How does racism divide everyone regardless of position in society?

i'm pretty sure that if we were all the same color (which I've read may happen in the future) that there would still be discrimination based on the shade of skin color - maybe too much or too little melatonin would make a difference.

shoot we do it now based on someone's geographic location and make assumptions on their political leanings, religious preference, acceptance of sexual preference, etc. ... without even asking a question.

we are an odd species and I'm surprised we haven't made us extinct already