Abstract
Factor analysis of allele frequencies was used to identify signals of polygenic selection on human intelligence. Four SNPs which reached genome-wide significance in previous meta-analyses were used. Allele frequencies for 26 population were obtained from 1000 Genomes. The resulting factor scores were highly correlated to average national IQ (r=0.92). A regression of IQ differences between subcontinental groups on the 4 SNPs g factor and an index of genome-wide genetic distances showed the former was an independent and significant predictor (Beta= 1.14), whereas genome-wide distances lost all predictive power. This finding suggests that the relationship between the 4 SNPs g factor and IQ is due to natural selection on a specific phenotype and not the result of a spurious correlation arising from genome-wide evolutionary processes such as random drift or migrations. A regression of IQs on genetic factor scores of developed countries was used to estimate the predicted genotypic IQs of developing countries. The residuals (difference between predicted and actual scores) were negatively correlated to per capita GDP and Human Development Index, implying that countries with low socioeconomic conditions have not yet reached their full intellectual potential.
Highlights
To date, a few genes have replicated their association with intelligence.Rietveld et al (2013)’s metaanalysis found ten SNPs that increased educational attainment, comprising three with nominal genome-wide significance and seven with suggestive significance
Piffer (2013) applied principal components analysis (PCA) to allele frequencies to obtain an estimate of natural selection on different alleles correlated to the same phenotype
Factor analysis was used to extract a factor from the frequencies of 4 alleles for 26 populations (1000 Genomes)
Summary
A few genes have replicated their association with intelligence.Rietveld et al (2013)’s metaanalysis found ten SNPs that increased educational attainment, comprising three with nominal genome-wide significance and seven with suggestive significance. A recent study has replicated the positive effect of these top three SNPs (rs9320913, rs11584700 and rs4851266) on mathematics and reading performance in an independent sample of school children (Ward et al, 2014). These SNPs were associated with g (general intelligence) in a sub-sample of Rietveld et al.’s original study. Another SNP (rs236330), located within gene FNBP1L, showed a significant association with general intelligence, reported in two separate studies (Davies et al, 2011; Benyamin et al, 2013). This gene is strongly expressed in neurons, including hippocampal neurons and developing brains, where it regulates neuronal morphology (Davies et al, 2011).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
