People can taste tens of thousands of flavors, not relying on the tongue, but on the nose

Eating is the basis for the survival of all animals, but for humans, "eating" has long surpassed the scope of survival. Since the development of human civilization, more than thousands of kinds of food have been created. The reason why we can taste so many flavors does not lie in the tongue, but in the nose.

The tongue, as a human taste organ, is actually very dull. It can only sense the five flavors of "sour, sweet, bitter, spicy, and salty". However, the world's delicacies are far from being measured by these five flavors. The reason why a dish is delicious is that it contains many unspeakable flavors, and it is not the tongue that senses these flavors, but the nose. The mouth and nose are connected. When food enters the mouth, the smell will enter the nose through the channel between the two, so the olfactory cells start to work, and we can perceive the rich flavors.

Because the nose, rather than the tongue, is the main organ that perceives taste, when a person has a stuffy nose due to a cold, the taste of everything they eat will be greatly reduced. Even some rhinitis patients will feel that food is not as delicious as before after suffering from rhinitis.

Compared to the tongue, which can only taste five flavors, the nose is really capable. So why can the nose recognize tens of thousands of flavors? Scientists have found that among the genes of mammals, the proportion of genes related to smell is very high. There are probably tens of thousands of gene types in mammals, and among these tens of thousands of genes, there are hundreds to thousands of genes related to smell. Even for animals like humans, whose sense of smell is not very good, there are more than 400 olfactory genes.

Why do olfactory genes account for such a large proportion? Biologists believe that smell is the most basic sense of living things.

Sensory organs such as vision and hearing gradually emerged on the long road of evolution. Before the emergence of vision and hearing, how did organisms seek food and avoid danger? Relying on touch is definitely not an option, because no organism can survive if it always takes risks. Organisms need a sense with predictive ability, which is the sense of smell. Through the sense of smell, organisms can perceive the chemical environment around them, so as to know where to go and where not to go. Since the sense of smell is the basic sense of organisms, it is normal for genes to account for a larger proportion. So how do these thousands of genes achieve the distinction between tens of thousands of tastes? Because each gene corresponds to a specific protein, which we call a "G protein-coupled receptor."

Taste, on the surface, seems invisible and intangible, but in fact it is a real substance.

The smells we usually talk about are gas molecules at the microscopic level. When these gas molecules enter the nasal cavity, they will meet the olfactory cells on the olfactory epithelium, where there are a large number of different types of "G protein-coupled receptors". A gas molecule can only bind to one or several G protein-coupled receptors. After binding, the G protein-coupled receptors will release G proteins, and different G proteins will release different ions through complex chemical reactions. When the olfactory cells meet these ions, they will generate electrical signals that are directly transmitted to the mitral cells in the brain. After processing these signals, the mitral cells recognize different smells.

The mitral cells simply recognize different tastes without judging them, and then transmit the taste information to other areas of the brain, which will produce different emotions, such as happiness or disgust, depending on the taste.

Therefore, the smells that everyone smells are actually the same, but different people will have different emotions about different smells. Therefore, the smells that some people like are what others want to avoid. However, it is precisely because the smells that everyone smells are the same, and the only difference is the processing of the smell information, that people's preferences for smells will also change. Some smells that you originally didn't like will no longer be so annoying after smelling them more. As a basic sense, the sense of smell is really powerful compared to other senses. It can not only distinguish tens of thousands of smells, but also has a very high sensitivity.

If someone farts around us, we will smell it after a while. But you may not know that the reason we can smell the fart is not because the smell is too strong, but because our sense of smell is too sensitive. Farts are actually almost odorless.

Farts are gases produced during the digestion process. The main components are nitrogen, hydrogen, oxygen, methane and carbon dioxide. These gases account for up to 99% of farts, and these gases are odorless. Among the farts, only one gas has a bad smell, that is hydrogen sulfide, and its proportion is less than 1%. Even this less than 1% is extremely strong to our nose, which shows how sensitive our sense of smell is.

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