How far are our eyes?

Do you know how far you can see, how many colors, how many times each day?

The eyes are the "window of the soul" of each person, connecting us to the world around us. Although familiar, there are certainly many interesting things about this "friend" that we've never heard of.

There are many interesting things about human eyes - (Photo: Open Walls).

At first, the eyes are all brown

The color of the eye is due to the amount of melanin pigment in the cells in the iris decided.

The Science Daily page said about 6,000-10,000 years ago, the human eye was only brown, then mutations affecting the OCA2 gene in the chromosome could help create other colors.

OCA2 gene helps to encode P protein which is related to the ability to produce melanin, pigment to create hair color, eye color, skin color for humans.

The more melanin, the darker the eyes will be brown. In contrast, less melanin, the eyes will be blue or green.

Brown is the original color of the eye, is also the most popular color today - (Photo: Getty Images).

How far can human eyes see on Earth?

According to the Livescience page, spherical by the Earth, the human eye can only see up to 5km because of the horizon.

Therefore, if the Earth is flat or standing on a high hill, you can see much further: you can see a light source hundreds of kilometers away. Or in completely dark nights, you can even see a candle up to 48km away.

2 eyes have independent blind spots

Each side of the human eye has a blind spot on the retina. Called blind spot is because there is no nerve to receive light.

But according to Discoveryeye, 2 eyes work at the same time so we don't feel these blind spots because they compensate for each other.

Children do not have tears

Babies cry a lot but we don't see tears - (Photo: Getty Images).

Do you find that babies are very crying from birth? But they just cried without tears. The reason is that the gland in babies is not fully developed, it must be from 1 to 3 months of age, babies can cry as usual.

Before that, babies just tear up their eyes to moisten their eyes. However, if the baby is still out of tears after 3 months, they should go to the doctor because they may have a lacrimal gland.

Recognize 10 million colors

In the book Color in Business, Science and Industry of American physicist Deane B. Judd, the human eye has 3 types of cone cells to recognize the three basic colors: red, green and blue.

In nature, these three colors can be combined to produce a multitude of colors. In the eyes, cones can also be combined to help the body recognize a diverse palette.

Estimates of human eyes can distinguish 10 million different colors.

Lightning 28,800 times a day

Scientists point out that the average eye blinks 15-20 times per minute, counting 1,200 times per hour and 28,800 times per day to keep the eyes moist.

Thus, the time of close-eye plays 10% of our wake time.

The most active eye muscles in the body

World Record Book estimates that eye muscles operate more than 100,000 times per day. Even when sleeping, eye muscles still have some activity, including rapid eye movement.

Only 8% of the population has blue eyes

Taylor Swift is one of the famous artists with beautiful blue eyes - (Photo: Meghan Mahar).

Brown eyes are the most popular in the world today with about 55%, which covers almost all African and Asian people.

Brown eyes are dominated by genes that regulate traits, which partly explains its popularity.

In contrast, blue eyes are recessive genes formed by a lack of pigment in the eye. Green eyes are less common than brown eyes in the world, estimated to be around 8% globally but are very common in Baltic and Northern European waters. In particular, Finland is the country with the most blue-eyed people in the world.

Green eyes are less common, only about 2% of the world's population, mainly in northern and central Europe.