Variation in the number of presacral vertebrae in Bantu-speaking South African Negroes.

Abstract

AbstractVariation in number of presacral vertebrae (PSV) was examined in 462 vertebral columns in four populations drawn from tribal groups of Southern African Negroes. The total incidence of numerical variants (23 PSV and 25 PSV) was 19% in males and 12.1% in females. Males have a higher frequency of 25 PSV and females a higher frequency of 23 PSV, a sex difference reported by previous workers. Significant differences in the incidence of 25 PSV in males were present between S.A. Negroes, American Negroes and other racial groups. The total number of variants (23 PSV and 25 PSV) is significantly higher in S.A. Negro males (and higher but not significantly in females) than in the other groups; owing mainly to the findings in the Nguni‐speaking sub‐samples of the S.A. Negro. These findings support a previous suggestion based on combined‐sex data that the frequency of numerical variations of PSV are characteristic of a population. It is suggested here that such frequencies are even more characteristic when males and females are considered separately.