How did we get the color of our skin?

Skin color is primarily determined by our genes, but exposure to sunlight throughout our lifetime plays a part, too. Many of the cells in our body contain a pigment called melanin. Not only is this pigment responsible for giving the color of our skin, eyes, and hair, it also helps to protect against damage from the sun.

Ultraviolet rays can damage skin cells and even contribute to conditions like skin cancer. People whose ancestors have...

Skin color is primarily determined by our genes, but exposure to sunlight throughout our lifetime plays a part, too. Many of the cells in our body contain a pigment called melanin. Not only is this pigment responsible for giving the color of our skin, eyes, and hair, it also helps to protect against damage from the sun.

Ultraviolet rays can damage skin cells and even contribute to conditions like skin cancer. People whose ancestors have historically lived in a place with lots of sun exposure typically have more melanin present, and therefore darker skin, hair, and eyes. Similarly, people whose ancestors come from a part of the world where sun exposure is limited (like the poles) typically have less melanin and more fair complexions. 

Unless someone is born with albinism, where the body has no melanin, even the fairest-skinned person has a little bit of  melanin in their cells. The more we expose our skin to sunlight, the more melanin is produced. This is the body's way of protecting against sun damage. Some people find that their "tan" will fade after decreasing exposure to the sun, but long periods of prolonged or frequent sun exposure can result in a long-term increase in pigmentation of the skin.