The reasons for the formation of ethnic groups are very complicated, which are generally considered to be the result of long-term influence of natural environment and historical conditions.

Affected by natural conditions for a long time, people living in different areas have certain adaptability to nature in some parts of their bodies, and some historical factors have also had a certain impact on the formation of ethnic groups. Ethnic differences are manifested in the external morphological characteristics of the body, such as skin color, hairstyle, eye shape, nose shape, body proportion and so on. These differences in appearance do not affect the basic anatomical and physiological characteristics and intellectual development of human beings, and it cannot be considered that different races have advantages and disadvantages.