Genetic timeline of human brain and cognitive traits

Humans have undergone several anatomical adaptations throughout evolution. Paleontological records are a prime method of studying these adaptations, but they can unfortunately provide only a limited view of how modifications of ‘soft traits’ such as brain and cognition have contributed to the emergence of Homo sapiens. An additional approach includes the examination of when genetic variations associated with human phenotypes emerged in our history. Combining data from genome-wide association studies (GWAS) with dating data on the human genome, we systematically analysed the temporal emergence of single-nucleotide polymorphisms (SNPs) associated with modern-day human phenotypes over the last five million years. We show the genetic timeline of human-characteristic phenotypes to follow a distinct pattern with two bursts of genetic variation that co-emerge with milestones in the human lineage. Our findings suggest that SNPs associated with neocortical, neuropsychiatric, and ophthalmological traits appeared relatively recently in hominin evolution, with genes containing recently emerged SNPs linked to intelligence and neocortical area.