system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do our eyes have color? Is there a role that the iris having a color plays?
gpt
If the iris wasn’t coloured, the amount of light entering our pupil would actually be increased due to the thinness of the membrane. Everyone technically has blue eyes (afaik) and then additional melanin deposits on top, adding to the brown colour. The darker it is, the more light it absorbs and the less light enters the eye. This acts in addition to the standard dilation and contraction.