Racism is a diverse creature. It survives as a pilot-fish ideology that attaches itself to human civilisation, suckled at the fringes where it starves or thrives depending on the current state of moral depravity. 

After a misspent youth muddling through genocides and slavery, our species is pretty confident that it can spot the exact moment when racism evolves from a limp joke into a machete-wielding lynch mob.