why do people have different skin colors
Take a. Look at the
in your neighborhood. Look at the kids in your school. Take notice of the around your town, at the mall, in church, and at sporting events. What do you notice? One thing that many Wonder Friends have noticed is that come in all sorts of colors. Why is that? noticed long ago that from parts of the world often had colors. For example, who lived in the usually had darker than who lived in. Over time, scientists who studied the human body learned that variations in appeared to be adaptive traits that were passed through genes from parents to children. These traits corresponded closely with geography and the Sun's ultraviolet (UV) radiation. A person's is determined by the amount of in his or her. is a dark brown to black produced by special cells called melanocytes. 's purpose is to protect the from the. Ultraviolet radiation can cause. acts as a natural sunscreen by absorbing these UV rays. The more your has, the darker your will be and the more protection it will have against UV rays. with light have just a little. with darker have more. with yellow tones have more or another type of called. who live in the are exposed to more of the.
As a result, their tends to become darker as the body produces more to counteract the effects of the Sun's rays. Over successive generations, genes are passed down from parents to their children, including the tendency to produce a certain amount of given the area where they live. Likewise, tend to have lighter colors, because they don't receive as many of the Sun's harmful UV rays. As a result, their bodies do not need to produce as much, which makes their lighter. Also, lighter tones in northern areas allow more UV rays to penetrate the to help produce the essential amounts of that the body needs. The body must always strike a careful balance to make sure it receives just enough UV radiation to make essential vitamin D, while avoiding overexposure that can lead to. For example, in some northern areas, such as and Canada, you'll notice that native peoples tend to have darker than you might otherwise expect.
This is usually because they eat a diet rich in seafood that provides all the vitamin D their bodies need. As a result, their produces more, which makes it darker. Of course, in today's modern world of international travel, of all races, ethnicities, and nationalities travel and live all over the globe. Their individual bodies adapt to conditions where they live over time, and they pass on these traits to their children, which helps explain the tones we see all around us every day. -A curious adult from California November 6, 2008 Human skin color can vary from almost translucent to almost black. This range of colors comes from the amount and type of a pigment called melanin found in the skin. There are two types of melanin--eumelanin and pheomelanin. In general, the more eumelanin in your skin, the darker your skin will be. People who make more pheomelanin than eumelanin tend to have lighter skin with freckles. Like many other traits, the amount and kind of pigment in your skin is controlled by genes.
The version you have of each of these genes work together to create the final product -- your skin color. To understand how this works, we'll talk about some of the genes that scientists have found that affect human coloring. And how some fish helped us find these genes! It is also interesting to think about why we have different skin colors. Later on, we'll see how vitamins and where your ancestors lived might have influenced what your skin color is. Melanin and Your Skin Melanin is made in special cells called melanocytes. These cells are found in the epidermis of your skin. There are at least three ways people can end up with different skin color. One way is if people make less pigment. Less pigment = lighter skin. Another way is when people have fewer melanocytes. Fewer melanocytes mean less pigment overall and so lighter skin. The third way is a bit more complicated and has to do with the kind of pigment someone makes. There are two types of melanin. Eumelanin is black or brown pigment and pheomelanin is red or yellow pigment.
People who make lots of pheomelanin tend to have lighter skin, often because of freckling. Freckles happen when melanocytes clump together. Melanocytes are usually spread pretty evenly in the skin. So when freckles form, some spots of the skin have lots of melanocytes (freckles) and other spots have few or none. Where there are no melanocytes, the skin is very fair. Skin Color Genes Scientists have figured out that several genes are involved in skin color. One of these genes is the melanocortin 1 receptor (MC1R). When MC1R is working well, it has melanocytes convert pheomelanin into eumelanin. If it's not working well, then pheomelanin builds up. Most people with red hair and/or very fair skin have versions of the MC1R gene that don't work well. This means they end up with lots of pheomelanin, which leads to lighter skin. (For more information on MC1R and red hair, check out. ) Two other skin color genes were first identified in fish. One gene was found in stickleback fish and the other in zebrafish.
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