People have skin that is white, black or yellow/orange in appearance, while some are said to have red skins. There are also subtle variations of the main colours, even amongst people of the same race, and interracial children develop unique skin colours that are based on their parents. There is also albinism, a special group of people with a skin disorder that makes them all look the same (in colour).
Why do we have all these different colours, and why do our skins respond differently when we are exposed to the sun and the elements? The answer is simple – melanin.
This is the pigment that gives the skin its colour. It is produced by special cells called melanocytes during a process called melanogenesis. According to study.com, every human being has almost the same number of melanocytes. What differs in each person is the amount of melanin that is produced. The different shades of colours seen in different people are genetically determined. But there are other factors that determine the appearance of the skin, depending on the amount of melanin that is present. These factors include:
There are many environmental factors that can determine the number of melanin deposits. Hormones can also play a role, including growth hormones and the hormonal changes that occur during pregnancy, which can lead to skin pigmentation in some women.
There are two types of melanin. These are:
Melanocytes produce melanin and transport it to the skin cells via arm-like structures called dendrites. The melanin pigments are contained in special organelles called melanosomes. The cells that receive the melanin are called keratinocytes, and the amount moved to them is demand driven. For example, if the skin is exposed to the sun (UV light), more melanin will move to the cells. This process also protects the DNA structure against UV rays damage.
A suntan is a change that occurs when more melanin is released and taken up by keratinocytes. This is a protective response to prevent further damage to the skin. So, as admirable as having a tan is, it is a sign of skin pigmentation due to UV rays damage.
The colour of dark skin is due to there being more melanin deposits in it which, in turn, is due to the melanocytes being larger. They also have more dendrites, which are larger and have more melanosomes.As a result, the overall amount of melanin transported to the keratinocytes is higher.
This offers more protection against UV rays and so dark-skinned people are better protected against photo ageing caused by these rays. This means dark skin photo ages slower than light skin. However, this doesn’t mean that dark or black skins are absolutely safe from the effects of UV rays, so the appropriate measure should always be taken against these rays.
On the other hand, light skins have:
The difference in the appearance of skin colour is also determined by the way the melanosomes are distributed. In white skins, melanin remains inside the melanosomes and is held together in the basal layer of the epidermis. Whereas in dark/black skins, melanosomes (that contain melanin pigments) move all the way to the upper part of the epidermis, where they burst and set free the melanin pigments into the keratinocytes cells. The melanin is distributed evenly, unlike in white skin.
Any changes in melanocytes production (melanogenesis) can determine the state of skin pigmentation. The distribution of melanin, and where it is deposited by the melanosomes, will also determine how the skin appears.
If you spot any type of pigmentation that has no obvious cause or makes you anxious, report it to a skin specialist for assessment.