Scientists have only speculated when the mutation occurred, and blue eyes appeared in humans, but some signs indicate that this most likely happened a few decades ago. During this period, there was a massive settlement of Europe, as agriculture from the Middle East began to spread to European countries.
Origin
Human Genetics magazine posted a note by scientists that the mutation that caused the appearance of blue eyes was likely to have occurred in the northwest of the Black Sea region.
Professor Eyberg noted that, by default, the color of human eyes should be brown. Dark blue eyes are the result of a mutation, because the dark skin pigment, melanin, affects the appearance of brown-eyed babies. However, in Northern Europe, the OCA2 gene underwent changes that disrupted the production of melanin in the iris, resulting in a blue color.
Professor Eyberg noted that everyone had brown eyes at first, but the mutation in our OCA2 gene chromosomes caused a “transformation” that “disabled” people's ability to produce brown.
In the iris, the amount of melanin varies, so brown tones are different. Blue eyes are people who had a common ancestor who changed the gene. All of them inherited the same mutation of their DNA.
Blue-eyed men and women have an almost identical genetic sequence of that part of the DNA molecule that is responsible for eye color.
Professor Ayberg analyzed the DNA of more than 800 people, from white-skinned Scandinavians blond to people with dark skin, but with blue eyes, living in Turkey and Jordan. His experiment confirmed the hypothesis of a single common ancestor.
It is not clear why blue eyes are more common among the population of southern Russia and northern Europe. It was previously assumed that this feature gives some advantage in summer white nights or in winter polar nights. Maybe this is considered more attractive and, therefore, the most favorable for sexual selection.
Features
Anatomically, the iris includes the ectoderm and mesoderm. The color depends on how pigment is distributed in them. Chromatophores are distributed in the mesoderm layer, they contain melanin. The back layer contains many pigment cells filled with fuscin.
Fibers and vessels of the iris also play a role.
The main light colors are blue, blue and gray.
The ectodermal layer is inherent in a dark blue color. If the external fibers of the iris have a low density and low melanin content, then high-frequency light is absorbed by the mesoderm layer, and low-frequency light is reflected from it. Blue eyes are the result of such refraction.
There are people who dream of changing their natural color to blue. They believe that the look will acquire beauty, depth and saturation. Most often, blue eyes are considered attractive, photos of blue-eyed people can be decorated using some programs, in particular photoshop. By experimenting with computer effects, you can choose your makeup and the right makeup.
