As surprising as it might seem now, during the late eighteenth century many early Americans asked themselves, "How could a person of one race come to be another?" Racial thought at the close of the eighteenth century differed radically from that of the nineteenth century, when the concept of race as a fixed biological category would emerge. Instead, many early Americans thought that race was an exterior bodily trait, incrementally produced by environmental factors and continuously subject to change. While historians have documented aspects of eighteenth-century racial thought,...