Strategic differentiation–integration effort amongst the 47 prefectures of Japan

The strategic differentiation–integration effort (SD–IE) hypothesis holds that high-K (slow life history) individuals and populations are specialists with respect to domains of behavior and personality, and that the converse is true for low-K populations. Here, we examine SD–IE at the national level, amongst the 47 prefectures of Japan. Aggregate data on height, IQ, divorce, homicide rates, skin reflectance, fertility rates, income and infant mortality were used as life history indicators. Principal Axis Factor analysis revealed the presence of a K super-factor on which the first five of these loaded preferentially. A second factor loaded highly on income and fertility and a third on infant mortality. As Japan is among the highest-K countries, the extraction of three factors indicates strong underlying SD–IE. Amongst the five K super-factor variables, SD–IE confirmatory effects were recovered on all variables except IQ. The effect magnitudes were positively mediated by the K super-factor saturation of the indicators. We conclude that SD–IE appears to be highly general across different populations and measures of life-history traits. Finally, we discuss how the second and third factors appear to conform to recent social phenomena specific to the Japanese culture, namely increasing behavioral asexuality and high-quality universal health coverage.     

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

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.     

Strategic differentiation and integration among the 50 states of the USA

Recent studies demonstrate that individuals and populations (at the scale of nations) exhibiting slower life history (LH) speeds are more differentiated amongst themselves with respect to the components of life history. Faster life history individuals and populations are more integrated by comparison. This phenomenon, termed strategic differentiation–integration effort (SD–IE), has not yet been tested on a national scale, however, which is an important remaining step in establishing its generalizability at different levels of aggregation among humans. SD–IE was tested with data on five LH variables from the fifty states of the US. Effects supportive of the SD–IE hypothesis were found in all LH variables, with an average effect magnitude slightly larger than that found in studies of SD–IE at the individual differences level. This is putatively attributed to population stratification, due to the varied racial make-up of the population in the US, including European, African, Native American, and Asian ancestries from multiple countries. This study indicates that SD–IE is a generalizable phenomenon occurring at various levels of aggregation.