Steve Hsu has a blog post up about new research showing intelligence is genetic:
General cognitive function is a prominent human trait associated with many important life outcomes including longevity. The substantial heritability of general cognitive function is known to be polygenic, but it has had little explication in terms of the contributing genetic variants. Here, we combined cognitive and genetic data from the CHARGE and COGENT consortia, and UK Biobank (total N=280,360). We found 9,714 genome-wide significant SNPs in 99 independent loci. Most showed clear evidence of functional importance. Among many novel genes associated with general cognitive function were SGCZ, ATXN1, MAPT, AUTS2, and P2RY6. Within the novel genetic loci were variants associated with neurodegenerative disorders, neurodevelopmental disorders, physical and psychiatric illnesses, brain structure, and BMI. Gene-based analyses found 536 genes significantly associated with general cognitive function; many were highly expressed in the brain, and associated with neurogenesis and dendrite gene sets. Genetic association results predicted up to 4% of general cognitive function variance in independent samples. There was significant genetic overlap between general cognitive function and information processing speed, as well as many health variables including longevity.
Of course predicting 4% of the variance is not all that exciting, giving that we already have biological variables (brain size) that can predict roughly 20% of the variance. But when you consider how hard these SNPs are to find with any reliability (each one explains such a tiny percentage of the variance that you need insanely large samples to take extremely g loaded tests as adults to find them) it’s a reasonable number. Scientists have made far more progress finding genes for IQ than they’ve made finding life on other planets, even though theoretically both exist in droves. And few doubt height is extremely genetic, even though the vast majority of assumed height genes have not been found.
More interesting to me is that the genes they did find were directly related to intelligence (i.e. associated with neurological impairments) because this suggests the genes are not just correlated with intelligence, but cause it too. One of my concerns was that the heritability of IQ could just be a by-product of test motivation being genetic, or some other indirect effect, so the fact that it’s directly related to neurological functioning is encouraging.
Of course the usual reaction norms disclaimer about these genes likely only being found in local populations always applies.