<i>Microcephalin</i> , a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans

TLDR

Microcephalin (MCPH1) regulates brain size and has evolved under strong positive selection in the human lineage. Microcephalin is a promising candidate locus for investigating the genetics of human brain‑related phenotypic variation. A variant that emerged ~37,000 years ago rose in frequency too rapidly for neutral drift, evidencing strong positive selection and demonstrating ongoing adaptive evolution of this brain gene.

Abstract

The gene Microcephalin ( MCPH1 ) regulates brain size and has evolved under strong positive selection in the human evolutionary lineage. We show that one genetic variant of Microcephalin in modern humans, which arose ∼37,000 years ago, increased in frequency too rapidly to be compatible with neutral drift. This indicates that it has spread under strong positive selection, although the exact nature of the selection is unknown. The finding that an important brain gene has continued to evolve adaptively in anatomically modern humans suggests the ongoing evolutionary plasticity of the human brain. It also makes Microcephalin an attractive candidate locus for studying the genetics of human variation in brain-related phenotypes.