Your natural skin colour is determined, predominantly, by the presence of melanin in your skin. Similarly, the colour of your eyes and hair are also controlled by the amount of melanin you have, while the amount and type of melanin produced is determined by genes.
Melanin plays an important role that is not limited to deciding what we look like! We all know that when we expose our skin to the sun, our skin darkens and ‘tans’. This is a sign that the melanin in our skin is reacting to Ultra Violet rays that are being absorbed by the skin and is trying to control and limit the amount of potentially-harmful rays that are absorbed.
Generally speaking, the more melanin contained in the skin, the greater the resistance to the harmful effects of the sun’s rays, although the reactions that take place within the skin are exactly the same, whatever the concentration of melanin.
One reaction involves the oxidising of the melanin in the skin, which results in a rapid but short-lived darkening. The other is the stimulation of melanin production, which results in a delayed but longer-lasting darkening of the skin.