Eye Color

How Is Eye Color Determined? Everything You Needs To Know!

A person’s eye color is unique, like fingerprints. Nobody else in the world has the exact eye color as yours. What we see as eye color is really just a combination of pigments produced in one of the layers of the iris (the colored part of the eye which controls the amount of light that enters the eye). The colors of human irises range from a wide variety of hues like light blue, green, or gray to very dark brown. They vary from person to person based on the amount of a pigment called melanin produced in your body.

Is Eye Color Genetically Determined?

Earlier, we believed that eye colors are determined solely by one gene. Scientists thought that a direct inheritance pattern from both parents to a child was responsible for the level of melanin in its body. According to this theory, a child born to two brown-eyed parents should never have blue eyes. However, this is not the case in reality because eye color, like all genetic characters, depends on several other factors than direct inheritance. Over the years, studies have proved that the inheritance pattern of eye color is more complex, and depends on the eye color of parents and many relatives tracing back through generations. 

Eye Color

Sometimes, genetic mutations occur, which cause a person to have a different color of eyes than any other family members or relatives. And then there are also certain disorders such as variation of the eye color in a person, known as ‘heterochromia iridize. It may be inherited, or caused by some kind of mutation resulting in genetic mosaicism or chimerism. It could also be an effect of some disease or injury. It is determined by the production, delivery, and concentration of melanin to the eyes.

The color of your eyes is determined by many genes that work together in the formation of melanin in your body. The production of melanin is mainly the responsibility of your skin cells called melanocytes. The darkness of your eye color is linked to the high amount of melanin whereas lighter eye colors are caused by lesser melanin levels. Out of the two layers of the iris, it is the amount of melanin in the front layer called stroma that affects eye color. The back layer of the iris is brown in almost everyone.

On a wider scale, we can see some trends in the general eye color of people in certain parts of the world. For example, people of European origin are more likely to have light shades of eye color than others, whereas Asians generally have brown eyes. This puts forward a theory that eye colors are a part of human evolution and genetic diversity, linked to different races, just like other genetic features such as skin and hair color, shape, etc. This also means that it is impossible to predict the eye color of a baby.

We refer to some eye colors as black. But the truth is that it is impossible to have completely black eyes. What we see as black eyes may be very dark brown eyes. This is due to various reasons such as gene combinations and extreme heat caused by the property of black color absorbing light radiations of all wavelengths. The excess heat would cause your eyes to tear up all the time in order to maintain the moisture of your eyes.

You may be surprised to know that the rarest eye color found is, actually, green! Only about 2% of the world population have green eyes.  

There are only two pigments that color the eye- specifically two types of melanin, eumelanin and pheomelanin. But the diversity in eye colorings is caused by the variation in concentration, distribution, and the ratio between these two pigments in the outer layer stroma of the iris. The effects of light scattering also play a role in determining eye color. There are no pigments for hazel or green or blue eyes.

These eye colors are only an appearance caused by the way light strikes the layers of the iris of a person and its reflection in the eyes of a viewer. For instance, a lack of melanin would cause your eyes to appear blue. These variations depend on the distance covered by light radiation to reach the melanin-containing layers of your iris, and the wavelength of different colors in the light spectrum that can cover the distance. Some theories claim we all had brown eyes originally, and other eye colors resulted from various genetic mutations. This would imply that all blue-eyed people are somehow (very distantly) related! 

It is likely that a child’s eye color changes during the early ages. The most potent changes occur during 3-6 months after birth, and sometimes up to 1 year. In rare cases, changes occur till 3 years old or so. Anyways, a person’s permanent eye color is usually set at 1 year old, at most at 3 years old. This is due to the continuous production of melanin in the early ages.

There are claims as to certain eye colors being more attractive than others. But the truth is that each unique eye color is beautiful in its own way, just like all other aspects of human creation. Eyes are almost an epitome of human beauty in addition to other functions, and the different eye colors play a highly significant role in enhancing it.

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