Some of the obvious differences in appearance and make-up of humans are the colors of the eyes, hair, and skin; a person's height, weight, and shoe size; and a person's blood type.
Since before recorded history humans have found the need to group and organize almost every part of their lives. The only reason for human survival since the first humans on earth is that they have not lived alone. Humans have a family, in which then the family grows and turns into a tribe. This "tribe" then grows larger, separates and then starts back over with a different family. A person is more likely to survive in a "tribe" than they are on their own. A "tribe" provides a lot more knowledge and skill to survive than the wee power of just one person by them self. This is an infinite cycle that will go on till the end of days. Whenever two different "tribes" come into contact with each other for the first time, there is this human need "group" and classify one another. .
A racial view was then invented to assign some "tribes" to a very low status while others to a very high status. This racial view was used to divide, rank and control colonized people. During the 18th century this racial view was used in populations that were brought together in colonial America. Such populations were English and other European settlers, conquered Indian people, and people from Africa brought to provide slave labor. The Africans brought over for slave labor and the conquered Indian people were thought of as less (or not at all) human and where assigned to an extremely low status (AAA 2). .
"Adolph Hitler, the leader of the Nazis party in Germany during World War II, expanded this racial view and took it to extremes. He exterminated 11 million people of "inferior races" (e.g., Jews, Gypsies, Africans, homosexuals, and so on) and did other unspeakable brutalities of the Holocaust (AAA 3)." As soon as Hitler took power in Germany this narcotic racial view was taught in every German school.