Brown eyes are the most popular eye color in the world, in terms of prevalence. More than 55 percent of the world's population has brown eyes.
Brown eyes are especially common in Africa and Asia, where almost all indigenous people have brown eyes. The brown color is a dominant genetic trait and is the result of melanin in the eye. Dark brown eyes may appear black in some individuals and occur as a result of a higher concentration of melanin in the eyes. In the same vein, light brown eyes are the result of lower amounts of melanin. Melanin is capable of protecting the body from certain types of cancer. Research suggests that people with brown eyes have a reduced chance of having melanoma cancer during their lifetime. In the absence of melanin, brown eyes appear blue. Green eyes are considered to be the rarest eye color in the world.