Alveolar dehiscences and fenestrae in dried south African Negro mandibles

The buccal and lingual roots of 1077 teeth from 100 mandibles of South African Negroes were examined for the presence of dehiscences and fenestrae. All specimens were obtained from cadavers of known sex, tribe, and stated age; 10.5% of teeth were affected. Canines and first premolars were the most common teeth associated with dehiscences and fenestrae. Dehiscences occurred more commonly than fenestrae (1:0.49). The defects were found exclusively in the buccal plate of the alveolar process.     

The number of vertebrae in the Southern African Negro,the American Negro and the Bushman (San)

The numbers of precoccygeal vertebrae (PCV) are compared in Southern African Negroes, Bushman (San) and American Negroes. The S.A. Negro and San males have an exceptionally high frequency of an increased total PCV number whilst the frequencies are significantly lower in a combined Caucasoid sample and the Mongoloid samples. The American Negro male, too, has a high frequency but not as high as in S.A. Negroes. The high frequency of increased PCV number in San, S.A. Negroes and American Negroes is in keeping with the view that the Khoisan peoples (here represented by the San), the Southern African Negroes and the African ancestors of American Blacks sprang from a common proto-negriform stock. Males have a significantly greater frequency of increased PCV to 30 or 31, whereas females are more likely to have a decreased number of 28 PCV. This sex difference is present in all the populations studied.     

The plasminogen polymorphism in South African Negro populations: genetics and anthropogenetics

Summary Genetic polymorphism of human plasminogen (PLG) was investigated in 1252 unrelated individuals from eight South African Bantu-speaking Negro tribes. PLG phenotypes were determined by isoelectric focusing (pH 3.5–9.5 and 5–8 gradients) of neuraminidase-treated samples and subsequent detection by caseinolytic overlay or immunoblotting with specific antibody. No significant difference in the distribution of PLG alleles among the eight ethnic groups was observed. The combined allele frequencies of the common alleles in South African Negroes were 0.6977 for PLG*A, 0.2736 for PLG*B. In addition, six rare alleles were seen: PLG*A3, *A1, *M2, *B1, *B2, *B3. The rare variant PLG*B2 was proven to segregate by autosomal Mendelian inheritance in a family. The combined frequency for the rare alleles was 0.0287. The distribution of phenotypes in the total population sample was found to be in Hardy-Weinberg equilibrium. A striking difference in PLG allele distribution between Negroes from South Africa and published Negroid frequencies from North America could be observed. This difference was also seen in comparison with Mongoloid populations; in contrast, PLG frequencies for South African Negroes were similar or almost identical to known Caucasoid distributions.     

Age-dependency of somatic selection in South African Negro G-6-PD heterozygotes

Summary The distribution of red cell G-6-PD phenotypes was analysed in terms of their manifestation in South African Negro females of different age classes. It was found that with increasing chronological age, over the age range from the teens to adulthood, the relative proportion of females expressing a non BB phenotype gradually decreases and the relative proportion of females expressing a B phenotype increases concomitantly. It is suggested that this phenomenon is attributable to age-dependent somatic selection against the deficient A^- cell line in appropriate heterozygotes. This process can give rise to the misinterpretation of recording a growing excess of homozygotes and a corresponding increasing deficit of heterozygotes with ongoing chronological ageing. It is speculated that the postulated process of age-dependent somatic selection may be in response to malaria as the underlying selective agent. Considerations in this respect are discussed in greater detail.Supported by a research fellowship awarded by the Alexander von Humboldt-Stiftung, Bonn-Bad GodesbergSupported by the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg