In 50 U.S. states, we found a positive manifold across 11 measures including IQ, skin color, birth rate, infant mortality, life expectancy, HIV/AIDS, violent crime, and state income with the first principal component accounting for 33% of the variance (median factor loading = .34). The correlation with a composite of total violent crime was higher with skin color [defined as % black] (r = .55), a more biologically influenced variable than with GDP [gross domestic product] (r = −.17), a more culturally influenced variable. These results corroborate and extend those found at the international level using INTERPOL crime statistics and at the county, provincial, and state levels within countries using local statistics. We interpret the cross-cultural consistency from an evolutionary life history perspective in which hierarchically organized traits culminate in a single, heritable, super-factor. Traits need to be genetically organized to meet the trials of life–survival, growth, and reproduction. We discuss brain size and the g nexus as central to understand individual and group differences and we highlight melanin and skin color as a potentially important new life history variable.
[Editor’s Note: The following appears in the discussion section of the full-length article:
The first factor [IQ] replicates and extends previous findings showing that diverse variables at the state level can be viewed from within Jensen’s (1998) g nexus, which includes psychometrically measured intelligence, intelligence as reflected in degree of life success and adaptive behavior, and biological variables. Violent crime has a high loading on the first factor, as do HIV/AIDS, infant mortality, life expectancy, income, and skin color (% Black). The more biological variables such as skin color yielded the highest correlations with violent crime, while income, a social variable, provided the lowest. We suggest this pattern of results is accounted for by evolutionary life history theory in which there is co-variation between reproductive effort, aggressiveness, high fertility, low altruism, and poor social organization.
Professors Templer and Rushton will be speaking at the American Renaissance conference in March. Their findings appear in the journal Intelligence.]