This may be a slight deviation from the question, but much of the original justification for chattel slavery in the New World originates from the crusades and the differences between Muslims and Christians. In The Chronicle of Discovery and Conquest of Guinea, Gomes Eanes de Zurara tells of the conquest of Cetua in Morocco and early Portuguese exploration of the coast of Africa. He writes that both the Moors of Cetua and the Natives of Guinea were dismayed by the sailors shouting the name of St. James. This shows that, in the minds of the Portuguese, they were the same kind of heathens. This set the precedent for Sub-Saharan Africans to be viewed in the same lens as North Africans and Arabs. The nature of Sub-Saharan African society allowed for easy purchase or capture of slaves (Walter Rodney:History of the Upper Guinea Coast 1545-1800) and a papal bull which gave rights to enslave pagans and Muslims meant that Sub-Saharan Africans made a convenient labor force. In time, blackness became associated with servitude. The John Punch case in Maryland was the first legal precedent of unequal treatment based on race where a black runaway indentured servant was sentenced to a life in bondage but his white counterparts were given much softer sentences. Later the French Code Noir created extensive formal legal definitions of slavery in 1680. To promote unity with majority slave populations, they mandated that all slaves be baptized Catholic. This removed all religious justification for slavery and instead formally based the institution on race. Hopefully this at least gives some background on the development of racism in the New World.