1. Caucasian race (white); 2. Mongolian race (yellow race); 3. African race (black); 4. Malay (brown).
Caucasian race (white): Originated from high latitude and cold areas, where the sunlight is oblique, the temperature is low, the ultraviolet rays are weak, the melanin content of residents is low, and the skin is white, which is convenient for absorbing sunlight. 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; Thick hair on the body surface is convenient for cold protection.
African race (black race): Originated in tropical areas at low latitudes, with long direct sunlight, high temperature and strong ultraviolet rays. People who have lived here for a long time have gradually formed a series of adaptive characteristics: the melanin content in the skin is high to absorb the ultraviolet rays in 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; Curly hair is convenient for heat insulation and sun protection, and protects the mind from harm.
Mongolian race (yellow race): originated from the temperate zone in mid-latitude, and its adaptability of skin color and physical characteristics has the transitional characteristics of black and white race: medium skin color, yellow skin, underdeveloped body hair, wide and flat facial bones, and cheekbones close to the eyes; The nasal bone is not high or low, the nasal bone is short, the nasal root is high (the lower end of the nose is far from the chin), and the alar is of medium width; The teeth are parabolic, the front teeth are shovel-shaped, and the teeth are small; The eyes are slender and small, with obvious inner canthus folds (also called Mongolian folds, that is, the upper eyelid at the inner corner of the eye covers the lower eyelid), the outer eye folds are developed, the eyes are dark brown, and some people's eyes are low inside and high outside; Hair is black, straight and thick, and male hair is extremely thick, round and hard; The head index (that is, the left and right width of the skull is larger than the front and back length) is large; The proportion of type B blood is the highest; The humerus (upper arm bone) is thick and long; The trunk is thick, and the male upper body is inverted triangle; Infant raw milk moss (birthmark, scientific name Mongolian spot).
Malay race (brown race): It is distributed on the islands with low latitudes in the central and western Pacific Ocean. The ancestors of the aborigines are very complicated. They live in a high temperature and humid environment for a long time. They are short, with tawny and dark brown skin, dark curly hair, well-developed brow ridge, round head, medium and narrow nose, wide nose, aquiline nose, thick lips, prominent snout and narrow shoulder blades. These physical characteristics are adapted to the living environment.
I hope I can help you.