Why Humans Don’t Have Black Eyes

The color of our eyes actually continues to develop and change up until we are about 3 years old. However, it’s actually impossible for human eyes to be truly black in color. Our eyes just appear to be black due to lighting, because of the reflection of the clothes we’re wearing, or the use of colored contacts.

Bright Side was curious as to why humans with naturally pure black eyes can only exist in fictional works, and we found out the following answer. We also discovered what the rarest eye color is, which you can read about at the end of the article as a bonus.

Our genes just won’t allow it.

There are about 16 different genes that are responsible for the color of our eyes. 2 of these genes are major factors, which are the HERC2 and OCA2 genes. These genes fine-tune our eye color through the amount of melanin present in our irises. The resulting colors of the melanin in our eyes can range from a wide variety of hues, like blue and gray, but the darkest possible color is very dark brown, not black.

We’d probably end up crying all the time.

Objects that are black absorb more light in order to appear really black. The excess light and energy it absorbs are converted into heat energy. That could mean that if our genes have somehow enabled us to have true black eyes, our eyes might need lots of tears to keep them from overheating and drying out.

Our eyes wouldn’t be safe against harmful light.

We would also have a hard time going out in broad daylight if we had black eyes. You see, the sun’s light rays contain ultraviolet or UV light, and black objects tend to absorb more UV light than other colors. Prolonged exposure to UV light can deteriorate our eye health and lead to problems, like cataracts or skin cancer. Thanks to our genetic makeup though, the melanin that provides color in our irises protects us from ultraviolet light. Studies show that melanin can annihilate over 99.9% of the UV radiation that it absorbs, protecting our eyes from damage due to being exposed to the sun.

Bonus: the rarest natural eye color

The rarest natural eye color is actually green. There are only about 2% of the entire world’s population that have green eyes. There are also some rare conditions where people have red or violet eyes due to ocular albinism, and others have different colored irises for each eye due to heterochromia.

What color are your eyes? Which eye color is your favorite, or which hue do you wish you had?