Fitness indicators, sexual selection

Prediction 4. Most of our uniquely human mental abilities should show particularly high -loadings and /loadings, compared to more ancient mental capacities common to other great apes, primates or mammals. Like other sexually selected fitness indicators, they should also show higher coefficients of genetic variation and phenotypic variation, and at least moderate heritabilities. 

Humphrey No, variation in the displays of g would be decorative, and this is where one would expect the sexual dimorphism. But the fact that there seems to be no sexual dimorphism in g itself suggests that it is a fitness indicator and not a consequence of runaway sexual selection. 

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