I tell you, not all black people have longer legs than yellow people. There are exchange students from various countries in the university. I once went to a public bathhouse and saw several foreign students taking a bath. In front of the big mirror, a row of men of all races are posing, which has little to do with race, but with everyone. Men of the same height, some yellow people have long legs, some black people have long legs and some white people have long legs. It is uneven and irregular. But there is a rule that thin people look longer than fat people.

The theory of racial evolution is controversial, and many people do not agree with the separate classification of black, yellow and white. (In order to avoid misleading. The following contents are only guesses, and there is no basis for papers or academic materials. It can only be said that human beings are divided into those who go to Europe, those who go to East Asia and those who stay in Africa. Generally speaking, the yellow race (East Asian race) is small, mainly living in temperate zone, subtropical zone and tropical zone. When an object expands year-on-year, the unit increment of surface area will be lower and lower with each unit volume increase. Small size can ensure a relatively large heat dissipation area. The explanations of other features are different and inconclusive. For example, someone summed up the advantages of the yellow race: low replication cost, strong disease resistance and larger brain capacity. But I personally oppose the theory that the yellow race originated in North Asia. The yellow race should have migrated from West Asia. Maybe he had a gene exchange with Homo erectus in East Asia.