What Is Tetrachromatism?

Tetrachromatism is a condition that arouses scientific curiosity. It is a term that refers to a visual quality and means that the  people or animals that have have a greatly increased vision index.

They can see up to 100 million colors. Tetrachromatism exists in certain animals, such as some birds, fish, insects and amphibians. The point is, apparently, some humans can also have it.

How is color vision produced?

Before explaining what tetrachromatism consists of, it is important to have some basics about how the process of vision takes place. The retina is a light-sensitive tissue  located at the back of the eyeball.

It is made up of different cells, among which rods and cones stand out. These are light sensitive cells. The cones allow you to see the colors, that is, the chromatic vision.

There are different types of cones depending on how they react to light. Most of the human population has three types. Each of them reacts to light with a different bandwidth. Information is transmitted through the optic nerve until it reaches the cerebral cortex.

Therefore, the  majority of people have the so-called  trichromatic vision. One type of cone detects red light, the other blue light, and the third type green light. In this way, it is possible to see almost 1 million different colors.

Something different happens in some types of animals, like some fish. They have a fourth type of cone that allows you to see variations for each of the colors.

What is tetrachromatism?

Tetrachromatism is a visual condition that allows you to capture a hundred times more colors than normal. It is estimated that almost 12% of all women in the world have this characteristic.

What happens is that they have a fourth type of cone. These people are called  tetrachromats . This fourth cone allows for a four-dimensional sensory color space. That is, these people have a much larger visible spectrum, as they can combine more primary colors.

The rest of the people can only make combinations with three colors (red, green and blue). These are called trichromats . This means that not all possible variations are covered.

How is it different from other categories?

Currently, there are different types of vision, depending on the cones of the retina. The first is trichromatism. It is the most common form of vision in humans.

However, vision can also be dichromatic. It is the most characteristic type in animals, such as dogs, in which there are only two cones sensitive to blue and green. Finally, we find tetrachromatism.

In practice, it is difficult to distinguish whether a person has trichromatic or tetrachromatic vision. Sometimes this can only be verified through a retinal tissue biopsy.

What causes tetrachromatism?

Apparently, this condition is almost exclusive to women.  The reason is a variation of the X chromosome, where the dichromatic gene is found.

On this chromosome are the genes responsible for the expression of red and green cones. The reason there are more in women than in men is that they have two X chromosomes, whereas men have only one.

As such, they are more likely to have two different versions of these genes. Thus, they would express four types of cones. However, this does not mean that there cannot be men with tetrachromatism.

How can it be identified?

Currently, there is no test that provides an accurate diagnosis of tetrachromatism. The  tests  online  that try to verify this condition do not have any scientific rigor.

The reason is that since they are made on digital screens, they are based on RGB technologies. That is, they are made with a trichromatic color representation system. However, methods to make an accurate diagnosis are being researched.

On the other hand, there is a way to accurately diagnose tetrachromatism, but that is a complex option. The main approach is to obtain a retinal sample. This type of biopsy is very difficult to perform as it poses many risks to the patient’s vision.

Tetrachromatism is more common than you think

Tetrachromatism is a visual condition primarily exhibited by women. It consists in the existence of one more type of cones, which are the retinal cells responsible for color vision. Normally there are three different varieties, but these people have four.

As a result, they can see almost a hundred times more colors than normal. However, currently there are no established methods for diagnosing the condition.