Racial categories are defined purely by ancestor counting, not physical features

Evidence

From a stronger theoretical probing of the issue of “mixed race” the concept of “race” as a “physically based” ethnic distinction may be fundamentally questioned, as Naomi Zack (1993) demonstrates. Naomi Zack has subjected the dualistic racial axioms to logical scrutiny and delineated the following schema: An individual, Jay, is black if Jay has one black forebear, any number of generations back. An individual, Kay, is white if Kay has no black forebears, any number of generations back. There is no other condition for racial blackness that applies to every black individual; there is no other condition for racial whiteness that applies to every white individual. — David Theo Goldberg, John Solomos, A Companion to Racial and Ethnic Studies, 718

Categorization

• DEFINE: Zack’s one-drop rule logic shows race reduces to genealogical counting, hollowing out the physical-basis claim.
• XREF: connects to: Early racial scientists classified species downward from humans without any theory of evolution. — Rebecca A. Martusewicz, Jeff Edmundson, and John Lupinacci, EcoJustice Education: Toward Diverse,…, 1155; Race categories result from social assignment, not biology — Noel Ignatiev, How the Irish Became White, 27