Youtor
The science of colour of eye and skin melanin science
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The color of human skin and eyes is determined primarily by genetics and is influenced by two types of melanin: eumelanin and pheomelanin. Melanin is a pigment that is produced by cells known as melanocytes in the skin and eyes. • *Eye Color:* • Eye color depends on the amount and type of pigments in the eye's iris, as well as how the iris scatters light that passes through it. The iris has a front and a back layer (the stroma and the epithelium, respectively). Both layers contain pigmented cells. • Generally, people with brown eyes have a high amount of melanin in the iris, which absorbs more light and results in a darker color. People with green or hazel eyes have less melanin, and their eyes can scatter light in a way that makes them appear green, blue, or gray. This is due to a phenomenon called Rayleigh scattering, the same principle that makes the sky appear blue. • A person's exact eye color can also be influenced by other pigments, such as lipofuscin (yellow to red pigments), and the blood vessels in the eye. • Blue eyes, interestingly, contain very low levels of melanin within the iris stroma (front layer of the iris), which lies over the dark epithelium layer. Rather than reflecting more blue light, blue eyes are actually a result of the light scattering effect mentioned above. • The exact determination of eye color is complex and not fully understood. It's controlled by multiple genes, and there's ongoing scientific research to pinpoint all the genes and their interactions that influence human eye color. • Skin Color • Skin color is determined by the amount, type, and distribution of melanin within the skin. Eumelanin, which is brown or black, can cause skin to darken or tan. Pheomelanin, which is yellow or red, can lead to freckles and affects the color of lips, nipples, and genitals. • People with darker skin typically have more melanin, specifically eumelanin. This gives the skin a brown or black appearance. People with lighter skin have less melanin and more pheomelanin, leading to a red, yellow, or pale appearance. • Environmental factors can also influence skin color. For instance, sunlight exposure can stimulate melanin production, leading to a tan or freckles. This is the body's way of protecting the skin from UV radiation, which can cause skin damage and cancer. • Like eye color, skin color is influenced by multiple genes. The MC1R gene is a major determinant of skin color, but there are many other genes that contribute as well. • Changes in skin color can be due to genetic mutations, certain diseases or conditions, or aging. For instance, albinism is a condition where the body produces little or no melanin, leading to very light skin and hair color, as well as vision problems. • It's important to note that variations in human skin and eye color are adaptations to our environments and are part of human diversity. Skin and eye color have no bearing on a person's intelligence, abilities, or worth. • subscribe @Factosci
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