Genetic drift happens when chance events cause alleles to spike or decline from one generation to the next. Sometimes a segment of a population gets isolated and continues to grow and mutate on it's own. Sometimes populations change as a result of natural disasters or human intervention. https://youtu.be/mFvmY9JASO4 | CrashCourse

One of the reasons it’s so difficult to untangle race from religion is because the two have rarely – if ever – been separate. Quite the opposite—they’ve sort of co-evolved. Throughout history, power structures have often reinforced and redefined both ideas together to further their goals. https://youtu.be/TY8p32K1js4 | CrashCourse