Skin Tones

Skin tone paletteWe human beings come in a delightful rainbow of colors, from porcelain to pink to olive and brown to darkest ebony. So while we’re not all dark skinned, in a way, we’re all “people of color,” and we have the innate intelligence of our bodies to thank for giving each of us the perfect skin tone for our native habitat.

As we developed as a species, skin color was determined by the amount of the sun’s natural radiation in our indigenous environments. The sun’s light brings many benefits – but it can harm us if we get too much. It is the job of melanocytes, specialized skin cells that respond to light, to monitor that delicate balance by producing the pigment melanin. Melanin is the source of our hair, eye, and skin color, and it protects us by absorbing harmful UV radiation.

Melanocytes produce more melanin in sun-drenched environments south of the equator and less in sun-starved northernmost environments. Melanin is Mother Nature’s original sunscreen, resulting in darker-skinned people where there is a lot of sun exposure and lighter-skinned people where there is less. Thanks to nature and parental genes, there are many variations in skin tone, depending on which of the 2 types of melanin is produced – pheomelanin (red) or eumelanin (very dark brown).

As humans migrated north from common origins in equatorial Africa, our systems and skin tones became lighter to allow our bodies to receive more sunlight, which facilitates the production of vitamin D, required for calcium absorption and bone growth. Researchers note that when human populations migrate to different UV environments, skin tones of descendants adapt within 1,000 years, turning lighter or darker in response to different requirements.

Here’s where that “delicate balance” comes into play, because there are actually two such competing requirements that affect human skin tones. On the one hand, we must be protected from too much damaging UV light. But on the other, we need a certain amount of sunlight to produce vitamin D, which is essential to the health of the human skeleton.

But there’s more to the story than just vitamin D. There is another interesting link with the effects of UV on folate, a B vitamin essential to the proper development of sperm, the spine, and neural tube – all crucial elements to survival of the species. Exposure to an hour of intense sunlight can cut folate levels in half, a situation that puts successful propagation at risk. In fact, some researchers believe that protecting folate stores in the body could be the real purpose spurring the development of darker skin tones.

So the magnificent range of human skin tones is prompted by a miraculous system that gives us precisely what we need to survive. This system is finely tuned to protect valuable folate from too much UV exposure while at the same time allowing enough light to produce valuable vitamin D – both crucial to growing embryos.

I’ve always admired the visual beauty of different skin tones. But understanding the science and purpose behind the human tapestry expands my appreciation even more. The body’s intelligence is awesome.

Published on 11/09/2009 | Last updated on 12/20/2016