Abstract
Higher cognitive functions are regarded as one of the main distinctive traits of humans. Evidence for the cognitive evolution of human beings is mainly based on fossil records of an expanding cranium and an increasing complexity of material culture artefacts. However, the molecular genetic factors involved in the evolution are still relatively unexplored. Here, we investigated whether genomic regions that underwent positive selection in humans after divergence from Neanderthals are enriched for genetic association with phenotypes related to cognitive functions. We used genome wide association data from a study of college completion (N = 111,114), one of educational attainment (N = 293,623) and two different studies of general cognitive ability (N = 269,867 and 53,949). We found nominally significant polygenic enrichment of associations with college completion (p = 0.025), educational attainment (p = 0.043) and general cognitive ability (p = 0.015 and 0.025, respectively), suggesting that variants influencing these phenotypes are more prevalent in evolutionarily salient regions. The enrichment remained significant after controlling for other known genetic enrichment factors, and for affiliation to genes highly expressed in the brain. These findings support the notion that phenotypes related to higher order cognitive skills typical of humans have a recent genetic component that originated after the separation of the human and Neanderthal lineages.
Highlights
Several lines of evidence support the idea that humans have developed complex language[5], executive functioning, and abstract thinking in the process of evolution[6]
Utilizing a post-Neanderthal selective sweep (PNSS) index[36], we assessed the effect of a variant’s affiliation to the selectively swept regions of the genome on traits related to cognition: college or university degree (College) completion (College) (N = 111,114), education attainment (EduYears) (N = 293,623) and two measures of general cognitive ability (GCA), GCA1 (N = 269,867) and GCA2 (N = 53,949))
Our analysis indicates that affiliation to HD regions significantly contributes to the LD score effect in College (p = 0.019), GCA2 (p = 0.020), GCA1 (p = 0.029) and EduYears (p = 0.046) after controlling for the other covariates
Summary
Several lines of evidence support the idea that humans have developed complex language[5], executive functioning, and abstract thinking in the process of evolution[6]. Recent studies suggest that Neanderthals could have had some ability to express themselves artistically and some sort of proto culture or religion[13] This is in line with the notion that human intelligence, while not completely innate, is shaped by natural selection and evolutionary processes which helped the species adapt to the environment. We applied the same polygenic enrichment approach in conjunction with a more recent and comprehensive post-Neanderthal selective sweep index[36] to study the evolutionary aspects of educational attainment and cognitive function, and determine enrichment in genomic regions that may have undergone recent positive selection in humans To this end, we analysed genome-wide association (GWAS) summary statistics for two measures of educational attainment, college completion (College)[37] and years of educational attainment (EduYears)[38], and two measures of fluid intelligence from two studies of general cognitive ability (GCA)[39,40]. We compared the cognitive phenotypes to height and body mass index (BMI), two human traits with GWASs of similar size, to assess the specificity of this enrichment
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