The General Factor of Personality and general intelligence: Testing hypotheses from Differential-K, Life History Theory, and strategic differentiation–integration effort

•The association between the GFP and g across racial groups was examined.•The strength of the association varied across racial groups.•The results support strategic differentiation–integration effort.

Life history as applied to human psychology has progressed on different levels of analysis including between racial groups (Differential-K) and between individuals (Life History Theory). While the approaches at each level have garnered significant research support, some findings at the level of individual differences are inconsistent with findings from the level of group differences. The association between the General Factor of Personality and general intelligence was examined across and within racial groups to investigate the inconsistency. The results were in line with predictions derived from strategic differentiation–integration effort (SD–IE), the proposition that aggregation amongst variables decreases as life history strategy slows. The results suggest SD–IE may be a useful tool in reconciling the apparent contradictions across the levels of analysis.