Gene Flow from White into Negro Populations in Brazil

Gene Flow from White into Negro Populations in Brazil

American Journal of Human Genetics
Volume 9, Number 4 (December 1957)
pages 299–309

P. H. Saldanha
Department of General Biology
University of Sao Paulo, Brazil

GLASS AND Li (1953) have introduced a statistical model that allows calculations to be made, not only of the intermixture between two base populations but also of the dynamic pattern of the gene flow from one population to another, during a known period of intermixture. The formula derived from Glass and Li is:

    qk – Q
(1 – m)k = —————
    q0 – Q

To use this formula it is necessary to know: a) the gene frequencies, q0 and Q, of the base populations; b) the gene frequency, qk, of the hybrid population; and c) the number of generations, k, of contact between the base populations. The average rates of gene flow (m) from one population to another varies according to the assumed value of k and to the amount of accumulated admixture in the hybrid population. Some limitations of this method have been stressed by Glass and Li.

It should be of interest to compare the process of hybridization between Negro and White populations in Brazil to that in the United States, since the social conditions in the two countries have been and still are different. This is a first attempt to do so.


An important problem, which is not yet completely settled, is the African origin of Brazilian Negroes. The comparative ethnography of the Brazilian Negro was worked out, in its fundamental aspects, by the pioneer work of Nina Rodrigues (1932) and the later work of Ramos (1951a). The data on the relations between African and Brazilian cultural groups of Negroes shown in Table I result from these studies…

Read the entire article here.

Tags: ,