Dark irises may have protected their eyes from being damaged by ultraviolet radiation and bright sunlight. As people moved north, sun damage was less of a problem. Eye color became lighter, which may have made it easier to see better during the cold, dark winters. Europeans have the widest variety of eye colors. Their eyes range from dark brown to light blue. In general, they have the lightest eye colors. Hazel, green, and blue eyes are common in Central and South America and some parts of the Middle East.
According to World Atlas , eye color tends to fall into these percentages:. If you have heterochromia , all or part of one of your irises is a different color than the other one.
It can be the result of:. Scientists used to think your eye color was determined by two eye color genes, one from each parent. Your eye color is determined by several genes that control melanin production in your iris.
Darker eyes have a lot of melanin, while light eyes have only a little. Melanin absorbs light. When an object absorbs light, it looks dark. Light reflected from your eye is from the blue part of the color spectrum.
Brown eyes have a lot of melanin, so they absorb light, which makes them dark. Hazel eyes have less melanin than brown eyes, but more than green eyes. Blue eyes have the least amount of melanin and reflect the most light. The gene does not create a blue iris, but rather, it turns off the mechanism that produces brown melanin pigment. Many believe that the blue-eyed gene, or indeed those for green eyes, only occurs naturally in Europeans, and that people of East Asian heritage with these eye colors are wearing color contact lenses.
The total number of search queries about Asians with blue or green eyes amounts to over 50, per year. Contrary to what many believe, blue and green eye colors do occur naturally in people of Chinese and East Asian ancestry.
As mentioned, gene mutation is one cause; the other occurs when a person of Asian ethnicity possesses Caucasian ancestry on both sides of their family who are carriers of the gene for that particular eye color. Mr Aso, seen by some as a possible successor to the prime minister, Shinzo Abe, is no stranger to controversy.
In he said a member of the burakumin, Japan's underclass, could never lead the country. He later angered Japan's indigenous Ainu population by describing the country as unique in being "one nation, one civilisation, one language, one culture and one race".
Brown melanin is the only pigment that exists in the eye; there is no pigment for hazel or green — or blue. Eyes only appear to be these colors because of the way light strikes the layers of the iris and reflects back toward the viewer.
At one time, it was believed that eye color, blue eyes included, was a simple genetic trait. Common knowledge said that you could predict a child's eye color if you knew the color of their parents' eyes, and possibly the color of their grandparents' eyes. Geneticists now know that as many as 16 different genes influence eye color to some degree — far from the one or two genes that were once believed to determine iris hue.
In addition to genetics, the anatomic structure of the iris can also affect eye color to some degree. In other words, it's impossible to know for sure if your children will have blue eyes — or any other color. Both parents may have icy blue eyes, but that's no guarantee their child's eyes will even be blue at all. Human eyes don't have their full amount of melanin pigment at birth.
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