Because Africa never had empires, conquerers, ethnic & religious conflict, slavery, human sacrifice, etc,
Rome and whomever else never had a bevy of renowned homoerotically brutal Emperors & uppers classes,
And women are all dutifully docile nurturers, as any kid who ever had one as a mother can testify, not to mention their driven-to-the-drink husbands?
Just because a culture is not burdened with feelings of guilt requiring redemption written into its DNA by its religion does not absolve it of its wondrous knack for commiting heinous deeds that separates humans from the beasts,,,