In the late eighteenth century, planters in the Caribbean and the American South insisted that only Black people could labor on plantations, arguing that Africans, unlike Europeans, had bodies particularly suited to cultivate crops in hot climates. Historians have mainly taken planters at their word, assuming that they observed differences in health between Black and white bodies and that these differences underpinned the maintenance of an enslaved Black plantation labor force.In The Nature of Slavery, Katherine Johnston disrupts this longstanding claim about biological racial difference. Drawing on extensive personal correspondence, colonial records, and a wealth of other sources, she reveals that planters observed no health differences between Black and white people. They made their claims about people''s ability to labor in spite of their experiences, not because of them. For planters and physicians, local environments, much more than skin color, affected bodily health. Moreover,