At the beginning of the transatlantic slave trade, most Europeans would have thought of Africans, if they thought of them at all, as savages because of their eating habits, morals, clothing, and social customs and as barbarians because of their language and methods of war. Despite lingering belief in a Christian Ethiopia under the legendary Prester John, they grouped Africans into the despised categories of pagan heathens and Muslim infidels. Africans were certainly not the only peoples subject to such dehumanizing attitudes. Jews were also viewed as alien people who, like Africans, were naturally sinful and depraved. More generally, elite Europeans were accustomed to viewing the peasant masses as a lower form of humanity. They scornfully compared rustic peasants to dogs, pigs, and donkeys and even reviled the dark skin color peasants acquired while laboring in the sun.22

As Europeans turned to Africa for new sources of slaves, they drew on and developed ideas about Africans’ primitiveness and barbarity to defend slavery and even argue that enslavement benefited Africans by bringing the light of Christianity to heathen peoples. In 1444 an observer defended the enslavement of the first Africans by Portuguese explorers as necessary for their salvation “because they lived like beasts, without any of the customs of rational creatures, since they did not even know what were bread and wine, nor garments of cloth, nor life in the shelter of a house; and worse still was their ignorance, which deprived them of knowledge of good, and permitted them only a life of brutish idleness.”23 Compare this with an early-seventeenth-century Englishman’s complaint that the Irish “be so beastly that they are better like beasts than Christians.”24

Over time, the institution of slavery fostered a new level of racial inequality. In contrast to peasants, Jews, and the Irish, Africans gradually became seen as utterly distinct from and wholly inferior to Europeans. From rather vague assumptions about non-Christian religious beliefs and a general lack of civilization, Europeans developed increasingly rigid ideas of racial superiority and inferiority to safeguard the growing profits gained from plantation slavery. Black skin became equated with slavery itself as Europeans at home and in the colonies convinced themselves that blacks were destined by God to serve them as slaves in perpetuity.

Support for this belief went back to the Greek philosopher Aristotle’s argument that some people are naturally destined for slavery and to biblical associations between darkness and sin. A more explicit justification was found in the story of Noah’s curse upon Canaan, the son of his own son Ham. According to the Bible, Ham defied Noah’s ban on sexual relations on the ark and further enraged his father by entering his tent and viewing him unclothed. To punish Ham, Noah cursed his son Canaan and all his descendants to be the “servant of servants.” Biblical genealogies listing Ham’s sons as those who peopled North Africa and Cush were read to mean that all inhabitants of those regions bore Noah’s curse. From the sixteenth century onward, defenders of slavery often cited this story as justification for their actions.

After 1700 the emergence of new methods of observing and describing nature led to the use of science to define race. Although the term originally referred to a nation or an ethnic group, henceforth “race” would mean biologically distinct groups of people, whose physical differences produced differences in culture, character, and intelligence. Biblical justifications for inequality thereby gave way to supposedly scientific ones.