The Color of Our Eyes

The color of our eyes is one of our most unique and beautiful physical characteristics and has some fascinating biology behind it

By Ioana Moga

Photo by Arteum.ro on Unsplash

Eye color is determined by the amount and type of pigments present in the iris, which is the colored part of the eye. The origins and science behind eye color are fascinating and have been the subject of many studies over the years.

Our genetic makeup is what determines the color of our eyes. Eye color is an inherited trait that is passed down from our parents and can be influenced by generations preceding them. The gene that determines eye color is called the OCA2 gene. This gene provides the instructions for making a protein that helps produce melanin, the pigment that gives color to our skin, hair, and eyes.

The science behind the color of our eyes is quite complex and very fascinating. The iris contains two layers of cells: the anterior layer and the posterior layer. The anterior layer contains the stroma, a layer of connective tissue that contains collagen and other proteins; the posterior layer contains the pigment-producing cells called melanocytes.

A light micrograph showing a transverse section of the pupillary portion of the iris that consists of its sphincter muscle. Source: https://basicmedicalkey.com/uvea/

The amount and type of pigments present in the iris determine the color of our eyes.

Brown eyes have a high concentration of melanin, while blue eyes have a lower concentration of melanin. Green eyes are a result of a combination of blue and brown pigments in the iris. There are different types of melanin, such as eumelanin and pheomelanin. Eumelanin is responsible for brown and black pigments, while pheomelanin is responsible for red and yellow pigments. The combination and concentration of these pigments in the iris can create a wide variety of eye colors, ranging from brown to green to blue.

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Epigenetic Factors Affecting Eye Color

While genetics is the primary determining factor for our eye color, several environmental factors can also play a significant role in shaping the color of our eyes. One such factor is sunlight exposure. Studies have shown that prolonged exposure to sunlight can lead to an increase in melanin production in the iris, resulting in a darker eye color. Melanin acts as a natural defence mechanism against harmful ultraviolet (UV) rays, which can cause damage to our eyes. The more melanin present in the iris, the better it can protect the eyes from UV radiation. As a result, people living in areas with intense sunlight exposure tend to have darker eye colors, as their bodies produce more melanin to protect their eyes.

To wrap things up, the color of our eyes is a complex and fascinating feature that is determined primarily by our genes and influenced by environmental factors such as sunlight exposure. The combination of such factors, in different proportions, is the reason we each have a distinctive eye colour that’s far more unique than our fingerprints. It is important to understand that the science behind eye color is still being studied, and new discoveries are constantly being made every day that slightly redefine how we comprehend eye color and the factors that affect it. I hope you got to the end of this article and learned new information about this unique physical feature that each and every one of us has.

Bibliography

https://www.sciencefocus.com/the-human-body/why-do-our-eyes-come-in-different-colours

https://www.edow.com/general-eye-care/eyecolor/

https://my.clevelandclinic.org/health/articles/21576-eye-colors