Strategic and cognitive differentiation–integration effort in a study of 76 countries

• We tested SD–IE and CD–IE hypotheses in 76 countries at cross-populations level.
• 10 life history indicators were selected. These gave rise to a K super factor.
• All 10 life history indicators became more differentiated as K level increased.
• The degree to which the indicators load on K mediated their sensitivity to SD–IE.
• CD–IE was tentatively corroborated in the two “cognition” components.

The phenomena of strategic and cognitive differentiation and integration (SD–IE and CD–IE) amongst life history indicators and cognitive abilities as a function of level of latent life history speed have been robustly demonstrated in individual differences samples. Here we examine a cross-national sample (N = 76 nations) with respect to ten aggregate life history indicators (birth rate, infant mortality, skin reflectance, prevalence of STDs, overall life satisfaction, life expectancy, national IQ, cranial capacity, savings rate and crime rate), all of which share substantive common variance stemming from a K-Super factor which accounts for 66.6% of the variance amongst these indicators. All indicators became significantly less strongly correlated with the super factor as the level of K increased indicating the presence of robust SD–IE effects. A ‘cognitive’ factor comprised of the national IQ and cranial capacity variables also exhibited differentiation as a function of increasing levels of K, suggesting the presence of CD–IE also. Consistently with the findings of individual differences studies investigating SD–IE, the degree to which the indicators loaded on the K super-factor positively mediated their sensitivity to the effect.