Is color blindness an esper power associated with trade-offs?

So far, there are still many people who cannot clearly distinguish between color blindness and color blindness, although studies of color blindness have been established for more than 200 years . John Dalton, a famous English chemist and physicist, wrote his own experience and became the earliest research paper on color blindness.

John Dalton.

Dalton discovered that there was more than one version of color blindness. The most widely circulated story is the story of Dalton buying socks.

The story goes that when Dalton was 28, he went to the department store to choose a gift for the elderly and planned to give it to his mother on his birthday. He searched the box for brightly colored gifts and suddenly found quality socks.

The most widely circulated story is the story of Dalton buying socks.

The socks are finely crafted and most importantly they have a gray-brown appearance and are quite suitable for the elderly. But when Dalton gave her socks, the mother was shocked.

Dalton's gray-brown socks were clearly cherry red. At first, the family thought it was a funny joke. But actually, with Dalton, he actually saw the socks were a gray-brown color, and everyone didn't know what was going on with Dalton's eyes.

And Dalton became really skeptical about this issue and began to study the problem of human color vision recognition.

But the story of Dalton buying socks for his mother is just an unconfirmed story, it first appeared in his biography and is associated with many literary creations.

But Dalton's research on color blindness still exists today. He published the first paper on color blindness in 1798.

The article mentions that because of his botanical research, Dalton gradually discovered his ability to identify unusual colors during flower identification.

The process of flower color recognition by Dalton.

Through the study of color recognition issues of later scientists, it was found that there are many manifestations and variations of color vision abnormal to humans.

It is divided into panchromatic vision abnormalities (full-color abnormalities ) , two-color vision abnormalities, and monochrome vision abnormalities . It is called color blind or weak according to its degree.

Many people think that color blindness and color loss are a defect and a genetic disease, however, this view is not entirely true, human color vision is not so simple, and even in a In this respect, this issue is also considered an advantage.

Color blindness and color weakness are not inherited.

First , let's start with the evolution of the eyes. The eyes can be considered one of the most elaborate structures of the animals on earth and the mystery of its origin has also caused a lot of controversy throughout history.

Even Darwin, who proposed the theory of natural selection, had to declare that the origin of the eye is difficult to explain from an evolutionary perspective.

The origin of the eye is difficult to explain from an evolutionary perspective.

Today, we have further studies on the evolution of living organisms before we can restore the evolution of the eyes.

In the 1990s, studies of molecular evolution showed that the eyes of every living thing on earth are the product of a single origin. The earliest and most primitive eye structure is very simple, consisting of individual pigmented photoreceptor cells, called the eye point.

This simple structure can only sense light and cannot see images. But for the creatures of that period, the sudden change in light could also mean that the predators were approaching and being able to sense such a change brought a survival advantage. very big.

After this structure appeared, to better sense the change of light in specific directions, the photoreceptors gradually sunk inward.

The structure changes from a plane to a pit and a hemisphere. The final structure is like a sphere with small holes.

Eye evolution diagram.

This structure has two great advantages. One is that it has a strong orientation and can evaluate the change of light in a specific direction.

The second is to use the pinhole image principle to recognize the movement of objects. And over time, the eye eventually evolved into a high-level structure with corneas, lenses and other structures like the eyes of most advanced animals today.

Over time, the eye has evolved into a high-level structure with corneas, lenses and other structures.

Through many studies, we know today that such eyes existed from 540 million years ago. At the same time, according to evolutionary history, the structure of the eye has changed, photosensitive cells on the retina have also grown greatly compared to the early period.

In about 60 million years, the number of cones that perceive colors in the eye has increased many times. Each cone cell has a different opsin, which can sense light at different frequencies to form a color vision.

Cones in the eye.

For hundreds of millions of years later, most animals on Earth have had such eyes and could recognize many different colors, including ancestors of mammals and dinosaurs. .

In the age of dinosaurs, mammals became vulnerable and became vulnerable groups, without many environments to survive. Therefore, mammals have to find a new evolutionary way to keep their small size and still be able to survive at the foot of the great dinosaurs.

Small mammals from the time of the dinosaurs.

Because dinosaurs are cold-blooded, they will move more slowly at night because of the lower temperatures, which means that the threats of mammals are also decreasing, so most mammals are. that period lived at night.

It is also because of that habit that makes them have new requirements for the eyes to continue evolving. Because the original four types of cones are not an advantage in dark environments at night, but a major disadvantage.

Mammals lived from the late Triassic to the early Jurassic.

Under survival pressure, mammals mutated an entirely new type of rod cell based on the original cones. Rod cells do not contribute to color determination, but they can sense low light.

This change made mammals better adapted to night survival and rod cells quickly surpassed the number of cones. But that is not the end. Mammals lose two opsin afterwards and only two types of cones remain. By current standards, it is one of the states of color blindness.

The human eye has 120 million rod cells and 6 to 7 million cone cells.

About 65 million years ago, a catastrophe caused a great extinction for dinosaurs, but it was also the wing for the evolution of mammals to evolve and become the rulers of the Earth. Of course, our ancestors did not miss this opportunity and opened a new chapter in the rise of mammals.

In only 20 million years, the "blind" eyes of mammals dominated the entire continent. So far, most mammals are blinded in red and green.

But people are special cases. Some opsins perceive the color of our ancestors that underwent some mutations, the wavelength range of light has changed and we have a new opsin to be able to see those two colors.

Humans have three types of cones instead of two like other animals.

One theory is that the presence of blue and red opsin is useful for primates who find ripe fruit on the tops of trees, so this feature is maintained for humans.

Human tri-color vision cannot cover the whole visible spectrum.

Due to the ambiguous relationship between red opsin and blue opsin, the most sensitive wavelengths of these two types differ only about 30 nanometers while the normal color wavelength range is about 200 nanometers.

In fact, the three-color vision of humans cannot cover the entire visible spectrum. Compared to the eyes of birds, fish and reptiles, humans are still somewhat color blind.

Compare the color vision between human and Pippi shrimp.

In addition, because the genes that control the two opsins are so close to each other, they are not completely stable, thus losing or reducing their ability to perceive colors accordingly. This group of people is what we call patients with color blindness or patients with poor color.

Among them, red-blue or weak-color blindness is most common . They have varying degrees of color vision impairment, which is reflected in the ability to distinguish between red and green.

The tigers in the vision are blue-red, and that's why they can easily camouflage themselves in the forest, because most animals are blind in those two colors.

Such a defect should be removed under natural selection. The number of people with color vision disorders actually accounts for 7% -10% of the current total population. It is commonly believed that the incidence of this disease from recessive genetic makeup accounts for more than 5%, suggesting that this trait has certain genetic advantages.

According to an article published in 1992, patients who are color blind or weak in color have a greater yellow-brown sensitivity in comparison to the normal person. Specifically, if in the wild with the position of predators, they will be able to identify prey faster than us.

In addition, some patients with color blindness are many times more likely to see at night than normal people. Rumor has it that during World War I, the British army recruited and used weak or color-blind soldiers to patrol at night.

The advantages of this color defect can lead to a whole new perspective.

The high rate of color blindness and color loss is not because they are not naturally removed, but rather, it is likely to be retained because of advantages.

Some patients with color blindness also have many times better night vision than normal people.

If the average person has an advantage in collecting fruits because of their good color recognition, those who are colorless or weak have a great advantage in hunting.

Historically, people have changed their diet from gathering, gathering to hunting. The male members go hunting, and the female members are responsible for collecting fruits.

The environmental inappropriate characteristics have been transformed into prominent features and the number of colorblind members in the community gradually increases.

Until the explosive development of human civilization, knowledge and technology have replaced these physical abilities.

In fact, today, people who are color blind and weak become a vulnerable group, and sometimes face discrimination and prejudice.

In China, patients with color blindness face many obstacles. The first problem is driving a motor vehicle. Many countries have improved the design of traffic lights so that more people with color vision impairment can also sit in the driving position.

Traffic lights are improved for people who are color blind and weak.

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