Human eye color is determined by two factors - the pigmentation of the iris and the way the iris scatters the light passing through it. Genes dictate how much melanin will be present in the eye. The more the melanin, the darker the eye. However, it might seem that in some individuals, their eye color tends to change depending on the amount of light present. This is because of the double layer of iris present in the eye. The color depends on which layer reflects the light. Approximately 79% of the world's population has brown eyes, which makes it the most common eye color in the world. After brown, 8%-10% of the world has blue eyes, 5% has amber or hazel eyes, and 2% of the world has green eyes. Rarer colored eyes include gray and red/violet.
What is the World's Most Common Eye Color? Eye Color Percentages
The brown iris is determined by its pigmentation, and can either appear as dark brown or light brown. The former results from a high concentration of melanin and is common in East Asia, Southeast Asia, and Africa. The light brown iris occurs due to a low level of melanin in the iris and is common in Europe, West Asia, and the Americas. The pigmentation of the eye is passed from parents to offspring through genetics. However, parents with brown eye color will not necessarily produce offspring with brown eye color as the variation of genes can result in another eye color.
Approximately 8% to 10% of the world has blue eyes. There is no blue pigmentation in the eye of blue-eyed people. Instead, the melanin content of iris is very low. Research conducted by the University of Copenhagen in 2008 revealed that a genetic mutation that occurred about 10,000 years ago led to the blue eye and that a gene that prevents the production of melanin in the eye could be passed genetically. Europe accounts for the largest percentage of people with blue eyes. Finland tops the list of countries with the largest percentage of blue-eyed people.
About 5% of the world has hazel eyes. The hazel color occurs due to the combination of melanin and the Rayleigh scattering of the light. Hazel eyes seem to change color from green to brown and blue. In some cases, the differences in light refraction may result in a multicolored iris where the dominant color depends on the wavelength of the light entering the eye.
About 5% of the world has amber eyes. The amber color occurs due to the presence of a yellow pigment known as lipochrome. This makes the iris portray a russet/coppery tint and a yellowish/golden color that may sometimes be confused with the hazel color. Although it is uncommon in humans, it is common in birds, fish, and canines.
Only about 2% of the world's population has green eyes. Low levels of melanin, the presence of a yellowish pigment called lipochrome, and a blue shade caused by Rayleigh scattering of reflected light act together to result in green eye color. People with green eyes are found in Central, Western, and Northern Europe.
Gray eyes are sometimes confused with light blue eyes. A low level of melanin in the front layer of the iris leads to gray eyes. The color is due to the Mie scattering of light off the darker epithelium. Gray eyes are most commonly found in Northern and Eastern Europe.
People with severe forms of albinism often have violet or red eyes. This is caused by the extremely low levels of melanin which allows the blood vessels to show through. The rate of occurrence of red/violet eyes is extremely rare.
Heterochromia-A Rare Case Of Two Eye Colours
Heterochromia is a rare case where a person exhibits two different eye colors. Complete heterochromia is when the two irises of the two eyes portray different colors. In partial heterochromia or sectoral heterochromia, the iris of one eye exhibits two different colors.
Which Eye Color is the Most Common in the World?
|Rank||Eye Color||Estimated Percentage of World Population|
|1||Brown||55% to 79%|
|2||Blue||8% to 10%|