Why can’t human eyes be black?

Why can’t human eyes be black?



Our eye color changes from the moment we are born until we reach the age of 3. However, contrary to popular belief, it is impossible for people to have completely black eyes. Your eye color may look black due to the ambient light, the clothing you wear, or if you are wearing colored lenses.

There are about 16 genes involved in eye color. Two of these genes, HERC2 and OCA2, are essential in eye color formation. These genes determine our eye color through the amount of Melanin in the eye iris. The colors that occur due to melanin can be very diverse, such as blue and gray. However, the darkest possible eye color is dark brown, not black.

Black objects absorb more light to appear blacker. The excess light and energy absorbed is also converted into heat energy. This means that even if it was possible for us to be genetically black-eyed, we would have to constantly shed tears to keep our eyes from drying out and getting hot!

If our eyes were black, we would have a hard time getting into daylight. Since the sun contains UV rays and the black color absorbs more light, prolonged exposure to UV rays could cause health problems such as skin cancer or cataracts. Studies show that the melanin, which makes up our eye color, protects the eyes by destroying 99 percent of the UV rays coming from the sun to the eye. This means that melanin effect is great in preventing damages due to UV rays.

The rarest eye color in the world is green. Only 2 percent of the world’s population is green eyed. In addition, there are rare people who have red or purple eyes due to ocular albinism. Different colored eyes may also be encountered due to heterochromia.

Translated by: Dilara Preserve

Reference: BirghtSide. Why Humans Don’t Have Black Eyes ?. Taken from: https://brightside.me/wonder-curiosities/why-humans-dont-have-black-eyes-801750/


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