The Average Conceptual Ability of a Nation is Determinative

According to Linda Gottfredson, on p.8 of the online version of "Accidents and Intelligence": "No culture can sustain new practices, however, that impose cognitive demands on the general populace that are beyond the capacity of its large cognitive middle." This is why quality of population is everything or nearly so, and institutions mirror, but do not themselves create this quality which is indicated by where the broad middle falls. A country can subdivide itself so thoroughly that one element may have its own middle and its own economy and cultural level, but this will not be able to 'sustain new practices' longterm, as the lower group can hardly be persuaded to believe that it is genetically so unworthy, as to require to be kept from contaminating the upper group.