​The extraordinary expansion of the cerebral cortex is one of the most distinctive morphological features of the human species. Over the course of evolution, cortical expansion and the associated increase in cortical folding may have contributed to the emergence of our superior cognitive abilities. Molecular analyses of genomic DNA sequencing data from humans, archaic hominins, and non-human primates have identified chromosomal regions with evolutionary changes at different times in our phylogenetic history. Such regions, annotated "Human Gained Enhancers", correspond to regulatory genetic elements that appeared since our last common ancestor with the Old World monkeys. The question of the contribution of these Enhancers during evolution is still relevant.

In this study, researchers evaluated the potential association of these genomic regions with human cortical sulcus morphology as measured by MRI in more than 18,000 subjects from the UK Biobank cohort. They show that variations within Human Gained Enhancers are associated with the degree of opening of certain sulci (left and right calloso-marginal fissures and right central sulcus). Interestingly, these genetic elements and brain sulci have already been associated with the evolution of locomotion in primates and, later, with bipedalism in our hominin ancestors.

Overall, the study provides new insights into the role of genetic variations in human brain evolution and suggests that enhancer elements may play a critical role in brain structure and function.

Contacts : Vincent Frouin (vincent.frouin@cea.fr) ; Hervé Lemaitre (herve.lemaitre@u-bordeaux.fr)

Human Gained Enhancers are regions of DNA that have been specifically acquired by the human lineage during evolution and that regulate gene expression. They have probably played an important role in the evolution of human-specific characteristics such as cognitive abilities and brain morphology.

See also Hervé Lemaitre's video on YouTube (Clinical Neuroanatomy Seminars)