The new genetics of intelligence

Abstract

Intelligence - the ability to learn, reason and solve problems - is at the forefront of behavioural genetic research. Intelligence is highly heritable and predicts important educational, occupational and health outcomes better than any other trait. Recent genome-wide association studies have successfully identified inherited genome sequence differences that account for 20% of the 50% heritability of intelligence. These findings open new avenues for research into the causes and consequences of intelligence using genome-wide polygenic scores that aggregate the effects of thousands of genetic variants.

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Figure 1. Variance explained by IQ GPS and by EA GPS in their target traits as a function of GWAS sample size.

GPS prediction of intelligence and educational attainment has increased linearly with sample size. The predictive power of GPS derived from GWAS of intelligence has risen in the last 2 years from 1% to 4%. The latest EA3 GPS predicts more than 10% of the variance in intelligence (P. D. Koellinger, personal communication), more than twice as much as the latest IQ3 GPS. Extrapolating from the results of EA3 with a sample size of over one million, we predict that more than 10% of the variance in intelligence will be predicted from an IQ GPS derived from a GWAS of intelligence with a sample size of one million. IQ1: n = 54,000, r² = 0.01. IQ2: n = 78,000, r² = 0.03. IQ3: n = 280,000, r² = 0.04. EA1: n = 125,000, r² = 0.02. EA2: n = 294,000, r² = 0.03. EA3: n = 1,100,000, r² > 0.10.