Although darkly-pigmented skin absorbs about 30 to 40% more sunlight than lightly pigmented skin, dark skin does not increase the body's internal heat intake in conditions of intense solar radiation. Solar radiation heats up the body's surface and not the interior.
Skin with more melanin defends better against sun rays, protecting better against sun burns and skin cancer. It has nothing to do with their body temperature.
For example, sun exposure in people who live close to the equator leads to melanin build-up, which protects them from UV damage, but also makes skin darker. The same skin cell (melanocytes) that produces melanin releases dopamine, which will increase skin's sensitivity to heat.
A person with dark skin absorbs more heat radiation and feels more heat. It also radiates more heat and feels more cold.
Melanin helps block out damaging UV rays up to a point, which is why people with naturally darker skin are less likely to get a sunburn. People with lighter or more pale skin have less melanin. They are more likely to burn from UV rays rather than tan.
Dark skin can get sunburn
Dark skin has more melanin, which is the substance that creates color in skin, eyes and hair. If your skin is darker, it means you have more of a type of melanin that can absorb a certain amount of the sun's harmful ultraviolet rays. But likely won't be enough to completely prevent sunburn.
When you spend time out in the sun, your body produces more melanin. The substance absorbs light from UV rays and redistributes it toward the upper layers of skin. It also protects the genetic material stored in your cells by keeping out harmful UV rays.
The melanin in darker skin also prevents photoaging by helping to protect the elastic fibers, etc. Therefore, deep wrinkles are less common.
Researchers agree that our early australopithecine ancestors in Africa probably had light skin beneath hairy pelts. “If you shave a chimpanzee, its skin is light,” says evolutionary geneticist Sarah Tishkoff of the University of Pennsylvania, the lead author of the new study.
People with very light skin (types I and II) make very little melanin in their melanocytes, and have very little or no ability to produce melanin in the stimulus of UV radiation. This can result in frequent sunburns and a more dangerous, but invisible, damage done to connective tissue and DNA underlying the skin.
The assumption that black individuals are genetically predisposed to withstand heat is a dangerous one. In the USA, the heat-related death rate is approximately four times higher in a black as opposed to a white population.
White skin, for example, was reported to be more resistant to cold weather, although groups like the Inuit are both dark and particularly resistant to cold.
The skin's immense blood supply helps regulate temperature: dilated vessels allow for heat loss, while constricted vessels retain heat. The skin regulates body temperature with its blood supply. The skin assists in homeostasis. Humidity affects thermoregulation by limiting sweat evaporation and thus heat loss.
According to a study called “Shades of beauty,” light brown skin tones are often the most physically attractive skin color (Frisby et al., 2006). They used four models for that study. They did not change the skin tone, but they imaged each model to three different skin tones: light, medium, and dark.
Melanin helps to regulate body temperature. It absorbs and releases heat, which helps to maintain a stable body temperature. Melanin is involved in the production of vitamin D, which is essential for the absorption of calcium and the maintenance of strong bones.
Topping the list is South Sudan, where some of the world's darkest skin tones can be found. The South Sudanese, particularly the Dinka and Nuer ethnic groups, are known for their exceptionally deep, dark complexions. South Sudan gained independence from Sudan in 2011 and has since been building its national identity.
The research shows that the OCA2 gene codes play a key role in the production of melanin, the pigment that colors hair, skin, and eyes. Eiberg's theory is that a mutation occurred between 6,000 and 10,000 years ago that switched on the ability for the gene to dilute brown eyes to blue.
Analysis of melanosomes extracted from the epidermis in these subjects indicates that the proportion of spheroidal melanosomes is low in all skin types examined (<10%). This suggests that in human skin, pheomelanin is a very minor component of epidermal melanin, even in the lightest (European) skin types.
Clearly, this is not the case, so by a process of deduction we can conclude that Adam and Eve were heterozygous, each having two dominant and two recessive genes, AaBb. They would thus have been middle-brown in color and from them, in one generation, the various shades of brown would have been produced.
Results: Findings indicated that non-Hispanic Blacks and Hispanics have accelerated aging, and non-Hispanic Whites have decelerated aging. Racial/ethnic differences were strongly tied to educational attainment. We also observed a significant difference by birthplace for Hispanics.
Besides, many epidemiological studies have shown a lower incidence for skin cancer in individuals with darker skin compared to those with fair skin. However, there is growing evidence that the relationship between pigmentation and photoprotection is far more complex than assumed.
In dermis, the dermal thickness, collagen content and melanin content are higher in Asians 8. On the other hand, there were no racial differences observed in skin elasticity on the volar forearm by using the Twistometer 9.
So melanin production by melanocytes in and around the eyes specifically may be reduced if they are shielded from UV by sunglasses. But sunglasses would not prevent the body from producing melanin in general. Skin exposed to UV will continue to produce melanin.
Microscopic appearance. Melanin is brown, non-refractile, and finely granular with individual granules having a diameter of less than 800 nanometers. This differentiates melanin from common blood breakdown pigments, which are larger, chunky, and refractile, and range in color from green to yellow or red-brown.