People all over the world are born with different colors of skin. And each of us have areas in our skin that are darker or lighter than other parts of our body. Because of our genes – plus something called melanin – we come in different shades of beige, tan, and brown!
What is melanin?
Melanin is the way that the body adds color to your skin. It also gives color to your hair and eyes.
The science of changing skin colors: tanning and sunburns
Have you noticed that your body can change after a long day outside? This is what happens under the skin when it turns browner or redder.
How skin tanning happens
Melanin is your body’s way of trying to protect your skin from burning. (Note the word trying, because melanin gives only some protection.) Because sun has ultraviolet (UV) rays that are harsh on skin, your melanocytes will make more melanin when they are under the sun. Usually, it takes a few hours for your melanocytes to make melanin.
So if you go outside for just a few minutes, your melanocytes would not have much time to work. But if you fall asleep on the beach for a few hours, you’ll probably wake up a different color! For example, beige skin may look a bit tanner, light brown skin may turn medium brown, and medium brown skin may turn dark brown. You might also get a sunburn.
How sunburns happen
When UV rays hurt the skin cells, the skin basically gets angry. Blood vessels dilate in that area so that more blood can flow there. This makes the skin look red and feel warm. The immune system also kicks into action and sends over white blood cells to heal and clean up damaged cells.
When the skin dies, the sunburned skin starts to peel off and feel very itchy.
People with light skin tones usually cannot make much melanin. That’s why they can easily get a sunburn. People with medium or dark skin tones can also get a sunburn, but it might take longer to happen. A sunburn is also less noticeable on darker skin.
Similar and different skin colors from family genes
Why are people born with different shades of beige and brown? This depends on our birth parents and all of the relatives that came before them – our ancestors!
Because skin cells make melanin in response to the environment, the genes in our body had to adapt.
- If our ancestors grew up in a hot and sunny part of the world, they developed darker skin. They also probably had darker hair and eye colors.
- If our ancestors grew up in a place with cold weather, they probably had lighter skin. They also probably had lighter hair and eye colors.
Over time, the genes that our ancestors passed on to their children and their children’s children.
- So if both parents have dark skin, their kids usually have dark skin.
- If both parents have light skin, their kids usually have light skin.
- If one parent has dark skin and another has light skin, their kids could have a skin color like one parent or a different shade in between.
Different skin colors around the body
No matter your skin color, many people have spots that are darker with extra melanin. This is very normal! Since they show up in different shapes and sizes, they make you unique.
Learn more about your amazing body
- EXPLORE: Amazing Facts About Your Brain, The Boss Of Your Body
- READ: Fun Human Body Books for Kids of All Ages