where do blue and green eyes come from
Eye color In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma.[4] The appearance of blue and green, as well as hazel eyes, results from the Tyndall scattering of light in the stroma, a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering.[5] Neither blue nor green pigments are ever present in the human iris or ocular fluid.[3][6] Eye color is thus an instance of structural color and varies depending on the lighting conditions, especially for lighter-colored eyes.
Eye color Dark brown eyes are dominant in humans[58] and in many parts of the world, it is nearly the only iris color present.[59] Dark pigment of brown eyes is common in Europe, South Europe, East Asia, Southeast Asia, Central Asia, South Asia, West Asia, Oceania, Africa, Americas, etc. as well as parts of Eastern Europe and Southern Europe.[17] The majority of people in the world overall have brown eyes to dark brown eyes.