Microcephalin , a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans

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 approximately 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.

Ethics: Taboo genetics

“…In 2005, for instance, geneticist Bruce Lahn of the University of Chicago in Illinois published studies 3,4 …”

Evolutionary Genetics: Is brain evolution still continuing in modern humans?

“…In both cases a single SNP that caused an amino acid change defined these common haplotypes: G37995C characterised haplotype 42 in Microcephalin and A44871G characterised haplotype 63 in ASPM. 1,2 The next interesting observation was the worldwide population distribution of the two common haplotypes: in both cases the globally dominant haplotype was at its lowest frequency in Africa. The migration of modern humans from an East African population out of Africa 200 -300 thousand years ago created a genetic bottleneck effect whereby a small pool of people become geographically isolated and expanded into a large, more genetically homogeneous population.…”

“…1,2 While this might initially seem incongruous (a SNP ¼ a paper!) it is the gene that each SNP is in and their recent evolutionary behaviour that is exciting.…”

Introduction: Genomics and philosophy of race

“…Some philosophers argue for a social constructivist account of race (e.g., Appiah, 2006;Haslanger, 2008); others for a pragmatic or deflationist account (e.g., Gannett, 2007;Hardimon, 2013); still others for a conventionalist account of bio-genomic 'race' see Mills, 1988 for a useful albeit slightly incomplete taxonomy of positions). The concept 'race' is linked with the philosophical literature on natural kinds (e.g., Hacking, 2005;Kitcher, 2007), in part because of interest in whether inferences about medical conditions and treatments (e.g., Risch, Buchard, Ziv, & Tang, 2002;Taylor et al, 2004;Wade, 2004Wade, , 2014, or about IQ and cognitive capacities (e.g., Evans et al, 2005;see Richardson, 2011 for a critique), can be underwritten using race. To what extent is race real, and which inferences about the body and mind could it ground?…”