Our skin is composed of several layers. Melanocytes are the cells that reside in the bottom portion of the epidermis, the outer most layer of skin cells. They are responsible for producing melanin, the pigment that determines the color of one’s skin.
The actual process in which melanin is produced is a bit complicated. In order to produce melanin, the melanocyte cells synthesize ultraviolet radiation (UV light) from the sun and the amino acid tyrosine, which is found in foods that are high in protein, such as beef, turkey, and dairy products.
What is the purpose of this process? Think of melanin as sun protection. Longer periods of exposure to the sun result in increased melanin production. The more melanin that is produced, the darker the skin becomes. This reduces the amount of radiation that is absorbed and protects the skin from the harmful side effects of the UV light, such as sunburn and, worse case scenario, skin cancer.
However there is a limit to how much protection can be offered. Those with higher melanin levels, and therefore higher concentrations of pigmentation, are generally less prone to the adverse side affects of sun exposure. That does not mean that darker skinned people cannot get sunburned or develop skin cancer. It just means they are less susceptible.
Melanocytes are the little factories inside our skin that are responsible for producing melanin. The process is called melanogenesis. All skin types have a minimum level of melanogenesis, which defines the “base” skin color. Increased exposure to UV light, primarily UV-B light, increases the melanogenesis rate of melanin production resulting in darker skin and a number of milder side effects such as age spots on hands.
Interestingly enough, melanogenesis, due to melanin’s genetic component, is actually a mild form of damage to the DNA that controls the production of tyrosine. So the price of a great tan may not be that high in the short term, but future generations may feel the effects of an increased tendency towards higher levels of melanocyte cells.
Although the difference may not be noticed by you or your children, or even your grandchildren, gradually those in your family tree who share the same genetic predisposition as you will begin to show darker complexions from birth due to the genetics of being exposed to the sun.
Melanocyte Stimulating Hormones
Melanocyte activity is controlled by a melanocyte stimulating hormone produced in the pituitary gland. They are referred to collectively as MSH or intermedins. Synthetic versions are in the works, so soon you will be able to get a killer tan just by taking a supplement.
These melanocyte stimulating hormones are the top of the ladder in the pigment management game, but they are still susceptible to outside forces. In the case of pregnant women, the increase in estrogen hormones often causes skin to darken, including areas not exposed to the sun such as nipples and the inside of the cheeks. In addition, old scars may darken as damaged melanocytes provide a boost of invigorating chemicals.
The opposite is also true as a deficiency of hormones can cause a drop in the production of the amino acids responsible for the production of melanin, which can lead to lightening of the skin. In this situation is it important to realize the increased risk of sunburn and its possible complications, especially for older women who are more susceptible to such deficiencies.
Melanocytes – A Balancing Act
It is important to remember that while melanocytes are critical to the production of pigment, they are also only a single cog in a complex system. While the body has many different systems, they are all tied to one central command control, and all these systems must work as a single unit.
In this case, for example, the skin must balance the intake and the blocking of ultraviolet radiation in order to compensate for a lack of vitamin D that might be present if there is not enough exposure of skin to the sun. While too much sun can be dangerous, it is important to expose the skin in order to receive enough vitamin D to stay healthy.
The theory behind varied skin colors comes from dark skinned humans migrating north, where sun exposure was less intense. In response, skin produced less melanocytes, which resulted in reduced melanin production. This allow more vitamin D to be absorbed through the skin.
This issue was compounded when humans abandoned the migratory hunter gatherer lifestyle (an outdoor lifestyle) for the agricultural town lifestyle (more of an indoor lifestyle). Compounding further, several food items that were naturally high in vitamin D dropped out of common circulation, and so a further scale back of melanin occurred.
Genetic and Hormonal Variations
It is important to remember that melanocytes are controlled by both genetic and hormonal variations, and because of this their levels and the effects of their influence are difficult to predict even from within the womb. It is because of these factors and the endless combinations that are possible between the various human races that we see the grand variety of skin tones that are common today.
Scottish to Scottish child bearing will, of course, produce a child with Scottish skin features. Contrarily, what type of skin tone would a third generation Pakistani woman and an indigenous Scandinavian man produce?
It is the combination of a multitude of factors that creates the millions of tiny variations in each individual melanocyte required to make each of us unique.
So, what are melanocytes, you may still ask? They are the brains behind our skin, the control for our protection from the harmful radiation of space. Without them there would be no melanin and we would all be running around as sunburned albinos.
In the same way that tyrosine allows plants to benefit from the sun’s rays instead of being destroyed by them, it allows us to survive the radiation and even glean something useful in the process. Without melanin and the pigment it creates, the pleasant warmth of the sun would become deadly radiation penetrating to our bones, and we would be far more susceptible to the damages and complications arising from skin cancer, in all its various forms.
Simply put, melanocytes were an important step in evolution that allowed mammals and humans to flourish, and is the reason that we are able to go outside and enjoy the world without having to worry, too much, about irreparable damage to our flimsy bodies.