TYPES OF COLORS IN HUMANS
- The tan, brown or chestnut contains large amounts of melanin in the iris frontal epithelium, to absorb a large amount of short-wavelength light.
- Amber is a mixture of brown and hazel. It is generated by the lipochrome.
- Hazelnut color is intermediate between brown and green.
- Green is mixture of brown and blue, or grey. In green eyes there are moderate amounts of melanin.
- Blue has very low densities of melanin pigment in the anterior epithelium. The stroma, which is a transparent tissue composed of collagen fibers, reflects outwards the light incident on the posterior epithelium. The light rays split across the stromal fibers and reflect the blue. Blue eyes first appeared 6,000 to 10,000 years in the northeast of the Black Sea, as a result of the mutation of a single individual. At present they are relatively common in Europe and other areas of continents with predominantly European ancestry. The world population estimated at about 7,000 billion, has some 150 million people with blue eyes. That is, about 2% of the whole.
- Grey. Caused by a high density of stromal tissue.