Heredity of Skin Color in Negro-White Crosses

Heredity of Skin Color in Negro-White Crosses

Carnegie Institution of Washington
106 pages
Number 188, Paper Number 20 of the Station for experimental evolution at Cold Spring Harbor, New York

Charles B. Davenport (1866-1944), Director
Eugenics Record Office, Carnegie Department of Genetics, and Biological Laboratory
Cold Spring Harbor, New York

Table of Contents

  • A. Statement of the problem
  • B. Method of investigation
  • C. Evaluation of the data
  • D. Ontogenetic development of the skin color of the negro
  • E. Results:
    • I. The skin color of Caucasians in Bermuda and Jamaica
    • II. Quantitative determination of the skin color of pure-bred negroes
    • III. Skin color of the children of a negro and a Caucasian (the Fi generation)
    • IV. Skin color of the children of two mulattoes (the F2 generation)
    • V. Hypothesis
    • VI. Test of the hypothesis
    • VII. Is there a sex-linkage or sex-dimorphism in skin color?
    • VIII. Do the children “take after” the mother and father equally?
    • IX. Selection of mates—”grading up” to white
    • X. The agreement of the hypothesis with popular observation and nomenclature
    • XI. The yellow element in the skin color
    • XII. The “fixed white,” the “pass for white,” and the “white by law”
    • XIII. Reversion to black skin color
  • F. Discussion of inheritance of traits associated with skin color:
    • I. Eye color
    • II. Hair color
    • III. Hair form
  • G. Correlation of characteristics in hybrids
    • I. Correlation between the color of the skin and of the hair in the F2 generation
    • II. Correlation between color of the skin and form of the hair in the F1 generation
  • H. Fecundity of hybrids
  • I. Summary of conclusions
  • K. Literature cited
  • Appendix A:
    • I. Bermudian families
    • II. Jamaican families
    • III. Louisianian families
  • Appendix B. Social data concerning miscegenation

Two years ago (1910) Mrs. Davenport and I published some measurements made on the color of the skin of descendants of matings between negroes and Caucasians; and we concluded that, in opposition to current belief, our data afforded evidence that there is segregation in skin color. We concluded that, while skin color is inherited in typical fashion, the pigmentation of the full-blooded negro is not dependent on two {i.e., the duplex) determiners, “but perhaps a myriad of them.” Lang (1911,*p. 122) cites these results with approval and brings them in line with other studies in which the presence of several factors for a single character is indicated, but he would query our statement “that offspring are rarely darker than the darker parent.” This statement merely summarized the empirical result obtained from the four quantitatively studied families and was not in complete harmony with the theoretical explanation offered—a disaccord upon which we laid no emphasis because our quantitative data were so limited. Our concluding sentence was as follows:

All studies indicate that blonds lack one or more units that brunets possess; that the negro skin possesses still additional units; that individuals with the heavier skin pigmentation may have slight pigmentation covered over—hypostatic, evidence of this condition appearing in the light offspring of such hybrids in the second or third generation; and that first-generation hybrids frequently show, somatically, a color grade less than that which they carry potentially and may segregate in their germ-cells.

The need for additional data was, however, recognized as great…

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