especially appropriate when it comes to having healthy children.
Although the ability to distinguish between the five taste impressions is innate, neither the taste nor the sense of smell is fully developed at birth. Some newborns think about the smell of rotten onions as badly as the smell of licorice, while others like the smell of sweat instead.
The feelings we get when we smell or taste something greatly influence how we later perceive the impressions. If we eat spaghetti and shortly afterward get stomach upset, we probably won’t be sucked on spaghetti for a while eventually. By contrast, the scent of Christmas food certainly evokes positive memories in many.
Our genes also seem to play a role in what flavors we like. People who do not like lemons and vinegar may have more genes for the sour taste and even higher sensitivity than people who cannot feel the taste of sour as well.
One of the reasons why our sense of taste and smell is not fully developed at birth is that humans can live in many different ecosystems.
We need to learn how to distinguish between edible and non-edible potential foods in different places, such as fish in the sea or fruits in the forest.
It would be an obvious problem if we were born with a preference for fish, but lived in the middle of a desert. The sense of taste and smell thus helps us survive in almost any place on earth.
The fifth flavor
For decades, schoolchildren had learned that the tongue has taste buds for four taste impressions: sweet, sour, salty, and bitter. In 1908, however, the Japanese chemist Kikunae Ikeda (1864-1936) discovered that there is a fifth flavor: Umami. Ikeda opened his eyes to the taste of umami when he ate dashi, a traditional Japanese seaweed soup.
The soup had a familiar taste, which was neither sweet, sour, bitter, nor salty. In the laboratory, Ikeda discovered that the secret taste came from the amino acid L-glutamate, and he called the taste “umami”, which means “good” in Japanese.
Fat, carbohydrates, and proteins in the food are in themselves tasteless, but trigger taste impressions through their degradation products. The individual sugar molecules from carbohydrates, mono- and disaccharides taste sweet while L-glutamate, which is the most common building block in proteins, gives the taste of umami.
Umami is quite weak even in high concentrations. However, since the 1980s, research on the taste sense has increased, and in 2002 researchers found the taste receptor that allows us to feel the taste of umami in protein-rich foods.