Scientists believe that until around 10 000 years ago, humans only had brown eyes. Our eyes may now have a rainbow of different colors but it hasn’t always been this way. According to a survey carried out in 2014 of 2000 Americans by the American Academy of Ophthalmology 45% of people in the US have brown eyes, while only 9% have green eyes. Globally, brown is the most common eye color, and this is the case in the US as well. Related: Will My Baby’s Eyes Change Color? People with gray eyes have low levels of melanin in the iris, just like blue eyes, but a higher-than-normal amount of collagen makes these eyes appear gray. This is exactly the same mechanism behind what makes the sky appear blue! Irises with a small amount of melanin will scatter the light and only the long wavelengths, which are blue in color, are reflected. Instead, blue eye color has to do with how eyes reflect light. It makes sense that irises with a lot of melanin are dark brown, but what is a little confusing is how having less melanin results in blue eyes. As the amount of melanin decreases, the color changes from brown to hazel eyes, then green eyes and finally blue. People with brown eyes have a lot of melanin in the iris. Melanin is a dark-colored pigment produced by different cells throughout the body and also determines skin color. Iris color exists in a continuum of different shades from light blue to dark brown and is determined by the amount of a colored pigment called melanin in the front layers of the iris. Its function is to change size to control how much light enters the eye through the hole in the center (the pupil). When we talk about someone’s eye color we are referring to the colored part of the eye called the iris. Related: Will My Baby’s Eyes Change Color? A Genetic Explanation One big question you might have is what eye color will your baby have? Science can go some way to predicting this but the genetics of eye color is a lot more complicated than you might think. What features will they inherit from Mom and Dad? If you are expecting a little one, you are probably wondering what your newborn baby will look like.
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