Human chromosomal polymorphism. V. Chromosomal Q polymorphism in African populations.

The distribution pattern of Q-heterochromatin variants in seven autosomes (3, 4, 13-15, 21, and 22) was studied in three aboriginal Negroid populations of Africa (Mozambique, Angola, and Ethiopia). It was shown that among African Negroids there are no individuals completely lacking Q-heterochromatin bands with fluorescence levels 4 and 5. The mean number of Q variants per individual was 3.47, 4.80, and 4.85 in the Ethiopian, Mozambique, and Angola populations, respectively. The observed homo- and heteromorphic frequencies always agreed with those predicted by the law of Hardy-Weinberg. The populations of tropical lowland Negroids (Mozambique and Angola) proved to be significantly homogeneous both in the frequency of Q variants and the mean number of these variants per individual, so they were examined as a single group. However, comparative analysis of highland (Ethiopians) and lowland Negroids revealed statistically significant differences. The following questions are discussed: (1) the possible selective value of chromosomal Q heterochromatin material in the adaptation of human populations to high-altitude climate; (2) the possible existence of intraracial heterogeneity in Negroids living in different ecological zones of Africa; (3) the possible taxonomic value of an inverted Q-heterochromatin band in chromosome 3 in ethnic anthropology.