The yellow eyes tilted by yellow people may be related to the windy sand in central Asia, because this structure can protect the eyes. Just like the hair of white people is linen, and a little transparent, this makes it easy for the scalp to absorb the heat of the sun and adapt The severe cold in high latitudes; black hair is more black and curly, which is good for blocking the heat brought by sunlight and protecting the brain. This text is talking about (). ['Appearance characteristics of various races.', 'Differences in appearance characteristics of different races.', 'Human appearance protects humanity itself.', 'Human appearance is the product of human adaptation to the natural environment.']