Most theories of human mental evolution assume that selection favored higher intelligence and larger brains, which should have reduced genetic variance in both. However, adult human intelligence remains highly heritable, and is genetically correlated with brain size. This conflict might be resolved by estimating the coefficient of additive genetic…

This article proposes that a complete account of cognitive evolution may have to accommodate a domain-general source of variance in mental abilities accounting for differences among primate taxa. Deaner, van Schaik, and Johnson [Deaner, R.O., van Schaik, C.P. and Johnson, V.E. (2006). Do some taxa have better domain-general cognition than others?…

Calculation of cranial capacities for the means from 4 Mongoloid and 20 Caucasoid samples (raw data from 57,378 individuals in 1978) found larger brain size for Mongoloids, a finding discussed in evolutionary terms. The conclusion is disputed by L. Willerman but supported by J. P. Rushton. (SLD)