Some genetic aspects of plantation slavery.

Abstract

SOME GENETIC ASPECTS OF PLANTATION SLAVERY NATHANIEL WEYL* Plantation slavery was necessarily characterized by variations in mortality and life expectancy between the skilled and the unskilled, the craftsmen and the field hands, the house servants and the plantation gangs, the workers on cotton farms and on sugar estates, and the bondsmen and the free. The processes affecting birth rates and mortality within the Negro population were considerably more complex than abolitionist literature suggests, varied a great deal in relation to time and place, and were by no means unidirectional. The estimates most commonly used ofthe white genetic component in the American Negro exaggerate the true state ofaffairs because they are based on urbanNorthern black populations, inwhich interracial gene flow was abnormally high. Differential mortality rates favored cotton and tobacco workers as against rice and sugar workers, house servants as against plantation hands, craftsmen as against unskilled laborers. This tended to give Negroes with white blood higher rates ofnatural increase. Manumission ofslaves, which was highly selective for white genes and which was regarded, by masters and servants alike, as a signal mark of favor, generally operated in the opposite direction. Demographic conditions conspired to decrease the rate of population growth among free Negroes far below that among slaves. This condition prevailed in the United States both because the medical care which masters gave their slaves from reasons ofself-interest was markedly better tlian that which the free Negroes obtained for themselves and because the emancipated black population was unwanted by white society, despised, impoverished, and socially degraded. In areas such as the West Indies where the mulatto and free Negro populations enjoyed a more stable social status (one superior to that of the slaves), this difference may not have prevailed. If so, the * 4201 South Ocean Boulevard, Delray Beach, Florida 33444. 618 Nathaniel Weyl · Plantation Slavery Perspectives in Biology and Medicine · Summer 1970 comparative survival rates offree Negroes and black-white crosses would be materially different in the Antilles than was the case in the United States. Geography ofRace Mixture The best single serological index of the percentage of Negro genes is the R0 chromosome combination in the Rhesus blood groups, which is cDe in the Fisher notation. Since the bulk of slaves came from West Africa, an unweighted mean was taken ofthe six samples from that region reported by Mourant [?, p. 394]. The average R0 was 58.5 percent.1 By comparison, Glass and Li found an R0 percentage of43.8 for their Baltimore Negroes, as compared with 2.8 percent for white Americans [2]. Thus, ifthe Baltimore sample were representative ofthe nation, American Negroes would have an average of 26.4 percent non-Negro genes. This, however, is not the case. A 1963 study by Workman, Blumberg, and Cooper of the serology of Negroes in Evans and Bullock counties in Georgia reported a mean R0 component of 53.5 percent, indicating a racial admixture of9.0 percent [3]. A study ofJames Island, South Carolina , blacks yielded an R0 of51.7 percent, or an admixture of12.2 percent [4], and a 1958 examination of Charleston Negroes by W. S. Pollitzer revealed an R0 factor of 56.5 percent, which would indicate only 3.6 percent white ancestry [5]. The differences between the indicated values for m, the coefficient of racial admixture, between the Baltimore and the rural Southern samples reflect the fact that miscegenation, emancipation, and migration have been historically linked. The Negro population of the Carolina-Georgia Sea Islands, of Charleston and of the northern Georgia counties studied by Workmanet al. consisted to alarge extent ofNegroes from Angola, called Gullahs, who worked the large-scale coastal cotton and rice plantations, had few social contacts with their white masters, and were therefore largely isolated from interracial gene flow. The Baltimore sample ofGlass and Li per contra consisted disproportionately of the descendants of free Negroes and of artisan and house slaves. Wherever the institution of chattel slavery prevails, emancipation is positively and high correlated with miscegenation. Since the Southern states regardedboth mulattoes and 1 The six groups are: southwestern Nigerians, southeastern Nigerians, northern Nigerians, pagan tribes oftheJos plateau in Nigeria, Gold Coast Ewes, and Gold Coast Ashantis. 619 freeNegroes as security...