Why do people have races?

Answer 1

German scientists in the 1700's at first believed that the perceived physical differences between humans (usually skin tone) meant there were significant genetic differences that appear in one race and not another.

At first, race was a biological rule that a specific 'type' of human had a specific piece of DNA that could not be altered.

In actuality there is no such thing as different races among humans. Race is a concept created by cultures and political bodies in order to organize people, space, distribution of wealth, to justify slavery, etc.