A review of intelligence GWAS hits: Their relationship to country IQ and the issue of spatial autocorrelation

Abstract

Published Genome Wide Association Studies (GWAS), reporting the presence of alleles exhibiting significant and replicable associations with IQ, are reviewed. The average between-population frequency (polygenic score) of nine alleles positively and significantly associated with intelligence is strongly correlated to country-level IQ (r = .91). Factor analysis of allele frequencies furthermore identified a metagene with a similar correlation to country IQ (r = .86). The majority of the alleles (seven out of nine) loaded positively on this metagene. Allele frequencies varied by continent in a way that corresponds with observed population differences in average phenotypic intelligence. Average allele frequencies for intelligence GWAS hits exhibited higher inter-population variability than random SNPs matched to the GWAS hits or GWAS hits for height. This indicates stronger directional polygenic selection for intelligence relative to height. Random sets of SNPs and Fst distances were employed to deal with the issue of autocorrelation due to population structure. GWAS hits were much stronger predictors of IQ than random SNPs. Regressing IQ on Fst distances did not significantly alter the results nonetheless it demonstrated that, whilst population structure due to genetic drift and migrations is indeed related to IQ differences between populations, the GWAS hit frequencies are independent predictors of aggregate IQ differences.

Cultural evolutionary theory: How culture evolves and why it matters

“…Such characterization is not correct for many reasons: Educational attainment is primarily determined by environmental factors" (55). Statistical relationships between genetic variants and behaviors need not be causal because assortative mating, spatial autocorrelation, and a shared environment can influence such relationships (55,(59)(60)(61). Twin studies of tobacco smoking point to interacting roles of genetics, environment, and assortative mating in the initiation and continuance of smoking (62).…”

Evidence for Recent Polygenic Selection on Educational Attainment and Intelligence Inferred from GWAS Hits: A Replication of Previous Findings Using Recent Data

“…Unlinked SNPs were used in order to have a sample with independent observations. Fst distances were obtained from [2], calculated using Vcftools with 1000 Genomes, phase 3 data. Average population IQ estimates were obtained from [8].…”

“…average population IQ). A goal of this study is to replicate the effects found by Piffer in 2015 [2], with the evidence from new intelligence and educational attainment GWAS published to date. Piffer [2] factor analyzed educational attainment and intelligence GWAS hits and found a factor that was highly predictive of population IQ.…”

“…A goal of this study is to replicate the effects found by Piffer in 2015 [2], with the evidence from new intelligence and educational attainment GWAS published to date. Piffer [2] factor analyzed educational attainment and intelligence GWAS hits and found a factor that was highly predictive of population IQ. The factor analytic method is based on the assumption that polygenic selection acts as a latent variable which accounts for commonalities among several genetic variants scattered across the genome [1].…”

“…polygenic models). Signals of polygenic selection can be identified by various methods, such as correlation of allele frequencies [1][2][3][4] and the regression of population average of trait values on polygenic scores (PS) [2,[5][6][7], which have been successfully applied to human stature [5][6][7] and cognitive abilities [2]. This paper has several aims: to test the presence of a factor among GWAS hits and the predictive power of polygenic scores (average frequencies of GWAS alleles with positive effect), independently of spatial autocorrelation.…”