In anthropology, skin color is considered as a sign that has an important relationship with racial differences. Compared with animals, human skin color varies greatly, from white to black. The factors that determine skin color are: the color and thickness of the skin itself. The number and distribution of melanin particles, the number of pigments such as carotene and blood. The formation of racial skin color difference is determined by melanin particles. If there are a large number of melanin particles, it can block ultraviolet rays with harmful wavelength to living cells and ultraviolet rays with the wavelength required to produce vitamin D. Therefore, dark skin is beneficial to the body in areas with strong sunlight, while light skin is beneficial to the body in areas with weak sunlight. (1) Noun expression: From dark black and dark brown to red-white and gray-white, a total of 12 color names have been formulated. But this method lacks objectivity.
(2) Method of using color model:
1.Luschan's skin color chart, represented by 36 pieces of stained glass:
1-5 (No.:1-5) Anemic skin color of Europeans.
6-35 (No.:6-35) Various normal skin colors.
No.36 (No:36) is pure black, as a contrast with dark black.
Due to too few grades and strong glass reflection, it has not been widely used.
2. Paul von Hintze skin color table:
It is the most widely used skin color card at present, which can carefully check the color of skin, mucosa and internal organs. According to F.W.Ost- wald's theory, this skin color map is a mixture of white and black in a certain proportion, which reproduces all the colors of external objects, that is, 24 basic colors; The basic color of no: 3.0-8.0 (no: 3.0-8.0) is enough for human body color.
(3). Spectrophotometry: It is a method of putting the skin film directly on the spectrophotometer to check the skin color, and this method is also being used now. With regard to racial division, the mainstream view holds that it can be divided into three categories: Caucasian race, East Asian race and Black Australian race.
The genetic characteristics of skin color is one of the indicators of racial division, but there are still great differences in skin color among the three major races. For example, Caucasians include Europeans, Arabs and Iranians, among whom Europeans have the lightest skin color; East Asians include people from Central Asia, East Asia and Southeast Asia, and the skin color of Southeast Asian residents is obviously darker. Nigro-Australians are usually divided into black and brown. According to the theory of black race, the skin color in North Africa is lighter, and the skin color in South Africa is deeper. That's probably the rule.
Indians are more difficult to classify. The earliest inhabitants there should be said to be East Asians, but Aryans of ancient Caucasian race invaded there thousands of years ago, and later people from Iran and Central Asia invaded there in batches, so it is hard to say whether Indians belong to East Asia or Caucasian race now. With regard to skin color and race, it should be noted that the influence of population migration and mixed blood is enormous in history. For example, Finns in Europe, according to their linguistic features, their ancestors came from East Asians in Asia, but today's Finns basically reflect the physical characteristics of Caucasians.
In the past, western scholars were used to racial discrimination and regarded brown people and blacks as inferior peoples. After coming to China, in order to protect their superior position, they regard the tanned skin of farmers as the standard skin color in East Asia, and call it yellow race, but there is little genetic difference between Europe and Asia. Caucasian race
Caucasians, also known as Eurasian or Caucasians, are the most populous race in the world, accounting for about 54% of the world's total population. It is characterized by light skin color; Soft curly hair, how golden in color; Eyes are blue or grayish brown; Thick hair; The cheekbones are not prominent; Jaw bone is flat; The nose is narrow and high; Lips are thin or medium. They are widely distributed all over the world. It is mainly distributed in Western Europe, West Asia and South Asia, North Africa and North America.
East Asian race
The East Asian race (Mongolian race) used to be called yellow race, Asian American race and Mongolian race. The Mongolian race got its name from: Europeans' fear of the ruthless expansion and massacre of the Mongolian empire. Therefore, when the German anthropologist Christoph Meiners left a deep impression on East Asians in his "dual race theory", he first thought of "Mongols". This is the first time to use the term "Mongolian race", but later it was renamed as East Asian race after the international opening up, and the skin color of this race is not much different from that of Caucasian race. In Europe and America, the usage of "yellow race" has been removed.
African race
African race, also known as black race and black race, is one of the four major races in the world, accounting for about 8.5% of the world's total population. Africans have dark skin, dark and curved hair, long and narrow heads, prominent cheekbones, prominent eyeballs, thick noses and swollen lips, and most of them are splayed feet. Except for northern Africans, all other Africans belong to it. The color of skin varies with race, age, sun exposure and location, and is mainly composed of three tones: the depth of black depends on the number of melanin particles in the skin; The depth of yellow depends on the thickness of stratum corneum; The appearance of red color is related to the density of capillary distribution in skin and the size of blood flow.
Observing the change of skin color is very helpful to judge the condition. If a person's skin color has changed greatly from the usual skin color, the possibility of disease should be considered if normal external influences are excluded.
If the skin mucosa becomes pale, it is caused by capillary spasm or insufficient blood filling, and anemia caused by the decrease of hemoglobin content in blood can be seen in cold, panic, collapse, aortic valve insufficiency, anemia, visceral bleeding and so on.
In the exposed parts of the body, as well as nipples, armpits, reproductive organs, joints, anus and other places, the color of the skin is darker than other parts. If the pigment in these parts is obviously deepened, or the melanin in the surface layer and basal layer of pigmentation in other parts increases, which makes part or all of the skin color deepen, it is called pigmentation. If sun exposure and other factors are excluded, it is necessary to consider whether it is infected with the disease. It is commonly seen in Addison's disease with chronic adrenal cortical hypofunction. Liver cirrhosis, advanced liver cancer, acromegaly, kala-azar, malaria and taking some drugs such as arsenic and anticancer drugs can also cause different degrees of skin pigmentation. Pigmented black spots only appear on lips, oral mucosa and palms of fingers and toes, which are common in gastrointestinal polyposis.
After 3 ~ 4 months of pregnancy, symmetrical yellowish brown or light black spots can appear on the face of women, which are mostly distributed around cheeks, forehead, lips, or the bridge of the nose or chin. This dark brown spot is called pregnancy spot. Most of them have no pathological significance, and only a few are related to systemic diseases. Common diseases are chronic liver disease or female reproductive system diseases, such as uterine tumor, ovarian tumor, irregular menstruation or amenorrhea.
When the skin capillaries dilate, congestion, blood flow is accelerated, and the number of red blood cells in the blood increases, the skin becomes red, which generally appears in fever diseases such as lobar pneumonia, tuberculosis and scarlet fever, as well as atropine poisoning and carbon monoxide poisoning. Persistent redness of the skin is often an endocrine disease of Cushing's syndrome, which is caused by the increased secretion of adrenocortical hormone and manifested as polycythemia vera. Patients with systemic lupus erythematosus can be found on both cheeks.
Butterfly erythema can be seen on the nose and nose skin, bright red or purple, with clear or fuzzy edges and smooth surface.
If the reduced hemoglobin without oxygen in the blood increases, the skin may be blue-purple, medically called cyanosis, which is often most obvious in the tongue, lips, auricles, cheeks and limbs.
When jaundice occurs, the skin mucosa can be yellow, and it only appears in the white eyeball and soft palate when it is light in the early stage, and only visible in the skin when it is obvious. Generally, it can be seen in patients with viral hepatitis, cirrhosis, hemolytic anemia and other biliary obstruction and liver cell damage. When jaundice occurs, due to the different degree and nature of bile increase in blood, the skin color can be different, such as lemon, orange, yellow-green, dark yellow, etc., but the yellowing of sclera of white eyeball is the most obvious. In addition, excessive consumption of carrots, pumpkins, orange juice and other vegetables or fruit juices can increase the content of carotene in the blood, leading to yellowing of the skin, but it generally only appears on the skin of palms and soles. Long-term use of yellow drugs, such as adipine and furan drugs, will also make the skin yellow. People with multiple nerve fiber pains often have a large area of brown pigment spots on their skin.
In short, we should not be nervous or careless about the change of skin color.