• Question: Why do people have different coloured eyes? (For example blue and green)

    Asked by trin_ to Triona, Shikha, Kevin, Colin on 19 Nov 2014.
    • Photo: Shikha Sharma

      Shikha Sharma answered on 19 Nov 2014:

      Hi trin_

      The difference in color is because of pigment called melanin. The part of the eye called the iris contains pigment which is what gives us our eye color. You know the color of the underlying structure of the iris in everyone is blue, but it is the addition of the pigment melanin that gives us our varying eye colors. It is the same molecule that causes people to have skin of different shades. As no melanin in the iris means it will appear more blue. More melanin and they take on a green appearance and the eyes with the most melanin appear hazel or dark brown. How much amount of melanin you will have in your iris is decided by your genes. 🙂

    • Photo: Kevin Motherway

      Kevin Motherway answered on 19 Nov 2014:

      Just a natural variation similar to skin colour. We all probably started off with brown eyes and dark skin as Homo Sapiens came from East Africa. As we migrated north to where the sun was weaker out melanin levels dropped to allow us to get more Vitamin D from sunshine. As the melanin reduced in our skin it also did in our Iris. We all actually have blue eyes but with the addition of melanin it generates different darker colours all the way to brown which has the maximum melanin. So genetic populations such as Scandinavians that have been in the north for a long time have really light blue eyes, blond hair, fair skin. Genetic population closer to the equator have more melanin, darker skin, black hair, brown eyes! In Ireland we’r in the middle i suppose and I have green/hazel eyes. Certain areas like Galway have lots of brown eyed locals with many theories that Spanish or even Berber raiders from Algeria are responsible!