Why are Africans so dark?

Race is the abbreviation of human beings in the world, which refers to people who share some common genetic traits (including skin color, eyes, hair color and hairstyle, height, face shape, head shape, nose shape, blood type, hereditary diseases, etc.). ) In a certain area in history. The concept of race was first put forward by French naturalist bernier in 1684. I. Classification of Ethnic Groups The earliest classification of ethnic groups was the mural of the tomb of Siti I, the 18th dynasty in ancient Egypt, more than 3,000 years ago. It distinguished human beings with different colors and divided them into four categories: First, Egyptians were painted red; Second, Asians are painted yellow; Third, blacks in the south are blacked out; Fourth, westerners and northerners paint white. It has become an arrow that divides human beings into white, yellow, black and brown today. In the classification made in 1758, Linnaeus, an outstanding Swedish scientist, divided the world races into: savage species-Fielas, monster species-Monstor Race, rational species-Sabines; Then, according to the number of continents known at that time, rational species are further divided into four major races: European white, Asian yellow, African black and American red. Ju Ye Wei, a famous French scholar, advocated that it should be divided into three major races and named after Noah's three sons in the Old Testament: Semite, Han and Japheth. It is difficult for people to accept this cultural and religious ethnic division. Known as "the originator of western anthropology" and "the father of mankind", Professor Brumenmacher of the University of G? ttingen in Germany first made scientific classification. According to the physical characteristics such as skin color, hair color and hairstyle, eyes, height and head shape, and the original living area, he divided the living human beings into five major races: ① Caucasian race (white). The skin is white, the hair is chestnut, the head is almost spherical, the face is oval and vertical, and the nose is very narrow. Residents of Europe, West Asia and North Africa all belong to it, except Finns and Laplanders. ② Mongolian race (yellow race). Yellow skin, straight black hair, square head, flat face, small nose, protruding cheekbones and narrow eyes. Asians outside West Asia and Inuit, Lapland and Finns in the north all belong to it, but not Malays. (3) African race (black). Black skin, black and curved hair, long and narrow head, prominent cheekbones, prominent eyeballs, thick nose and thick lips, and most people have splayed feet. Except for northern Africans, all other Africans belong to it. (4) American race (red race). The skin is copper, the hair is black and straight, the eyeball is sunken, the nose is tall and wide, and the cheekbones are prominent. Except Inuit, other Native Americans belong to it. ⑤ Malay race (brown race). Yellow-brown skin, dark and atrophic hair, medium narrow head, wide nose and big mouth. The inhabitants of Pacific islands and Malay Peninsula belong to it. This division can be said to be the geographical classification of ethnic groups. In fact, there are no red people in America. Indians are a big branch of the yellow race. Because of their reverence for red, they often paint their faces with red paint and are mistaken for red people. Moreover, the blood characteristics, genetic diseases and genetic genes of different races are different, so scholars have different standards for the division of races. Therefore, there is no consensus on the classification of modern races. However, since 1950s, fingerprints, blood types and other indicators have been added on the basis of Brucella classification, and the racial classification has been gradually combined with modern science, gradually forming the currently recognized racial classification standard. Second, the adaptability of ethnic black people originated in the tropical equatorial region, where it was exposed to the sun for a long time, and the temperature was high and the ultraviolet rays were strong within one year. People who have lived here for a long time have gradually formed a series of adaptive characteristics through long-term natural selection: the skin has high melanin content to absorb ultraviolet rays from the sun and protect the internal structure of the skin from damage; The density of sweat glands on the body surface is particularly high, which can maintain normal body temperature or recover quickly when it is extremely hot; The nose is low and wide, the nostril passage is short, the lips are thick, the mouth is cracked, and the body hair is less, which is convenient for heat dissipation; Hair is curly like wool, so that there are many gaps around every curly hair, and the gaps are full of air, which leads to poor heat transfer. Therefore, curly hair has the function of heat insulation and protects the mind from harm. White people originated in cold areas, where the sunlight is oblique, the light is weak and the ultraviolet rays are weak. Local residents have low melanin content and light skin color. The body is stout and tall, reducing heat loss; The nose is high and narrow, and the nostril passage is long to preheat the inhaled cold air; The hair on the body surface is thick, which can prevent cold. The yellow race originated in temperate regions, and its adaptability of skin color and physical characteristics transited to the black and white race. The history of recent hundreds of years has proved that the mixture of the above three major races can be stable in a certain area for a long time, and new races can also be produced. For example, African Americans, whose ancestors came from Africa, have long been mixed with white Americans who went to Europe. At present, there are more than 20% white genetic factors among African-Americans, so they are obviously different from African-Americans in physique and constitute a new race. In Brazil, it is a mixture of Indians, Spaniards, Portuguese, Japanese and China. After a long period of time, a new race-mixed race has also formed. Third, the distribution of ethnic groups. After 10 years of deliberation and investigation, the American scientist S.M. Chang En believes that there are 9 geographical races in the world and 32 regional races are divided. 1. American Indian species are the original inhabitants of North America. Before the arrival of Europeans and Africans, they started in Alaska in the north and reached the southern tip of South America in the south. They are scattered in remote areas, mainly hunting, gathering or semi-agriculture, with a small population and often completely independent in heredity. It is characterized by brown skin, thick black hair, shovel-shaped front teeth, prominent cheekbones, prominent nose and sparse body hair. In ABO blood group series, O type and B type appear frequently, which are obviously different from the blood groups of related Asian geographical races. 2. Polynesian race refers to people who are distributed in a vast area of the eastern Pacific, from Hawaii and Polynesia to New Zealand. 3. Melanesian-Papuans refer to people distributed in New Guinea, Fiji Islands and the west, with brown skin color, wide nose, straight or curly black hair and little body hair. In ABO blood group series, type B appears less frequently. People from other Pacific islands. It is characterized by dark brown skin, round head, curly hair, developed eyebrow ridge, hooked nose tip and narrow scapula. Australian race refers to the original population distributed in Australia before the arrival of Europeans. It is characterized by brown skin, wavy or curly hair, linear body shape, large teeth, obvious eyebrow ridge, prominent jaw and medium concentration of body hair. In ABO blood group series, the frequency of B type is very low. 5. Asian geographical races mainly refer to the races distributed in the Asian continent, even Japan, the Philippines, Sumatra, Borneo Islands and other places, also known as Mongolian geographical races. It is characterized by light yellow skin, black and straight hair, sparse beard and hair, flat face, high cheekbones, wavy Mongolian folds in eyelids, and high frequency of B type in ABO blood group. 6. Indian geographical race refers to the people who are distributed in South Asia, from the southern foothills of the Himalayas to the hot Indian Ocean. It is characterized by shallow to deep skin from north to south, blue eyes, black or yellow hair and straight wavy hair. In ABO blood group series, the frequency of type B is higher, which is different from European geographical races, but similar to Asian geographical races. 7. European races include several geographical races distributed in Europe, and some white races scattered in West Asia, North Africa and West Africa, also known as Caucasian geographical races. It is characterized by light skin color, narrow nose, straight or wavy hair, golden yellow or brown black, thin lips, dense body hair, and particularly developed beard and cheek hair. The frequency of male baldness is very high. In ABO blood group series, A2 blood group is often mixed, and Rn type appears frequently. 8. African race refers to several geographical races distributed in sub-Saharan Africa, also known as black geographical races. It is characterized by black to dark brown skin, short curly hair, thick everted lips, short and wide nose, prominent chin and sparse body hair. In the Rn blood group series, R0 type appears frequently, and there are often sickle blood cells that are relatively immune to malaria in the body. 9. Micronesians refer to people living in Micronesia and some islands in the western Pacific. It is characterized by short stature, dark skin color and coat color, long head shape, wavy and spiral hair and hairy body surface. The frequency of blood group is similar to Polynesian race, but the frequency of type B is higher. Chang En's classification of nine geographical races is simple and easy to remember, which is more in line with the objective reality, so it has been paid attention to and recognized by academic circles. But there are also some shortcomings, such as the large population of American Indians; South American Indians and North American Indians also have obvious differences in constitution, so we should consider the issue of separate ownership. For another example, Chang En's racial division was limited to the racial classification and distribution before 1500 years ago (that is, before the era of geographical discovery), ignoring the great migration of Europeans and Africans to South America and Australia after the era of geographical discovery, which led to racial integration and fundamentally changed the racial distribution of the United States and Australia. With the passage of time, this kind of integration is getting closer and closer, so it is more appropriate to divide North and South America into North American geographical races and Latin American geographical races.