Why do humans have different eye colors?

Some people have eyes that have different colored patches. For example, blue eyes with a green or brown circle around the pupil are pretty common. In these eyes, different parts of the iris make different amounts of melanin. What we don't have yet is a good handle on how this all happens genetically. read more

There's complete heterochromia, when each eye is a distinctly different color, say, one blue and one brown. Central heterochromia is when the eyes show various colors, such as a blue iris with a golden-brown ring around the pupil. read more

Brown eyes are rich in melanin deposits, and blue eyes indicate a lack of melanin. The melanocytes of the iris rest in a richly innervated psuedosyncytium, which is necessary to maintain eye color. Two genes control eye color: EYCL3, found on chromosome 15, which codes for brown/blue eye color (BEY), and EYCL1, found on chromosome 19, which codes for green/blue eye color (GEY). read more

Eye color is the result of variations in the amount of melanin, a pigment found in the front part of the iris of the eye. The lack of this pigment results in blue eyes, some pigment gives green and lots of pigment gives brown eyes. read more