It comes from Louis Farrakhan's bizarre fuzzy-muzzy theology, which is roughly based on the islamic myth that humanity was originally all moslem. The story goes that 6000 years ago, there were no white people. Black people lived in an advanced islamic Utopia comparable to Wakanda. An evil black genius created a weapon of mass destruction in the form of white people. These laboratory creations, so the story goes, were evil because they lacked melanin, which is produced by the melanin gland in the brain, and is the seat of the soul. No melanin, no soul. The soulless ice-monsters ran amok and destroyed fuzzy-muzzy Utopia and then all migrated north, where they became 'Cave Dwellers,' a common insult for white people. These cave dwellers mated with apes to produce Jews, and with donkeys to produce Europeans. This garbage began to be taught seriously in Black Studies courses, along with critical race theory.