A Note on the Permeability of the Races:
It can be stated as a general rule that - regarding miscegenation - only hierarchically adjacent races penetrate one another. The hierarchy, in its most broad sense, can be expressed chromatically from lightness to darkness, or from white to black, with Caucasians at the helm (simply put, White > Brown > Black). This explains why the Boers seldom interbred with the Africans, and why the Spaniards interbred with the indigenous South Americans. Further refining this rule, we can state that the populations lowest on the internal hierarchy of a superior race are more likely to interbreed with the populations higher on the internal hierarchy of the lower race, as opposed to the lower populations within the lower race. (Simply put, the lowest Whites interbreed with the highest Browns.) These rules are general, recall - and exceptions to rules always occur (namely, in which a high White mates with a high Brown - but, also, occasionally, in which a White mates with a Black). The mechanisms working on these outliers, however, must be analyzed on a case-by-case basis. Generally, however, we can assume that a high White breeding with anyone other than a White must have a defective sense of self-worth.
Seeing that women are the more hypergamous sex, it is natural that one, low on the transracial-heirarchy, yet high in their race's own hierarchy, will mate up rather than mate adjacent. (Simply put, a hierarchically high Brown woman will mate with a hierarchically low White man before she does a Brown man of equal footing.) The rule, then, that the lowest Browns interbreed with the highest Blacks, applies mainly in the context of the racially inferior woman mating up the racial hierarchy. This is evident when one considers that Asian women living in the West (Asians, on the racial hierarchy, being mostly beneath Whites but, on occasion, adjacent to them) date White men exclusively at a rate of 40% (Simply put, 4 out of every 10 westernized Asian women date White men exclusively).