By the 1970s, it had become clear that (1) most human differences were cultural; (2) what was not cultural was principally polymorphic – that is to say, found in diverse groups of people at different frequencies; (3) what was not cultural or polymorphic was principally clinal – that is to say, gradually variable over geography; and (4) what was left – the component of human diversity that was not cultural, polymorphic, or clinal – was very small.

A consensus consequently developed among anthropologists and geneticists that race as the previous generation had known it – as largely discrete, geographically distinct, gene pools – did not exist.