however black people do not like to be called Negros, because that's the word which was used for them during slavery in the USA, so its not a good word to use.
See, that's actually because that's the official term used for their gene pool - "Aboriginal/Negroid". Which explains how it was originally considered quite correct by Caucasians and Negroes alike to use the term to describe the people. Then they started making a fuss about that and it became "colored", with "Negro" being unacceptable. Then they started making a fuss about that
and it became "African-American". Fortunately at this point we're apparently getting over all that and people find it perfectly acceptable to just say "black" and "white", instead of "African-American" and "Caucasian".
Though scientists always have and still continue to use the word "Negro(id)".