Why do people have different eye colors?

A basic characteristic of humans is the color of their eyes. Whether brown, blue or green – this is also shown in the passport, among other things. But why do people have different eye colors?

iris and pupil

The iris or iris is the colored part of the eye and represents a kind of diaphragm for the eye. It controls the incidence of light: when it is bright, it narrows – the incidence of light becomes less. The iris acts like the aperture of a camera. The activity of these muscles is controlled by nerves and happens unconsciously for humans. The  pupil  is the opening in the iris that allows light to enter the eye. The pupil is at its smallest (1.2mm) in bright light and at its largest (9mm) in the dark.

How does the color of the eyes come about?

The pigment melanin, which also determines the tone of skin and hair, is responsible for eye color. Depending on how much pigment is stored in the cells, the eyes also get their individual color. A high concentration of melanin results in brown eyes; these people also tend to have darker skin than others. Conversely, one rarely sees someone with dark hair and blue eyes. A lower pigment content makes the iris appear green, blue or grey, depending on the dosage. The less melanin, the bluer eyes a person has.

As babies, we usually have blue eyes…

The final color is genetically determined. The iris is still light blue in the womb and only later reaches its full colour. The reason: the pigment only develops in the body in the first few years of life. This means that the color of the eyes also changes with age.

Eye color – an unchanging feature

Once this process has come to a standstill, our eye color always remains the same. So if you have brown eyes, you can no longer get blue ones and vice versa, blue-eyed people have blue eyes their entire lives. By the way : If you still want to try a different eye color, you have this option with the so-called iris lenses.