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Modern Human Diversity - Skin Color

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❶Albinism is a recessively inherited trait in humans where both pigmented parents may be carriers of the gene and pass it down to their children. While some light skinned people tan or use cosmetic means to darken their skin, dark-skinned people may use cosmetic means to lighten their skin.

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Melanins, the pigments that color our eyes, hair and skin
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It is important for these people individually to adjust their diet and lifestyle according to their skin color, the environment they live in, and the time of year.

The following list shows the six categories of the Fitzpatrick scale in relation to the 36 categories of the older von Luschan scale: Dark skin with large concentrations of melanin protects against ultraviolet light and skin cancers; light-skinned people have about a tenfold greater risk of dying from skin cancer, compared with dark-skinned persons, under equal sunlight exposure. Furthermore, UV-A rays from sunlight are believed to interact with folic acid in ways that may damage health.

Midday was a time when people stayed in the shade and had the main meal followed by a nap, [90] a practice similar to the modern siesta. Furthermore, in some parts of the world where people from different regions have mixed extensively, the connection between skin color and ancestry has substantially weakened. In general, people living close to the equator are highly darkly pigmented, and those living near the poles are generally very lightly pigmented.

The rest of humanity shows a high degree of skin color variation between these two extremes, generally correlating with UV exposure. The main exception to this rule is in the New World, where people have only lived for about 10, to 15, years and show a less pronounced degree of skin pigmentation. In recent times, humans have become increasingly mobile as a consequence of improved technology, domestication, environmental change, strong curiosity, and risk-taking.

Migrations over the last years, and especially the last years, have been the fastest in human history and have led to many people settling in places far away from their ancestral homelands. This means that skin colors today are not as confined to geographical location as they were previously.

According to classical scholar Frank Snowden, skin color did not determine social status in ancient Egypt , Greece or Rome. These ancient civilizations viewed relations between the major power and the subordinate state as more significant in a person's status than their skin colors. Nevertheless, some social groups favor specific skin coloring. The preferred skin tone varies by culture and has varied over time. A number of indigenous African groups, such as the Maasai , associated pale skin with being cursed or caused by evil spirits associated with witchcraft.

They would abandon their children born with conditions such as albinism and showed a sexual preference for darker skin. Many cultures have historically favored lighter skin for women. Before the Industrial Revolution , inhabitants of the continent of Europe preferred pale skin, which they interpreted as a sign of high social status.

The poorer classes worked outdoors and got darker skin from exposure to the sun, while the upper class stayed indoors and had light skin. Hence light skin became associated with wealth and high position. Other methods also aimed at achieving a light-skinned appearance, including the use of arsenic to whiten skin, and powders.

Women would wear full-length clothes when outdoors, and would utilize gloves and parasols. Colonization and enslavement as carried out by European countries became involved with colorism and racism , associated with the belief that people with dark skin were uncivilized, inferior, and should be subordinate to lighter-skinned invaders.

This has been perpetuated [ by whom? For example, they had a chance to get an education, [] while darker African-Americans worked in the fields and did not get an education.

African-American journalist Jill Nelson wrote that, "To be both prettiest and black was impossible," [] and elaborated:. We learn as girls that in ways both subtle and obvious, personal and political, our value as females is largely determined by how we look. Black women find themselves involved in a lifelong effort to self-define in a culture that provides them no positive reflection. A preference for fair or lighter skin continues in some countries, including Latin American countries where whites form a minority.

In India , society regards pale skin as more attractive and associates dark skin with lower class status; this results in a massive market for skin-whitening creams.

Skin-whitening products have remained popular over time, often due to historical beliefs and perceptions about fair skin. In ancient China and Japan, for example, pale skin can be traced back to ancient drawings depicting women and goddesses with fair skin tones. Thus skin-whitening cosmetic products are popular in East Asia. Skin whitening is also not uncommon in Africa , [] [] and several research projects have suggested a general preference for lighter skin in the African-American community.

Significant exceptions to a preference for lighter skin started to appear in Western culture in the midth century. From Wikipedia, the free encyclopedia. This is the latest accepted revision , reviewed on 26 August For animal skin pigmentation, see Biological pigment. Human genetic variation , Race and genetics , and Human genetic clustering.

Discrimination based on skin color. Human skin Carnation heraldry Color terminology for race Complexion Health effects of sun exposure Race human classification Afro-textured hair Eye color Human hair color Human physical appearance. University of California Press. American Journal of Dermatopathology. Archived from the original on 10 June Retrieved 30 April Progress in Biophysics and Molecular Biology. Archived PDF from the original on Archived from the original on Berkeley, Los Angeles, London: Philosophical Transactions of the Royal Society B.

Human skin pigmentation as an adaptation to UV radiation". Proceedings of the National Academy of Sciences. Journal of Human Evolution. Archived from the original PDF on January 5, Identification, structure and consequences of polymorphic variation". J Eur Acad Dermatol Venereol.

The Case of Desiree's Baby". Archived from the original on 6 May Retrieved 14 April Silk, How Humans Evolved, 6th edition, W. Annual Review of Anthropology. American Journal of Human Biology.

Molecular Biology and Evolution. A review highlighting photobiological and photobiophysical aspects". Journal of Photochemistry and Photobiology B: Luca Cavalli-Sforza … that the early immigrants to Europe … survived on ready-made sources of vitamin D in their diet. But when farming spread in the past 6, years, he argued, Europeans had fewer sources of vitamin D in their food and needed to absorb more sunlight to produce the vitamin in their skin.

Our data suggest that inactive MC1R variants evolved independently in both modern humans and Neanderthals. Annals of Human Genetics. The American Journal of Human Genetics. Journal of Forensic Sciences. SNP report for rs Journal of Biological Chemistry. International Journal of Legal Medicine. Archived from the original PDF on International Journal of Cancer.

American Journal of Clinical Nutrition. Melanocytes modulate skin color in response to stress". Human Heridity Principles and Issues'. BBC News online edition. Seminars in Cutaneous Medicine and Surgery. American Journal of Human Genetics. Although melanins are ubiquitous in humankind, our understanding of their chemistry is surprisingly limited.

Melanin pigments have a complex natural structure that has defied detailed analysis. Once separated from living tissue, they form an amorphous mass and lose their inherent structure, making them very difficult to analyze. Melanins seem to be heterogeneous, with some small regions of order at the nanometer scale. The optical properties we can see depend on the ability of monomers and oligomers made up of small numbers of monomers that make up melanin to absorb light, and the ability of melanin particles to reflect and scatter incident light for different wavelengths.

Melanins seem to have some semiconductor properties, and none of the proposed band models adequately account for this. Eumelanin and pheomelanin play key roles in eye, hair, and skin color. Neuromelanin colors certain distinctive regions of the brain. This coloration is independent of skin and hair type. Melanin is responsible for the color of our eyes. Variation in the color of our eyes from brown to green depends on the amount of melanin in the iris, which in turn is determined genetically.

Those with blue, green, or hazel eyes have little protection from the sun and may experience discomfort, irritation, burning, and tissue damage if the eyes are not protected by sunglasses when exposed to bright light. Snow blindness is a well-known example of this kind of damage.

Our hair color is also determined by varying amounts of melanin. The actual appearance of hair, and its overall reflective quality, is determined primarily by the pigment type, but also by the density and distribution of the pigment granules. There are different types of melanin, and the ratio of these pigments produces different hair colors, again genetically determined. Eumelanin is a dark pigment that predominates in black and brunette hair. There are two different types of eumelanin brown eumelanin and black eumelanin.

A small amount of brown eumelanin in the absence of other pigments apparently causes blond hair. Pheomelanin is a lighter pigment found in red hair, and is concentrated in the redder areas of the skin such as the lips.

Because people with red hair are less able to make the dark eumelanin pigment, their skin is generally quite pale and burns easily with sun exposure. Although people with dark hair may still produce the yellow-orange pheomelanin, it is largely masked by the dark eumelanin pigment and cannot easily be seen. However, the red-yellow pheomelanin is believed to cause the warm, golden, or auburn tones found in some types of brown hair. The range of colors produced by melanins is limited to shades of yellow, brown, red, and black.

Grey hairs contain only a few melanin granules, spread out through the hair. White hairs contain no melanin at all: Often you find either eumelanin or pheomelanin in hair, but not both.

Adjacent patches of hair follicles may show a very precise split between the two pigment types. This effect is most obvious in the patterns and markings of other mammals, such as leopards, tigers, and certain breeds of dog.

Low levels of pheomelanin in the absence of eulamelanin are characteristic of cream-colored hair in many animals. Pigments are discussed in more detail in the pages on blue eyes and green plants. Melanin reduces ultraviolet induced DNA damage by absorbing or scattering the ultraviolet radiation that otherwise would have been absorbed by the DNA. This prevents the development of melanoma, a potentially deadly form of skin cancer, as well as other health problems related to exposure to strong solar radiation.

The amount of UV radiation that is absorbed or scattered is determined by a number of factors: Skin color depends upon the size, number, shape, and distribution of melanosomes, as well as the chemical nature level of activity of their melanin content. There are 6 different skin types that are defined by dermatologists. Skin type Description Type 1 Always burns, never tans. Very fair skin with red or blond hair and freckles. Type 2 Burns easily, tans minimally. Type 3 Sometimes burns, gradually tans.

Type 4 Minimum burning, always tans. The most important adaptation that early humans developed? The ability to survive sunlight. In the heart of sub-Saharan Africa, where it is believed that all humans originally came from, the sun is incredibly intense. Conveniently enough, melanin functions as a shield against ultraviolet radiation, thus protecting the cells from the many dangers of excess exposure. Imagine this video… but in reverse.

For this reason, we see darker-skinned people most commonly near the Equator, where sunlight is in abundance throughout the year; this extends beyond Africa — to Asia, South America, and the Middle East as well!

Humans were dark-skinned for the vast majority of their history. However, as human beings began spreading throughout the globe — into Europe, northern Asia, and eventually the Americas, they discovered areas with decidedly less sunshine. This is where the second stumble in the human history of skin color arose — vitamin deficiency. Unfortunately, our primary source of vitamin D is linked to sunshine; the radiation actually helps to synthesize vitamin D in the skin, in conjunction with another chemical.

Thus, for people living in colder climates, or areas which experience darkness for extended periods of time throughout the year, having dark skin meant blocking that radiation, and thus lacking in vitamin D.

Reverse adaptation occurred as humanity sprawled across the planet to different climes, and eventually, their skin color faded over the course of many generations. The majority of genes that control pigmentation have now been identified, and we can trace the progression of skin color across the world — and throughout history!

For example, the melanocortin 1 receptor gene is what determines whether the body produces eumelanin and pheomelanin at all, and by comparing the genetics of chimpanzees and early humans, we see that this particular gene was positively selected in a major way once apes lost their fur. Similarly, the KIT ligand gene and Agouti signaling peptide gene control eumelanin production, and were positively selected in populations that moved out of Africa, to areas where less eumelanin brown and black pigment was needed.

John Staughton is a traveling writer, editor and publisher who earned his English and Integrative Biology degrees from the University of Illinois in Champaign, Urbana. He is the co-founder of a literary journal, Sheriff Nottingham, and calls the most beautiful places in the world his office.

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Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin color of darker-skinned humans. The skin color of people with light skin is determined mainly by the bluish-white connective tissue under the dermis and by the .

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Skin color is one of the most visible indicators that helps distinguish human appearance, and a new study provides more detail as to how one protein helps produce this wide palette.

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Modern Human Diversity - Skin Color Why do people from the tropics generally have darker skin color than those who live in colder climates? Variations in human skin color are adaptive traits that correlate closely with geography and the sun’s ultraviolet (UV) radiation. Our skin color is determined by a pigment called melanin, and while everyone has melanin (both fair and dark-skinned people), it comes in different forms and ratios. The two forms of melanin are called eumelanin and pheomelanin.

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A page from the "Causes of Color" exhibit Melanins, the pigments that color our eyes, hair and skin Human beings come in a glorious spectrum of different colors: light, dark, plain or freckly skin; black, brunette, blond, auburn, and white hair; and eyes that are blue, hazel, green, amber and brown, to . What Determines Skin Color? In the human body, everything that is controlled by proteins is controlled by genes, since it is the genes which encode the proteins. This case applies for melanin as well. There are two ways in which skin color can be affected by genetics. One, if the genes responsible for formation of an enzyme known as.