Eye color is a fascinating human trait. Many with hazel eyes wonder about their unique color’s prevalence. Their distinctive appearance, which can seem to change, often sparks this interest. Exploring their characteristics and biology helps understand their place among other shades.
The Rarity of Hazel Eyes
Hazel eyes are not as common as brown or blue eyes, found in approximately 5% of the world’s population. Brown is the most widespread eye color, found in 70-79% worldwide, while blue eyes are the second most common, found in 8-10% globally. Green eyes are considered the rarest, found in about 2%. In the United States, hazel eyes are more frequent, found in roughly 18% of the population.
Defining Hazel Eye Color
Hazel is characterized by a blend of multiple hues, including brown, green, and gold or amber tones. Unlike solid colors like pure brown or blue, hazel eyes display a multi-tonal, mosaic-like pattern within the iris. Their appearance can change depending on lighting conditions or even surrounding colors. This dynamic quality contributes to their distinctive look, appearing lighter or darker throughout the day.
The Science Behind Eye Color
Eye color, including hazel, is determined by the amount and distribution of melanin within the iris. There are no actual blue, green, or hazel pigments in the human eye. Hazel eyes have a moderate concentration of melanin in the front layer of the iris, less than brown eyes but more than blue or green eyes. The unique appearance of hazel eyes results from the scattering of light by the turbid medium in the stroma of the iris, similar to Rayleigh scattering. This light scattering causes shorter wavelengths, like blue and green, to reflect more readily, creating the varied hues seen in hazel eyes.
How Eye Color is Passed Down
The inheritance of eye color is a complex process, involving multiple genes, not a simple dominant or recessive pattern. This is known as polygenic inheritance, where several genes influence eye color. Key genes, such as OCA2 and HERC2, play a role by regulating melanin production and distribution in the iris. Due to numerous genes, the exact outcome of eye color in offspring can be difficult to predict. This genetic complexity contributes to the wide spectrum of eye colors, including hazel.