What pigment determines eye and skin color in humans?

Melanin is the primary pigment responsible for determining the color of both eyes and skin in humans. This pigment is produced by specialized cells called melanocytes, which are located in the skin, hair follicles, and the iris of the eyes. The amount and type of melanin produced give rise to variations in color; for example, higher levels of eumelanin lead to darker skin and hair, while lower levels result in lighter colors.

In addition to melanin, other pigments and factors can influence appearance. Carotene, which is found in certain fruits and vegetables, can contribute a yellow-orange tint to the skin but is not the main determinant of skin or eye color. Hemoglobin primarily influences the color of blood and can affect skin tone due to blood flow and oxygen levels but does not determine base pigmentation. Collagen, while crucial for skin structure and elasticity, does not have any role in pigmentation.

Understanding this distinction illustrates the significant role of melanin in human pigmentation, contrasting with the other substances that impact color in different ways.