Natural selection has, thus, affected varied genetic and physiological mechanisms in order to protect folate and 5-MTHF in the face of high UVR. The primary role of constitutive dark skin colour in hominin and modern human evolution is that of a natural sunscreen to conserve folate.
Human skin pigmentation is the product of two clines produced by natural selection to adjust levels of constitutive pigmentation to levels of UV radiation (UVR). One cline was generated by high UVR near the equator and led to the evolution of dark, photoprotective, eumelanin-rich pigmentation.
The genetic mechanism behind human skin color is mainly regulated by the enzyme tyrosinase, which creates the color of the skin, eyes, and hair shades. Differences in skin color are also attributed to differences in size and distribution of melanosomes in the skin. Melanocytes produce two types of melanin.
Skin pigmentation is directly correlated with geographical latitude, as it protects against damage from the sun, but also hinders vitamin D production. As humans migrated away from the equator and into less sunny areas, it rapidly became evolutionarily advantageous to have lighter skin.
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.
The evolution of dark skin is believed to have begun around 1.2 million years ago, in light-skinned early hominid species after they moved from the equatorial rainforest to the sunny savannas.
Scientists are sure that Homo sapiens first evolved in Africa, and we know that every person alive today can trace their genetic ancestry to there. It has long been thought that we began in one single east or south African population, which eventually spread into Asia and Europe.
Consequently, it is widely accepted that Europeans evolved low concentrations of melanin in their skin cells as an adaptation that allows to increase the penetration of UV through 2 Page 3 the skin (Norton, H.L. et al 2007; Jablonski, N.G. & Chaplin, G. 2010; Basu Mallick, C. et al 2013).
Average skin colors are seen as most attractive. Typically, tan is the average skin color, making it very attractive to most people. However, the most attractive skin color varies on preference, culture, and sex. A healthy skin complexion and rosy “glow” is always considered attractive.
The First Humans
One of the earliest known humans is Homo habilis, or “handy man,” who lived about 2.4 million to 1.4 million years ago in Eastern and Southern Africa.
She suggests that people living far from the equator developed light skin to produce adequate amounts of vitamin D during winter with low levels of UV radiation. Genetic studies suggest that light-skinned humans have been selected for multiple times.
Asian skin has an increased amount of melanin (or dark brown pigment) as well as the melanin-producing cells known as melanocytes. Asians in general have more melanin and more numerous melanocytes in the skin compared to Caucasian skin. Even fair-skinned Asians have more melanocytes than most Caucasians.
In this view, humanity began with dark skin in Africa to protect against the harmful effects of the sun's ultraviolet radiation. As people migrated to other continents, some groups evolved lighter skin, to more effectively produce vitamin D in areas where sunlight is scarce.
Summary: The quantity and quality of melanin are regulating by the expression of genes. The enzyme tyrosinase is primarily responsible for the genetic mechanism that controls human skin color. Genetics determines constitutive skin color, which is reinforced by facultative melanogenesis and tanning reactions.
Your baby's skin colour is a polygenic trait
Genetics determine melanin, which in turn decides your baby's natural complexion. The more melanin, the darker the complexion. Your baby's skin color is not determined solely by the genes of either parent, but instead by a mix of both.
Northern Europeans, particularly those from Scandinavian countries, tend to have the lightest skin color. Genetic adaptations to lower UV radiation in these regions contribute to their lighter skin.
“Work in our lab has shown that darkly pigmented skin has far better function, including a better barrier to water loss, stronger cohesion, and better antimicrobial defense, and we began to ponder the possible evolutionary significance of that,” said Peter Elias, MD, professor of dermatology.
Japan, China and other countries located in Asia have a rich diet of vitamins (specifically A and C, which benefit skin elasticity) and minerals including antioxidants from fruits and green tea. The Asian diet is very low in saturated and total fat.
Seeing Red: The Color of Passion
Studies have shown that women find men wearing red more attractive and sexually desirable. It's not just a coincidence that red is the color of love and passion – it's deeply rooted in our psychology and even our biology.
The finding confirms that modern Europeans didn't gain their pale skin from Neanderthals – adding to evidence suggesting that European Homo sapiens and Neanderthals generally kept their relationships strictly platonic.
Theory held that darker skin had evolved in order to afford early humans—who had recently lost the cover of fur—a protection against skin cancer under the tropical sun.
Vitamin D synthesis is highly dependent on the concentration of melanin in the skin as melanin absorbs and scatters UVR-B, resulting in a less efficient conversion of 7-dehydrocholesterol to previtamin D3[3]. Therefore, dark-skinned individuals will experience slower vitamin D synthesis than light-skinned ones.
Once again, Africa was the location of this development, with modern humans most likely first emerging somewhere around modern-day Ethiopia. So, if we're looking for a scientific Garden of Eden, it looks like South Africa and Ethiopia are our best bet.
A new genomic study has revealed that Aboriginal Australians are the oldest known civilization on Earth, with ancestries stretching back roughly 75,000 years.
The evolving theories have shown that neanderthals did not simply die out. A moderate population of Neanderthals interbred with early humans, some migrated to much further corners of the globe where they lived out their days and solitude, and others disappeared due to changing climate and resource competition.