The miniscule natural historical community in colonial America was widely regarded in the scientific centers of Europe as provincial and lacking in theoretical sophistication; with few exceptions, would-be American scientists acknowledged their subordinate status. Until well into the nineteenth century, most American natural historians were concerned only with the work of description and classification or with the applied work of medical and economic botany—important functions to be sure, but hardly at the leading edge. A few, like the Quaker botanists John Bartram (1699-1777) and Humphry Marshall (1722-1801), gained a measure of respect in Europe as collectors and suppliers of native plants and animals, but very few American scientists were admitted as intellectual equals.
In the midst of the political and social adjustments of the post-Revolutionary years, however, American natural historians sought to distinguish themselves from their European peers and to establish an approach to science that coincided with nationalist and republican principles. No area of natural historical research became more heavily emphasized than the study of the origins and relationships of human races. In part, the intensity of this focus grew out of scientific opportunism: Americans claimed that they, not Europeans, were daily presented with the opportunity to observe three races. But inevitably, American race science was tied up in the struggle over political and social power in the new nation and in debates over slavery and the racial order. Above all, it offered the alluring prospect of revealing a natural, stable, and predictable social order.
Although race was a fairly flexible concept, encompassing aspects of what in the twenty-first century would be considered nationality, creed, and ethnicity, most theorists accepted the typology of the German scientist Johann Friedrich Blumenbach (17521840), who distinguished five races, each with its own characteristic skin color and physical traits: Caucasian, Mongolian, Malay, American, and Ethiopian. In American practice, these races were often conceived as representing stages in the evolution of human culture, with the more primitive, "savage" races—those that relied upon hunting for subsistence—progressing through a historical process into pastoral and agricultural stages and ultimately into the "civilized" world of commerce.
From the 1770s, the key priorities for American racial theorists were to determine how racial differences originated, how the races related to one another and to the scale of cultural progression, and whether they were permanently fixed or could progress or degrade through time. Two discrete but crossfertilizing polarities guided their inquiries: the first, environmentalism (racial traits seen as the product of factors in the environment and thus could change) versus innatism (race regarded as an inherent and unchanging factor), and the second, monogenism (the belief that all human races share a common origin) versus polygenism (the view that the races have separate origins).
Drawing authority in part from the Christian scriptural belief that all humanity descended from the Garden of Eden, monogenism and environmentalism were particularly influential during the 1780s and 1790s. Advocates like the moral philosopher Samuel Stanhope Smith (1750-1819) or the physicians Benjamin Rush (1746-1813) and Benjamin Smith Barton (1766-1815) often tended toward a rationalist, anti-evangelical epistemology, citing anatomical, physiognomic, behavioral, or linguistic evidence to support the claim, in Barton's words, that "the physical differences between nations are but inconsiderable." To the long-standing question of the origins of American Indians, for instance, Barton presented linguistic evidence to show that Indians were a single race, possibly related to "Asiatics," although he left open the possibility that some of them might have descended from the lost tribe of Israel or from a wayfaring Welsh prince.
Differences in skin color, environmentalists argued, were the result of exposure to different environmental conditions after the time of creation, with the color varying in proportion to the "heat" or other factors in the native climate. Stanhope Smith attributed the dark skin of Ethiopians to an excess of bile caused by the "putrid exhalations" of the tropical environment, while Rush argued that blackness resulted from endemic exposure to leprosy. In either case, blackness was a function of the environment, and although it might be a sign of cultural inferiority, it was potentially "curable."
American polygenism and innatism may be traced at least to Bernard Romans (c.1720-c.1784), and before him to the Scottish Enlightenment figure Henry Home, Lord Kames (1696-1782). In his Concise Natural History of East and West Florida (1775), Romans bluntly asserted that considerations of both behavior and biology suggested that the races were species apart and that "there were as many Adams and Eves . . . as we find different species of the human genus" (p. 55). Indians were entirely unlike Caucasians and were "incapable of civilization," while race was so deep-seated that even the bones of Africans were black.
In making race a fundamental, innate, and unalterable characteristic of humanity, Romans prefigured the approach that dominated American racial science after the turn of the century, propelled by the entrenchment of slavery and the fears inspired by the Haitian revolution. Influenced by phrenological theory, physicians such as Charles Caldwell (1772-1853)—a onetime pupil of Rush—focused increasingly on racial differences in intellect and the mind, culminating in the craniological work of Samuel George Morton (1799-1851), who amassed statistical evidence to demonstrate that Caucasians had larger skulls, and were therefore more intelligent, than other races. The so-called American School of Ethnology used scientific authority to demonstrate that Africans occupied the lowest rungs in the scale of civilization and Caucasians the highest, and for many such theorists, slavery and the extirpation of Indians could be seen merely as a reflection of the state of nature and the will of God.
Yet while polygenism offered powerful support for slavery and racial inequality, many proslavery writers objected to its apparent conflict with Scripture, while some polygenists rejected slavery purely on ethical grounds. On the other hand, despite their belief that race was mutable, few white monogenists ever questioned the inferiority of nonwhites. The plasticity of biological argumentation made race science supremely adaptable and resilient, the influence of its conclusions often lasting long after its specific contentions had been rejected. Thomas Jefferson epitomized the situation in his Notes on the State of Virginia (1785) when he claimed that regardless of whether "blacks" were created separately or had become black through time, he considered them clearly "inferior to the whites in the endowments both of body and mind."